Dislocation behavior in a polycrystalline Mg-Y alloy using multi-scale characterization and VPSC simulation

Abstract

In this study, the dislocation behavior of a polycrystalline Mg-5Y alloy during tensile deformation was quantitatively studied by an in-situ tensile test, visco-plastic self-consistent (VPSC) modeling, and transmission electron microscopy (TEM). The results of the in-situ tensile test show that <a> dislocations contribute to most of the deformation, while a small fraction of <c + a> dislocations are also activated near grain boundaries (GBs). The critical resolved shear stresses (CRSSs) of different dislocation slip systems were estimated. The CRSS ratio between prismatic and basal <a> dislocation slip in the Mg-Y alloy (~13) is lower than that of pure Mg (~80), which is considered as a major reason for the high ductility of the alloy. TEM study shows that the <c + a> dislocations in the alloy have high mobility, which also helps to accommodate the deformation near GBs.