Microstructure and mechanical properties of as-cast Mg-5Sn-2Ce- x Zn alloys

The microstructure, mechanical properties and compression creep resistance of as-cast Mg-5Sn-2Ce-xZn (x=0, 2 wt.%, 4 wt.%) alloys were investigated in this paper. The results showed that the Ce-containing compounds were MgSnCe phase and an unknown phase, and they were the dominant intermetallics in as-cast Mg-5Sn-2Ce-xZn alloys. At x=0 wt.%, the Ce-containing compounds formed in interdendritic regions with the shape of rod. As the Zn content was increased to 2 wt.%, the Ce-containing compounds partly changed from rod-like to sheet-like. However, there were few further changes in the Ce-containing compounds with further increase in Zn content to 4 wt.%. Compared with Mg-5Sn-2Ce alloy, the tensile strength and elongation of the alloy containing 4 wt.% Zn increased by 39% and 112%, respectively, and the secondary creep rate (175 °C/55 MPa) decreased at least by an order of magnitude. These improvement could be attributed to the combined effects of the high content of Zn dissolving in α-Mg matrix and the modification of Ce-containing compounds by Zn addition.