期刊
ACTA MATERIALIA
卷 59, 期 13, 页码 5202-5215出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2011.04.057
关键词
Nanoindentation; Molecular dynamics; Micromechanical modeling; Dislocations; Gold nanoparticles
资金
- US-Israel Bi-National Science Foundation [2006-109]
- Fine Fellowship
- Office of Science, Office of Basic Energy Sciences, of the US Department of Energy [DE-FG02-04ER46163]
- Alexander von Humboldt foundation
Single-crystal Au microparticles on a sapphire substrate were deformed under compression. Most of microparticles yield with a large strain burst, and there is a strong dependence of the yield strength on microparticle size. With the help of molecular dynamics simulations and finite-element analysis we conclude that the deformation is dislocation nucleation-controlled and that the stress levels reached at the onset of plasticity approach the theoretical shear strengths of Au. A significant size effect is identified in both the experimentally measured and computed strength of the microparticles; the smaller microparticles yield at higher compressive stresses. We propose a stress-gradient nucleation model relating this size effect to stress gradients along the slip plane. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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