Microstructure, texture and mechanical properties of Mg-3.0Zn-0.2Ca alloys fabricated by extrusion at various temperatures

The Mg-3.0Zn-0.2Ca (wt.%) alloy has been extruded at temperature range of 25-300 °C and the resulting microstructure, texture and mechanical properties are systematically investigated. The results show that the grain size monotonically increases with the increasing of the extrusion temperature and the texture intensity increases firstly and decreases subsequently. In addition, a large number of nano-scale precipitates are formed in alloys extruded above 250 °C. The weakest basal texture developed in the cold extrusion alloy is related to the deformation twinning, while, the combining effects of activation of multiple deformation mechanisms and dynamic precipitates contribute to developing the weaker basal texture in alloys extruded above 250 °C. A sharp basal texture enhances the yield strength of alloy extruded at 150 °C greatly at the cost of work hardening rate. The highest elongation is achieved in the alloy extruded at 300 °C. The enhanced formability is considered to be associated with the dependence of the weaker basal texture and dynamic precipitates on the strain hardening behavior. Among the multiple strengthening mechanisms, the fine grain strengthening and the solid solution strengthening play a dominant role in the increment of strength for the as-extruded alloys.