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On the effects of dislocation density on micropillar strength

Published online by Cambridge University Press:  31 January 2011

Amine Benzerga
Amine Benzerga*
Affiliation:
[email protected], Texas A&M Univ, Aerospace Engineering, TAMU 3141, College Station, Texas, 77843, United States
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Abstract

There is an increasing amount of experimental evidence that the plastic behavior of crystals changes at micro- and nano-scales in a way that is not necessarily captured by state-of-the-art plasticity models. In this paper, length scale effects in the plasticity of crystals are analyzed by means of direct numerical simulations that resolve the scale of the carriers of plasticity, i.e., the dislocations. A computationally efficient, atomistically informed dislocation dynamics framework which has the capability of reaching high dislocation densities and large strains at moderately low strain rates in finite volumes is recalled. Using this theoretical framework, a new type of size effect in the hardening of crystals subject to nominally uniform compression is discovered. In light of such findings, behavior transitions in the space of meaningful structural parameters, from forest-hardening dominated regime to an exhaustion hardening dominated regime are discussed. Various scalings of the flow stress with crystal size emerge in the simulations, which are compared with recent experimental data on micro- and nano-pillars.

Keywords

dislocationsnanoscalesimulation
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1185: Symposium II – Probing Mechanics at Nanoscale Dimensions , 2009 , 1185-II05-07
Copyright
Copyright © Materials Research Society 2009

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