Effect of W-phase on the mechanical properties of as-cast Mg-Zn-Y-Zr alloys

This work mainly investigated the mechanical properties of as-cast Mg-Zn-Y-Zr Mg alloys with Zn/Y ratio about 0.97. Tensile results show that when Zn/Y ratio is constant, the alloy (with Zn and Y contents of 3.93 and 4.14 wt.%, respectively) has the highest strength. XRD analysis shows that the alloys are mainly composed of alpha-Mg matrix and W-phase. With the contents of Zn and Y increasing, the diffraction peaks of W-phase are gradually intensified. In addition, microstructure observation indicates that with the increase of Zn and Y contents, the grain boundaries are gradually coarsened by W-phase. Based on the microstructure observation and fracture analysis, the change of the mechanical properties has been explained. (C) 2007 Elsevier B.V. All rights reserved.