Size effect in compression of single-crystal gold microparticles

作者：Mordehai Dan^*; Lee Seok Woo; Backes Bjoern; Srolovitz David J; Nix William D; Rabkin Eugen

来源：Acta Materialia, 2011, 59(13): 5202-5215.

DOI：10.1016/j.actamat.2011.04.057

• Nanoindentation
• Molecular dynamics
• Micromechanical modeling
• Dislocations
• Gold nanoparticles

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.

• 出版日期2011-8