Effects of hot extrusion and rare earth addition on grain refinement of ZK20 magnesium alloy

The Mg, ZK20 (Mg-2Zn -0.5Zr), and ZEK200 (Mg-2Zn-0.5Zr-0.5RE) alloys were studied in the as-cast and extruded conditions. It was revealed that the addition of 0.5 wt% mischmetal to ZK20 alloy to form ZEK200 alloy is an effective way for grain refinement in the as-cast condition. Moreover, a low fraction of an additional phase containing rare earth elements was observed in the case of ZEK200 alloy. After the extrusion process, fine and recrystallized microstructures were obtained. The refinement of grain size and also fracturing and dispersion of second-phase particles along the extrusion direction (ED) were evident in the extruded ZEK200 alloy. Conclusively, this study revealed the potential of grain refinement of Mg alloys via addition of rare earth elements and application of hot extrusion process.

کلیدواژه ها:

Mg-Zn-Zr alloys ، Rare earth addition ، Hot extrusion ، Grain size.