Effects of calcium addition on as-cast microstructure and mechanical properties of Mg-5Zn-5Sn alloy

The effects of Ca addition on the as-cast microstructure and mechanical properties of the Mg-5Zn-5Sn (mass fraction, %) alloy were investigated. The results indicate that an addition of 0.5%-1.5% (mass fraction) Ca to the Mg-5Zn-5Sn alloy not only refines the as-cast microstructure of the alloy but also causes the formation of the primary and/or eutectic CaMgSn phases with high thermal stability; an increase in Ca amount from 0.5% to 1.5% (mass fraction) increases the amount and size of the CaMgSn phase. In addition, Ca addition to the Mg-5Zn-5Sn alloy improves not only the tensile properties at room temperature and 150 °C but also the creep properties. Among the Ca-containing Mg-5Zn-5Sn alloys, the one added 0.5% (mass fraction) Ca obtains the optimum ultimate tensile strength and elongation at room temperature and 150 °C, however, the alloy added 1.5% (mass fraction) Ca exhibits the optimum yield strength and creep properties.