ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Discrete dislocation dynamics simulations of surface induced size effects in plasticity

C. S. Han, A. Hartmaier, H. Gao, Y. G. Huang.

Materials Science and Engineering, A 415, 225-233, (2006)

Experiments have shown that the presence of free surfaces may induce harder as well as softer deformation behaviors in a crystalline solid. In order to shed some light on these apparently contradictory findings, two-dimensional discrete dislocation dynamics simulations are performed to investigate the surface induced size effects. The simulations indicate that, depending on the surface density of dislocation sources, a free surface may act either as a dislocation sink or as a net dislocation source, and can accordingly exert opposite effects on dislocation density over a boundary layer thickness of up to 500 nm into the bulk. This finding provides a possible explanation for the apparent contradictions in experimental observations. (c) 2005 Elsevier B.V. All rights reserved.

Keyword(s): plasticity; discrete dislocation dynamics; size effects; surface effects; STRAIN GRADIENT PLASTICITY; THIN-FILMS; EDGE DISLOCATION; MODEL; NANOINDENTATION; DEFORMATION; HARDNESS
DOI: 10.1016/j.msea.2005.09.075
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