Ho对铸态Mg-5Y-3Sm-0.5Zr合金显微组织和力学性能的影响

采用光学显微镜、扫描电镜、X射线衍射仪、电子拉伸实验机、布氏硬度计等研究了铸态Mg-5Y-3Sm-xHo-0.5Zr(x=0,2,4,6)合金的组织和力学性能。结果表明:铸态Mg-5Y-3Sm-0.5Zr合金主要由α-Mg和大部分位于晶界的Mg24Y5和Mg41Sm5第二相组成。添加Ho后,在晶界处出现了Mg24Ho5新相,Ho的含量高低对合金相组成没有影响。随着Ho含量的不断提高,析出的第二相逐渐增多,晶粒尺寸逐渐减小。当Ho含量为4%时,该铸态合金的综合力学性能最好,抗拉强度、屈服强度、硬度和伸长率分别为193 MPa、170 MPa、72.8 HBW和4.15%。

Effect of Ho on microstructure and mechanical properties of as-cast Mg-5Y-3Sm-0.5Zr alloy

Microstructure and mechanical properties of as-cast Mg-5 Y-3 Sm-xHo-0.5 Zr(x=0,2,4,6)alloys were studied by means of optical microscope,scanning electron microscopy,X-ray diffraction,electronic tensile testing machine and Brinell hardness tester.The results show that the as-cast Mg-5 Y-3 Sm-0.5 Zr alloy is mainly composed ofα-Mg and most of the Mg24Y5 and Mg41Sm5 phases located at grain boundaries.After adding Ho,a new phase of Mg24Ho5 appears at the grain boundary of the alloy,and the content of Ho has no effect on the phase composition of the alloy.With the increase of Ho content,the amount of the second phase increases and the grain size decreases.When the content of Ho is 4%,the comprehensive mechanical properties of the as-cast alloy are the best,the tensile strength,yield strength,hardness and elongation are 193 MPa,170 MPa,72.8 HBW and 4.15%,respectively.