Influence of solution treatments on the age-hardening response of Mg–Gd(–Mn–Sc) alloys

Abstract

The microstructures and age-hardening response of a Mg–5 wt.%Gd alloy and a Mg–5 wt.%Gd–1.1 wt.%Mn–0.8 wt.%Sc alloy have been examined under different solution treatment conditions. Both alloys exhibit little or no age-hardening response during isothermal ageing at temperatures above 200 °C when the alloys are solution treated at 520 °C for 24 h. Solution treatment at 610 °C for 24 h does not improve the age-hardening response of the binary alloy. However, it leads to a significant increase in hardness during ageing for the quaternary alloy. This improved age-hardening response in the quaternary alloy is ascribed to the dense precipitation of two fine-scale precipitate phases during ageing.