Effects of Zn Addition on the Microstructure, Tensile Properties and Formability of As-Extruded Mg-1Sn-0.5Ca Alloy

In the present study, the influence of the Zn content (0.0, 0.5, 1.0, and 2.0 wt.%) on the microstructure, texture, tensile mechanical properties and formability of Mg-1.0Sn-0.5Ca-based alloys after extrusion were investigated via extrusion of Mg sheets and analysis of the extruded materials. Adding Zn improved the microstructure uniformity and accelerated the formation of more CaMgSn and the Ca2Mg6Zn3 phase. In addition, after the addition of Zn, the texture evolved from the initial extrusion direction tilted bimodal texture to a weakened and symmetrical texture. Compared with the Mg-1.0Sn-0.5Ca alloy, the average tensile yield strength and elongation values were simultaneously improved after 0.5 wt.% Zn addition due to the synergistic effect of the solid solution of elemental Zn, the decreased amount of coarse unrecrystallized grains, and the existence of an additional tilted direction texture component. The formability first increased and then decreased with increasing Zn content. In contrast, the deterioration of formability after the further addition of Zn was closely associated with the increased volume fractions of the coarse CaMgSn and Ca2Mg6Zn3 phases.