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采用X射线衍射仪、光学显微镜、扫描电镜、能谱分析仪以及拉伸试验机,研究了不同热处理对Mg-9Gd-4Y-1Zn-0.5Zr合金组织和性能的影响。结果表明:不论是铸态、固溶态,还是时效态,合金组织都主要由α-Mg基体以及稀土化合物Mg5(Gd,Y,Zn)、Mg24(Y,Gd,Zn)5和Mg12Zn(Gd,Y)组成;但铸态下合金中第二相主要为Mg5(Gd,Y,Zn),在晶内呈平行的流线状排列,晶粒粗大。通过固溶时效处理,Mg12Zn(Gd,Y)相在晶界处析出并向晶内生长,成为合金的主要强化相,其强化方式主要为固溶强化和时效强化。室温下,铸态合金抗拉强度为138 MPa,伸长率为2.16%,时效态合金抗拉强度为223 MPa,伸长率为3.94%,合金力学性能得到明显提升。
The effects of different heat treatments on microstructure and properties of Mg-9Gd-4Y-1Zn-0.5Zr alloy were studied by X-ray diffraction, optical microscope, scanning electron microscope, energy spectrum analyzer and tensile tester. The results show that the alloy microstructure consists of α-Mg matrix and rare earth compounds Mg5 (Gd, Y, Zn), Mg24 (Y, Gd, Zn) 5 and Mg12Zn (Gd , Y). However, the second phase in the as-cast alloy is dominated by Mg5 (Gd, Y, Zn). Through solution treatment, the Mg12Zn (Gd, Y) phase precipitates at the grain boundary and grows into the grains, which becomes the main strengthening phase of the alloy. The strengthening modes are mainly solid solution strengthening and aging strengthening. The tensile strength of as-cast alloy is 138 MPa, the elongation is 2.16%, the tensile strength of aged alloy is 223 MPa and the elongation is 3.94% at room temperature. The mechanical properties of the alloy are obviously improved.