Improvement of both strength and elongation of high-purity Mg via Zn addition prepared by vacuum distillation

High-purity (HP) Mg and Mg-xZn (x = 0.2, 1.0 mass%) alloys were prepared by vacuum distillation. They were extruded and hot-rolled to investigate the tensile properties and microstructures of wrought materials. HP Mg showed poor tensile properties with an ultimate tensile strength and a 0.2 % proof stress (UTS and PS) of 155 MPa and 116 MPa, respectively. The elongation to failure (EF) was also small, 2.1 %. Zn addition was effective in improving both strengths and ductility. In particular, the UTS and PS of the HP Mg-1.0Zn alloy increased to 272 MPa and 231 MPa, respectively. Furthermore, the EF of the HP Mg-1.0Zn alloy was 6.9 %, which was ~3.5 times larger than that of the Zn-free sample. The excellent tensile properties, which were achieved by Zn addition, resulted from a bimodal grain distribution having fine recrystallized grains, activation of non-basal prismatic slip, and suppression of twinning.