Ca对铸态Mg-11Gd-3Y-0.5Zr合金显微组织和性能的影响

Effect of Ca on microstructure and poperties of as-cast Mg-11Gd-3Y-0.5Zr alloy

采用光学显微镜、扫描电镜、X射线衍射仪、能谱仪、硬度计以及拉伸试验机,研究分析了Mg-11Gd-3Y-xCa-0.5Zr(x=0、0.2、0.8 mass%)合金的显微组织及力学性能。结果表明:铸态Mg-11Gd-3Y-0.5Zr合金由α-Mg基体以及大量处于晶界上的Mg_5Gd和Mg_(24)Y_5相组成,添加0.2 mass%Ca对合金相种类没有影响,而当添加0.8 mass%的Ca时,晶界处有新相Mg_2Ca的出现且晶粒显著细化。随着Ca元素含量的增加,合金的抗拉强度及硬度不断增加,但伸长率不断降低,当Ca含量为0.8 mass%时,抗拉强度和硬度达到217 MPa和92 HBW,与基体合金相比提高了12.43%和16.46%,但伸长率仅为3.4%。

The microstructure and mechanical properties of Mg-11 Gd-3 Y-xCa-0.5 Zr(x=0,0.2,0.8 mass%)alloys were studied by means of metallographic microscope,scanning electron microscopy,X-ray diffraction,energy dispersive spectrometer,hardness tester and tensile testing machine.The results show that the as-cast Mg-11 Gd-3 Y-0.5 Zr alloy consists ofα-Mg matrix and a large number of Mg5Gd and Mg24Y5 phases at the grain boundary.0.2 mass%Ca has no effect on the phase type of the alloy,while 0.8 mass%Ca is added,there is a new phase Mg2Ca at the grain boundary and the grains are remarkably refined.With the increase of Ca content,the tensile strength and hardness of the alloy increase continuously,but the elongation decreases continuously.When the content of Ca is 0.8 mass%,the tensile strength and hardness reach 217 MPa and 92 HBW,respectively.Compared with the matrix alloy,it increases by 12.43%and 16.46%,respectively,but the elongation is only 3.4%.