Gd对铸态Mg-4Y-2Sm-0.5Zr合金组织与性能的影响

Effect of Gd on microstructure and properties of as-cast Mg-4Y-2Sm-0. 5Zr alloy

采用光学显微镜、X射线衍射仪、扫描电子显微镜等仪器对铸态Mg-4Y-2Sm-xGd-0.5Zr(x=0、1、2、3)合金进行了微观组织及物相分析,同时用拉伸试验机对其进行了力学性能测试。研究结果表明:铸态Mg-4Y-2Sm-0.5Zr合金组织由α-Mg基体、第二相Mg24Y5和Mg41Sm5组成;随着稀土元素Gd的加入,合金组织中有Mg5Gd相生成;Gd含量为1%时,Mg-4Y-2Sm-1Gd-0.5Zr合金中的第二相分布均匀,晶粒得到细化,综合力学性能达到峰值,抗拉强度为203 MPa,伸长率为12.68%,与Mg-4Y-2Sm-0.5Zr合金相比分别提高了50 MPa,8.46%。随着Gd元素含量的增加,第二相增多且主要沿晶界逐渐呈连续网状析出,力学性能下降。适量Gd元素的加入可以显著改善Mg-4Y-2Sm-0.5Zr合金的力学性能和伸长率,过量Gd元素的加入则会降低合金的综合力学性能。

The microstructure and phase of the cast Mg-4Y-2Sm-xGd-0.5Zr(x=0,1,2,3)alloy were analyzed by means of optical microscope,X ray diffractometer and scanning electron microscope,and the mechanical properties of the alloy were tested by the tensile test machine.The results show that the microstructure of the as-cast Mg-4Y-2Sm-0.5Zr alloy consists of the matrix ofα-Mg,the second phases Mg24Y5 and Mg41Sm5.With the addition of the rare earth element Gd,the Mg5Gd phase is formed in the alloy.When the content of Gd is 1%,the second phases in Mg-4Y-2Sm-1Gd-0.5Zr alloy can be evenly distributed,and the grain is refined.The mechanical properties reach the peak value with the tensile strength 203 MPa and the elongation 12.68%,compared with the Mg-4Y-2Sm-0.5Zr alloy,the tensile strength and elongation increased 50 MPa and 8.46%respectively.With the increase of Gd content,the second phases increases,and most of them gradually appears continuous net precipitated along the grain boundary,and the mechanical properties decrease.The addition of appropriate amount of Gd element can significantly improve the tensile properties and elongation of Mg-4Y-2Sm-0.5Zr alloy.The addition of excessive Gd elements will reduce the comprehensive mechanical properties of the alloy.