Effects of Al addition on the microstructure and mechanical properties of Mg–4Y alloys

The effects of Al additions (≤4 wt-%) on the microstructure and mechanical properties of Mg–4Y alloys were investigated. The microstructure of the as-cast Mg–4Y–1Al alloy consisted of an α-Mg matrix, together with Mg 24 Y 5 and Al 2 Y phases. Al 2 Y formed preferentially when Al was added, replacing the Mg 24 Y 5 phase by consuming Y solute. The eutectic reaction occurred, forming α-Mg and Mg 24 Y 5 phases for Al contents below 2 wt-%; however, the pseudo-binary eutectic reaction occurred, forming α-Mg and Al 2 Y phases, for Al contents higher than 2 wt-%. The addition of Al improved mechanical properties. The Mg–4Y–4Al alloy exhibited the optimal ultimate tensile strength and yield strength, with values of 208 and 81 MPa, respectively. This paper is part of a thematic issue on Light Alloys.