Effect of hot extrusion on microstructure and mechanical properties of Mg-Zn-0.5Ca-0.5RE alloys

Mg-Zn-0.5Ca-0.5RE magnesium alloys with zinc contents of 4 and 6 wt%, were considered to study the effect of zinc content and hot extrusion process on the microstructure and mechanical properties. The Mg12Re and Mg7Zn3-Ca-RE phases were observed in both alloys. Based on the competition of favorable grain refinement and unfavorable grain boundary phases, the Mg-4Zn-0.5Ca-0.5RE (ZEX400) alloy showed higher UTS compared to Mg-4Zn-0.5Ca-0.5RE (ZEX600) alloy. Intense grain refinement introduced by extrusion and the fracturing and dispersion of the grain-boundary phase resulted in the significant enhancement of strength and ductility. It was also found that high Zn content (~ 6 wt%) limits the usability and working temperature range of the alloys due to the problem of intergranular fracture.

کلیدواژه ها:

Magnesium alloys ، Microstructure ، Grain size ، Mechanical properties.