Effects of Sn Addition on as-Cast Microstructure and Mechanical Properties of Mg-3.8Zn-2.2Ca Magnesium Alloy

The as-cast microstructure, tensile and creep properties of Mg-3.8Zn-2.2Ca-xSn (x=0, 0.5, 1, 2, wt%) alloys were investigated. The results indicate that the CaMgSn phase is formed in the Sn-containing alloys, and an increase in Sn content from 0.46 wt% to 1.88 wt% causes the amount of the CaMgSn phase to increase. Simultaneously, the morphology of the Ca2Mg6Zn3 phase changes from the initial continuous and/or quasi-continuous net to the quasi-continuous and/or disconnected shapes. Furthermore, the grains of the Sn-containing alloys are effectively refined, and the grains of the alloy with 0.90 wt%Sn are the finest. Compared with the ternary alloy, the tensile and creep properties of the alloys with the additions of 0.46 wt% and 0.90 wt%Sn are effectively improved. However, the ultimate tensile strength and elongation of the alloy with 1.88 wt%Sn are decreased though its yield strength and creep properties are improved. Among the three Sn-containing alloys with the additions of 0.46 wt%, 0.90 wt% and 1.88 wt%Sn, the alloy with 0.90 wt%Sn exhibits the relatively optimal tensile and creep properties.