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Effect of Sr Addition on the Microstructure of Mg-6Zn-2Al-2Ca Alloy

The effect of Sr addition on microstructure evolution of Mg-6Zn-2Al-2Ca-xSr (x=0.5, 1, 2, 3）alloys were investigated by using scanning electron microscope (SEM), X-ray diffraction (XRD) and optical microscope. The result show that Sr constitutional under cooling can significantly refined microstructure of alloys and formed rod-shaped Al4Sr phase in Mg-6Zn-2Al-2Ca alloys, while alloy microstructure turned to be coarse with further increase in Sr content. The addition of Sr slows down the precipitation power of Mg-6Zn-2Al-2Ca alloys and inhabits the β phase continuous precipitation.