On the thermal stability of ultrafine-grained Al stabilized by in-situ amorphous Al2O3 network. Balog, M., Hu, T., Krizik, P., Castro Riglos, M. V., Saller, B. D., Yang, H., Schoenung, J. M., & Lavernia, E. J. Materials Science and Engineering: A, 648(Supplement C):61–71, November, 2015.
On the thermal stability of ultrafine-grained Al stabilized by in-situ amorphous Al2O3 network [link]Paper  doi  abstract   bibtex   
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{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},
}

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