@article{bertoli_stability_2018,
	title = {Stability of cellular microstructure in laser powder bed fusion of {316L} stainless steel},
	issn = {0921-5093},
	url = {http://www.sciencedirect.com/science/article/pii/S0921509318314230},
	doi = {10.1016/j.msea.2018.10.051},
	abstract = {Laser powder bed fusion additive manufacturing (L-PBF AM) offers great potential for local microstructure control. During this process, solidification occurs in conditions that are far from equilibrium and possesses – in the majority of cases – a strong directionality. In general, the size and morphology of the resulting microstructure is a function of two well-known parameters: the temperature gradient within the liquid phase (G) and the velocity of the solidification front (R). To provide guidance in selecting appropriate, systematically defined, process parameters for L-PBF of 316L stainless steel square pillars, we developed an intentionally simple thermal model to express these two parameters, G and R, as a function of selected process variables (laser scan speed, laser power) and material properties (thermal diffusivity). Results from both microstructural and mechanical characterization of the pillars indicate that high-strength, fully-dense parts with a highly oriented cellular microstructure can be obtained when using significantly different sets of process parameters. Furthermore, despite its simplicity, the numerical model correlates well with experimental evidence and confirms that rather than creating variable microstructures, the process parameter constraints actually lead to a stable cellular microstructure regardless of the wide process window studied.},
	urldate = {2018-10-12},
	journal = {Materials Science and Engineering: A},
	author = {Bertoli, Umberto Scipioni and MacDonald, Benjamin E. and Schoenung, Julie M.},
	month = oct,
	year = {2018},
	keywords = {316L stainless steel, Directional solidification, Microstructure control, Powder bed fusion additive manufacturing, Selective Laser Melting},
}

Laser powder bed fusion additive manufacturing (L-PBF AM) offers great potential for local microstructure control. During this process, solidification occurs in conditions that are far from equilibrium and possesses – in the majority of cases – a strong directionality. In general, the size and morphology of the resulting microstructure is a function of two well-known parameters: the temperature gradient within the liquid phase (G) and the velocity of the solidification front (R). To provide guidance in selecting appropriate, systematically defined, process parameters for L-PBF of 316L stainless steel square pillars, we developed an intentionally simple thermal model to express these two parameters, G and R, as a function of selected process variables (laser scan speed, laser power) and material properties (thermal diffusivity). Results from both microstructural and mechanical characterization of the pillars indicate that high-strength, fully-dense parts with a highly oriented cellular microstructure can be obtained when using significantly different sets of process parameters. Furthermore, despite its simplicity, the numerical model correlates well with experimental evidence and confirms that rather than creating variable microstructures, the process parameter constraints actually lead to a stable cellular microstructure regardless of the wide process window studied.

@article{smith_anomalous_2018,
	title = {Anomalous {Annealing} {Response} of {Directed} {Energy} {Deposited} {Type} {304L} {Austenitic} {Stainless} {Steel}},
	issn = {1047-4838, 1543-1851},
	url = {https://link.springer.com/article/10.1007/s11837-017-2711-1},
	doi = {10.1007/s11837-017-2711-1},
	abstract = {Directed energy deposited (DED) and forged austenitic stainless steels possess dissimilar microstructures but can exhibit similar mechanical properties. In this study, annealing was used to evolve the microstructure of both conventional wrought and DED type 304L austenitic stainless steels, and significant differences were observed. In particular, the density of geometrically necessary dislocations and hardness were used to probe the evolution of the microstructure and properties. Forged type 304L exhibited the expected decrease in measured dislocation density and hardness as a function of annealing temperature. The more complex microstructure–property relationship observed in the DED type 304L material is attributed to compositional heterogeneities in the solidification microstructure.},
	language = {en},
	urldate = {2018-01-08},
	journal = {JOM},
	author = {Smith, Thale R. and Sugar, Joshua D. and Schoenung, Julie M. and Marchi, Chris San},
	month = jan,
	year = {2018},
	keywords = {Published, Reviewed},
	pages = {1--6},
}

Directed energy deposited (DED) and forged austenitic stainless steels possess dissimilar microstructures but can exhibit similar mechanical properties. In this study, annealing was used to evolve the microstructure of both conventional wrought and DED type 304L austenitic stainless steels, and significant differences were observed. In particular, the density of geometrically necessary dislocations and hardness were used to probe the evolution of the microstructure and properties. Forged type 304L exhibited the expected decrease in measured dislocation density and hardness as a function of annealing temperature. The more complex microstructure–property relationship observed in the DED type 304L material is attributed to compositional heterogeneities in the solidification microstructure.

@article{wang_reversed_2018,
	title = {Reversed compressive yield anisotropy in magnesium with microlaminated structure},
	volume = {146},
	issn = {1359-6454},
	url = {https://www.sciencedirect.com/science/article/pii/S1359645417310303},
	doi = {10.1016/j.actamat.2017.12.025},
	abstract = {To investigate the effect of grain morphology on the mechanical properties of polycrystalline Mg, two types of bulk Mg samples with equiaxed and microlaminated grain structures were fabricated by spark plasma sintering (SPS) of as-received Mg powder and cryomilled disc-shaped Mg powder particles, respectively. Based on a detailed microstructural investigation, the mechanisms by which microstructure evolves and texture development occurs were identified and are discussed. The basal fiber textures in the SPS consolidated samples allow the plastic anisotropy in such textured Mg to be investigated. Compression tests at room temperature parallel and perpendicular to the SPS compaction axis determined that, in comparison to the conventional anisotropy observed in the equiaxed sample, the anisotropy of yield strength is reversed in the microlaminated sample, with the yield strength for c-axis extension being higher than that for c-axis contraction. The reversed compressive yield strength anisotropy observed in the sample that was cryomilled is related to the low twinning activity, limited twinning growth and the anisotropy induced by the microlaminated grain structure, which offers an opportunity to reduce or even reverse the intrinsic plastic anisotropy of hexagonal close packed Mg.},
	urldate = {2018-01-08},
	journal = {Acta Materialia},
	author = {Wang, Xin and Jiang, Lin and Zhang, Dalong and Beyerlein, Irene J. and Mahajan, Subhash and Rupert, Timothy J. and Lavernia, Enrique J. and Schoenung, Julie M.},
	month = mar,
	year = {2018},
	keywords = {Dislocations, Magnesium, Microlaminated structure, Published, Reviewed, Twinning, Yield anisotropy},
	pages = {12--24},
}

To investigate the effect of grain morphology on the mechanical properties of polycrystalline Mg, two types of bulk Mg samples with equiaxed and microlaminated grain structures were fabricated by spark plasma sintering (SPS) of as-received Mg powder and cryomilled disc-shaped Mg powder particles, respectively. Based on a detailed microstructural investigation, the mechanisms by which microstructure evolves and texture development occurs were identified and are discussed. The basal fiber textures in the SPS consolidated samples allow the plastic anisotropy in such textured Mg to be investigated. Compression tests at room temperature parallel and perpendicular to the SPS compaction axis determined that, in comparison to the conventional anisotropy observed in the equiaxed sample, the anisotropy of yield strength is reversed in the microlaminated sample, with the yield strength for c-axis extension being higher than that for c-axis contraction. The reversed compressive yield strength anisotropy observed in the sample that was cryomilled is related to the low twinning activity, limited twinning growth and the anisotropy induced by the microlaminated grain structure, which offers an opportunity to reduce or even reverse the intrinsic plastic anisotropy of hexagonal close packed Mg.

@incollection{meyers_hazardous_2018,
	address = {New York, NY},
	title = {Hazardous {Materials} {Characterization} and {Assessment}},
	isbn = {978-1-4939-2493-6},
	url = {http://link.springer.com/10.1007/978-1-4939-2493-6_91-3},
	language = {en},
	urldate = {2018-01-08},
	booktitle = {Encyclopedia of {Sustainability} {Science} and {Technology}},
	publisher = {Springer New York},
	author = {Lam, Carl W. and He, Haoyang and Schoenung, Julie M.},
	editor = {Meyers, Robert A.},
	year = {2018},
	doi = {10.1007/978-1-4939-2493-6_91-3},
	keywords = {Invited, Published, Reviewed},
	pages = {1--21},
}

@article{nieto_synthesis_2017,
	title = {Synthesis and {Multi} {Scale} {Tribological} {Behavior} of {WC}-{Co}/{Nanodiamond} {Nanocomposites}},
	volume = {7},
	copyright = {2017 The Author(s)},
	issn = {2045-2322},
	url = {https://www.nature.com/articles/s41598-017-07324-3},
	doi = {10.1038/s41598-017-07324-3},
	abstract = {Nanodiamonds (ND) present a unique combination of desirable mechanical, functional, and chemical characteristics that are ideally suited for reinforcing and enhancing the wear resistance of carbide based materials. Tungsten carbide cobalt (WC-Co) matrix nanocomposites reinforced with varying amounts of ND (2 – 10 vol.\%) were synthesized here by spark plasma sintering. The rapid thermal consolidation route enabled attainment of dense samples with a significant retention of the metastable diamond phase. NDs affected the microstructural evolution, chemistry, and mechanical properties of WC-Co. Macroscale reciprocating pin-on-disk tests were conducted to assess wear behavior under conditions relevant to service environments, e.g., high cycles and high contact pressure. Microscale tribological properties were assessed using microscratch tests in order to investigate the intrinsic effects of ND on the localized mechanical and tribological response of WC-Co-ND composites. The incorporation of 10 vol.\% ND enhanced wear resistance at both the micro- and macroscale, by 28\% and 35\%, respectively.},
	language = {En},
	number = {1},
	urldate = {2018-01-08},
	journal = {Scientific Reports},
	author = {Nieto, Andy and Jiang, Lin and Kim, Jaekang and Kim, Dae-Eun and Schoenung, Julie M.},
	month = aug,
	year = {2017},
	keywords = {Published, Reviewed},
	pages = {7060},
}

Nanodiamonds (ND) present a unique combination of desirable mechanical, functional, and chemical characteristics that are ideally suited for reinforcing and enhancing the wear resistance of carbide based materials. Tungsten carbide cobalt (WC-Co) matrix nanocomposites reinforced with varying amounts of ND (2 – 10 vol.%) were synthesized here by spark plasma sintering. The rapid thermal consolidation route enabled attainment of dense samples with a significant retention of the metastable diamond phase. NDs affected the microstructural evolution, chemistry, and mechanical properties of WC-Co. Macroscale reciprocating pin-on-disk tests were conducted to assess wear behavior under conditions relevant to service environments, e.g., high cycles and high contact pressure. Microscale tribological properties were assessed using microscratch tests in order to investigate the intrinsic effects of ND on the localized mechanical and tribological response of WC-Co-ND composites. The incorporation of 10 vol.% ND enhanced wear resistance at both the micro- and macroscale, by 28% and 35%, respectively.

@article{scipioni_bertoli_-situ_2017,
	title = {In-situ characterization of laser-powder interaction and cooling rates through high-speed imaging of powder bed fusion additive manufacturing},
	volume = {135},
	issn = {0264-1275},
	url = {http://www.sciencedirect.com/science/article/pii/S0264127517308894},
	doi = {10.1016/j.matdes.2017.09.044},
	abstract = {Detailed understanding of the complex melt pool physics plays a vital role in predicting optimal processing regimes in laser powder bed fusion additive manufacturing. In this work, we use high framerate video recording of Selective Laser Melting (SLM) to provide useful insight on the laser-powder interaction and melt pool evolution of 316L powder layers, while also serving as a novel instrument to quantify cooling rates of the melt pool. The experiment was performed using two powder types – one gas- and one water-atomized – to further clarify how morphological and chemical differences between these two feedstock materials influence the laser melting process. Finally, experimentally determined cooling rates are compared with values obtained through computer simulation, and the relationship between cooling rate and grain cell size is compared with data previously published in the literature.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Materials \& Design},
	author = {Scipioni Bertoli, Umberto and Guss, Gabe and Wu, Sheldon and Matthews, Manyalibo J. and Schoenung, Julie M.},
	month = dec,
	year = {2017},
	keywords = {316L stainless steel, High speed imaging, Powder bed fusion additive manufacturing, Published, Reviewed, Selective Laser Melting, Ultra-high cooling rate, Water atomized powder},
	pages = {385--396},
}

Detailed understanding of the complex melt pool physics plays a vital role in predicting optimal processing regimes in laser powder bed fusion additive manufacturing. In this work, we use high framerate video recording of Selective Laser Melting (SLM) to provide useful insight on the laser-powder interaction and melt pool evolution of 316L powder layers, while also serving as a novel instrument to quantify cooling rates of the melt pool. The experiment was performed using two powder types – one gas- and one water-atomized – to further clarify how morphological and chemical differences between these two feedstock materials influence the laser melting process. Finally, experimentally determined cooling rates are compared with values obtained through computer simulation, and the relationship between cooling rate and grain cell size is compared with data previously published in the literature.

@article{nieto_reinforcement_2017,
	title = {Reinforcement size effects on the abrasive wear of boron carbide reinforced aluminum composites},
	volume = {390-391},
	issn = {0043-1648},
	url = {http://www.sciencedirect.com/science/article/pii/S0043164817305161},
	doi = {10.1016/j.wear.2017.08.002},
	abstract = {The use of ceramic nanoparticle reinforcements has shown significant promise for enhancing the mechanical properties of metal matrix composites due to the high specific surface area and superior intrinsic mechanical properties of nanoparticles. In this study, the effect of B4C reinforcement particle size on the abrasive wear behavior of Al-B4C composites was investigated. Composites with a homogenous dispersion of micrometric-B4C, submicron-B4C, and nano-B4C in a nanostructured Al alloy 5083 (AA5083) matrix were fabricated using cryogenic mechanical alloying and dual mode dynamic forging. Hardness was seen to increase with decreasing B4C reinforcement size, with the Al-nanoB4C composite exhibiting a 56\% enhancement over unreinforced AA5083. The abrasive wear resistance of the Al-nanoB4C composite was 7\% higher than the unreinforced AA5083. The other Al-B4C composites exhibited equivalent or reduced abrasive wear resistance as compared to AA5083. Analysis of the abrasive wear scars demonstrated that larger B4C reinforcements are prone to particle pull-out, thereby negating the benefit of higher hardness. The Al-nanoB4C composite has superior wear resistance due its high hardness and greater interfacial area, which hindered pull-out of nano-B4C particles.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Wear},
	author = {Nieto, Andy and Yang, Hanry and Jiang, Lin and Schoenung, Julie M.},
	month = nov,
	year = {2017},
	keywords = {Abrasive wear, Metal matrix composite, Nanoparticles, Published, Reinforcement size effects, Reviewed},
	pages = {228--235},
}

The use of ceramic nanoparticle reinforcements has shown significant promise for enhancing the mechanical properties of metal matrix composites due to the high specific surface area and superior intrinsic mechanical properties of nanoparticles. In this study, the effect of B4C reinforcement particle size on the abrasive wear behavior of Al-B4C composites was investigated. Composites with a homogenous dispersion of micrometric-B4C, submicron-B4C, and nano-B4C in a nanostructured Al alloy 5083 (AA5083) matrix were fabricated using cryogenic mechanical alloying and dual mode dynamic forging. Hardness was seen to increase with decreasing B4C reinforcement size, with the Al-nanoB4C composite exhibiting a 56% enhancement over unreinforced AA5083. The abrasive wear resistance of the Al-nanoB4C composite was 7% higher than the unreinforced AA5083. The other Al-B4C composites exhibited equivalent or reduced abrasive wear resistance as compared to AA5083. Analysis of the abrasive wear scars demonstrated that larger B4C reinforcements are prone to particle pull-out, thereby negating the benefit of higher hardness. The Al-nanoB4C composite has superior wear resistance due its high hardness and greater interfacial area, which hindered pull-out of nano-B4C particles.

@book{meyers_proceedings_2017,
	title = {Proceedings of the 3rd {Pan} {American} {Materials} {Congress}},
	isbn = {978-3-319-52132-9},
	abstract = {This collection covers a variety of materials science topics and has contributions from leading scientists and engineers representing 8 countries and 9 international materials, metals, and minerals societies. Papers are organized into the following sections: Advanced Biomaterials Advanced Manufacturing Materials for Green Energy Materials for Infrastructure Materials for the Oil and Gas Industry Materials for Transportation and Lightweighting Minerals Extraction and Processing Nanocrystalline and Ultra-fine Grain Materials and Bulk Metallic Glasses Steels.},
	language = {en},
	publisher = {Springer},
	editor = {Meyers, Marc André and Benavides, Hector Alfredo Calderon and Brühl, Sonia P. and Colorado, Henry A. and Dalgaard, Elvi and Elias, Carlos Nelson and Figueiredo, Roberto B. and Garcia-Rincon, Omar and Kawasaki, Megumi and Langdon, Terence G. and Mangalaraja, R. V. and Marroquin, Mery Cecilia Gomez and Rocha, Adriana da Cunha and Schoenung, Julie M. and Silva, Andre Costa e and Wells, Mary and Yang, Wen},
	month = feb,
	year = {2017},
	note = {doi: 10.1007/978-3-319-52132-9},
	keywords = {Edited, Published, Technology \& Engineering / Manufacturing, Technology \& Engineering / Materials Science / General, Technology \& Engineering / Metallurgy},
}

This collection covers a variety of materials science topics and has contributions from leading scientists and engineers representing 8 countries and 9 international materials, metals, and minerals societies. Papers are organized into the following sections: Advanced Biomaterials Advanced Manufacturing Materials for Green Energy Materials for Infrastructure Materials for the Oil and Gas Industry Materials for Transportation and Lightweighting Minerals Extraction and Processing Nanocrystalline and Ultra-fine Grain Materials and Bulk Metallic Glasses Steels.

@article{ma_particulate_2017,
	title = {Particulate {Reinforced} {Aluminum} {Alloy} {Matrix} {Composites} – a {Review} on the {Effect} of {Microconstituents}},
	volume = {48},
	issn = {16065131},
	abstract = {Particulate reinforced aluminum-based metal matrix composites (Al MMCs) continue to be of interest, partly due to their low density, but also because of their ability to provide tailored property combinations, such as high specific stiffness, specific strength and creep resistance. This article provides a review on the progress that has been made in the field of particulate reinforced Al MMCs during the past decade, paying particular attention to the influence of size and spatial distributions of the Al alloy matrix grains and the reinforcing particles on the mechanical performance of the composites. In addition, the current state-of-the-art as well as the challenges facingAl MMCs that involve heat treatableAl alloys as the matrix are addressed. Finally, our recent findings related to B4C particulate reinforced 7xxx series Al alloy (Al-Zn-Mg) MMCs are also discussed.},
	number = {2},
	journal = {Reviews on Advanced Materials Science},
	author = {Ma, Kaka and Lavernia, Enrique J. and Schoenung, Julie M.},
	month = apr,
	year = {2017},
	keywords = {ALUMINUM alloys, BULK solids, CEMENT composites, Published, REINFORCED concrete, Reviewed, SPATIAL distribution (Quantum optics), STIFFNESS (Engineering)},
	pages = {91--104},
}

Particulate reinforced aluminum-based metal matrix composites (Al MMCs) continue to be of interest, partly due to their low density, but also because of their ability to provide tailored property combinations, such as high specific stiffness, specific strength and creep resistance. This article provides a review on the progress that has been made in the field of particulate reinforced Al MMCs during the past decade, paying particular attention to the influence of size and spatial distributions of the Al alloy matrix grains and the reinforcing particles on the mechanical performance of the composites. In addition, the current state-of-the-art as well as the challenges facingAl MMCs that involve heat treatableAl alloys as the matrix are addressed. Finally, our recent findings related to B4C particulate reinforced 7xxx series Al alloy (Al-Zn-Mg) MMCs are also discussed.

@article{nieto_elevated_2017,
	title = {Elevated temperature wear behavior of thermally sprayed {WC}-{Co}/nanodiamond composite coatings},
	volume = {315},
	issn = {0257-8972},
	url = {http://www.sciencedirect.com/science/article/pii/S0257897217301913},
	doi = {10.1016/j.surfcoat.2017.02.048},
	abstract = {This study investigates the effects of nanodiamonds (ND) on the wear behavior of WC-Co coatings during dry sliding under ambient and elevated temperature environments. The nanometric dimensions and exceptional hardness of ND are envisioned to enhance hardness while maintaining toughness, thereby enhancing wear resistance. ND reinforced WC-Co coatings were successfully fabricated by high velocity oxygen fuel spray (HVOF) and air plasma spraying (APS). The tribological behavior of WC-Co-ND composite coatings was evaluated at room temperature and at 300°C using reciprocating dry sliding wear tests. At room temperature, the addition of ND led to an enhancement in wear resistance of 8.5\% and 13\% in HVOF and APS coatings, respectively. The composite coatings exhibited increased formation of a protective silica tribolayer, which was attributed to enhanced heat transfer induced by the excellent thermal conductivity of diamond. At 300°C, however, the composite coatings exhibited poorer wear resistance than the counterpart WC-Co coatings as a result of the degradation of the ND phase. The loss of the diamond phase was believed to decrease hardness and weaken splat interfaces, which led to more facile delamination in HVOF coatings, as well as severe brittle wear and fracture in APS coatings.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Surface and Coatings Technology},
	author = {Nieto, Andy and Kim, Jaekang and Penkov, Oleksiy V. and Kim, Dae-Eun and Schoenung, Julie M.},
	month = apr,
	year = {2017},
	keywords = {Cermets, Nanocomposite, Nanodiamond, Published, Reviewed, Thermal spray, Wear},
	pages = {283--293},
}

This study investigates the effects of nanodiamonds (ND) on the wear behavior of WC-Co coatings during dry sliding under ambient and elevated temperature environments. The nanometric dimensions and exceptional hardness of ND are envisioned to enhance hardness while maintaining toughness, thereby enhancing wear resistance. ND reinforced WC-Co coatings were successfully fabricated by high velocity oxygen fuel spray (HVOF) and air plasma spraying (APS). The tribological behavior of WC-Co-ND composite coatings was evaluated at room temperature and at 300°C using reciprocating dry sliding wear tests. At room temperature, the addition of ND led to an enhancement in wear resistance of 8.5% and 13% in HVOF and APS coatings, respectively. The composite coatings exhibited increased formation of a protective silica tribolayer, which was attributed to enhanced heat transfer induced by the excellent thermal conductivity of diamond. At 300°C, however, the composite coatings exhibited poorer wear resistance than the counterpart WC-Co coatings as a result of the degradation of the ND phase. The loss of the diamond phase was believed to decrease hardness and weaken splat interfaces, which led to more facile delamination in HVOF coatings, as well as severe brittle wear and fracture in APS coatings.

@article{saller_iron_2017,
	title = {Iron in solution with aluminum matrix after non-equilibrium processing: an atom probe tomography study},
	volume = {97},
	issn = {0950-0839},
	shorttitle = {Iron in solution with aluminum matrix after non-equilibrium processing},
	url = {https://doi.org/10.1080/09500839.2017.1292055},
	doi = {10.1080/09500839.2017.1292055},
	abstract = {In this paper, we report on the influence of rapid solidification and severe plastic deformation on the solid solubility of Fe in Al. Atom probe tomography, for the first time, was performed on fine (3–4 μm diameter) and coarse ( 100 μm) as-atomised Al-5 at.\% Fe powder and cryomilled Al-5 at.\% Fe powder. The atomised powders exhibited negligible Fe in solution with Al, whereas the cryomilled powder contained 2 at.\% Fe in solution. Moreover, our results suggest that severe plastic deformation is preferable to atomisation/rapid solidification for increasing the non-equilibrium solid solubility of Fe in Al.},
	number = {3},
	urldate = {2018-01-08},
	journal = {Philosophical Magazine Letters},
	author = {Saller, Brandon D. and Sha, Gang and Yang, Li Mei and Liu, Fan and Ringer, Simon P. and Schoenung, Julie M.},
	month = mar,
	year = {2017},
	keywords = {Al–Fe alloys, Atom probe, Published, Reviewed, cryomilling, rapid solidification, solubility, ultrafine-grained metals},
	pages = {118--124},
}

In this paper, we report on the influence of rapid solidification and severe plastic deformation on the solid solubility of Fe in Al. Atom probe tomography, for the first time, was performed on fine (3–4 μm diameter) and coarse ( 100 μm) as-atomised Al-5 at.% Fe powder and cryomilled Al-5 at.% Fe powder. The atomised powders exhibited negligible Fe in solution with Al, whereas the cryomilled powder contained 2 at.% Fe in solution. Moreover, our results suggest that severe plastic deformation is preferable to atomisation/rapid solidification for increasing the non-equilibrium solid solubility of Fe in Al.

@article{ma_environmental_2017,
	series = {International {Conference} on {Sustainable} {Materials} {Processing} and {Manufacturing}, {SMPM} 2017, 23-25 {January} 2017, {Kruger}},
	title = {Environmental {Sustainability} of {Laser} {Metal} {Deposition}: {The} {Role} of {Feedstock} {Powder} and {Feedstock} {Utilization} {Factor}},
	volume = {7},
	issn = {2351-9789},
	shorttitle = {Environmental {Sustainability} of {Laser} {Metal} {Deposition}},
	url = {http://www.sciencedirect.com/science/article/pii/S2351978916302128},
	doi = {10.1016/j.promfg.2016.12.049},
	abstract = {Metal additive manufacturing (AM) is commonly promoted as a sustainable technology because of its capability to produce engineering components of complex geometries in a single step. Prior studies on environmental impact assessment of metal AM have underestimated the resource consumption due to the overestimation of the material utilization factor and neglecting the energy consumption needed to produce the desirable feedstock powder. This paper aims to address the role of feedstock powder and the actual material utilization factor in environmental impact assessment of laser metal deposition. Recycling and reuse of the unfused powder as the feedstock for subsequent depositions are proposed.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Procedia Manufacturing},
	author = {Ma, Kaka and Smith, Thale and Lavernia, Enrique J. and Schoenung, Julie M.},
	month = jan,
	year = {2017},
	keywords = {Published, Reviewed, additive manufacturing, environmental impact, laser metal deposition, life cycle assessment, sustainability},
	pages = {198--204},
}

Metal additive manufacturing (AM) is commonly promoted as a sustainable technology because of its capability to produce engineering components of complex geometries in a single step. Prior studies on environmental impact assessment of metal AM have underestimated the resource consumption due to the overestimation of the material utilization factor and neglecting the energy consumption needed to produce the desirable feedstock powder. This paper aims to address the role of feedstock powder and the actual material utilization factor in environmental impact assessment of laser metal deposition. Recycling and reuse of the unfused powder as the feedstock for subsequent depositions are proposed.

@article{scipioni_bertoli_limitations_2017,
	title = {On the limitations of {Volumetric} {Energy} {Density} as a design parameter for {Selective} {Laser} {Melting}},
	volume = {113},
	issn = {0264-1275},
	url = {http://www.sciencedirect.com/science/article/pii/S0264127516313363},
	doi = {10.1016/j.matdes.2016.10.037},
	abstract = {Energy density is often used as a metric to compare components manufactured with Selective Laser Melting (SLM) under different sets of deposition parameters (e.g., laser power, scan speed, layer thickness, etc.). We present a brief review of the current literature on additive manufacturing of 316L stainless steel (SS) related to input parameter scaling relations. From previously published work we identified a range of Volumetric Energy Density (VED) values that should lead to deposition of fully dense parts. In order to corroborate these data, we designed a series of experiments to investigate the reliability of VED as a design parameter by comparing single tracks of 316L SS deposited with variable deposition parameters. Our results show the suitability of VED as a design parameter to describe SLM to be limited to a narrow band of applicability, which is attributed to the inability of this parameter to capture the complex physics of the melt pool. Caution should be exercised when using VED as a design parameter for SLM.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Materials \& Design},
	author = {Scipioni Bertoli, Umberto and Wolfer, Alexander J. and Matthews, Manyalibo J. and Delplanque, Jean-Pierre R. and Schoenung, Julie M.},
	month = jan,
	year = {2017},
	keywords = {316L stainless steel, Energy density, Keyhole-mode laser melting, Powder-bed fusion, Published, Reviewed, Selective Laser Melting},
	pages = {331--340},
}

Energy density is often used as a metric to compare components manufactured with Selective Laser Melting (SLM) under different sets of deposition parameters (e.g., laser power, scan speed, layer thickness, etc.). We present a brief review of the current literature on additive manufacturing of 316L stainless steel (SS) related to input parameter scaling relations. From previously published work we identified a range of Volumetric Energy Density (VED) values that should lead to deposition of fully dense parts. In order to corroborate these data, we designed a series of experiments to investigate the reliability of VED as a design parameter by comparing single tracks of 316L SS deposited with variable deposition parameters. Our results show the suitability of VED as a design parameter to describe SLM to be limited to a narrow band of applicability, which is attributed to the inability of this parameter to capture the complex physics of the melt pool. Caution should be exercised when using VED as a design parameter for SLM.

@article{huang_situ_2017,
	title = {In situ oxide dispersion strengthened tungsten alloys with high compressive strength and high strain-to-failure},
	volume = {122},
	issn = {1359-6454},
	url = {http://www.sciencedirect.com/science/article/pii/S1359645416307339},
	doi = {10.1016/j.actamat.2016.09.034},
	abstract = {In this work a novel process methodology to concurrently improve the compressive strength (2078 MPa at a strain rate of 5 × 10−4 s−1) and strain-to-failure (over 40\%) of bulk tungsten materials has been described. The process involves the in situ formation of intragranular tungsten oxide nanoparticles, facilitated by the application of a pressure of 1 GPa at a low sintering temperature of 1200 °C during spark plasma sintering (SPS). The results show that the application of a high pressure of 1 GPa during SPS significantly accelerates the densification process. Concurrently, the second phase oxide nanoparticles with an average grain size of 108 nm, which are distributed within the interiors of the W grains, simultaneously provide strengthening and plasticity by inhibiting grain growth, and generating, blocking, and storing dislocations.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Acta Materialia},
	author = {Huang, Lin and Jiang, Lin and Topping, Troy D. and Dai, Chen and Wang, Xin and Carpenter, Ryan and Haines, Christopher and Schoenung, Julie M.},
	month = jan,
	year = {2017},
	keywords = {High-pressure spark plasma sintering (HP-SPS), Improved compressive behavior, In situ oxide dispersion strengthening, Published, Reviewed, Tungsten},
	pages = {19--31},
}

In this work a novel process methodology to concurrently improve the compressive strength (2078 MPa at a strain rate of 5 × 10−4 s−1) and strain-to-failure (over 40%) of bulk tungsten materials has been described. The process involves the in situ formation of intragranular tungsten oxide nanoparticles, facilitated by the application of a pressure of 1 GPa at a low sintering temperature of 1200 °C during spark plasma sintering (SPS). The results show that the application of a high pressure of 1 GPa during SPS significantly accelerates the densification process. Concurrently, the second phase oxide nanoparticles with an average grain size of 108 nm, which are distributed within the interiors of the W grains, simultaneously provide strengthening and plasticity by inhibiting grain growth, and generating, blocking, and storing dislocations.

@article{malloy_advancing_2017,
	title = {Advancing {Alternative} {Analysis}: {Integration} of {Decision} {Science}},
	volume = {125},
	issn = {0091-6765},
	shorttitle = {Advancing {Alternative} {Analysis}},
	url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5743447/},
	doi = {10.1289/EHP483},
	abstract = {Background:
Decision analysis—a systematic approach to solving complex problems—offers tools and frameworks to support decision making that are increasingly being applied to environmental challenges. Alternatives analysis is a method used in regulation and product design to identify, compare, and evaluate the safety and viability of potential substitutes for hazardous chemicals.

Objectives:
We assessed whether decision science may assist the alternatives analysis decision maker in comparing alternatives across a range of metrics.

Methods:
A workshop was convened that included representatives from government, academia, business, and civil society and included experts in toxicology, decision science, alternatives assessment, engineering, and law and policy. Participants were divided into two groups and were prompted with targeted questions. Throughout the workshop, the groups periodically came together in plenary sessions to reflect on other groups’ findings.

Results:
We concluded that the further incorporation of decision science into alternatives analysis would advance the ability of companies and regulators to select alternatives to harmful ingredients and would also advance the science of decision analysis.

Conclusions:
We advance four recommendations: a) engaging the systematic development and evaluation of decision approaches and tools; b) using case studies to advance the integration of decision analysis into alternatives analysis; c) supporting transdisciplinary research; and d) supporting education and outreach efforts. https://doi.org/10.1289/EHP483},
	number = {6},
	urldate = {2018-01-08},
	journal = {Environmental Health Perspectives},
	author = {Malloy, Timothy F. and Zaunbrecher, Virginia M. and Batteate, Christina M. and Blake, Ann and Carroll, William F. and Corbett, Charles J. and Hansen, Steffen Foss and Lempert, Robert J. and Linkov, Igor and McFadden, Roger and Moran, Kelly D. and Olivetti, Elsa and Ostrom, Nancy K. and Romero, Michelle and Schoenung, Julie M. and Seager, Thomas P. and Sinsheimer, Peter and Thayer, Kristina A.},
	month = jun,
	year = {2017},
	pmid = {28669940},
	pmcid = {PMC5743447},
	keywords = {Published, Reviewed},
}

Background: Decision analysis—a systematic approach to solving complex problems—offers tools and frameworks to support decision making that are increasingly being applied to environmental challenges. Alternatives analysis is a method used in regulation and product design to identify, compare, and evaluate the safety and viability of potential substitutes for hazardous chemicals. Objectives: We assessed whether decision science may assist the alternatives analysis decision maker in comparing alternatives across a range of metrics. Methods: A workshop was convened that included representatives from government, academia, business, and civil society and included experts in toxicology, decision science, alternatives assessment, engineering, and law and policy. Participants were divided into two groups and were prompted with targeted questions. Throughout the workshop, the groups periodically came together in plenary sessions to reflect on other groups’ findings. Results: We concluded that the further incorporation of decision science into alternatives analysis would advance the ability of companies and regulators to select alternatives to harmful ingredients and would also advance the science of decision analysis. Conclusions: We advance four recommendations: a) engaging the systematic development and evaluation of decision approaches and tools; b) using case studies to advance the integration of decision analysis into alternatives analysis; c) supporting transdisciplinary research; and d) supporting education and outreach efforts. https://doi.org/10.1289/EHP483

@article{wehage_open_2017,
	title = {An open framework for automated chemical hazard assessment based on {GreenScreen} for {Safer} {Chemicals}: {A} proof of concept},
	volume = {13},
	issn = {1551-3793},
	shorttitle = {An open framework for automated chemical hazard assessment based on {GreenScreen} for {Safer} {Chemicals}},
	url = {http://onlinelibrary.wiley.com/doi/10.1002/ieam.1763/abstract},
	doi = {10.1002/ieam.1763},
	abstract = {GreenScreen® for Safer Chemicals is a framework for comparative chemical hazard assessment. It is the first transparent, open and publicly accessible framework of its kind, allowing manufacturers and governmental agencies to make informed decisions about the chemicals and substances used in consumer products and buildings. In the GreenScreen® benchmarking process, chemical hazards are assessed and classified based on 18 hazard endpoints from up to 30 different sources. The result is a simple numerical benchmark score and accompanying assessment report that allows users to flag chemicals of concern and identify safer alternatives. Although the screening process is straightforward, aggregating and sorting hazard data is tedious, time-consuming, and prone to human error. In light of these challenges, the present work demonstrates the usage of automation to cull chemical hazard data from publicly available internet resources, assign metadata, and perform a GreenScreen® hazard assessment using the GreenScreen® “List Translator.” The automated technique, written as a module in the Python programming language, generates GreenScreen® List Translation data for over 3000 chemicals in approximately 30 s. Discussion of the potential benefits and limitations of automated techniques is provided. By embedding the library into a web-based graphical user interface, the extensibility of the library is demonstrated. The accompanying source code is made available to the hazard assessment community. Integr Environ Assess Manag 2017;13:167–176. © 2016 SETAC},
	language = {en},
	number = {1},
	urldate = {2018-01-08},
	journal = {Integrated Environmental Assessment and Management},
	author = {Wehage, Kristopher and Chenhansa, Panan and Schoenung, Julie M},
	month = jan,
	year = {2017},
	keywords = {Published, Reviewed},
	pages = {167--176},
}

GreenScreen® for Safer Chemicals is a framework for comparative chemical hazard assessment. It is the first transparent, open and publicly accessible framework of its kind, allowing manufacturers and governmental agencies to make informed decisions about the chemicals and substances used in consumer products and buildings. In the GreenScreen® benchmarking process, chemical hazards are assessed and classified based on 18 hazard endpoints from up to 30 different sources. The result is a simple numerical benchmark score and accompanying assessment report that allows users to flag chemicals of concern and identify safer alternatives. Although the screening process is straightforward, aggregating and sorting hazard data is tedious, time-consuming, and prone to human error. In light of these challenges, the present work demonstrates the usage of automation to cull chemical hazard data from publicly available internet resources, assign metadata, and perform a GreenScreen® hazard assessment using the GreenScreen® “List Translator.” The automated technique, written as a module in the Python programming language, generates GreenScreen® List Translation data for over 3000 chemicals in approximately 30 s. Discussion of the potential benefits and limitations of automated techniques is provided. By embedding the library into a web-based graphical user interface, the extensibility of the library is demonstrated. The accompanying source code is made available to the hazard assessment community. Integr Environ Assess Manag 2017;13:167–176. © 2016 SETAC

@article{wu_influence_2016,
	title = {Influence of particle size and spatial distribution of {B4C} reinforcement on the microstructure and mechanical behavior of precipitation strengthened {Al} alloy matrix composites},
	volume = {675},
	issn = {0921-5093},
	url = {http://www.sciencedirect.com/science/article/pii/S0921509316309753},
	doi = {10.1016/j.msea.2016.08.062},
	abstract = {We report on an investigation of the influence of reinforcement particle size on the microstructure and mechanical behavior of Al metal matrix composites. In our work, Al 7075/B4C composites containing three types of B4C particle sizes (56.9µm, 4.2µm and 2.0µm) were synthesized and studied. For a constant value of volume fraction of B4C, the composite with coarse reinforcement particles exhibited a relatively homogeneous and discrete distribution of the B4C particles while the composites with fine reinforcement exhibited agglomeration of the B4C particles. The composite with the smallest B4C particles possessed the highest yield strength and fracture strength. Quantitative analysis of the strengthening mechanisms revealed that smaller B4C particles lead to larger values in strain gradient strengthening as well as CTE mismatch strengthening, which are significantly correlated to the geometrically necessary dislocations caused by the presence of B4C. In addition, the different spatial distributions of the B4C particles contributed to different fracture mechanisms in the composites.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Materials Science and Engineering: A},
	author = {Wu, Chuandong and Ma, Kaka and Wu, Jialu and Fang, Pan and Luo, Guoqiang and Chen, Fei and Shen, Qiang and Zhang, Lianmeng and Schoenung, Julie M. and Lavernia, Enrique J.},
	month = oct,
	year = {2016},
	keywords = {Fracture mechanism, Metal matrix composites, Published, Reinforcement, Reviewed, Strengthening mechanism},
	pages = {421--430},
}

We report on an investigation of the influence of reinforcement particle size on the microstructure and mechanical behavior of Al metal matrix composites. In our work, Al 7075/B4C composites containing three types of B4C particle sizes (56.9µm, 4.2µm and 2.0µm) were synthesized and studied. For a constant value of volume fraction of B4C, the composite with coarse reinforcement particles exhibited a relatively homogeneous and discrete distribution of the B4C particles while the composites with fine reinforcement exhibited agglomeration of the B4C particles. The composite with the smallest B4C particles possessed the highest yield strength and fracture strength. Quantitative analysis of the strengthening mechanisms revealed that smaller B4C particles lead to larger values in strain gradient strengthening as well as CTE mismatch strengthening, which are significantly correlated to the geometrically necessary dislocations caused by the presence of B4C. In addition, the different spatial distributions of the B4C particles contributed to different fracture mechanisms in the composites.

@incollection{zhang_deformation_2016,
	title = {Deformation {Twinning} ({Update})},
	isbn = {978-0-12-803581-8},
	url = {https://www.sciencedirect.com/science/article/pii/B9780128035818028782},
	abstract = {Dislocation mechanisms for the formation of twins in b.c.c., f.c.c., and h.c.p. crystals have been briefly reviewed. An attempt has been made to understand in terms of these models the influence of temperature, composition, pre-strain, and microstructure on deformation twinning. Furthermore, accommodation processes occurring at twins terminating within a crystal, and twin–twin and grain boundary interactions are covered. Finally, recent advances in understanding twinning in h.c.p. materials using EBSD and HRTEM/in-situ TEM are briefly reviewed.},
	urldate = {2018-01-08},
	booktitle = {Reference {Module} in {Materials} {Science} and {Materials} {Engineering}},
	publisher = {Elsevier},
	author = {Zhang, D. and Jiang, L. and Zheng, B. and Schoenung, J. M. and Mahajan, S. and Lavernia, E. J. and Beyerlein, I. J.},
	year = {2016},
	doi = {10.1016/B978-0-12-803581-8.02878-2},
	keywords = {Deformation twinning, Dislocations, EBSD, Published, Reviewed, Transmission electron microscopy, b.c.c., f.c.c., h.c.p.},
}

Dislocation mechanisms for the formation of twins in b.c.c., f.c.c., and h.c.p. crystals have been briefly reviewed. An attempt has been made to understand in terms of these models the influence of temperature, composition, pre-strain, and microstructure on deformation twinning. Furthermore, accommodation processes occurring at twins terminating within a crystal, and twin–twin and grain boundary interactions are covered. Finally, recent advances in understanding twinning in h.c.p. materials using EBSD and HRTEM/in-situ TEM are briefly reviewed.

@article{zhang_yield_2016,
	title = {Yield symmetry and reduced strength differential in {Mg}-2.{5Y} alloy},
	volume = {120},
	issn = {1359-6454},
	url = {http://www.sciencedirect.com/science/article/pii/S1359645416306152},
	doi = {10.1016/j.actamat.2016.08.037},
	abstract = {In this study we report novel results obtained with an extruded fine-grained Mg-2.5 at.\% Y alloy (FG Mg-2.5Y) exhibiting tension/compression yield symmetry and reduced strength differential, in addition to well-balanced strength and ductility. On the basis of detailed post-mortem transmission electron microscopy studies, atom probe tomography, and electron back-scattered diffraction (EBSD) characterization, we propose that the presence of a supersaturated solid solution strengthening for basal slip, and the enhanced activity of prismatic slip are the major causes for the unusual mechanical behavior.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Acta Materialia},
	author = {Zhang, Dalong and Wen, Haiming and Kumar, M. Arul and Chen, Fei and Zhang, Lianmeng and Beyerlein, Irene J. and Schoenung, Julie M. and Mahajan, S. and Lavernia, Enrique J.},
	month = nov,
	year = {2016},
	keywords = {Crystal plasticity, Dislocation imaging, Magnesium alloy, Published, Reviewed, Tension/compression asymmetry, Texture},
	pages = {75--85},
}

In this study we report novel results obtained with an extruded fine-grained Mg-2.5 at.% Y alloy (FG Mg-2.5Y) exhibiting tension/compression yield symmetry and reduced strength differential, in addition to well-balanced strength and ductility. On the basis of detailed post-mortem transmission electron microscopy studies, atom probe tomography, and electron back-scattered diffraction (EBSD) characterization, we propose that the presence of a supersaturated solid solution strengthening for basal slip, and the enhanced activity of prismatic slip are the major causes for the unusual mechanical behavior.

@article{hu_strategies_2016,
	title = {Strategies to {Approach} {Stabilized} {Plasticity} in {Metals} with {Diminutive} {Volume}: {A} {Brief} {Review}},
	volume = {6},
	copyright = {http://creativecommons.org/licenses/by/3.0/},
	shorttitle = {Strategies to {Approach} {Stabilized} {Plasticity} in {Metals} with {Diminutive} {Volume}},
	url = {http://www.mdpi.com/2073-4352/6/8/92},
	doi = {10.3390/cryst6080092},
	abstract = {Micrometer- or submicrometer-sized metallic pillars are widely studied by investigators worldwide, not only to provide insights into fundamental phenomena, but also to explore potential applications in microelectromechanical system (MEMS) devices. While these materials with a diminutive volume exhibit unprecedented properties, e.g., strength values that approach the theoretical strength, their plastic flow is frequently intermittent as manifested by strain bursts, which is mainly attributed to dislocation activity at such length scales. Specifically, the increased ratio of free surface to volume promotes collective dislocation release resulting in dislocation starvation at the submicrometer scale or the formation of single-arm dislocation sources (truncated dislocations) at the micrometer scale. This article reviews and critically assesses recent progress in tailoring the microstructure of pillars, both extrinsically and intrinsically, to suppress plastic instabilities in micrometer or submicrometer-sized metallic pillars using an approach that involves confining the dislocations inside the pillars. Moreover, we identify strategies that can be implemented to fabricate submicrometer-sized metallic pillars that simultaneously exhibit stabilized plasticity and ultrahigh strength.},
	language = {en},
	number = {8},
	urldate = {2018-01-08},
	journal = {Crystals},
	author = {Hu, Tao and Jiang, Lin and Mukherjee, Amiya K. and Schoenung, Julie M. and Lavernia, Enrique J.},
	month = aug,
	year = {2016},
	keywords = {Published, Reviewed, in situ TEM, nanopillars, plastic instability, softening, strain bursts},
	pages = {92},
}

Micrometer- or submicrometer-sized metallic pillars are widely studied by investigators worldwide, not only to provide insights into fundamental phenomena, but also to explore potential applications in microelectromechanical system (MEMS) devices. While these materials with a diminutive volume exhibit unprecedented properties, e.g., strength values that approach the theoretical strength, their plastic flow is frequently intermittent as manifested by strain bursts, which is mainly attributed to dislocation activity at such length scales. Specifically, the increased ratio of free surface to volume promotes collective dislocation release resulting in dislocation starvation at the submicrometer scale or the formation of single-arm dislocation sources (truncated dislocations) at the micrometer scale. This article reviews and critically assesses recent progress in tailoring the microstructure of pillars, both extrinsically and intrinsically, to suppress plastic instabilities in micrometer or submicrometer-sized metallic pillars using an approach that involves confining the dislocations inside the pillars. Moreover, we identify strategies that can be implemented to fabricate submicrometer-sized metallic pillars that simultaneously exhibit stabilized plasticity and ultrahigh strength.

@inproceedings{zheng_review_2016,
	title = {Review on laser powder injection additive manufacturing of novel alloys and composites},
	volume = {9738},
	url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/9738/97380O/Review-on-laser-powder-injection-additive-manufacturing-of-novel-alloys/10.1117/12.2217909.short},
	doi = {10.1117/12.2217909},
	abstract = {In this paper, recent research and progress associated with development of alloys and composites using LENS are reviewed. The microstructure of novel materials can be tailored by controlling both composition and process parameters. For process control, closed-loop diagnostics and controls such as in-situ molten pool sensor and Z-height control subsystems are utilized, while the thermal behavior measurement with thermal imaging methods and numerical simulation are also investigated. The existing problems with residual stress and porosity in deposited materials are discussed.},
	urldate = {2018-01-08},
	publisher = {International Society for Optics and Photonics},
	author = {Zheng, B. and Yang, N. and Yee, J. and Gaiser, K. and Lu, W. Y. and Clemon, L. and Zhou, Y. and Lavernia, E. J. and Schoenung, J. M.},
	month = apr,
	year = {2016},
	keywords = {Invited, Published},
	pages = {97380O},
}

In this paper, recent research and progress associated with development of alloys and composites using LENS are reviewed. The microstructure of novel materials can be tailored by controlling both composition and process parameters. For process control, closed-loop diagnostics and controls such as in-situ molten pool sensor and Z-height control subsystems are utilized, while the thermal behavior measurement with thermal imaging methods and numerical simulation are also investigated. The existing problems with residual stress and porosity in deposited materials are discussed.

@article{jiang_deformation_2016,
	title = {Deformation of a ceramic/metal interface at the nanoscale},
	volume = {8},
	url = {http://pubs.rsc.org/en/Content/ArticleLanding/2016/NR/C6NR02011A},
	doi = {10.1039/C6NR02011A},
	language = {en},
	number = {20},
	urldate = {2018-01-08},
	journal = {Nanoscale},
	author = {Jiang, Lin and Hu, Tao and Yang, Hanry and Zhang, Dalong and Topping, Troy and J. Lavernia, Enrique and M. Schoenung, Julie},
	year = {2016},
	keywords = {Published, Reviewed},
	pages = {10541--10547},
}

@article{liu_microstructure_2016,
	title = {Microstructure and mechanical behavior of {NS}/{UFG} aluminum prepared by cryomilling and spark plasma sintering},
	volume = {679},
	issn = {0925-8388},
	url = {http://www.sciencedirect.com/science/article/pii/S0925838816310271},
	doi = {10.1016/j.jallcom.2016.04.073},
	abstract = {We report on a study of the microstructure and mechanical behavior of a bulk nanostructured (NS)/ultra-fine grained (UFG) aluminum fabricated by cryomilling and high-pressure spark plasma sintering (SPS). The compressive yield stress of the consolidated material is determined to be 380 MPa, which is significantly higher than that of commercial strain hardened aluminum (124 MPa). Microstructural studies reveal that the nanometric grains are embedded inside a matrix of ultra-fine grains in the bulk material. The corresponding average grain size is approximately 125 nm and with a distribution of grains that are smaller than 500 nm. Moreover, chemical analysis of the powder particles and the consolidated samples indicates that carbon and oxygen levels remain unchanged, and that there is a slight decrease in the nitrogen level and a significant reduction in the hydrogen level after spark plasma sintering. Semi-quantitative analysis suggests that the mechanisms that contribute to the strength of the consolidated material include: grain boundary strengthening, second phase strengthening and dislocation strengthening.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Journal of Alloys and Compounds},
	author = {Liu, Dongming and Xiong, Yuhong and Li, Ping and Lin, Yaojun and Chen, Fei and Zhang, Lianmeng and Schoenung, Julie M. and Lavernia, Enrique J.},
	month = sep,
	year = {2016},
	keywords = {Chemical analysis, Mechanical property, Nanostructured materials, Published, Reviewed, Spark plasma sintering, Strengthening mechanisms, Ultra-fine grained materials},
	pages = {426--435},
}

We report on a study of the microstructure and mechanical behavior of a bulk nanostructured (NS)/ultra-fine grained (UFG) aluminum fabricated by cryomilling and high-pressure spark plasma sintering (SPS). The compressive yield stress of the consolidated material is determined to be 380 MPa, which is significantly higher than that of commercial strain hardened aluminum (124 MPa). Microstructural studies reveal that the nanometric grains are embedded inside a matrix of ultra-fine grains in the bulk material. The corresponding average grain size is approximately 125 nm and with a distribution of grains that are smaller than 500 nm. Moreover, chemical analysis of the powder particles and the consolidated samples indicates that carbon and oxygen levels remain unchanged, and that there is a slight decrease in the nitrogen level and a significant reduction in the hydrogen level after spark plasma sintering. Semi-quantitative analysis suggests that the mechanisms that contribute to the strength of the consolidated material include: grain boundary strengthening, second phase strengthening and dislocation strengthening.

@article{ma_mechanistic_2016,
	title = {Mechanistic investigation into the role of aluminum diffusion in the oxidation behavior of cryomilled {NiCrAlY} bond coat},
	volume = {31},
	issn = {1000-2413, 1993-0437},
	url = {https://link.springer.com/article/10.1007/s11595-016-1326-7},
	doi = {10.1007/s11595-016-1326-7},
	abstract = {High temperature oxidation behavior of the bond coat layer is a critical factor that controls the failure mechanism of thermal barrier coatings (TBCs). Previous work reveald that TBCs with cryomilled NiCrAlY bond coats exhibited an improved oxidation behavior compared to equivalent TBCs with conventional bond coats. The cryomilled NiCrAlY bond coats contributed to a slower growth rate of thermally grown oxides (TGO) with a final thinner thickness and enhanced homogeneity in TGO composition. To better understand the improved oxidation behavior, a mechanistic investigation based on diffusion theory and quantum mechanics is performed to elucidate the role of aluminum diffusion in the oxidation behavior and how the microstructural features of the cryomilled NiCrAlY bond coats, i e, the creation of a thermally stable, uniform distribution of ultrafine Al-rich oxide dispersoids, affect the diffusion kinetics of Al and the migration of free electrons. It is revealed that these Al-rich oxide dispersoids result in a uniform diffusion of Al and slow migration of free electrons within the NiCrAlY bond coat, consequently leading to the improved oxidation behavior.},
	language = {en},
	number = {1},
	urldate = {2018-01-08},
	journal = {Journal of Wuhan University of Technology-Mater. Sci. Ed.},
	author = {Ma, Kaka and Tang, Xiaochuan and Schoenung, Julie M.},
	month = feb,
	year = {2016},
	keywords = {Published, Reviewed},
	pages = {35--43},
}

High temperature oxidation behavior of the bond coat layer is a critical factor that controls the failure mechanism of thermal barrier coatings (TBCs). Previous work reveald that TBCs with cryomilled NiCrAlY bond coats exhibited an improved oxidation behavior compared to equivalent TBCs with conventional bond coats. The cryomilled NiCrAlY bond coats contributed to a slower growth rate of thermally grown oxides (TGO) with a final thinner thickness and enhanced homogeneity in TGO composition. To better understand the improved oxidation behavior, a mechanistic investigation based on diffusion theory and quantum mechanics is performed to elucidate the role of aluminum diffusion in the oxidation behavior and how the microstructural features of the cryomilled NiCrAlY bond coats, i e, the creation of a thermally stable, uniform distribution of ultrafine Al-rich oxide dispersoids, affect the diffusion kinetics of Al and the migration of free electrons. It is revealed that these Al-rich oxide dispersoids result in a uniform diffusion of Al and slow migration of free electrons within the NiCrAlY bond coat, consequently leading to the improved oxidation behavior.

@article{nieto_microscale_2016,
	title = {Microscale tribological behavior and in vitro biocompatibility of graphene nanoplatelet reinforced alumina},
	volume = {61},
	issn = {1751-6161},
	url = {http://www.sciencedirect.com/science/article/pii/S1751616116000230},
	doi = {10.1016/j.jmbbm.2016.01.020},
	abstract = {Graphene nanoplatelets were added as reinforcement to alumina ceramics in order to enhance microscale tribological behavior, which would be beneficial for ceramic-on-ceramic hip implant applications. The reduction in microscale wear is critical to hip implant applications where small amounts of wear debris can be detrimental to patients and to implant performance. The addition of the GNPs lead to improvements in fracture toughness and wear (scratch) resistance of 21\% and 39\%, respectively. The improved wear resistance was attributed to GNP-induced toughening, which generates fine ({\textasciitilde}100nm) microcracks on the scratch surface. In addition, active participation of GNPs was observed in the scratch subsurface of GNP-reinforced samples through focused ion beam sectioning. Friction coefficients are not significantly influenced by the addition of GNPs, and hence GNPs do not act as solid state lubricants. In vitro biocompatibility with human osteoblasts was assessed to evaluate any possible cytotoxic effects induced by GNPs. Osteoblast cells were observed to survive and proliferate robustly in the GNP-reinforced samples, particularly those with high (10–15vol\%) GNP content.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Journal of the Mechanical Behavior of Biomedical Materials},
	author = {Nieto, Andy and Zhao, Jing Ming and Han, Young-Hwan and Hwang, Kyu Hong and Schoenung, Julie M.},
	month = aug,
	year = {2016},
	keywords = {Biocompatibility, Ceramic matrix composites, Graphene nanoplatelets, Microscratch, Nanotribology, Osteoblasts, Published, Reviewed},
	pages = {122--134},
}

Graphene nanoplatelets were added as reinforcement to alumina ceramics in order to enhance microscale tribological behavior, which would be beneficial for ceramic-on-ceramic hip implant applications. The reduction in microscale wear is critical to hip implant applications where small amounts of wear debris can be detrimental to patients and to implant performance. The addition of the GNPs lead to improvements in fracture toughness and wear (scratch) resistance of 21% and 39%, respectively. The improved wear resistance was attributed to GNP-induced toughening, which generates fine (~100nm) microcracks on the scratch surface. In addition, active participation of GNPs was observed in the scratch subsurface of GNP-reinforced samples through focused ion beam sectioning. Friction coefficients are not significantly influenced by the addition of GNPs, and hence GNPs do not act as solid state lubricants. In vitro biocompatibility with human osteoblasts was assessed to evaluate any possible cytotoxic effects induced by GNPs. Osteoblast cells were observed to survive and proliferate robustly in the GNP-reinforced samples, particularly those with high (10–15vol%) GNP content.

@article{li_synthesis_2016,
	title = {Synthesis and mechanical behavior of nanostructured {Al} 5083/n-{TiB2} metal matrix composites},
	volume = {656},
	issn = {0921-5093},
	url = {http://www.sciencedirect.com/science/article/pii/S0921509316300326},
	doi = {10.1016/j.msea.2016.01.031},
	abstract = {Nanostructured Al 5083-based composites with nano-TiB2 reinforcement particles were fabricated via cryomilling and spark plasma sintering (SPS). TEM observation revealed that the Al matrix consists of equiaxed nano-grains (average size, ∼74nm), and the reinforcement, TiB2 nanoparticles (n-TiB2), was distributed discretely and homogeneously in the Al matrix. The interface between the Al-matrix and n-TiB2 appears to be free of defects, and no obvious discontinuities were observed. The composite exhibits a compressive strength of 817MPa with 6.0\% strain-to-failure. The strength is 20\% higher than that of an equivalent SPS consolidated Al 5083 without reinforcement. Nanoindentation was used in our study to provide fundamental insight into the local microscopic mechanical properties. The strengthening mechanisms of the composites are analyzed taking into account the grain boundaries, the Orowan strengthening from the n-TiB2 particles and dispersoids such as Al2O3, AlN and Al6Mn, as well as geometrically necessary dislocations induced in the matrix by the nano-TiB2 particles.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Materials Science and Engineering: A},
	author = {Li, Meijuan and Ma, Kaka and Jiang, Lin and Yang, Hanry and Lavernia, Enrique J. and Zhang, Lianmeng and Schoenung, Julie M.},
	month = feb,
	year = {2016},
	keywords = {Al metal matrix composite, Mechanical properties, Nanostructure, Published, Reviewed, Spark plasma sintering},
	pages = {241--248},
}

Nanostructured Al 5083-based composites with nano-TiB2 reinforcement particles were fabricated via cryomilling and spark plasma sintering (SPS). TEM observation revealed that the Al matrix consists of equiaxed nano-grains (average size, ∼74nm), and the reinforcement, TiB2 nanoparticles (n-TiB2), was distributed discretely and homogeneously in the Al matrix. The interface between the Al-matrix and n-TiB2 appears to be free of defects, and no obvious discontinuities were observed. The composite exhibits a compressive strength of 817MPa with 6.0% strain-to-failure. The strength is 20% higher than that of an equivalent SPS consolidated Al 5083 without reinforcement. Nanoindentation was used in our study to provide fundamental insight into the local microscopic mechanical properties. The strengthening mechanisms of the composites are analyzed taking into account the grain boundaries, the Orowan strengthening from the n-TiB2 particles and dispersoids such as Al2O3, AlN and Al6Mn, as well as geometrically necessary dislocations induced in the matrix by the nano-TiB2 particles.

@article{zhang_3d_2016,
	title = {{3D} {Microstructure}-based finite element modeling of deformation and fracture of {SiCp}/{Al} composites},
	volume = {123},
	issn = {0266-3538},
	url = {http://www.sciencedirect.com/science/article/pii/S0266353815301342},
	doi = {10.1016/j.compscitech.2015.11.014},
	abstract = {The mechanical behavior, with particular emphasis on the damage mechanisms, of SiCp/Al composites was studied by both experiments and finite element analysis in this paper. A 3D microstructure-based finite element model was developed to predict the elasto-plastic response and fracture behavior of a 7vol.\% SiCp/Al composite. The 3D microstructure of SiCp/Al composite was reconstructed by implementing a Camisizer XT particle size analysis device and a random sequential adsorption algorithm. The constitutive behavior of the elastoplastic-damage in the metal matrix, the elastic-brittle failure for the particle reinforcement, and the traction-separation for interfaces, were independently simulated in this model. The validity of the modeling results were validated by the agreement of the experimental stress-strain curve and the morphology of fracture section with those predicted by the simulation. The visual elasto-plastic deformation process, along with crack generation and propagation was well simulated in this model. The numerical results were used to provide insight into the damage mechanisms of SiCp/Al composites, and the effects of interfacial strength and particle strength on material properties were also discussed in detail.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Composites Science and Technology},
	author = {Zhang, Jie and Ouyang, Qiubao and Guo, Qiang and Li, Zhiqiang and Fan, Genlian and Su, Yishi and Jiang, Lin and Lavernia, Enrique J. and Schoenung, Julie M. and Zhang, Di},
	month = feb,
	year = {2016},
	keywords = {Damage mechanics, Finite element analysis (FEA), Interfacial strength, Metal-matrix composites (MMCs), Published, Reviewed},
	pages = {1--9},
}

The mechanical behavior, with particular emphasis on the damage mechanisms, of SiCp/Al composites was studied by both experiments and finite element analysis in this paper. A 3D microstructure-based finite element model was developed to predict the elasto-plastic response and fracture behavior of a 7vol.% SiCp/Al composite. The 3D microstructure of SiCp/Al composite was reconstructed by implementing a Camisizer XT particle size analysis device and a random sequential adsorption algorithm. The constitutive behavior of the elastoplastic-damage in the metal matrix, the elastic-brittle failure for the particle reinforcement, and the traction-separation for interfaces, were independently simulated in this model. The validity of the modeling results were validated by the agreement of the experimental stress-strain curve and the morphology of fracture section with those predicted by the simulation. The visual elasto-plastic deformation process, along with crack generation and propagation was well simulated in this model. The numerical results were used to provide insight into the damage mechanisms of SiCp/Al composites, and the effects of interfacial strength and particle strength on material properties were also discussed in detail.

@article{behm_quasi-static_2016,
	title = {Quasi-static and high-rate mechanical behavior of aluminum-based {MMC} reinforced with boron carbide of various length scales},
	volume = {650},
	issn = {0921-5093},
	url = {http://www.sciencedirect.com/science/article/pii/S0921509315305244},
	doi = {10.1016/j.msea.2015.10.064},
	abstract = {We report on an investigation of the quasi-static and dynamic mechanical behavior of an ultrafine-grained (UFG) aluminum composite reinforced with nanoscale boron carbide under uniaxial compression. Aluminum composites reinforced with either nanometric or half-micron sized B4C exhibit high strength {\textasciitilde}900MPa and considerable strain-to-failure under compression ({\textgreater}15pct.) at quasi-static (10−3s−1) and dynamic (103s−1) strain rates. Microstructural analyses of the composites and unreinforced aluminum alloy were performed to determine the strengthening mechanisms and plastic behavior that govern the structure–property relationships for this class of materials. Our results reveal that the flow stress of the composites does not depend strongly on strain rate if high rate data are included, while strain rate jump tests via instrumented nanoindentation indicate that the strain rate sensitivity exhibits similar behavior as the unreinforced matrix. The unreinforced alloy undergoes strain hardening at both quasi-static and dynamic strain rates, while the composites show strain softening at dynamic strain rates and elastic nearly-perfectly plastic behavior at quasi-static rates. Adiabatic shear band formation was evident in the composite samples during dynamic loading, whereas no shear banding was observed in the unreinforced alloy for the strain rates studied herein. The notion of adiabatic shear band toughness was adopted to identify the increased propensity to shear localization in the composites vis-a-vis the unreinforced material. An attempt is made to account for the effect of the boron carbide reinforcement size on the strengthening mechanism and overall plastic response for these metal matrix composites.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Materials Science and Engineering: A},
	author = {Behm, Nathan and Yang, Hanry and Shen, Jianghua and Ma, Kaka and Kecskes, Laszlo J. and Lavernia, Enrique J. and Schoenung, Julie M. and Wei, Qiuming},
	month = jan,
	year = {2016},
	keywords = {Adiabatic shear bands, High strain rate behavior, Metal matrix composites (MMCs), Published, Reviewed, Strain rate effect.},
	pages = {305--316},
}

We report on an investigation of the quasi-static and dynamic mechanical behavior of an ultrafine-grained (UFG) aluminum composite reinforced with nanoscale boron carbide under uniaxial compression. Aluminum composites reinforced with either nanometric or half-micron sized B4C exhibit high strength ~900MPa and considerable strain-to-failure under compression (\textgreater15pct.) at quasi-static (10−3s−1) and dynamic (103s−1) strain rates. Microstructural analyses of the composites and unreinforced aluminum alloy were performed to determine the strengthening mechanisms and plastic behavior that govern the structure–property relationships for this class of materials. Our results reveal that the flow stress of the composites does not depend strongly on strain rate if high rate data are included, while strain rate jump tests via instrumented nanoindentation indicate that the strain rate sensitivity exhibits similar behavior as the unreinforced matrix. The unreinforced alloy undergoes strain hardening at both quasi-static and dynamic strain rates, while the composites show strain softening at dynamic strain rates and elastic nearly-perfectly plastic behavior at quasi-static rates. Adiabatic shear band formation was evident in the composite samples during dynamic loading, whereas no shear banding was observed in the unreinforced alloy for the strain rates studied herein. The notion of adiabatic shear band toughness was adopted to identify the increased propensity to shear localization in the composites vis-a-vis the unreinforced material. An attempt is made to account for the effect of the boron carbide reinforcement size on the strengthening mechanism and overall plastic response for these metal matrix composites.

@article{hu_disordered_2016,
	title = {Disordered dislocation configuration in submicrometer {Al} crystal subjected to plane strain bending},
	volume = {113},
	issn = {1359-6462},
	url = {http://www.sciencedirect.com/science/article/pii/S1359646215300087},
	doi = {10.1016/j.scriptamat.2015.10.008},
	abstract = {Bending tests of submicrometer Al pillars were performed in-situ in a transmission electron microscope (TEM). The Al crystal in the bent region experienced substantial lattice distortion, as well as grain refinement resulting in a disordered dislocation configuration arising from a random distribution of low angle grain boundaries (LAGBs). This observed disordered dislocation configuration is in contrast to formation of a low energy dislocation configuration, as predicted on the basis of the theory of strain gradient plasticity, for bulk materials subjected to plane strain bending.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Scripta Materialia},
	author = {Hu, T. and Ma, K. and Topping, T. D. and Jiang, L. and Zhang, D. and Mukherjee, A. K. and Schoenung, J. M. and Lavernia, E. J.},
	month = mar,
	year = {2016},
	keywords = {Dislocation configuration, Low angle grain boundary, Published, Reviewed, Strain bending, Submicrometer pillars, TEM},
	pages = {35--38},
}

Bending tests of submicrometer Al pillars were performed in-situ in a transmission electron microscope (TEM). The Al crystal in the bent region experienced substantial lattice distortion, as well as grain refinement resulting in a disordered dislocation configuration arising from a random distribution of low angle grain boundaries (LAGBs). This observed disordered dislocation configuration is in contrast to formation of a low energy dislocation configuration, as predicted on the basis of the theory of strain gradient plasticity, for bulk materials subjected to plane strain bending.

@article{jiang_toughening_2016,
	title = {Toughening of aluminum matrix nanocomposites via spatial arrays of boron carbide spherical nanoparticles},
	volume = {103},
	issn = {1359-6454},
	url = {http://www.sciencedirect.com/science/article/pii/S1359645415007466},
	doi = {10.1016/j.actamat.2015.09.057},
	abstract = {To enhance the toughness of metal matrix nanocomposites, we demonstrate a strategy that involves the introduction of spatial arrays of nanoparticles. Specifically, we describe an approach to synthesize a microstructure characterized by arrays of fiber-like nanoparticle-rich (NPR) zones that contain spherical nanoparticles of boron carbide (sn-B4C) embedded in an ultrafine grained (UFG) aluminum alloy matrix. A combination of cryomilling and hot-extrusion was used to obtain this particular microstructure, and the mechanical behavior and operative strengthening and deformation mechanisms were investigated in detail. When compared to an equivalent unreinforced material, the presence of the array of NPR zones contributed to a 26\% increase in tensile strength. Moreover, when compared to a nanocomposite containing a homogeneous distribution of nanoparticles, a 30\% increase in toughness was observed. High nanohardness values obtained for the NPR zones and the observation of “pull-out” phenomena on fracture surfaces, suggest that the NPR zones behave as “hard” fiber-like units that can effectively sustain tensile loading and thereby enhance the strengthening efficiency of sn-B4C. Also, the presence of the array of NPR zones surrounded by nanoparticle-free (NPF) zones led to an enhancement in strength with limited loss in ductility. This behavior was rationalized on the basis of a low value of the Schmid factor in regions adjacent to NPR zones, coupled with the ease of dislocation movement in NPF zones. Finally, the ratio of the plastic zone size to the size of the “hard” NPR zones is proposed as an important factor that governs the overall toughness of the nanocomposite.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Acta Materialia},
	author = {Jiang, Lin and Yang, Hanry and Yee, Joshua K. and Mo, Xuan and Topping, Troy and Lavernia, Enrique J. and Schoenung, Julie M.},
	month = jan,
	year = {2016},
	keywords = {Aluminum, Metal matrix nanocomposites, Microstructural toughening, Nanoparticles, Published, Reviewed, Size effects},
	pages = {128--140},
}

To enhance the toughness of metal matrix nanocomposites, we demonstrate a strategy that involves the introduction of spatial arrays of nanoparticles. Specifically, we describe an approach to synthesize a microstructure characterized by arrays of fiber-like nanoparticle-rich (NPR) zones that contain spherical nanoparticles of boron carbide (sn-B4C) embedded in an ultrafine grained (UFG) aluminum alloy matrix. A combination of cryomilling and hot-extrusion was used to obtain this particular microstructure, and the mechanical behavior and operative strengthening and deformation mechanisms were investigated in detail. When compared to an equivalent unreinforced material, the presence of the array of NPR zones contributed to a 26% increase in tensile strength. Moreover, when compared to a nanocomposite containing a homogeneous distribution of nanoparticles, a 30% increase in toughness was observed. High nanohardness values obtained for the NPR zones and the observation of “pull-out” phenomena on fracture surfaces, suggest that the NPR zones behave as “hard” fiber-like units that can effectively sustain tensile loading and thereby enhance the strengthening efficiency of sn-B4C. Also, the presence of the array of NPR zones surrounded by nanoparticle-free (NPF) zones led to an enhancement in strength with limited loss in ductility. This behavior was rationalized on the basis of a low value of the Schmid factor in regions adjacent to NPR zones, coupled with the ease of dislocation movement in NPF zones. Finally, the ratio of the plastic zone size to the size of the “hard” NPR zones is proposed as an important factor that governs the overall toughness of the nanocomposite.

@article{ma_coupling_2016,
	title = {Coupling of dislocations and precipitates: {Impact} on the mechanical behavior of ultrafine grained {Al}–{Zn}–{Mg} alloys},
	volume = {103},
	issn = {1359-6454},
	shorttitle = {Coupling of dislocations and precipitates},
	url = {http://www.sciencedirect.com/science/article/pii/S1359645415006837},
	doi = {10.1016/j.actamat.2015.09.017},
	abstract = {Intragranular coupling of dislocations and precipitates is accomplished in an ultrafine grained aluminum 7000 series alloy through a unique thermo-mechanical processing route that involves high strain rate extrusion at ambient temperature as the last step. The as-extruded materials also exhibited a unique bimodal microstructure consisting of: (1) elongated lamellar grains with dimensions of ∼1 μm consisting of sub-grains via low angle grain boundaries, and (2) ultrafine grains approximately ∼100 nm in size with high angle grain boundaries. Our investigation shows that coupling of dislocations and precipitates within the ultrafine grains has a beneficial impact on the mechanical behavior, and results in an extremely high strength, i.e., ultimate tensile strength ∼878 MPa, with uniform elongation of 4.1\% strain at fracture. Interestingly, the T6 temper leads to a decrease in strength for the ultrafine grained material with intragranular dislocations while it enhances ductility, which is opposite the behavior observed in the ultrafine grained material that does not contain a high density of intragranular dislocations. This phenomenon is attributed to the loss in dislocation strengthening and grain boundary strengthening, which could not be compensated for by the strength increase due to precipitation. The underlying mechanisms are discussed on the basis of in-situ heating in a transmission electron microscope, theoretical analysis of diffusion controlled precipitation and microstructure characterization, including transmission Kikuchi diffraction.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Acta Materialia},
	author = {Ma, Kaka and Hu, Tao and Yang, Hanry and Topping, Troy and Yousefiani, Ali and Lavernia, Enrique J. and Schoenung, Julie M.},
	month = jan,
	year = {2016},
	keywords = {Aluminum alloy, Deformation, Dislocations, Precipitation, Published, Reviewed, Ultrafine grained},
	pages = {153--164},
}

Intragranular coupling of dislocations and precipitates is accomplished in an ultrafine grained aluminum 7000 series alloy through a unique thermo-mechanical processing route that involves high strain rate extrusion at ambient temperature as the last step. The as-extruded materials also exhibited a unique bimodal microstructure consisting of: (1) elongated lamellar grains with dimensions of ∼1 μm consisting of sub-grains via low angle grain boundaries, and (2) ultrafine grains approximately ∼100 nm in size with high angle grain boundaries. Our investigation shows that coupling of dislocations and precipitates within the ultrafine grains has a beneficial impact on the mechanical behavior, and results in an extremely high strength, i.e., ultimate tensile strength ∼878 MPa, with uniform elongation of 4.1% strain at fracture. Interestingly, the T6 temper leads to a decrease in strength for the ultrafine grained material with intragranular dislocations while it enhances ductility, which is opposite the behavior observed in the ultrafine grained material that does not contain a high density of intragranular dislocations. This phenomenon is attributed to the loss in dislocation strengthening and grain boundary strengthening, which could not be compensated for by the strength increase due to precipitation. The underlying mechanisms are discussed on the basis of in-situ heating in a transmission electron microscope, theoretical analysis of diffusion controlled precipitation and microstructure characterization, including transmission Kikuchi diffraction.

@article{vu_graphene_2016,
	title = {Graphene {Nano}-{Platelets} {Reinforced} {ZrO2} {Consolidated} by {Spark} {Plasma} {Sintering}},
	volume = {8},
	doi = {10.1166/sam.2016.2485},
	abstract = {ZrO2/graphene nano-platelets (GNPs) composites were sintered by spark plasma sintering (SPS). Microstructure and surface morphology were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The mechanical properties of composites with various
GPN contents were investigated employing nano-indentation techniques. Transitional behavior in hardness and elastic modulus of the composites was found and attributed to the beneficial effects of GNP addition. The experimental results have shown that the addition of GNPs could also lead to
inhibition of crystal growth and enhance fracture toughness as well as hardness value of consolidated composites.},
	number = {2},
	journal = {Science of Advanced Materials},
	author = {Vu, Duc-Thuan and Han, Young-Hwan and Chen, Fei and Jin, Dongqin and Schoenung, Julie M. and Lee, Dong-Yeon},
	month = feb,
	year = {2016},
	keywords = {MECHANICAL PROPERTY, Published, Reviewed, SPARK PLASMA SINTERING, ZRO2/GNP COMPOSITE},
	pages = {312--317},
}

ZrO2/graphene nano-platelets (GNPs) composites were sintered by spark plasma sintering (SPS). Microstructure and surface morphology were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The mechanical properties of composites with various GPN contents were investigated employing nano-indentation techniques. Transitional behavior in hardness and elastic modulus of the composites was found and attributed to the beneficial effects of GNP addition. The experimental results have shown that the addition of GNPs could also lead to inhibition of crystal growth and enhance fracture toughness as well as hardness value of consolidated composites.

@article{zhang_metal/ceramic_2015,
	title = {Metal/ceramic {Interface} {Structures} and {Segregation} {Behavior} in {Aluminum}-based {Composites}},
	volume = {21},
	copyright = {Copyright © Microscopy Society of America 2015},
	issn = {14319276},
	url = {https://search.proquest.com/docview/1871737868?pq-origsite=gscholar},
	doi = {http://dx.doi.org/10.1017/S1431927615006066},
	language = {English},
	urldate = {2018-01-08},
	journal = {Microscopy and Microanalysis; Cambridge},
	author = {Zhang, Xinming and Hu, Tao and Rufner, Jorgen F. and LaGrange, Thomas and Campbell, Geoffrey H. and Lavernia, Enrique J. and Schoenung, Julie M. and van Benthem, Klaus},
	month = aug,
	year = {2015},
	keywords = {Biology--Microscopy, Instruments, Not Reviewed, Published},
	pages = {1053--1054},
}

@article{zhang_determination_2015,
	title = {Determination of {Reliable} {Grain} {Boundary} {Orientation} using {Automated} {Crystallographic} {Orientation} {Mapping} in the {Transmission} {Electron} {Microscope}},
	volume = {21},
	copyright = {Copyright © Microscopy Society of America 2015},
	issn = {14319276},
	url = {https://search.proquest.com/docview/1871732583?pq-origsite=gscholar},
	doi = {http://dx.doi.org/10.1017/S1431927615009095},
	language = {English},
	urldate = {2018-01-08},
	journal = {Microscopy and Microanalysis; Cambridge},
	author = {Zhang, Xinming and Rufner, Jorgen F. and LaGrange, Thomas and Castro, Ricardo H. R. and Schoenung, Julie M. and Campell, Geoffrey H. and van Benthem, Klaus},
	month = aug,
	year = {2015},
	note = {pdf from : https://www.cambridge.org/core/services/aop-cambridge-core/content/view/DF812E62170DE8092C60F8723E8DFFCD/S1431927615009095a.pdf/div-class-title-determination-of-reliable-grain-boundary-orientation-using-automated-crystallographic-orientation-mapping-in-the-transmission-electron-microscope-div.pdf},
	keywords = {Biology--Microscopy, Instruments, Not Reviewed, Published},
	pages = {1663--1664},
}

@article{zhang_tem_2015,
	title = {{TEM} study on relationship between stacking faults and non-basal dislocations in {Mg}},
	volume = {95},
	issn = {1478-6435},
	url = {https://doi.org/10.1080/14786435.2015.1100764},
	doi = {10.1080/14786435.2015.1100764},
	abstract = {Recent interest in the study of stacking faults and non-basal slip in Mg alloys is partly based on the argument that these phenomena positively influence mechanical behaviour. Inspection of the published literature, however, reveals that there is a lack of fundamental information on the mechanisms that govern the formation of stacking faults, especially I1-type stacking faults (I1 faults). Moreover, controversial and sometimes contradictory mechanisms have been proposed concerning the interactions between stacking faults and dislocations. Therefore, we describe a fundamental transmission electron microscope investigation on Mg 2.5 at. \% Y (Mg–2.5Y) processed via hot isostatic pressing (HIP) and extrusion at 623 K. In the as-HIPed Mg–2.5Y, many 〈c〉 and 〈a〉 dislocations, together with some 〈c + a〉 dislocations were documented, but no stacking faults were observed. In contrast, in the as-extruded Mg–2.5Y, a relatively high density of stacking faults and some non-basal dislocations were documented. Specifically, there were three different cases for the configurations of observed stacking faults. Case (I): pure I2 faults; Case (II): mixture of I1 faults and non-basal dislocations having 〈c〉 component, together with basal 〈a〉 dislocations; Case (III): mixture of predominant I2 faults and rare I1 faults, together with jog-like dislocation configuration. By comparing the differences in extended defect configurations, we propose three distinct stacking fault formation mechanisms for each case in the context of slip activity and point defect generation during extrusion. Furthermore, we discuss the role of stacking faults on deformation mechanisms in the context of dynamic interactions between stacking faults and non-basal slip.},
	number = {34},
	urldate = {2018-01-08},
	journal = {Philosophical Magazine},
	author = {Zhang, Dalong and Jiang, Lin and Schoenung, Julie M. and Mahajan, Subhash and Lavernia, Enrique J.},
	month = dec,
	year = {2015},
	keywords = {Mg-rare earth alloys, Published, Reviewed, non-basal dislocations, point defects, stacking faults, transmission electron microscopy},
	pages = {3823--3844},
}

Recent interest in the study of stacking faults and non-basal slip in Mg alloys is partly based on the argument that these phenomena positively influence mechanical behaviour. Inspection of the published literature, however, reveals that there is a lack of fundamental information on the mechanisms that govern the formation of stacking faults, especially I1-type stacking faults (I1 faults). Moreover, controversial and sometimes contradictory mechanisms have been proposed concerning the interactions between stacking faults and dislocations. Therefore, we describe a fundamental transmission electron microscope investigation on Mg 2.5 at. % Y (Mg–2.5Y) processed via hot isostatic pressing (HIP) and extrusion at 623 K. In the as-HIPed Mg–2.5Y, many 〈c〉 and 〈a〉 dislocations, together with some 〈c + a〉 dislocations were documented, but no stacking faults were observed. In contrast, in the as-extruded Mg–2.5Y, a relatively high density of stacking faults and some non-basal dislocations were documented. Specifically, there were three different cases for the configurations of observed stacking faults. Case (I): pure I2 faults; Case (II): mixture of I1 faults and non-basal dislocations having 〈c〉 component, together with basal 〈a〉 dislocations; Case (III): mixture of predominant I2 faults and rare I1 faults, together with jog-like dislocation configuration. By comparing the differences in extended defect configurations, we propose three distinct stacking fault formation mechanisms for each case in the context of slip activity and point defect generation during extrusion. Furthermore, we discuss the role of stacking faults on deformation mechanisms in the context of dynamic interactions between stacking faults and non-basal slip.

@article{balog_thermal_2015,
	title = {On the thermal stability of ultrafine-grained {Al} stabilized by in-situ amorphous {Al2O3} network},
	volume = {648},
	issn = {0921-5093},
	url = {http://www.sciencedirect.com/science/article/pii/S0921509315303774},
	doi = {10.1016/j.msea.2015.09.037},
	abstract = {Bulk Al materials with average grain sizes of 0.47 and 2.4µm, were fabricated by quasi-isostatic forging consolidation of two types of Al powders with average particle sizes of 1.3 and 8.9μm, respectively. By utilizing the native amorphous Al2O3 (am-Al2O3) film on the Al powders surfaces, a continuous, ∼7nm thick, am-Al2O3 network was formed in situ in the Al specimens. Systematic investigation of the changes to the am-Al2O3 network embedded in the Al matrix upon heating and annealing up to 600°C was performed by transmission electron microscopy (TEM). At the same time, the stability of the Al grain structure was studied by transmission Kikuchi diffraction (TKD), electron back-scatter diffraction (EBSD), and TEM. The am-Al2O3 network remained stable after annealing at 400°C for 24h. In-situ TEM studies revealed that at temperatures ≥450°C, phase transformation of the am-Al2O3 network to crystalline γ-Al2O3 particles occurred. After annealing at 600°C for 24h the transformation was completed, whereby only nanometric γ-Al2O3 particles with an average size of 28nm resided on the high angle grain boundaries of Al. Due to the pinning effect of γ-Al2O3, the Al grain and subgrain structures remained unchanged during annealing up to 600°C for 24h. The effect of the am-Al2O3→γ-Al2O3 transformation on the mechanical properties of ultrafine- and fine-grained Al is discussed from the standpoint of the underlying mechanisms.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Materials Science and Engineering: A},
	author = {Balog, Martin and Hu, Tao and Krizik, Peter and Castro Riglos, Maria Victoria and Saller, Brandon D. and Yang, Hanry and Schoenung, Julie M. and Lavernia, Enrique J.},
	month = nov,
	year = {2015},
	keywords = {Alumina (AlO), Aluminum (Al), Metal matrix composite (MMC), Powder metallurgy (PM), Published, Reviewed, Thermal stability, Ultrafine-grained (UFG) materials},
	pages = {61--71},
}

Bulk Al materials with average grain sizes of 0.47 and 2.4µm, were fabricated by quasi-isostatic forging consolidation of two types of Al powders with average particle sizes of 1.3 and 8.9μm, respectively. By utilizing the native amorphous Al2O3 (am-Al2O3) film on the Al powders surfaces, a continuous, ∼7nm thick, am-Al2O3 network was formed in situ in the Al specimens. Systematic investigation of the changes to the am-Al2O3 network embedded in the Al matrix upon heating and annealing up to 600°C was performed by transmission electron microscopy (TEM). At the same time, the stability of the Al grain structure was studied by transmission Kikuchi diffraction (TKD), electron back-scatter diffraction (EBSD), and TEM. The am-Al2O3 network remained stable after annealing at 400°C for 24h. In-situ TEM studies revealed that at temperatures ≥450°C, phase transformation of the am-Al2O3 network to crystalline γ-Al2O3 particles occurred. After annealing at 600°C for 24h the transformation was completed, whereby only nanometric γ-Al2O3 particles with an average size of 28nm resided on the high angle grain boundaries of Al. Due to the pinning effect of γ-Al2O3, the Al grain and subgrain structures remained unchanged during annealing up to 600°C for 24h. The effect of the am-Al2O3→γ-Al2O3 transformation on the mechanical properties of ultrafine- and fine-grained Al is discussed from the standpoint of the underlying mechanisms.

@article{zhang_two-step_2015,
	title = {Two-{Step} {SPD} {Processing} of a {Trimodal} {Al}-{Based} {Nano}-{Composite}},
	volume = {46},
	issn = {1073-5623, 1543-1940},
	url = {https://link.springer.com/article/10.1007/s11661-015-3151-6},
	doi = {10.1007/s11661-015-3151-6},
	abstract = {An ultrafine-grained (UFG) aluminum nano-composite was fabricated using two severe plastic deformation steps: cryomilling of powders (and subsequent consolidation of blended powders by forging) followed by high-pressure torsion (HPT). The forged bulk composite featured a trimodal structure comprised of UFG, coarse grain (CG) regions, and ceramic particles. The additional HPT processing introduced finer grain sizes and altered the morphology and spatial distribution of the ductile CG regions. As a result, both strength and ductility increased substantially compared to those of the Al nano-composite prior to HPT. The increases were attributed to the more optimal shape and spacing of the CG regions which promoted uniform elongation and yielding during tensile loading. Microstructural changes were characterized at each processing step to establish the evolution of microstructure and to elucidate structure-property relationships. The toughening effect of the CG regions was documented via fracture analysis, providing a potential strategy for designing microstructures with enhanced strength and toughness.},
	language = {en},
	number = {12},
	urldate = {2018-01-08},
	journal = {Metallurgical and Materials Transactions A},
	author = {Zhang, Yuzheng and Sabbaghianrad, Shima and Yang, Hanry and Topping, Troy D. and Langdon, Terence G. and Lavernia, Enrique J. and Schoenung, Julie M. and Nutt, Steven R.},
	month = dec,
	year = {2015},
	keywords = {Published, Reviewed},
	pages = {5877--5886},
}

An ultrafine-grained (UFG) aluminum nano-composite was fabricated using two severe plastic deformation steps: cryomilling of powders (and subsequent consolidation of blended powders by forging) followed by high-pressure torsion (HPT). The forged bulk composite featured a trimodal structure comprised of UFG, coarse grain (CG) regions, and ceramic particles. The additional HPT processing introduced finer grain sizes and altered the morphology and spatial distribution of the ductile CG regions. As a result, both strength and ductility increased substantially compared to those of the Al nano-composite prior to HPT. The increases were attributed to the more optimal shape and spacing of the CG regions which promoted uniform elongation and yielding during tensile loading. Microstructural changes were characterized at each processing step to establish the evolution of microstructure and to elucidate structure-property relationships. The toughening effect of the CG regions was documented via fracture analysis, providing a potential strategy for designing microstructures with enhanced strength and toughness.

@article{moreno_integrated_2015,
	title = {An integrated approach for probing the structure and mechanical properties of diatoms: {Toward} engineered nanotemplates},
	volume = {25},
	issn = {1742-7061},
	shorttitle = {An integrated approach for probing the structure and mechanical properties of diatoms},
	url = {http://www.sciencedirect.com/science/article/pii/S174270611530026X},
	doi = {10.1016/j.actbio.2015.07.028},
	abstract = {The wide variety of diatom frustule shapes and intricate architectures provide viable prototypes to guide the design and fabrication of nanodevices and nanostructured materials for applications ranging from sensors to nanotemplates. In this study, a combined experimental–simulation method was developed to probe the porous structure and mechanical behavior of two distinct marine diatom species, Coscinodiscus sp. (centric) and Synedra sp. (pennate), through ambient nanoindentation and finite element method analysis. These diatom frustule dimensions differed largely depending on diatom species with pore diameters d ranging from 0.3 to 3.0μm. Young’s modulus E and hardness H measurements of the diatom frustules were obtained via nanoindentation experiments. These values varied depending on diatom species (E between 1.1–10.6GPa, H between 0.10–1.03GPa for the Coscinodiscus sp.; and E between 13.7–18.6GPa, H between 0.85–1.41GPa for the Synedra sp.). Additionally, the mechanical response of diatom structures to uniform compression was examined. Predictive simulations were performed on the aforementioned diatom frustules, as well as another diatom structure (pennate Fragilariopsis kerguelensis), to correlate the mechanical response with specific morphology variables (e.g., pore or slit sizes). Results from calculated von Mises stress and displacement distributions unveil unique information on the effect that uniform loads have on these frustules, which can aid the design of tailored nanotemplates. A correlation between mechanical properties and porosity was established for selected frustules, and reported for the first time in this study.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Acta Biomaterialia},
	author = {Moreno, Miguel Diaz and Ma, Kaka and Schoenung, Julie and Dávila, Lilian P.},
	month = oct,
	year = {2015},
	keywords = {Bio-inspired materials, Diatoms, Mechanical properties, Nanoindentation, Published, Reviewed, Simulation},
	pages = {313--324},
}

The wide variety of diatom frustule shapes and intricate architectures provide viable prototypes to guide the design and fabrication of nanodevices and nanostructured materials for applications ranging from sensors to nanotemplates. In this study, a combined experimental–simulation method was developed to probe the porous structure and mechanical behavior of two distinct marine diatom species, Coscinodiscus sp. (centric) and Synedra sp. (pennate), through ambient nanoindentation and finite element method analysis. These diatom frustule dimensions differed largely depending on diatom species with pore diameters d ranging from 0.3 to 3.0μm. Young’s modulus E and hardness H measurements of the diatom frustules were obtained via nanoindentation experiments. These values varied depending on diatom species (E between 1.1–10.6GPa, H between 0.10–1.03GPa for the Coscinodiscus sp.; and E between 13.7–18.6GPa, H between 0.85–1.41GPa for the Synedra sp.). Additionally, the mechanical response of diatom structures to uniform compression was examined. Predictive simulations were performed on the aforementioned diatom frustules, as well as another diatom structure (pennate Fragilariopsis kerguelensis), to correlate the mechanical response with specific morphology variables (e.g., pore or slit sizes). Results from calculated von Mises stress and displacement distributions unveil unique information on the effect that uniform loads have on these frustules, which can aid the design of tailored nanotemplates. A correlation between mechanical properties and porosity was established for selected frustules, and reported for the first time in this study.

@article{song_influence_2015,
	title = {Influence of interfaces on the mechanical behavior of {SiC} particulate-reinforced {Al}–{Zn}–{Mg}–{Cu} composites},
	volume = {644},
	issn = {0921-5093},
	url = {http://www.sciencedirect.com/science/article/pii/S0921509315302021},
	doi = {10.1016/j.msea.2015.07.050},
	abstract = {In particulate-reinforced metal matrix composites (MMCs), geometrically necessary dislocations (GNDs) form in the vicinity of reinforcement/matrix interfaces. In this study, the hardness distribution across the interface was studied using nanoindentation with high spatial resolution, for composites treated under different aging conditions. The size of the GND punched zone, as determined from the hardness measurement, was found to be in agreement with that estimated by transmission electron microscopy (TEM). Mechanical characterization of bulk composites revealed a reduction in failure strain with decreasing punched zone size, while the strength of the composites was found to depend more on the intrinsic strength of the matrix alloy. These observations were interpreted in terms of the load transfer capacity between the matrix and reinforcement through the interface.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Materials Science and Engineering: A},
	author = {Song, Jingya and Guo, Qiang and Ouyang, Qiubao and Su, Yishi and Zhang, Jie and Lavernia, Enrique J. and Schoenung, Julie M. and Zhang, Di},
	month = sep,
	year = {2015},
	keywords = {Aging, Dislocation distribution, Interface structure, Metal matrix composites, Nanoindentation, Published, Reviewed},
	pages = {79--84},
}

In particulate-reinforced metal matrix composites (MMCs), geometrically necessary dislocations (GNDs) form in the vicinity of reinforcement/matrix interfaces. In this study, the hardness distribution across the interface was studied using nanoindentation with high spatial resolution, for composites treated under different aging conditions. The size of the GND punched zone, as determined from the hardness measurement, was found to be in agreement with that estimated by transmission electron microscopy (TEM). Mechanical characterization of bulk composites revealed a reduction in failure strain with decreasing punched zone size, while the strength of the composites was found to depend more on the intrinsic strength of the matrix alloy. These observations were interpreted in terms of the load transfer capacity between the matrix and reinforcement through the interface.

@article{wen_efficient_2015,
	title = {An {Efficient} and {Cost}-{Effective} {Method} for {Preparing} {Transmission} {Electron} {Microscopy} {Samples} from {Powders}},
	volume = {21},
	issn = {1431-9276, 1435-8115},
	url = {https://www.cambridge.org/core/journals/microscopy-and-microanalysis/article/an-efficient-and-cost-effective-method-for-preparing-transmission-electron-microscopy-samples-from-powders/0EF7E43BF2871DB22D6D091061A44570},
	doi = {10.1017/S1431927615014695},
	abstract = {Abstract
The preparation of transmission electron microcopy (TEM) samples from powders with particle sizes larger than {\textasciitilde}100 nm poses a challenge. The existing methods are complicated and expensive, or have a low probability of success. Herein, we report a modified methodology for preparation of TEM samples from powders, which is efficient, cost-effective, and easy to perform. This method involves mixing powders with an epoxy on a piece of weighing paper, curing the powder–epoxy mixture to form a bulk material, grinding the bulk to obtain a thin foil, punching TEM discs from the foil, dimpling the discs, and ion milling the dimpled discs to electron transparency. Compared with the well established and robust grinding–dimpling–ion-milling method for TEM sample preparation for bulk materials, our modified approach for preparing TEM samples from powders only requires two additional simple steps. In this article, step-by-step procedures for our methodology are described in detail, and important strategies to ensure success are elucidated. Our methodology has been applied successfully for preparing TEM samples with large thin areas and high quality for many different mechanically milled metallic powders.},
	language = {en},
	number = {5},
	urldate = {2018-01-08},
	journal = {Microscopy and Microanalysis},
	author = {Wen, Haiming and Lin, Yaojun and Seidman, David N. and Schoenung, Julie M. and Rooyen, Isabella J. van and Lavernia, Enrique J.},
	month = oct,
	year = {2015},
	keywords = {Published, Reviewed, TEM, epoxy, ion milling, powders, sample preparation},
	pages = {1184--1194},
}

Abstract The preparation of transmission electron microcopy (TEM) samples from powders with particle sizes larger than ~100 nm poses a challenge. The existing methods are complicated and expensive, or have a low probability of success. Herein, we report a modified methodology for preparation of TEM samples from powders, which is efficient, cost-effective, and easy to perform. This method involves mixing powders with an epoxy on a piece of weighing paper, curing the powder–epoxy mixture to form a bulk material, grinding the bulk to obtain a thin foil, punching TEM discs from the foil, dimpling the discs, and ion milling the dimpled discs to electron transparency. Compared with the well established and robust grinding–dimpling–ion-milling method for TEM sample preparation for bulk materials, our modified approach for preparing TEM samples from powders only requires two additional simple steps. In this article, step-by-step procedures for our methodology are described in detail, and important strategies to ensure success are elucidated. Our methodology has been applied successfully for preparing TEM samples with large thin areas and high quality for many different mechanically milled metallic powders.

@article{zhang_metal/ceramic_2015-1,
	title = {Metal/ceramic interface structures and segregation behavior in aluminum-based composites},
	volume = {95},
	issn = {1359-6454},
	url = {http://www.sciencedirect.com/science/article/pii/S1359645415003420},
	doi = {10.1016/j.actamat.2015.05.021},
	abstract = {Trimodal Al alloy (AA) matrix composites consisting of ultrafine-grained (UFG) and coarse-grained (CG) Al phases and micron-sized B4C ceramic reinforcement particles exhibit combinations of strength and ductility that render them useful for potential applications in the aerospace, defense and automotive industries. Tailoring of microstructures with specific mechanical properties requires a detailed understanding of interfacial structures to enable strong interface bonding between ceramic reinforcement and metal matrix, and thereby allow for effective load transfer. Trimodal AA metal matrix composites typically show three characteristics that are noteworthy: nanocrystalline grains in the vicinity of the B4C reinforcement particles; Mg segregation at AA/B4C interfaces; and the presence of amorphous interfacial layers separating nanocrystalline grains from B4C particles. Interestingly, however, fundamental information related to the mechanisms responsible for these characteristics as well as information on local compositions and phases are absent in the current literature. In this study, we use high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy-loss spectroscopy, and precession assisted electron diffraction to gain fundamental insight into the mechanisms that affect the characteristics of AA/B4C interfaces. Specifically, we determined interfacial structures, local composition and spatial distribution of the interfacial constituents. Near atomic resolution characterization revealed amorphous multilayers and a nanocrystalline region between Al phase and B4C reinforcement particles. The amorphous layers consist of nonstoichiometric AlxOy, while the nanocrystalline region is comprised of MgO nanograins. The experimental results are discussed in terms of the possible underlying mechanisms at AA/B4C interfaces.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Acta Materialia},
	author = {Zhang, Xinming and Hu, Tao and Rufner, Jorgen F. and LaGrange, Thomas B. and Campbell, Geoffrey H. and Lavernia, Enrique J. and Schoenung, Julie M. and van Benthem, Klaus},
	month = aug,
	year = {2015},
	keywords = {Aluminum alloy, Interface, Published, Reviewed, Segregation, Transmission electron microscopy},
	pages = {254--263},
}

Trimodal Al alloy (AA) matrix composites consisting of ultrafine-grained (UFG) and coarse-grained (CG) Al phases and micron-sized B4C ceramic reinforcement particles exhibit combinations of strength and ductility that render them useful for potential applications in the aerospace, defense and automotive industries. Tailoring of microstructures with specific mechanical properties requires a detailed understanding of interfacial structures to enable strong interface bonding between ceramic reinforcement and metal matrix, and thereby allow for effective load transfer. Trimodal AA metal matrix composites typically show three characteristics that are noteworthy: nanocrystalline grains in the vicinity of the B4C reinforcement particles; Mg segregation at AA/B4C interfaces; and the presence of amorphous interfacial layers separating nanocrystalline grains from B4C particles. Interestingly, however, fundamental information related to the mechanisms responsible for these characteristics as well as information on local compositions and phases are absent in the current literature. In this study, we use high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy-loss spectroscopy, and precession assisted electron diffraction to gain fundamental insight into the mechanisms that affect the characteristics of AA/B4C interfaces. Specifically, we determined interfacial structures, local composition and spatial distribution of the interfacial constituents. Near atomic resolution characterization revealed amorphous multilayers and a nanocrystalline region between Al phase and B4C reinforcement particles. The amorphous layers consist of nonstoichiometric AlxOy, while the nanocrystalline region is comprised of MgO nanograins. The experimental results are discussed in terms of the possible underlying mechanisms at AA/B4C interfaces.

@article{hu_stabilized_2015,
	title = {Stabilized plasticity in ultrahigh strength, submicron {Al} crystals},
	volume = {94},
	issn = {1359-6454},
	url = {http://www.sciencedirect.com/science/article/pii/S1359645415002967},
	doi = {10.1016/j.actamat.2015.04.044},
	abstract = {It is well known that micrometer-sized and/or submicrometer-sized metallic crystals exhibit “smaller is stronger” size effect: the yield strength σ varies with sample dimension D roughly as a power-law σ∼D−m. For some materials, near-theoretical strength values can be attained by reducing the dimensions of crystals to sub-micrometric or nanometric values. At these size scales, however, plastic instabilities, such as strain bursts, strain softening or low strain hardening rates, become operative due to the avalanche-like dislocation generation and escape; such instabilities contribute to disappointing flow intermittency. From a scientific standpoint, the onset of plastic instabilities has hindered fundamental study of the deformation behavior of materials near theoretical strength values. From a technological standpoint, these instabilities limit potential applications in microelectromechanical devices, for example. In this study we demonstrate that by concurrently introducing grain boundaries and secondary phase particles, plastic instabilities can be dramatically suppressed in submicron Al pillars at large strain and that this behavior is attributable to substantial dislocation storage and subsequent grain boundary (GB) mediated plasticity. Consequently the crystals possess superior strength with flow stress larger than 1.0GPa.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Acta Materialia},
	author = {Hu, Tao and Jiang, Lin and Yang, Hanry and Ma, Kaka and Topping, Troy D. and Yee, Joshua and Li, Meijuan and Mukherjee, Amiya K. and Schoenung, Julie M. and Lavernia, Enrique J.},
	month = aug,
	year = {2015},
	keywords = {Aluminum, Nano-mechanics, Published, Reviewed, Size effect, Submicron crystals, TEM},
	pages = {46--58},
}

It is well known that micrometer-sized and/or submicrometer-sized metallic crystals exhibit “smaller is stronger” size effect: the yield strength σ varies with sample dimension D roughly as a power-law σ∼D−m. For some materials, near-theoretical strength values can be attained by reducing the dimensions of crystals to sub-micrometric or nanometric values. At these size scales, however, plastic instabilities, such as strain bursts, strain softening or low strain hardening rates, become operative due to the avalanche-like dislocation generation and escape; such instabilities contribute to disappointing flow intermittency. From a scientific standpoint, the onset of plastic instabilities has hindered fundamental study of the deformation behavior of materials near theoretical strength values. From a technological standpoint, these instabilities limit potential applications in microelectromechanical devices, for example. In this study we demonstrate that by concurrently introducing grain boundaries and secondary phase particles, plastic instabilities can be dramatically suppressed in submicron Al pillars at large strain and that this behavior is attributable to substantial dislocation storage and subsequent grain boundary (GB) mediated plasticity. Consequently the crystals possess superior strength with flow stress larger than 1.0GPa.

@article{saller_comparative_2015,
	title = {A comparative analysis of solubility, segregation, and phase formation in atomized and cryomilled {Al}–{Fe} alloy powders},
	volume = {50},
	issn = {0022-2461, 1573-4803},
	url = {https://link.springer.com/article/10.1007/s10853-015-9019-8},
	doi = {10.1007/s10853-015-9019-8},
	abstract = {Bulk nanostructured and ultrafine-grained binary Al–Fe alloys have been studied in the past for their remarkable strength, hardness, and thermal stability. These properties have been attributed to a combination of solid solution strengthening, precipitate strengthening, and grain boundary strengthening. However, to date, no systematic investigation has been performed to address the factors that govern the evolution of the various metastable and equilibrium precipitates that form as a result of thermal exposure. In this study, Al–2at.\%Fe and Al–5at.\%Fe powders were synthesized via helium gas atomization and argon gas atomization, respectively. Cooling rates upwards of 106 K s−1 were achieved resulting in an intermetallic-free starting structure, and a map of the structure as a function of cooling rate was established. Electron backscatter diffraction analysis revealed the presence of a larger number of low-angle grain boundaries relative to high-angle grain boundaries, which influenced nucleation and precipitation of the metastable Al6Fe phase. Cryomilling of the atomized powder was subsequently performed, which led to grain refinement into the nanometer regime, dispersion of the Fe-containing phases, and forcing of 2at.\%Fe into solution within the Al matrix compared to negligible Fe in solution in the as-atomized state. Finally, differential scanning calorimetry was utilized to elucidate the metastable Al6Fe precipitation temperature ({\textasciitilde}300 °C) and subsequent phase transformation to the equilibrium Al13Fe4 phase ({\textasciitilde}400 °C). An activation energy analysis utilizing the Kissinger method revealed three important factors, in order of importance, for ease of Al6Fe precipitation: segregated regions containing iron, availability of nucleation sites, and the number of diffusion pathways.},
	language = {en},
	number = {13},
	urldate = {2018-01-08},
	journal = {Journal of Materials Science},
	author = {Saller, Brandon D. and Hu, Tao and Ma, Kaka and Kurmanaeva, Lilia and Lavernia, Enrique J. and Schoenung, Julie M.},
	month = jul,
	year = {2015},
	keywords = {Published, Reviewed},
	pages = {4683--4697},
}

Bulk nanostructured and ultrafine-grained binary Al–Fe alloys have been studied in the past for their remarkable strength, hardness, and thermal stability. These properties have been attributed to a combination of solid solution strengthening, precipitate strengthening, and grain boundary strengthening. However, to date, no systematic investigation has been performed to address the factors that govern the evolution of the various metastable and equilibrium precipitates that form as a result of thermal exposure. In this study, Al–2at.%Fe and Al–5at.%Fe powders were synthesized via helium gas atomization and argon gas atomization, respectively. Cooling rates upwards of 106 K s−1 were achieved resulting in an intermetallic-free starting structure, and a map of the structure as a function of cooling rate was established. Electron backscatter diffraction analysis revealed the presence of a larger number of low-angle grain boundaries relative to high-angle grain boundaries, which influenced nucleation and precipitation of the metastable Al6Fe phase. Cryomilling of the atomized powder was subsequently performed, which led to grain refinement into the nanometer regime, dispersion of the Fe-containing phases, and forcing of 2at.%Fe into solution within the Al matrix compared to negligible Fe in solution in the as-atomized state. Finally, differential scanning calorimetry was utilized to elucidate the metastable Al6Fe precipitation temperature (~300 °C) and subsequent phase transformation to the equilibrium Al13Fe4 phase (~400 °C). An activation energy analysis utilizing the Kissinger method revealed three important factors, in order of importance, for ease of Al6Fe precipitation: segregated regions containing iron, availability of nucleation sites, and the number of diffusion pathways.

@article{hashemi-sadraei_influence_2015,
	title = {The {Influence} of {Grain} {Size} {Determination} {Method} on {Grain} {Growth} {Kinetics} {Analysis}},
	volume = {17},
	issn = {1527-2648},
	url = {http://onlinelibrary.wiley.com/doi/10.1002/adem.201500057/abstract},
	doi = {10.1002/adem.201500057},
	abstract = {The full-width at half-maximum (FWHM), integral width (IntW), and Scherrer methodologies were used jointly with X-ray diffraction (XRD) peak broadening and transmission electron microscopy (TEM) data to provide insight into the mechanisms that govern grain growth behavior in an Al 5083-B4C nanocomposite. Grain growth kinetics were studied by fitting the appropriate grain size data from the three XRD-based methods to the well-known Burke equation. Variations observed in the absolute grain sizes calculated from different methods were in agreement with previous studies. In spite of these variations, consistent grain growth trends were observed, which resulted in relatively similar Arrhenius plots indicating two grain growth regimes. Consequently, the applicability as well as any relevant uncertainties within each method are described and discussed.},
	language = {en},
	number = {11},
	urldate = {2018-01-08},
	journal = {Advanced Engineering Materials},
	author = {Hashemi-Sadraei, Leyla and Mousavi, S. Ebrahim and Lavernia, Enrique J. and Schoenung, Julie M.},
	month = nov,
	year = {2015},
	keywords = {Published, Reviewed},
	pages = {1598--1607},
}

The full-width at half-maximum (FWHM), integral width (IntW), and Scherrer methodologies were used jointly with X-ray diffraction (XRD) peak broadening and transmission electron microscopy (TEM) data to provide insight into the mechanisms that govern grain growth behavior in an Al 5083-B4C nanocomposite. Grain growth kinetics were studied by fitting the appropriate grain size data from the three XRD-based methods to the well-known Burke equation. Variations observed in the absolute grain sizes calculated from different methods were in agreement with previous studies. In spite of these variations, consistent grain growth trends were observed, which resulted in relatively similar Arrhenius plots indicating two grain growth regimes. Consequently, the applicability as well as any relevant uncertainties within each method are described and discussed.

@article{li_effects_2015,
	title = {Effects of {Sb} oxidation state on the densification and electrical properties of antimony-doped tin oxide ceramics},
	volume = {26},
	issn = {0957-4522, 1573-482X},
	url = {https://link.springer.com/article/10.1007/s10854-015-2938-y},
	doi = {10.1007/s10854-015-2938-y},
	abstract = {For antimony-doped tin oxide (ATO), Sb content and oxidation state remarkably influence the densification, microstructure and electrical properties of ATO ceramics. In this work, ATO powders doped with Sb(III) or Sb(V) are prepared via chemical precipitation method and are then consolidated by spark plasma sintering (SPS). Results demonstrate that ATO ceramics with a small content of nanoscaled antimony oxides, either Sb(III) or Sb(V), can be densified through the rapid SPS process. The relative density of 1.5 mol\% Sb-doped samples is greater than 96.5 \%. However, increased Sb doping concentration, especially for Sb(V), restrains both the densification and grain growth in SPS-consolidated ATO. In contrast, Sb(V)-doped material exhibits improved electrical conductivity. The resistivity of 1.5 mol\% Sb(V)-doped sample is only 0.01699 Ω cm, far lower than that of the 1.5 mol\% Sb(III)-doped sample (0.1338 Ω cm). XPS results indicate a higher Sb5+/Sb3+ ratio in Sb(V)-doped ATO powder and ceramic than in Sb(III)-doped samples. The higher Sb5+/Sb3+ ratio contributes to the increase of carrier concentration and the decrease of resistivity of ATO ceramics.},
	language = {en},
	number = {6},
	urldate = {2018-01-08},
	journal = {Journal of Materials Science: Materials in Electronics},
	author = {Li, Mei-juan and Cheng, Ping and Luo, Guo-qiang and Schoenung, Julie M. and Shen, Qiang},
	month = jun,
	year = {2015},
	keywords = {Published, Reviewed},
	pages = {4015--4020},
}

For antimony-doped tin oxide (ATO), Sb content and oxidation state remarkably influence the densification, microstructure and electrical properties of ATO ceramics. In this work, ATO powders doped with Sb(III) or Sb(V) are prepared via chemical precipitation method and are then consolidated by spark plasma sintering (SPS). Results demonstrate that ATO ceramics with a small content of nanoscaled antimony oxides, either Sb(III) or Sb(V), can be densified through the rapid SPS process. The relative density of 1.5 mol% Sb-doped samples is greater than 96.5 %. However, increased Sb doping concentration, especially for Sb(V), restrains both the densification and grain growth in SPS-consolidated ATO. In contrast, Sb(V)-doped material exhibits improved electrical conductivity. The resistivity of 1.5 mol% Sb(V)-doped sample is only 0.01699 Ω cm, far lower than that of the 1.5 mol% Sb(III)-doped sample (0.1338 Ω cm). XPS results indicate a higher Sb5+/Sb3+ ratio in Sb(V)-doped ATO powder and ceramic than in Sb(III)-doped samples. The higher Sb5+/Sb3+ ratio contributes to the increase of carrier concentration and the decrease of resistivity of ATO ceramics.

@article{yang_novel_2015,
	title = {Novel fabrication of bulk {Al} with gradient grain size distributions via powder metallurgy},
	volume = {95},
	issn = {0950-0839},
	url = {https://doi.org/10.1080/09500839.2015.1028504},
	doi = {10.1080/09500839.2015.1028504},
	abstract = {We describe a novel approach to synthesize gradient microstructures, defined hereafter as containing a broad but continuous distribution of grain sizes. These microstructures extend the concept of a bimodal grain size distribution and the ability to design with multiple length scales. We demonstrate the proposed approach via experiments involving cryogenic ball milling of Al–4.5Mg–0.4Mn–0.05Fe and Al–50Mg powder followed by subsequent consolidation. Our results reveal that the grains in the consolidated powder present a gradient size distribution ranging from {\textless}100 nm to {\textgreater}3 μm. Moreover, phase composition analysis revealed a unique “interfingered” structure where the two starting phases were intermixed in a complex three-dimensional mesh. Hardness studies of this gradient microstructure show average Vickers hardness values of 200 ± 2.6, 204 ± 4.3 and 266 ± 50 for macrohardness, microhardness and nanoindentation, respectively. The standard deviation values highlight that the gradient microstructure is disordered locally, but homogenous macroscopically.},
	number = {3},
	urldate = {2018-01-08},
	journal = {Philosophical Magazine Letters},
	author = {Yang, Hanry and Lavernia, Enrique J. and Schoenung, Julie M.},
	month = mar,
	year = {2015},
	keywords = {Published, Reviewed, aluminium alloys, gradient cryomilling, microstructural characterization, nanograined structures},
	pages = {177--186},
}

We describe a novel approach to synthesize gradient microstructures, defined hereafter as containing a broad but continuous distribution of grain sizes. These microstructures extend the concept of a bimodal grain size distribution and the ability to design with multiple length scales. We demonstrate the proposed approach via experiments involving cryogenic ball milling of Al–4.5Mg–0.4Mn–0.05Fe and Al–50Mg powder followed by subsequent consolidation. Our results reveal that the grains in the consolidated powder present a gradient size distribution ranging from \textless100 nm to \textgreater3 μm. Moreover, phase composition analysis revealed a unique “interfingered” structure where the two starting phases were intermixed in a complex three-dimensional mesh. Hardness studies of this gradient microstructure show average Vickers hardness values of 200 ± 2.6, 204 ± 4.3 and 266 ± 50 for macrohardness, microhardness and nanoindentation, respectively. The standard deviation values highlight that the gradient microstructure is disordered locally, but homogenous macroscopically.

@article{jiang_influence_2015,
	title = {Influence of length-scales on spatial distribution and interfacial characteristics of {B4C} in a nanostructured {Al} matrix},
	volume = {89},
	issn = {1359-6454},
	url = {http://www.sciencedirect.com/science/article/pii/S1359645415000750},
	doi = {10.1016/j.actamat.2015.01.062},
	abstract = {To provide fundamental insight into the influence of length scales on the spatial distribution and characteristics of ceramic/metal interfaces in nanostructured metal matrix composites, we studied an Al alloy reinforced with a broad size distribution of B4C particles, ranging from several nanometers to submicrometers. The B4C was incorporated into an ultrafine grained Al matrix using cryomilling and thermomechanical consolidation. The characteristics of the B4C/Al interface, namely the local chemistry and interfacial structure, were studied in detail using transmission electron microscopy (TEM) and atom-probe tomography. Results reveal significant differences in these characteristics as a function of particle length scale. A significant proportion (∼40\%) of B4C nanoparticles was located intragranularly, i.e., within ultrafine grain interiors, whereas submicron B4C particles were surrounded by multiple Al grains, creating intergranular interfaces. Mg–O–N layers, Al2O3 nanoparticles and amorphous regions were observed at the intergranular interfaces, whereas most of the intragranular interfaces were semicoherent and free of other phases or segregation. By combining crystal structure modeling and high-resolution TEM, a specific orientation relationship was identified for the intragranular interfaces: (1−11)Al//(024)B4C, 3.4° angle between (002)Al and (003)B4C, and 7.8° angle between (2−20)Al and (021)B4C. Mechanisms related to length scale effects on the formation of intragranular versus intergranular interfaces and corresponding structures and chemistries are discussed, as well as the implications of these interface characteristics on strength and ductility.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Acta Materialia},
	author = {Jiang, Lin and Wen, Haiming and Yang, Hanry and Hu, Tao and Topping, Troy and Zhang, Dalong and Lavernia, Enrique J. and Schoenung, Julie M.},
	month = may,
	year = {2015},
	keywords = {Grain growth, Interface chemistry, Interface structure, Metal matrix composites, Nanoparticles, Published, Reviewed},
	pages = {327--343},
}

To provide fundamental insight into the influence of length scales on the spatial distribution and characteristics of ceramic/metal interfaces in nanostructured metal matrix composites, we studied an Al alloy reinforced with a broad size distribution of B4C particles, ranging from several nanometers to submicrometers. The B4C was incorporated into an ultrafine grained Al matrix using cryomilling and thermomechanical consolidation. The characteristics of the B4C/Al interface, namely the local chemistry and interfacial structure, were studied in detail using transmission electron microscopy (TEM) and atom-probe tomography. Results reveal significant differences in these characteristics as a function of particle length scale. A significant proportion (∼40%) of B4C nanoparticles was located intragranularly, i.e., within ultrafine grain interiors, whereas submicron B4C particles were surrounded by multiple Al grains, creating intergranular interfaces. Mg–O–N layers, Al2O3 nanoparticles and amorphous regions were observed at the intergranular interfaces, whereas most of the intragranular interfaces were semicoherent and free of other phases or segregation. By combining crystal structure modeling and high-resolution TEM, a specific orientation relationship was identified for the intragranular interfaces: (1−11)Al//(024)B4C, 3.4° angle between (002)Al and (003)B4C, and 7.8° angle between (2−20)Al and (021)B4C. Mechanisms related to length scale effects on the formation of intragranular versus intergranular interfaces and corresponding structures and chemistries are discussed, as well as the implications of these interface characteristics on strength and ductility.

@article{nieto_sintering_2015,
	title = {Sintering behavior of spark plasma sintered alumina with graphene nanoplatelet reinforcement},
	volume = {41},
	issn = {0272-8842},
	url = {http://www.sciencedirect.com/science/article/pii/S0272884215000668},
	doi = {10.1016/j.ceramint.2015.01.027},
	abstract = {Graphene nanoplatelet (GNP) reinforced alumina is synthesized by spark plasma sintering (SPS) using process conditions of 1100–1500°C, 3–10min dwell time, and 45–90MPa in order to investigate the effects of GNP on sintering behavior. High volume fractions of GNP (5–15vol\%) are utilized in order to accentuate effects of GNPs. GNP effects on sintering behavior are assessed by evaluating microstructural evolution, grain growth kinetics, and microhardness. The addition of GNPs is found to suppress grain growth by a grain wrapping mechanism resulting in a 10\% increase in activation energy when GNP content is increased beyond 5vol \%. Grain growth suppression partially mitigates a decrease in hardness due to the introduction of the soft GNP phase. Evidence of GNPs serving as a sintering aid are seen at short sintering times (3min), while densification and grain size are observed to level off with extended sintering time (10min). The application of higher pressures enhances densification, which enables GNPs to more effectively wrap around grains resulting in enhanced grain growth suppression.},
	number = {4},
	urldate = {2018-01-08},
	journal = {Ceramics International},
	author = {Nieto, Andy and Huang, Lin and Han, Young-Hwan and Schoenung, Julie M.},
	month = may,
	year = {2015},
	keywords = {A. Sintering, B. Nanocomposite, Graphene, Published, Reviewed, SPS},
	pages = {5926--5936},
}

Graphene nanoplatelet (GNP) reinforced alumina is synthesized by spark plasma sintering (SPS) using process conditions of 1100–1500°C, 3–10min dwell time, and 45–90MPa in order to investigate the effects of GNP on sintering behavior. High volume fractions of GNP (5–15vol%) are utilized in order to accentuate effects of GNPs. GNP effects on sintering behavior are assessed by evaluating microstructural evolution, grain growth kinetics, and microhardness. The addition of GNPs is found to suppress grain growth by a grain wrapping mechanism resulting in a 10% increase in activation energy when GNP content is increased beyond 5vol %. Grain growth suppression partially mitigates a decrease in hardness due to the introduction of the soft GNP phase. Evidence of GNPs serving as a sintering aid are seen at short sintering times (3min), while densification and grain size are observed to level off with extended sintering time (10min). The application of higher pressures enhances densification, which enables GNPs to more effectively wrap around grains resulting in enhanced grain growth suppression.

@article{kurmanaeva_strengthening_2015,
	title = {Strengthening mechanisms and deformation behavior of cryomilled {Al}–{Cu}–{Mg}–{Ag} alloy},
	volume = {632},
	issn = {0925-8388},
	url = {http://www.sciencedirect.com/science/article/pii/S0925838815002583},
	doi = {10.1016/j.jallcom.2015.01.160},
	abstract = {In the last decade, the commercially available heat-treatable aluminum alloy (AA) 2139 (Al–Cu–Mg–Ag) has generated interest within the aerospace and defense communities because of its high strength and damage tolerance as compared to those of other AA 2XXX alloys. In this work we investigate the possibility of enhancing the performance of AA 2139 via a nanostructuring approach involving the consolidation of cryomilled powders. For comparison purposes, two types of feedstock powders (cryomilled and unmilled, gas-atomized powder), were consolidated via dual mode dynamic forging. Our results show that, following heat treatment (HT), the strength of the cryomilled material increases in the range of ∼25\% to ∼200\% relative to that of the unmilled counterparts, depending on specific processing parameters. We present microstructural data, including grain size and precipitate chemistry, to provide insight into the underlying strengthening mechanisms. Vickers microhardess tests are used to evaluate peak heat treatments, and tensile testing is performed to characterize mechanical behavior. The kinetics of precipitation, strengthening mechanisms and deformation behavior are discussed. It is proposed that the combination of elemental segregation with the presence of oxides along grain boundaries, both facilitated by enhanced diffusion paths, are responsible for the observed change in HT kinetics in the cryomilled material.},
	number = {Supplement C},
	urldate = {2018-01-08},
	journal = {Journal of Alloys and Compounds},
	author = {Kurmanaeva, Lilia and Topping, Troy D. and Wen, Haiming and Sugahara, Haruka and Yang, Hanry and Zhang, Dalong and Schoenung, Julie M. and Lavernia, Enrique J.},
	month = may,
	year = {2015},
	keywords = {Al alloys, Atom probe microscopy, Cryomilling, Precipitation, Published, Reviewed, Strengthening mechanisms, Ultra-fine grained materials},
	pages = {591--603},
}

In the last decade, the commercially available heat-treatable aluminum alloy (AA) 2139 (Al–Cu–Mg–Ag) has generated interest within the aerospace and defense communities because of its high strength and damage tolerance as compared to those of other AA 2XXX alloys. In this work we investigate the possibility of enhancing the performance of AA 2139 via a nanostructuring approach involving the consolidation of cryomilled powders. For comparison purposes, two types of feedstock powders (cryomilled and unmilled, gas-atomized powder), were consolidated via dual mode dynamic forging. Our results show that, following heat treatment (HT), the strength of the cryomilled material increases in the range of ∼25% to ∼200% relative to that of the unmilled counterparts, depending on specific processing parameters. We present microstructural data, including grain size and precipitate chemistry, to provide insight into the underlying strengthening mechanisms. Vickers microhardess tests are used to evaluate peak heat treatments, and tensile testing is performed to characterize mechanical behavior. The kinetics of precipitation, strengthening mechanisms and deformation behavior are discussed. It is proposed that the combination of elemental segregation with the presence of oxides along grain boundaries, both facilitated by enhanced diffusion paths, are responsible for the observed change in HT kinetics in the cryomilled material.

@article{chen_field_2015,
	title = {Field assisted sintering of graphene reinforced zirconia ceramics},
	volume = {41},
	issn = {0272-8842},
	url = {http://www.sciencedirect.com/science/article/pii/S0272884214020689},
	doi = {10.1016/j.ceramint.2014.12.147},
	abstract = {Threemol. \% yttria stabilized zirconia (3Y-TZP) with Graphene platelets (GNPs) powder mixture was produced by ball milling using dimethyl formamide (DMF) as dispersion media. The GNPs-reinforced 3Y-TZP composites were densified ({\textasciitilde}99\%) by field assisted sintering technology (FAST). A homogeneous dispersion of GNPs in 3Y-TZP is observed from the sintered samples, and the GNPs are bent and embedded between the grains, which results in increasing the contact area. The trans-granular mechanism of crack propagation becomes increasingly dominant by adding GNPs. The fracture toughness reaches 15.3MPa·m1/2, as tested by single-edge notched beam method, which reflects an increase of 61\% compared to GNPs-free 3Y-TZP. On the other hand, with higher GNPs content, the improvement in fracture toughness is limited. Toughening mechanisms, as determined through micro-hardness testing, including pull out, crack deflection, crack bridging, and micro-cracks, are observed and discussed.},
	number = {4},
	urldate = {2018-01-08},
	journal = {Ceramics International},
	author = {Chen, Fei and Jin, Dongqin and Tyeb, Khalid and Wang, Botao and Han, Young-Hwan and Kim, Sukyoung and Schoenung, Julie M. and Shen, Qiang and Zhang, Lianmeng},
	month = may,
	year = {2015},
	keywords = {3Y-TZP, Field assisted sintering technology, Fracture toughness, Graphene platelets, Published, Reviewed},
	pages = {6113--6116},
}

Threemol. % yttria stabilized zirconia (3Y-TZP) with Graphene platelets (GNPs) powder mixture was produced by ball milling using dimethyl formamide (DMF) as dispersion media. The GNPs-reinforced 3Y-TZP composites were densified (~99%) by field assisted sintering technology (FAST). A homogeneous dispersion of GNPs in 3Y-TZP is observed from the sintered samples, and the GNPs are bent and embedded between the grains, which results in increasing the contact area. The trans-granular mechanism of crack propagation becomes increasingly dominant by adding GNPs. The fracture toughness reaches 15.3MPa·m1/2, as tested by single-edge notched beam method, which reflects an increase of 61% compared to GNPs-free 3Y-TZP. On the other hand, with higher GNPs content, the improvement in fracture toughness is limited. Toughening mechanisms, as determined through micro-hardness testing, including pull out, crack deflection, crack bridging, and micro-cracks, are observed and discussed.

@article{xue_waste_2015,
	title = {Waste {Management} of {Printed} {Wiring} {Boards}: {A} {Life} {Cycle} {Assessment} of the {Metals} {Recycling} {Chain} from {Liberation} through {Refining}},
	volume = {49},
	issn = {0013-936X},
	shorttitle = {Waste {Management} of {Printed} {Wiring} {Boards}},
	url = {http://dx.doi.org/10.1021/es504750q},
	doi = {10.1021/es504750q},
	abstract = {Due to economic and societal reasons, informal activities including open burning, backyard recycling, and landfill are still the prevailing methods used for electronic waste treatment in developing countries. Great efforts have been made, especially in China, to promote formal approaches for electronic waste management by enacting laws, developing green recycling technologies, initiating pilot programs, etc. The formal recycling process can, however, engender environmental impact and resource consumption, although information on the environmental loads and resource consumption is currently limited. To quantitatively assess the environmental impact of the processes in a formal printed wiring board (PWB) recycling chain, life cycle assessment (LCA) was applied to a formal recycling chain that includes the steps from waste liberation through materials refining. The metal leaching in the refining stage was identified as a critical process, posing most of the environmental impact in the recycling chain. Global warming potential was the most significant environmental impact category after normalization and weighting, followed by fossil abiotic depletion potential, and marine aquatic eco-toxicity potential. Scenario modeling results showed that variations in the power source and chemical reagents consumption had the greatest influence on the environmental performance. The environmental impact from transportation used for PWB collection was also evaluated. The results were further compared to conventional primary metals production processes, highlighting the environmental benefit of metal recycling from waste PWBs. Optimizing the collection mode, increasing the precious metals recovery efficiency in the beneficiation stage and decreasing the chemical reagents consumption in the refining stage by effective materials liberation and separation are proposed as potential improvement strategies to make the recycling chain more environmentally friendly. The LCA results provide environmental information for the improvement of future integrated technologies and electronic waste management.},
	number = {2},
	urldate = {2018-01-08},
	journal = {Environmental Science \& Technology},
	author = {Xue, Mianqiang and Kendall, Alissa and Xu, Zhenming and Schoenung, Julie M.},
	month = jan,
	year = {2015},
	keywords = {Published, Reviewed},
	pages = {940--947},
}

Due to economic and societal reasons, informal activities including open burning, backyard recycling, and landfill are still the prevailing methods used for electronic waste treatment in developing countries. Great efforts have been made, especially in China, to promote formal approaches for electronic waste management by enacting laws, developing green recycling technologies, initiating pilot programs, etc. The formal recycling process can, however, engender environmental impact and resource consumption, although information on the environmental loads and resource consumption is currently limited. To quantitatively assess the environmental impact of the processes in a formal printed wiring board (PWB) recycling chain, life cycle assessment (LCA) was applied to a formal recycling chain that includes the steps from waste liberation through materials refining. The metal leaching in the refining stage was identified as a critical process, posing most of the environmental impact in the recycling chain. Global warming potential was the most significant environmental impact category after normalization and weighting, followed by fossil abiotic depletion potential, and marine aquatic eco-toxicity potential. Scenario modeling results showed that variations in the power source and chemical reagents consumption had the greatest influence on the environmental performance. The environmental impact from transportation used for PWB collection was also evaluated. The results were further compared to conventional primary metals production processes, highlighting the environmental benefit of metal recycling from waste PWBs. Optimizing the collection mode, increasing the precious metals recovery efficiency in the beneficiation stage and decreasing the chemical reagents consumption in the refining stage by effective materials liberation and separation are proposed as potential improvement strategies to make the recycling chain more environmentally friendly. The LCA results provide environmental information for the improvement of future integrated technologies and electronic waste management.

@article{zhang_micro-strain_2015,
	title = {Micro-strain {Evolution} and {Toughening} {Mechanisms} in a {Trimodal} {Al}-{Based} {Metal} {Matrix} {Composite}},
	volume = {46},
	issn = {1073-5623, 1543-1940},
	url = {https://link.springer.com/article/10.1007/s11661-014-2729-8},
	doi = {10.1007/s11661-014-2729-8},
	abstract = {A trimodal metal matrix composite (MMC) based on AA (Al alloy) 5083 (Al-4.4Mg-0.7Mn-0.15Cr wt pct) was synthesized by cryomilling powders followed by compaction of blended powders and ceramic particles using two successive dual mode dynamic forgings. The microstructure consisted of 66.5 vol pct ultrafine grain (UFG) region, 30 vol pct coarse grain (CG) region and 3.5 vol pct reinforcing boron carbide particles. The microstructure imparted high-tensile yield strength (581 MPa) compared to a conventional AA 5083 (242 MPa) and enhanced ductility compared to 100 pct UFG Al MMC. The deformation behavior of the heterogeneous structure and the effects of CG regions on crack propagation were investigated using in situ scanning electron microscopy micro-tensile tests. The micro-strain evolution measured using digital image correlation showed early plastic strain localization in CG regions. Micro-voids due to the strain mismatch at CG/UFG interfaces were responsible for crack initiation. CG region toughening was realized by plasticity-induced crack closure and zone shielding of disconnected micro-cracks. However, these toughening mechanisms did not effectively suppress its brittle behavior. Further optimization of the CG distribution (spacing and morphology) is required to achieve toughness levels required for structural applications.},
	language = {en},
	number = {3},
	urldate = {2018-01-08},
	journal = {Metallurgical and Materials Transactions A},
	author = {Zhang, Yuzheng and Topping, Troy D. and Yang, Hanry and Lavernia, Enrique J. and Schoenung, Julie M. and Nutt, Steven R.},
	month = mar,
	year = {2015},
	keywords = {Published, Reviewed},
	pages = {1196--1204},
}

A trimodal metal matrix composite (MMC) based on AA (Al alloy) 5083 (Al-4.4Mg-0.7Mn-0.15Cr wt pct) was synthesized by cryomilling powders followed by compaction of blended powders and ceramic particles using two successive dual mode dynamic forgings. The microstructure consisted of 66.5 vol pct ultrafine grain (UFG) region, 30 vol pct coarse grain (CG) region and 3.5 vol pct reinforcing boron carbide particles. The microstructure imparted high-tensile yield strength (581 MPa) compared to a conventional AA 5083 (242 MPa) and enhanced ductility compared to 100 pct UFG Al MMC. The deformation behavior of the heterogeneous structure and the effects of CG regions on crack propagation were investigated using in situ scanning electron microscopy micro-tensile tests. The micro-strain evolution measured using digital image correlation showed early plastic strain localization in CG regions. Micro-voids due to the strain mismatch at CG/UFG interfaces were responsible for crack initiation. CG region toughening was realized by plasticity-induced crack closure and zone shielding of disconnected micro-cracks. However, these toughening mechanisms did not effectively suppress its brittle behavior. Further optimization of the CG distribution (spacing and morphology) is required to achieve toughness levels required for structural applications.

@article{chen_spark_2015,
	title = {Spark {Plasma} {Sintering} and {Densification} {Mechanisms} of {Conductive} {Ceramics} under {Coupled} {Thermal}/{Electric} {Fields}},
	volume = {98},
	issn = {1551-2916},
	url = {http://onlinelibrary.wiley.com/doi/10.1111/jace.13381/abstract},
	doi = {10.1111/jace.13381},
	abstract = {In spark plasma sintering (SPS), thermal and electric fields are applied simultaneously as a material is densified under pressure. The interactions between these two types of physical fields influence the densification behavior during SPS. Moreover, the uniformity and spatial distribution of these fields are also influenced by sample size. In the current investigation, the densification behavior of electrically conductive aluminum-doped zinc oxide (AZO) ceramics is studied to provide insight into the role played by the thermal and electric fields on densification mechanisms, as a function of sample size. Our results demonstrate that field uniformity and densification behavior depend on sample size, and that ultimately, this behavior can be rationalized in terms of the electrical conductivity characteristics. Our results show that in small samples with a diameter of 20 mm, both thermal and electric fields are spatially uniform, which result in homogeneous microstructure. In large samples with a diameter of 80 mm, however, spatial variations in both thermal and electric fields lead to microstructural inhomogeneities, such as incomplete particle–particle bonding. Furthermore, as the density of the AZO sample increases, the effective electrical conductivity increases due to a decrease in void/pore volume, which changes the densification mechanisms, especially for the larger sample. Thus, for effective sintering of larger samples, a two-stage sintering sequence is proposed, which relies on the thermal field that evolves once the effective electrical conductivity increases in the sample. We provide experimental confirmation to this suggestion on the basis of results which demonstrate that by extending the hold time from 3 to 30 min, high-density (99.4\%), homogeneous AZO ceramic samples with a diameter of 80 mm can be achieved after sintering at 1200°C.},
	language = {en},
	number = {3},
	urldate = {2018-01-08},
	journal = {Journal of the American Ceramic Society},
	author = {Chen, Fei and Yang, Shuang and Wu, Junyan and Galaviz Perez, Jorge A. and Shen, Qiang and Schoenung, Julie M. and Lavernia, Enrique J. and Zhang, Lianmeng},
	month = mar,
	year = {2015},
	keywords = {Published, Reviewed},
	pages = {732--740},
}

In spark plasma sintering (SPS), thermal and electric fields are applied simultaneously as a material is densified under pressure. The interactions between these two types of physical fields influence the densification behavior during SPS. Moreover, the uniformity and spatial distribution of these fields are also influenced by sample size. In the current investigation, the densification behavior of electrically conductive aluminum-doped zinc oxide (AZO) ceramics is studied to provide insight into the role played by the thermal and electric fields on densification mechanisms, as a function of sample size. Our results demonstrate that field uniformity and densification behavior depend on sample size, and that ultimately, this behavior can be rationalized in terms of the electrical conductivity characteristics. Our results show that in small samples with a diameter of 20 mm, both thermal and electric fields are spatially uniform, which result in homogeneous microstructure. In large samples with a diameter of 80 mm, however, spatial variations in both thermal and electric fields lead to microstructural inhomogeneities, such as incomplete particle–particle bonding. Furthermore, as the density of the AZO sample increases, the effective electrical conductivity increases due to a decrease in void/pore volume, which changes the densification mechanisms, especially for the larger sample. Thus, for effective sintering of larger samples, a two-stage sintering sequence is proposed, which relies on the thermal field that evolves once the effective electrical conductivity increases in the sample. We provide experimental confirmation to this suggestion on the basis of results which demonstrate that by extending the hold time from 3 to 30 min, high-density (99.4%), homogeneous AZO ceramic samples with a diameter of 80 mm can be achieved after sintering at 1200°C.

@article{lim_potential_2013,
	title = {Potential {Environmental} {Impacts} from the {Metals} in {Incandescent}, {Compact} {Fluorescent} {Lamp} ({CFL}), and {Light}-{Emitting} {Diode} ({LED}) {Bulbs}},
	volume = {47},
	issn = {0013-936X},
	url = {http://dx.doi.org/10.1021/es302886m},
	doi = {10.1021/es302886m},
	abstract = {Artificial lighting systems are transitioning from incandescent to compact fluorescent lamp (CFL) and light-emitting diode (LED) bulbs in response to the U.S. Energy Independence and Security Act and the EU Ecodesign Directive, which leads to energy savings and reduced greenhouse gas emissions. Although CFLs and LEDs are more energy-efficient than incandescent bulbs, they require more metal-containing components. There is uncertainty about the potential environmental impacts of these components and whether special provisions must be made for their disposal at the end of useful life. Therefore, the objective of this study is to analyze the resource depletion and toxicity potentials from the metals in incandescent, CFL, and LED bulbs to complement the development of sustainable energy policy. We assessed the potentials by examining whether the lighting products are to be categorized as hazardous waste under existing U.S. federal and California state regulations and by applying life cycle impact-based and hazard-based assessment methods (note that “life cycle impact-based method” does not mean a general life cycle assessment (LCA) but rather the elements in LCA used to quantify toxicity potentials). We discovered that both CFL and LED bulbs are categorized as hazardous, due to excessive levels of lead (Pb) leachability (132 and 44 mg/L, respectively; regulatory limit: 5) and the high contents of copper (111 000 and 31 600 mg/kg, respectively; limit: 2500), lead (3860 mg/kg for the CFL bulb; limit: 1000), and zinc (34 500 mg/kg for the CFL bulb; limit: 5000), while the incandescent bulb is not hazardous (note that the results for CFL bulbs excluded mercury vapor not captured during sample preparation). The CFLs and LEDs have higher resource depletion and toxicity potentials than the incandescent bulb due primarily to their high aluminum, copper, gold, lead, silver, and zinc. Comparing the bulbs on an equivalent quantity basis with respect to the expected lifetimes of the bulbs, the CFLs and LEDs have 3–26 and 2–3 times higher potential impacts than the incandescent bulb, respectively. We conclude that in addition to enhancing energy efficiency, conservation and sustainability policies should focus on the development of technologies that reduce the content of hazardous and rare metals in lighting products without compromising their performance and useful lifespan.},
	number = {2},
	urldate = {2018-01-05},
	journal = {Environmental Science \& Technology},
	author = {Lim, Seong-Rin and Kang, Daniel and Ogunseitan, Oladele A. and Schoenung, Julie M.},
	month = jan,
	year = {2013},
	keywords = {Featured on Cover, Published, Reviewed},
	pages = {1040--1047},
}

Artificial lighting systems are transitioning from incandescent to compact fluorescent lamp (CFL) and light-emitting diode (LED) bulbs in response to the U.S. Energy Independence and Security Act and the EU Ecodesign Directive, which leads to energy savings and reduced greenhouse gas emissions. Although CFLs and LEDs are more energy-efficient than incandescent bulbs, they require more metal-containing components. There is uncertainty about the potential environmental impacts of these components and whether special provisions must be made for their disposal at the end of useful life. Therefore, the objective of this study is to analyze the resource depletion and toxicity potentials from the metals in incandescent, CFL, and LED bulbs to complement the development of sustainable energy policy. We assessed the potentials by examining whether the lighting products are to be categorized as hazardous waste under existing U.S. federal and California state regulations and by applying life cycle impact-based and hazard-based assessment methods (note that “life cycle impact-based method” does not mean a general life cycle assessment (LCA) but rather the elements in LCA used to quantify toxicity potentials). We discovered that both CFL and LED bulbs are categorized as hazardous, due to excessive levels of lead (Pb) leachability (132 and 44 mg/L, respectively; regulatory limit: 5) and the high contents of copper (111 000 and 31 600 mg/kg, respectively; limit: 2500), lead (3860 mg/kg for the CFL bulb; limit: 1000), and zinc (34 500 mg/kg for the CFL bulb; limit: 5000), while the incandescent bulb is not hazardous (note that the results for CFL bulbs excluded mercury vapor not captured during sample preparation). The CFLs and LEDs have higher resource depletion and toxicity potentials than the incandescent bulb due primarily to their high aluminum, copper, gold, lead, silver, and zinc. Comparing the bulbs on an equivalent quantity basis with respect to the expected lifetimes of the bulbs, the CFLs and LEDs have 3–26 and 2–3 times higher potential impacts than the incandescent bulb, respectively. We conclude that in addition to enhancing energy efficiency, conservation and sustainability policies should focus on the development of technologies that reduce the content of hazardous and rare metals in lighting products without compromising their performance and useful lifespan.

@inproceedings{ye_compressive_2005,
	title = {Compressive {Behavior} of a {Novel} {Aluminum} {Matrix} {Composite}},
	isbn = {0-87339-591-3},
	booktitle = {Materials {Processing} and {Manufacturing} {Division} {Sixth} {Global} {Innovations} {Proceedings}, {Trends} in {Materials} and {Manufacuring} {Technologies} for {Transportation} {Industry} and {Powder} {Metallurgy} {Research} and {Development} in the {Transportation} {Industry}},
	author = {Ye, Jichun and Han, Bing Q. and Lee, Zonghoon and Ahn, Byungmin and Nutt, Steve R. and Schoenung, Julie M.},
	editor = {Bieler, T. R. and Carsley, J. E. and Fraser, H. L. and Sears, J. W. and Smugeresky, J. E.},
	year = {2005},
	keywords = {Published, Reviewed},
	pages = {383--389},
}

@incollection{ajdelsztajn_extended_2005,
	title = {Extended {Thermal} {Cycle} {Lifetime} in {Thermal} {Barrier} {Coatings} with {Bond} {Coats} made from {Cryomilled} {Powders}},
	isbn = {0-87339-590-5},
	booktitle = {Surface {Engineering} in {Materials} {Science} {III}},
	publisher = {TMS},
	author = {Ajdelsztajn, L. and Tang, F. and Kim, G. E. and Provenzano, V. and Dallek, S. and Schoenung, J. M.},
	editor = {Seal, S. and Dahotre, N. B. and Moore, J. and Agarwal, A. and Suryanarayana, TMS},
	year = {2005},
	keywords = {Published, Reviewed},
	pages = {229--239},
}

@inproceedings{kang_assessment_2005,
	title = {Assessment of {Costs} and {Revenues} for an {Electronic} {Waste} {Materials} {Recovery} {Facility}},
	isbn = {0-87339-581-6},
	booktitle = {{EPD} {Congress} 2005},
	author = {Kang, Hai-Yong and Schoenung, Julie M.},
	year = {2005},
	keywords = {Published, Reviewed},
	pages = {837--844},
}

@inproceedings{schoenung_green_2004,
	address = {Stuttgart, Germany},
	title = {Green {Electronics}: {A} {U}.{S}. {Perspective} on {Policy}, {Risk}, and {Product} {Design}},
	abstract = {53.	Ab2	2004	Julie M. Schoenung, Oladele A. , Jean-Daniel M. Saphores, and Andrew A. Shapiro, “Green Electronics: A U.S. Perspective on Policy, Risk, and Product Design,” Electronics Goes Green 2004+, H. Reichl, H. Griese, and H. Poetter (Editors), Fraunhofer IRB Verlag, Stuttgart, Germany, 2004, pp. 83-88.},
	booktitle = {Electronics {Goes} {Green} 2004+},
	author = {Schoenung, J. M. and Ogunseitan, Oladele A. and Saphores, Jean-Daniel M. and Shapiro, Andrew A.},
	year = {2004},
	keywords = {Abstract Reviewed, Published},
	pages = {83--88},
}

53. Ab2 2004 Julie M. Schoenung, Oladele A. , Jean-Daniel M. Saphores, and Andrew A. Shapiro, “Green Electronics: A U.S. Perspective on Policy, Risk, and Product Design,” Electronics Goes Green 2004+, H. Reichl, H. Griese, and H. Poetter (Editors), Fraunhofer IRB Verlag, Stuttgart, Germany, 2004, pp. 83-88.

@inproceedings{tang_effects_2004,
	address = {Osaka Japan},
	title = {Effects of {Cryomilling} on the {Oxidation} of {Thermally} {Sprayed} {MCrAlY}},
	booktitle = {Proceedings of the {International} {Thermal} {Spray} {Conference}},
	publisher = {ASM International},
	author = {Tang, Feng and Ajdelsztajn, Leonardo and Schoenung, Julie M.},
	month = may,
	year = {2004},
	keywords = {Published, Reviewed},
}

@incollection{schoenung_lead_2003,
	title = {Lead {Free} {Electronics}: {Current} and {Pending} {Legislation}},
	booktitle = {Environmental {Issues} and {Waste} {Management} {Technologies} {VIII}},
	publisher = {American Ceramic Society},
	author = {Schoenung, J. M.},
	year = {2003},
	keywords = {Published, Reviewed},
	pages = {75--82},
}

@incollection{he_low_2003,
	address = {Chicago, IL},
	title = {Low {Temperature} {Synthesis} of {Boron} {Carbide} {Reinforced} {Nanocrystalline} {Aluminum} {Composites}},
	booktitle = {Affordable {Metal} {Matrix} {Composites}},
	publisher = {TMS Fall Meeting},
	author = {He, J. and Ye, J. and Schoenung, J. M.},
	month = nov,
	year = {2003},
	keywords = {Abstract Reviewed, Published},
}

@incollection{he_microstructure_2003,
	address = {Chicago, IL},
	title = {Microstructure and {Recrystallization} {Behavior} of {Boron} {Carbide} {Reinforced} {Nanocrystalline} {Aluminum} {Composites}},
	booktitle = {Affordable {Metal} {Matrix} {Composites}},
	publisher = {TMS Fall Meeting},
	author = {He, J. and Ye, J. and Witkin, D. and Schoenung, J. M.},
	month = nov,
	year = {2003},
	keywords = {Abstract Reviewed, Published},
}

@incollection{zhou_application_2003,
	address = {San Francisco, CA},
	title = {Application of a {Modified} {Production} {Quality} {Tool} for {Environmental} {Impact} {Assessment} of {Lead}-{Free} {Solder} {Alternatives}},
	booktitle = {Sustainability {Metrics}},
	publisher = {AIChE Fall Meeting},
	author = {Zhou, X. and Schoenung, J. M.},
	month = nov,
	year = {2003},
	keywords = {Abstract Reviewed, Published},
}

@inproceedings{chung_grain_2003,
	address = {Las Vegas, NV},
	title = {Grain {Refinement} {Mechanism} during {Cryomilling} in the {Presence} of {Hard} {Particles}},
	booktitle = {Proceedings of the 2003 {International} {Conference} on {Powder} {Metallurgy} and {Particulate} {Materials} ({PM2})},
	author = {Chung, K. H. and Lavernia, E. J. and Schoenung, J. M.},
	month = jun,
	year = {2003},
	keywords = {Abstract Reviewed, Published},
}

@incollection{ajdelsztajn_nanocrystalline_2003,
	address = {San Diego, CA},
	title = {Nanocrystalline {MCrAlY} {Bond} {Coat} for {Thermal} {Barrier} {Coating} {Applications}},
	booktitle = {Surface {Engineering} in {Materials} {Science} {II}},
	publisher = {TMS Annual Meeting and Exhibition},
	author = {Ajdelsztajn, L. and He, J. and Kim, G.E. and Provenzano, V. and Lavernia, E.J. and Schoenung, J. M.},
	editor = {Seal, S. and Dahotre, N. B. and Moore, J. and Agarwal, A. and Suryanarayana, S.},
	month = mar,
	year = {2003},
	keywords = {Abstract Reviewed, Published},
	pages = {71--80},
}

@incollection{he_synthesis_2002,
	series = {Ceramic {Transactions}},
	title = {Synthesis of {Nanocrystalline} {Ni} {Coatings} {Reinforced} with {Ceramic} {Nanoparticles}},
	volume = {137},
	booktitle = {Ceramic {Nanomaterials} and {Nanotechnology}},
	publisher = {American Ceramic Society},
	author = {He, J. and Schoenung, J. M.},
	year = {2002},
	keywords = {Published, Reviewed},
	pages = {143--159},
}

@incollection{schoenung_advanced_2001,
	address = {Oxford, UK},
	title = {Advanced {Structural} {Ceramics}: {Markets} and {Production} {Costs}},
	volume = {10},
	shorttitle = {Encyclopedia of {Materials}},
	booktitle = {Encyclopedia of {Materials}: {Science} and {Technology}},
	publisher = {Pergamon},
	author = {Schoenung, K. H. J.},
	editor = {Cahn, R. W. and Flemings, M. C. and Ilschner, B. and Kramer, E. J. and Mahajan, S.},
	year = {2001},
	keywords = {Invited, Published},
}

@article{schoenung_advanced_1999,
	title = {Advanced {Silicon} {Nitride} {Components}: {A} {Cost} {Analysis}},
	volume = {20},
	copyright = {Copyright © 1999 The American Ceramic Society},
	shorttitle = {Advanced {Silicon} {Nitride} {Components}},
	url = {http://onlinelibrary.wiley.com/doi/10.1002/9780470294574.ch58/summary},
	abstract = {This paper describes the development and use of two technical cost models, both of which use the process-based cost estimating approach. The first model was developed jointly between Cal Poly Pomona and Cercom, and has been used to estimate the costs for producing a Grade-1, bearing-quality, sintered-reaction bonded silicon nitride (SRBSN) outer race and a SRBSN inner racekhaft for an all-ceramic bearing. The process includes materials preparation steps for the silicon raw material, forming steps (cold isostatic pressing plus green machining), heat treatment steps including nitriding of the silicon compact, grinding, and inspection. The second model was developed by Kyocera with review by Cal Poly Pomona, and has been used to estimate the costs for producing three different sintered silicon nitride components (a nozzle and two rotors). The process steps for these components are similar to those for the bearing components, except the starting material is silicon nitride and different forming operations were evaluated (slip casting, bisque processing and hybrid molding). The methodologies for each technical cost model are described. The costs and cost drivers for representative case studies are discussed, as are the distributions of cost by cost element, such as direct labor, and by unit operation, such as forming.},
	language = {en},
	number = {4},
	urldate = {2018-01-10},
	journal = {Ceramic Engineering and Science Proceedings},
	author = {Schoenung, Julie M. and Kraft, Edwin H. and Ashkin, Daniel},
	year = {1999},
	doi = {10.1002/9780470294574.ch58},
	keywords = {Published, Reviewed, electricity, hybrid, nozzle, rotors, silicon},
	pages = {497--504},
}

This paper describes the development and use of two technical cost models, both of which use the process-based cost estimating approach. The first model was developed jointly between Cal Poly Pomona and Cercom, and has been used to estimate the costs for producing a Grade-1, bearing-quality, sintered-reaction bonded silicon nitride (SRBSN) outer race and a SRBSN inner racekhaft for an all-ceramic bearing. The process includes materials preparation steps for the silicon raw material, forming steps (cold isostatic pressing plus green machining), heat treatment steps including nitriding of the silicon compact, grinding, and inspection. The second model was developed by Kyocera with review by Cal Poly Pomona, and has been used to estimate the costs for producing three different sintered silicon nitride components (a nozzle and two rotors). The process steps for these components are similar to those for the bearing components, except the starting material is silicon nitride and different forming operations were evaluated (slip casting, bisque processing and hybrid molding). The methodologies for each technical cost model are described. The costs and cost drivers for representative case studies are discussed, as are the distributions of cost by cost element, such as direct labor, and by unit operation, such as forming.

@article{schoenung_cost_1999,
	title = {Cost {Modeling} and {Analysis} for {Advanced} {Structural} {Silicon} {Nitride} {Turbomachinery} {Ceramics}},
	volume = {20},
	number = {3},
	journal = {Ceramic Engineering and Science Proceedings},
	author = {Schoenung, Julie M.},
	year = {1999},
	keywords = {Published, Reviewed},
	pages = {209--216},
}

@inproceedings{schoenung_economic_1997,
	title = {Economic analysis of alternative fabrication approaches for advanced structural silicon nitride ceramics.},
	booktitle = {Proceedings of the {Julian} {Szekely} {Memorial} {Symposium} on {Materials} {Processing}},
	author = {Schoenung, J. M. and Tuazon, H. and Santos, M. and Masseth, R. and Draskovich, B. and Mascarin, A.},
	year = {1997},
	keywords = {Invited, Published},
	pages = {631--651},
}

@inproceedings{schoenung_process_1995,
	address = {Albuquerque, NM},
	title = {Process cost modeling - {A} summary},
	booktitle = {Conference {Proceedings}, {Smart} {Processing} of {Materials} {Symposium}, 27th {International} {SAMPE} {Technical} {Conference}},
	author = {Schoenung, Julie M.},
	month = oct,
	year = {1995},
	keywords = {Invited, Published},
	pages = {1--10},
}

@article{schoenung_economics_1991,
	title = {The {Economics} of {Silicon} {Carbide} {Whisker} {Fabrication}},
	volume = {12},
	issn = {0196-6219},
	url = {https://www.osti.gov/scitech/biblio/6077859},
	language = {English},
	number = {9-10},
	urldate = {2018-01-09},
	journal = {Ceramic Engineering and Science Proceedings},
	author = {Schoenung, J. M.},
	month = oct,
	year = {1991},
	keywords = {\& refractories-- preparation \& fabrication, Published, Reviewed, carbides, carbon, carbon compounds, cermets, chalcogenides, chemical reactions, cost, crystals, economics, elements, fabrication, materials science, minerals, monocrystals, nonmetals, oxide minerals, oxides, oxygen compounds, silica, silicon carbides, silicon compounds, silicon oxides 360201*  -- ceramics, whiskers},
	pages = {1943--51},
}

@article{laverna_calcium_1991,
	title = {Calcium phosphate ceramics as bone substitutes},
	volume = {70},
	number = {1},
	journal = {American Ceramic Society Bulletin},
	author = {Laverna, C. and Schoenung, J. M.},
	year = {1991},
	keywords = {Published, Reviewed},
	pages = {95--100},
}

@article{schoenung_analysis_1991,
	title = {Analysis of the economics of silicon nitride powder production},
	volume = {70},
	number = {1},
	journal = {American Ceramic Society Bulletin},
	author = {Schoenung, Julie M.},
	year = {1991},
	keywords = {Published, Reviewed},
	pages = {112--116},
}

@article{schoenung_markets_1989,
	title = {Markets for {Advanced} {Ceramics} in {Engines}},
	volume = {13},
	abstract = {J.M. Schoenung, "Markets for Advanced Ceramics in Engines," , Vol. 13, No. 3, pp 233-246 (1989).},
	number = {3},
	journal = {Materials and Society},
	author = {Schoenung, J. M.},
	year = {1989},
	keywords = {Published, Reviewed},
	pages = {233--246},
}

J.M. Schoenung, "Markets for Advanced Ceramics in Engines," , Vol. 13, No. 3, pp 233-246 (1989).

@inproceedings{jacob_economic_1989,
	address = {Denver, CO},
	title = {Economic feasibility of producing metal matrix composites[{MMC}'s] by spray atomization and deposition},
	booktitle = {Proceedings of the {University}-{Industry} {Advanced} {Materials} {Conference}},
	author = {Jacob, Jeffrey E. and Schoenung, Julie and Lavernia, Enrique J.},
	month = mar,
	year = {1989},
	keywords = {Published, Reviewed},
	pages = {154--63},
}

@inproceedings{schoenung_markets_1988,
	address = {Las Vegas, NV},
	title = {Markets for {Advanced} {Ceramics} in {Internal} {Combustion} {Engines}},
	volume = {13:3},
	url = {https://www.osti.gov/scitech/biblio/5464320},
	language = {English},
	urldate = {2018-01-09},
	booktitle = {Proceedings of the {Third} {International} {Symposium} on {Ceramic} {Materials} and {Components} for {Engines}},
	author = {Schoenung, J. M.},
	month = nov,
	year = {1988},
	keywords = {\& refractories, Published, Reviewed, automotive industry, ceramics, cermets, control equipment, cost, data, engines, equipment, flow regulators, heat engines, heat resistant materials, industry, information, internal combustion engines, machine parts, market, marketing research, materials 360200*  -- ceramics, materials science, prices, valves},
}

@inproceedings{schoenung_silicon_1988,
	address = {Montreal},
	title = {Silicon nitride powders: investigating the costs of production},
	isbn = {978-0-08-036448-3},
	shorttitle = {Silicon nitride powders},
	url = {https://www.sciencedirect.com/science/article/pii/B978008036448350061X},
	abstract = {KEYWORDS
Silicon nitride; silicon nitride powder; ceramic powders; economic modeling; cost modeling; nitridation; laser synthesis.
ABSTRACT
The market for advanced structural ceramics has been growing and is forecasted to grow exponentially in the future. The potential for growth in this industry, however, is limited by the ability to manufacture ceramic components that are technically reliable and economically competitive. The ceramic powders used to fabricate components have been identified as a key variable to overcoming both of these limitations.
This paper discusses a methodology that has been developed to gain an understanding of the economic limitations associated with powder costs. This methodology involves the creation of process cost models that can be used to investigate the primary cost drivers involved in the manufacture of ceramic powders. Results of two case studies, including a conventional and a novel technique for producing silicon nitride powders, are presented.},
	urldate = {2018-01-09},
	booktitle = {Proceedings of the {International} {Symposium} on the {Production} and {Processing} of {Fine} {Particles}},
	author = {Schoenung, J. M.},
	month = aug,
	year = {1988},
	doi = {10.1016/B978-0-08-036448-3.50061-X},
	keywords = {Published, Reviewed},
}

KEYWORDS Silicon nitride; silicon nitride powder; ceramic powders; economic modeling; cost modeling; nitridation; laser synthesis. ABSTRACT The market for advanced structural ceramics has been growing and is forecasted to grow exponentially in the future. The potential for growth in this industry, however, is limited by the ability to manufacture ceramic components that are technically reliable and economically competitive. The ceramic powders used to fabricate components have been identified as a key variable to overcoming both of these limitations. This paper discusses a methodology that has been developed to gain an understanding of the economic limitations associated with powder costs. This methodology involves the creation of process cost models that can be used to investigate the primary cost drivers involved in the manufacture of ceramic powders. Results of two case studies, including a conventional and a novel technique for producing silicon nitride powders, are presented.

@article{jacob_cost_1987,
	title = {Cost {Modeling} {RS} {Powders} {Produced} by {Inert} {Gas} {Atomization}},
	volume = {39},
	issn = {1047-4838, 1543-1851},
	url = {https://link.springer.com/article/10.1007/BF03258958},
	doi = {10.1007/BF03258958},
	language = {en},
	number = {10},
	urldate = {2018-01-09},
	journal = {JOM},
	author = {Jacob, J. E. and Schoenung, J. M. and Lavernia, E. J. and Clark, J. P. and Grant, N. J.},
	month = oct,
	year = {1987},
	keywords = {Published, Reviewed},
	pages = {19--21},
}

@article{schoenung_gallium_1987,
	title = {Gallium {Demand} for {Electronic} {Devices}},
	volume = {39},
	issn = {1047-4838, 1543-1851},
	url = {https://link.springer.com/article/10.1007/BF03258060},
	doi = {10.1007/BF03258060},
	language = {en},
	number = {6},
	urldate = {2018-01-09},
	journal = {JOM},
	author = {Schoenung, J. M. and Clark, J. P.},
	month = jun,
	year = {1987},
	keywords = {Published, Reviewed},
	pages = {36--38},
}

@article{schoenung_simulations_1986,
	title = {Simulations of the {Potential} {Market} for {Ceramic} {Engine} {Components}},
	journal = {Verlag Deutsche Keramische Gesellschaft,},
	author = {Schoenung, J. and Rothman, E. and Bowen, H. and Clark, J.},
	year = {1986},
	keywords = {Published, Reviewed},
	pages = {1091--1098},
}

@inproceedings{schoenung_properties_1985,
	address = {Washington D.C.},
	title = {Properties, {Costs} and {Applications} of {Ceramics} and {Ceramic} {Matrix} {Composites}},
	author = {Schoenung, J. M. and Rothman, E. P. and Clark, J. P.},
	month = dec,
	year = {1985},
	keywords = {Limited Distribution, Published, Reviewed},
}

@inproceedings{schoenung_case_1985,
	address = {Washington D.C.},
	title = {Case {Study} on {Utilization} of {Ceramics} in {Heat} {Engines}},
	author = {Schoenung, J. M. and Moteff, J.},
	month = oct,
	year = {1985},
	keywords = {Limited Distribution, Published, Reviewed},
}