Mg-12Gd-3Y-0.5Zr镁合金的显微组织、力学性能及时效析出相

通过光学显微镜、扫描电子显微镜、透射电镜、X射线衍射仪、高温拉伸试验机等对不同状态下Mg-12Gd-3Y-0.5Zr镁合金的显微组织、高温力学性能及时效析出相进行了分析。结果表明:该合金铸态组织由α-Mg固溶体、Mg5Gd析出相及α-Mg+Mg24Y5共晶体组成;挤压变形后合金的晶粒尺寸明显减小;合金挤压轧制板材在常温及150℃时有较高的抗拉强度,当温度进一步升高时强度下降较快;合金轧制板材时效析出相在高温(高于250℃)拉伸过程中没有发生相变,但在拉伸过程中会改变分布及形貌,使得变形抗力减小。

Microstructure,Mechanical Properties and Aging Precipitation Phases of Mg-12Gd-3Y-0.5Zr Magnesium Alloy

The microstructure,high temperature mechanical properties and the precipitation phase of Mg-12Gd-3Y-0.5Zr alloy under different states were investigated by using optical microscopy,scanning electron microscopy,transmission electron microscopy,X-ray diffraction and high temperature tensile testing machine.The results show that the as-cast alloy was consisted of α-Mg solid-solution and Mg5Gd precipitation phase and α-Mg+Mg24Y5 eutectic.The grains size of the alloy decreased obviously after hot extrusion.The extruded and rolled sheets had fairly high tensile strength at room temperature and 150 ℃,and the strength decreased rapidly as the temperature raised further.The aging precipitate phases of the alloy sheet did not change in the process of high temperature(>250 ℃)extruding,but the distribution and morphology were changed,which led to the decrease of deformation resistance.