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

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 dislocations contribute to most of the deformation, while a small fraction of 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 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 dislocations in the alloy have high mobility, which also helps to accommodate the deformation near GBs.