Size effect in compression of single-crystal gold microparticles

D Mordehai and SW Lee and B Backes and DJ Srolovitz and WD Nix and E Rabkin, ACTA MATERIALIA, 59, 5202-5215 (2011).

DOI: 10.1016/j.actamat.2011.04.057

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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