Modeling the mechanical response and microstructure evolution of magnesium single crystals under c-axis compression

Abstract

Atomistically informed multiscale dislocation dynamics plasticity (MDDP) framework is used to investigate the mechanical response and microstructure evolution in bulk magnesium single crystals subjected to c-axis compression. The MDDP framework was modified to account for the 〈c+a〉 dislocation slip on the pyramidal I and pyramidal II planes. Several aspects of the 〈c+a〉 dislocation reactions such as the transition of pyramidal I near edge and pyramidal II pure edge segments to basal plane, and the thermally activated cross slip are considered. Additionally, a generalized mobility law and anisotropic frictional stress models are implemented based on the findings of several molecular dynamics studies. MDDP predictions of the yielding and strain hardening behaviors, as well as the maximum stress prior to failure are in good agreement with the reported experimental values. Moreover, detailed study of the dislocation microstructure evolution and the dislocation density dependence on the applied stress are presented and compared with available experimental results.