Microstructure and mechanical properties of Mg-7Zn-3Al alloy with Nd and Y additions

The effects of combined addition of 0.6 wt.% Nd and 0.4 wt.% Y on the microstructure and mechanical properties of Mg-7Zn-3Al alloy were investigated. The results indicated that the Nd and Y addition led to obvious dendrite coarsening. However, it could modify the morphology and distribution of τ-Mg32(Al, Zn)49 intermetallics. Moreover, Al2REZn2 phase could be introduced into the alloy with the Nd and Y addition. With the effective second-phase strengthening, the ultimate tensile strength and elongation in as-cast state can be improved by the Nd and Y addition. After ageing treatment, the alloy with the Nd and Y addition exhibited better precipitation strengthening effects by forming finer MgZn2 and Mg32(Al,Zn)49 precipitates into the α-Mg matrix. As a result, the yield and ultimate strength of Mg-7Zn- 3Al-0.6Nd-0.4Y alloy could be increased to 182 and 300 MPa by peak-ageing treatment.