Journal
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
Volume 57, Issue 1, Pages 32-50Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmps.2008.10.004
Keywords
Size effects; Dislocations dynamics; Plasticity; Micropillars; Nickel
Funding
- U.S. Air Force Office for Scientific Research (AFOSR) [FA9550-07-1-0396]
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We present a computational study on the effects of sample size on the strength and plastic flow characteristics of micropillars under compression loading. We conduct three-dimensional simulations using the parametric dislocation dynamics coupled with the boundary element method. Two different loading techniques are performed. The plastic flow characteristics as well as the stress-strain behavior of simulated micropillars are shown to be in general agreement with experimental observations. The flow strength versus the diameter of the micropillar follows a power law with an exponent equal to -0.69. A stronger correlation is observed between the flow strength and the average length of activated dislocation sources. This relationship is again a power law, with an exponent -0.85. Simulation results with and without the activation of cross-slip are compared. Discontinuous hardening is observed when cross-slip is included. Experimentally observed size effects on plastic flow and work-hardening are consistent with a weakest-link activation mechanism. (C) 2008 Elsevier Ltd. All rights reserved.
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