时效温度对Mg-12Gd-3Y-1Sm-0.5Zr合金组织和力学性能的影响

采用X射线衍射、光学显微镜、透射电子显微镜、显微硬度和拉伸性能测试等手段,研究时效热处理温度对Mg-12Gd-3Y-1Sm-0.5Zr合金组织和性能的影响。结果表明,Mg-12Gd-3Y-1Sm-0.5Zr合金在200,250℃和300℃峰时效时,晶粒大小随时效温度的升高而逐渐增大,晶内颗粒状的第二相数量增多,硬度峰值出现的时间逐渐缩短。合金时效温度在200,250℃时,析出相为β′相,时效温度在300℃时,析出相为β相。合金在250℃峰时效时力学性能最优。在200,250℃峰时效热处理的合金在从室温到200,250℃和300℃拉伸过程中抗拉强度随拉伸温度的升高先升高后降低,出现了抗拉强度反常温度效应,而在300℃峰时效热处理后的合金未出现该反常现象。

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

Mg-12 Gd-3 Y-1 Sm-0.5 Zr 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-12 Gd-3 Y-1 Sm-0.5 Zr alloy is peak aged at 200,250℃and 300℃.The precipitated phase isβ′when the aging temperature is 200℃and 250℃,and the precipitated phase isβphase 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℃.