Effects of Zr addition on as cast microstructure, tensile and creep properties of Mg–3·8Zn–2·2Ca magnesium alloy

Abstract

The effects of Zr addition on the as cast microstructure, tensile and creep properties of Mg-3?8Zn-2?2Ca (wt-%) magnesium alloy were investigated. The results indicate that adding 0?19-0?81 wt-%Zr to the Mg-3?8Zn-2?2Ca does not cause the formation of any new phases but causes the morphology of the Ca 2 Mg 6 Zn 3 phase to change from the initial continuous and/or quasicontinuous net to the quasi-continuous and/or disconnected shapes. Furthermore, adding 0?19-0?81 wt-%Zr can effectively refine the grains of the Mg-3?8Zn-2?2Ca alloy, and an increase in Zr amount from 0?19 to 0?81 wt-% causes the grain size to gradually decrease. In addition, adding 0?19-0?81 wt-%Zr to the Mg-3?8Zn-2?2Ca alloy can improve the tensile properties but decreases the creep properties. Among these Mg-3?8Zn-2?2Ca alloys with the additions of 0?19, 0?52 and 0?81 wt-%Zr, the alloy with the addition of 0?81 wt-%Zr exhibits the relatively optimal tensile and creep properties.