Effects of Zn on the microstructure and tensile properties of as-extruded Mg-8Al-2Sn alloy

Effects of Zn addition on the microstructure and tensile properties of as-extruded Mg-8Al-2Sn (AT82) alloy were investigated in the present work. All the extruded AT82 alloys exhibited a fully dynamically recrystallized (DRXed) microstructure, while the grains were slightly refined with Zn addition. Moreover, second phase particles (Mg2Sn and Mg17Al12) increased significantly in amount with increasing Zn content. It was found the ultimate tensile strength (UTS) and yield strength (YS) gradually increased with increasing Zn content from 0 to 1.5 wt%, meanwhile the elongation maintained unchanged at a high level, i.e. ~17-19%. In particular, the as-extruded AT82-1.0Zn alloy exhibited both a high strength and high ductility at room temperature, e.g. UTS of ~357 MPa and elongation of ~19%. The superior combination of strength and ductility is mainly benefited from the enhanced work-hardening ability resulted from Zn solid solutes and the presence of more well-dispersed fine particles in AT82-1.0Zn alloy.