Effect of Mn content on the microstructure and mechanical properties of as-extruded Zn-0.2Mg-Mn (wt%) alloys

Abstract

Zn-0.2 Mg-(0.1–0.8)Mn (wt%) alloys were prepared by indirect extrusion at 200 °C. The granular and strip-shaped Mg2Zn11 and MnZn13 distributed along grain boundaries. With the increase of Mn addition, the amount of MnZn13 increased, and the size was in the range from tens of nanometers to tens of microns. Equiaxed grains with average sizes between 2 μm and 5 μm formed during the extrusion. Non-basal texture with 〈0001〉 tilted away from ED (extrusion direction) about 65° ∼ 85° was the major texture component, and the basal texture was the minor texture component. The refined grains and MnZn13 contributed to the linearly increase of tensile yield strength from 247 MPa for Zn-0.2 Mg-0.1Mn alloy to 348 MPa for Zn-0.2 Mg-0.8Mn alloy. The evolution of non-basal texture contributed to the elongation increasing from 23% for Zn-0.2 Mg-0.1Mn alloy to 30% for Zn-0.2 Mg-0.5Mn alloy, but micron-scaled MnZn13 contributed to the elongation decreasing to 21% for Zn-0.2 Mg-0.8Mn alloy. Thus, with Mn addition between 0.1 wt% and 0.5 wt%, both the yield strength and elongation improved simultaneously.