Effect of Y Contents on Microstructure and Mechanical Properties for as-Cast Mg-Zn-Zr Alloy

The effects of different Y contents (0, 0.94wt%, 0.267wt% and 4.61wt%) on the microstructure and mechainical properties of the as-cast Mg-6Zn-0.7Zr were studied. The results show that Y elements was rich in grain boundaries. The precipitation phases appeared in fishbone-like and block, and continuously distributed along grain bondaries in network form. When the content of Y element was 0.94wt%, the phases was α-Mg, Mg7Zn3 and Mg3Y2Zn3, and when the content of Y element was 2.67wt%, the phases was α-Mg, Mg12YZn and Mg3Y2Zn3. The tensile strength, yield strength and elongation increased firstly and then decreased with the increase of Y contents. The properties of the alloy was best when the content of Y element was 2.67wt%, and the tensile strength, yield strength and elongation was 250.4, 125.3 MPa and 12.73%, respectively.