Effect of Al and Zn content on the preparation of semisolid Mg-Al-Zn magnesium alloy

The thermodynamic parameter and microstructure of three contents as-cast magnesium alloys were researched by phase picture, X-ray diffraction and thermodynamic analysis, whereafter prepared semisolid billets by strain induced melt activation (SIMA). The microstructure observation and rheology parameter analysis demonstrated that add zinc content consumedly reduced formation temperature of semisolid microstructure, decreased isothermal holding time, and accelerated microstructure evolution. With increasing zinc content, the semisolid morphology better and better that is propitious to semisolid process. The analysis verified that on the one hand, with increasing aluminum and zinc content the melting point of compound and the nucleation temperature of liquid phase decreased, and the nucleation quantity of liquid phase increased; on the other hand, with increasing alloy content the as-cast microstructure much finer, which to caused much more fine and spherical semisolid microstructure.