Effect of ageing treatment on the microstructure, texture and mechanical properties of extruded Mg–8.2Gd–3.8Y–1Zn–0.4Zr (wt%) alloy

Abstract

Extruded Mg–8.2Gd–3.8Y–1Zn–0.4Zr (wt%) alloy was subjected to ageing treatment at 200°C. The microstructures, textures and mechanical properties of the as-extruded and peak-aged alloys were investigated. Recrystallization occurred during ageing treatment. A large number of β′ phases were observed in the peak-aged alloy, accompanied with the decrease of the volume fraction of LPSO phases. A basal fiber texture and an unusual texture component with basal planes perpendicular to the extrusion direction were found in the as-extruded alloy, and the basal fiber texture was strengthened after ageing treatment. The peak-aged alloy exhibited a tensile yield strength (TYS), an ultimate tensile strength (UTS) and an elongation to failure of 395MPa, 470MPa and 8%, respectively, at ambient temperature, and 271MPa, 311MPa and 19%, respectively, at 300°C. The superior strength of the peak-aged alloy was mainly attributed to the precipitation of fine β′ phases, the remaining LPSO phases and the texture modification.