Effect of extrusion temperature on microstructure and tensile properties of Mg–Gd–Er–Zn–Zr alloy containing LPSO phase

The Mg–1Gd–0.75Er–0.5Zn–0.18Zr (at.%) alloy with long-period stacking ordered (LPSO) phase was prepared by metal mold casting and hot extrusion. The extruded samples had a typical bimodal microstructure. The different fractions of equiaxed grains were observed in annealed samples. The percentage of fine grains decreased in the extruded Mg alloys with and without annealing treatment when the extrusion temperature was increased. The LPSO phases promote recrystallization behavior in the samples through particle-stimulated nucleation (PSN) mechanism. The Mg alloys extruded at 300 °C with or without annealing treatment obtained the best tensile properties. At the low extrusion temperature, more finely equiaxed grains with random texture are formed through PSN, and more LPSO phase kink bands are formed, which could improve the mechanical properties of the extruded Mg alloys.