Effect of aging temperature on microstructure and mechanical properties of Mg-12Gd-3Y-1Sm-0.5Zr alloy

Mg-12Gd-3Y-1Sm-0.5Zr alloy was prepared by induction melting, and the microstructure and properties of the alloy after heat treatment at different aging temperatures were analyzed by X-ray diffraction(XRD), optical microscope(OM), transmission electron microscopy(TEM), micro-hardness and tensile test. The results show that the alloy grain size gradually increases with the increase of aging temperature, the number of the second phase in the grain increases, and the time during which the hardness peak appears gradually decreases when Mg-12Gd-3Y-1Sm-0.5Zr alloy is peak aged at 200, 250 ℃ and 300 ℃. The precipitated phase is β' when the aging temperature is 200 ℃ and 250 ℃, and the precipitated phase is β phase when the aging temperature is 300 ℃. The mechanical properties of the alloy peak aged at 250 ℃ are the best. In the process of stretching at room temperature, 200, 250 ℃ and 300 ℃, the tensile strength of the aging peak alloy at 200 ℃ and 250 ℃ shows the abnormal temperature effect of increasing at first and then decreasing, but while no such abnormal phenomenon appears in the alloy after peak aging heat treatment at 300 ℃