Plastic deformation mechanism of Mg-Gd-Y-(Sm)-Zr alloys at room and cryogenic temperature

In this study, Mg-Gd-Y-(Sm)-Zr (GW-(Sm)) alloys were subjected to compression tests at both 293 and 77 K. The effect of Sm addition on the plastic deformation mechanism of Mg-Gd-Y-Zr (GW) alloy was investigated, and a detailed analysis was conducted on the relationships between mechanical responses and the microstructure of the alloys. The findings suggest that dislocation slip plays a predominant role in the plastic deformation of GW-(Sm) alloys. The addition of Sm reduces the stacking fault energy (SFE) of the alloy, which promotes < c + a > slip and inhibits twinning. Meanwhile, Sm plays a role in solution strengthening, causing an elevation in the flow stress of the alloy. At cryogenic temperature (CT), the critical resolved shear stress (CRSS) of dislocation slip is increased, so the dislocation motion requires greater external force. In addition, the extensive crossed twins exhibited in the microstructure, which shorten the dislocation slip path and enhance the grain boundary strengthening. This research contributes to the advancement of plastic deformation theories for magnesium-rare earth (Mg-RE) alloys.