Temperature dependent plasticity in BCC micropillars

Abstract

Recent experiments in micron- or sub-micron metallic pillars have displayed size dependent plasticity. Dislocation dynamics (DD) simulations can be a useful tool in studying dislocation-mediated plasticity, which is widely believed to contribute to observed size effects at small length scale. In particular, the plasticity in body-centered cubic (BCC) metals is known to have a strong temperature dependence, which stems from the thermally activated motion of screw dislocations. In this study, we develop a DD model based on the atomistic characterization of dislocation mobility and potential source mechanisms to investigate the temperature dependent plasticity in BCC micropillars. Our models show the dislocation source mechanism changes with respect to temperature due to the change in mobility of screw dislocations, and these results are compared with experimental results and theoretical models. In addition, the size dependence increases with temperature, which agrees with recent experimental observations.