Effects of RE on the microstructure and mechanical properties of Mg–8Zn–4Al magnesium alloy

Effects of rare earth (RE) alloy element on the microstructure and mechanical properties of Mg–8Zn–4Al (ZA84) alloy have been investigated. The differential scanning calorimetry (DSC) technique was used to study the solidification and aging process of ZA84 and ZA84–xRE alloys. The results show that a new quaternary precipitate Mg3Al4Zn2RE forms during the solidification and its phase transformation temperature point is 413 °C in RE-containing ZA84 alloys. The microstructure of ZA84 alloy can be refined, ɛ phases formed, microhardness of the matrix increased and time for attaining microhardness peak value of aging ZA84–xRE alloys delayed, with increasing RE. Thus, the room temperature and high temperature tensile properties of as-cast and aged ZA84 alloys can be improved by RE addition.