Microstructure and mechanical properties of Mg–Zn–Gd alloys after rolling or extrusion processes

Abstract

A series of Mg–Zn–Gd alloys were developed for large strain hot rolling, cold rolling and high-speed extrusion. The hot rolled Mg–2.0Zn–0.3Gd (wt%) alloys can be successfully rolled at 300 °C for a single pass reduction of 80% without any edge cracks, and the rolled sheet exhibited high yield strength of ~210 MPa and moderate elongation of ~22% due to fine grains and weak basal texture with broad angle distribution. The hot rolled Mg–2.0Zn–0.8Gd sheet showed excellent cold rollability due to the activation of {1012} extension twins and dislocation slips. Cold rolling could further modify the texture and enhance the strength. Besides, Mg–1.58Zn–0.52Gd alloy can be successfully extruded at high die-exit speed of 60 m/min without any surface defects in a wide temperature range due to the absence of thermally unstable eutectic phase and high solidus temperature. The high-speed extruded alloy showed high ductility of ~30%, which was twice than AZ31 alloy, because of the formation of rare earth texture.