Plastic deformation mechanisms of fcc single crystals at small scales

TitlePlastic deformation mechanisms of fcc single crystals at small scales
Publication TypeJournal Article
Year of Publication2011
AuthorsZhou CZ, Beyerlein IJ, LeSar R
Journal TitleActa Materialia
Date Published12
Type of ArticleArticle
ISBN Number1359-6454
Accession NumberWOS:000297822200025
Keywordscross-slip, discrete dislocation simulations, dislocation, dislocation dynamics, dynamics, mean free, micro-pillars, nickel microcrystals, PATHS, size dependence, size effects, small scales, starvation, strain gradient plasticity, strength, UNIAXIAL COMPRESSION

Three-dimensional (3-D) dislocation dynamics simulations were employed to examine the fundamental mechanisms of plasticity in small-scale face-centered cubic single crystals. Guided by the simulation results, we examined two distinct modes of behavior that reflect the dominant physical mechanisms of plastic deformation at small scales. We found that the residence lifetimes of internal dislocation sources formed by cross-slip decrease as the system size decreases. Below a critical sample size (which depends on the initial density of dislocations) the dislocation loss rate exceeds the multiplication rate, leading to the loss of internal dislocation sources. In this case nucleation of surface dislocations is required to provide dislocations for deformation and the "starvation hardening" mechanism becomes the dominant deformation process. When the sample is larger than a critical size multiplication of internal dislocation sources provides the dominant mechanism for plastic flow. As the strain is increased the rising dislocation density leads to reactions that shut off these sources, creating "exhaustion hardening". Published by Elsevier Ltd. on behalf of Acta Materialia Inc.

Alternate JournalActa Mater.