Simulation on microstructure evolution and mechanical properties of Mg-Y alloys: Effect of trace Y

The influence of trace Y on the microstructure evolution and mechanical properties of Mg100-xYx (x=0.25, 0.75, 1.5, 3, 4, 5, at.%) alloys during solidification process was investigated via molecular dynamics (MD) simulations. The results show that the Mg100-xYx alloys are mainly characterized by a face-centered cubic (FCC) crystal structure; this is different from pure metal Mg, which exhibits a hexagonal close packed (HCP) structure at room temperature. Among these alloys, Mg99.25Y0.75 has a larger proportion of FCC cluster structures, with the highest fraction reaching 56.65%. As the content of the Y increases up to 5 at.% (Mg95Y5 alloy), the amount of amorphous structures increases. The mechanical properties of the Mg100-xYx alloys are closely related to their microstructures. The Mg99.25Y0.75 and Mg97Y3 alloys exhibit the highest yield strengths of 1.86 and 1.90 GPa, respectively. The deformation mechanism of the Mg-Y alloys is described at the atomic level, and it is found that a difference in the FCC proportion caused by different Y contents leads to distinct deformation mechanisms.