Influence of Sn on Microstructure and Tensile Property of Mg-5Zn-1Mn Alloy

The as-cast Mg-5Zn-Mn-xSn (x=0, 0.3, 0.6, 0.9, mass fraction/%) alloys were homogenized with process of 330℃×24 h+400℃×2 h, and then rolled into 2 mm thick alloy plates at the strain rate of 9.1 s^-1. The influence of Sn addition on the microstructures and tensile properties of as-cast and as-rolled alloys was studied.The results show that the Sn addition can refine the microstructure of the as-cast alloys and homogenized alloys, leading to the formation of the Mg₂Sn phase with high melting point, which can promote the dynamic recrystallization and refine the grain size during the subsequent rolling process. After rolling, the tensile property of the tested alloy was better than that of as-cast alloy. Meanwhile with the increase of Sn content, the strength and plasticity of as-rolled alloy first increased then decreased, and the fracture mode transformed from quasi-cleavage fracture to plastic fracture. The tensile property of Mg-5Zn-1Mn-0.6Sn alloy was the best with the tensile strength and elongation of 337 MPa and 21%, respectively.