As-cast microstructures and mechanical properties of Mg–4Zn–xY–1Ca (x=1.0, 1.5, 2.0, 3.0) magnesium alloys

Abstract The as-cast microstructures and mechanical properties of Mg–4Zn– x Y–1Ca ( x =1.0, 1.5, 2.0 and 3.0, mass fraction, %) alloys were investigated and compared. The results indicate that all the as-cast alloys are mainly composed of α -Mg, Mg 2 Ca, Ca 2 Mg 6 Zn 3 , I (Mg 3 YZn 6 ) and W (Mg 3 Y 2 Zn 3 ) phases. However, with Y content increasing from 0.86% to 2.68%, the amount of the Ca 2 Mg 6 Zn 3 phase gradually decreases but that of the I (Mg 3 YZn 6 ) and W (Mg 3 Y 2 Zn 3 ) phases gradually increases. Furthermore, an increase in Y content from 0.86% to 2.68% also causes the grain size of the as-cast alloys to gradually decrease. In addition, the tensile and creep properties of the as-cast alloys vary with Y content. Namely, with Y content increasing from 0.86% to 2.68%, the creep properties gradually increase, whereas the tensile properties firstly increase and attain the maximum at 1.77% Y, beyond that they decrease. Amongst the as-cast alloys with 0.86% Y, 1.19% Y, 1.77% Y and 2.68% Y, the alloy with 1.77% Y exhibits the relatively optimal tensile and creep properties.