Phase transformation occurring during the heat-treatment of magnesium rare earth alloys

Abstract

This work discusses the phase transformations occurring and mechanical properties of a cast and extruded Mg-5%Y-4%Gd alloy, 90 and 20 mm in diameter bar, after various heat treatments. The influence of quenching temperature, artificial and natural ageing on microstructure, microhardness and mechanical properties is presented. It is demonstrated that the alloy strengthens during natural ageing and initially recovers during artificial ageing. An understanding of the alloy behavior leads to optimization of the heat-treatment procedures; the best combination of mechanical properties is obtained after artificial aging at 200° for 3 days.