The Effect of Y Content on the Strength and Toughness of Mg-Y-Zn Alloys

The microstructure and properties of Mg-Y-Zn as-cast alloys with the Y/Zn ratio of approximately 1.3 (wt%) and different Y contents were studied, including an analysis of the main factors and mechanisms affecting their toughness and ductility, such as dendritic morphology, mass fraction of different compound phases, and degree of solid solution. The results showed that the alloys with Y contents ranging from 3.5% to 5% exhibit high toughness. The 4.4% alloy has the best comprehensive mechanical properties with the UTS, YS, EL, and tensile deformation work of 188.9 MPa, 124.4 MPa, 5.9%, and 0.50 MJ/m2, respectively. It is beneficial for achieving higher strength and toughness by maintaining the content of the W phase and the combined content of the W phase and LPSO phase at approximately 5.8 wt% and 28.8 wt%, respectively.