Microstructure and mechanical properties of Mg-3.0Zn-1.0Sn-0.3Mn-0.3Ca alloy extruded at different temperatures

Abstract

A new type of wrought magnesium alloy Mg-3.0Zn-1.0Sn-0.3Mn-0.3Ca (ZTMX3100) was developed in this work. The effects of extrusion temperature (200–400 °C) on grain structure, second phase particle, texture, and mechanical properties of the alloy were systematically investigated by combining microstructure observations and mechanical properties tests. The results indicated that dynamic recrystallization occurs at 200–400 °C in the alloy. As the extrusion temperature increases, the average grain size increases gradually from 2.6 μm to 17.8 μm due to different degrees of grain growth, the continuous CaMgSn phase bands are gradually broken into discontinuous chain-like or dot-like structures, and the grains and CaMgSn phases distribute more uniformly. The as-extruded alloys exhibit a typical extruding texture with (0001) basal planes parallel to the extrusion direction. The bar extruded at 300 °C presents the optimum comprehensive mechanical properties, which is attributed to the combined effect of relatively small grain size, uniformly distributed discontinuous particles, and weak basal texture. Finally, the quantitative relationship between grain size and Zener-Hollomon parameter and the quantitative relationship between the yield strength of the alloy and extrusion temperature were obtained.