Stabilized plasticity in ultrahigh strength, submicron Al crystals. Hu, T., Jiang, L., Yang, H., Ma, K., Topping, T. D., Yee, J., Li, M., Mukherjee, A. K., Schoenung, J. M., & Lavernia, E. J. Acta Materialia, 94(Supplement C):46–58, August, 2015.
Stabilized plasticity in ultrahigh strength, submicron Al crystals [link]Paper  doi  abstract   bibtex   
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{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},
}

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