Zn对铸态Mg-Y-Nd-Zr合金组织和力学性能的影响

采用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射分析及力学性能测试等研究Zn元素对Mg-Y-Nd-Zr铸态合金显微组织及力学性能的影响。结果表明:随着Zn含量的增加,Mg-Y-Nd-Zr-xZn(x=0.0%,0.5%,1.0%,1.5%,质量分数)合金的晶粒逐渐细化,平均晶粒尺寸由(57±0.8)μm细化至(30±0.3)μm,晶界处共晶相的体积分数也逐渐增加。Mg-Y-Nd-Zr铸态合金中主要存在Mg12Nd相和Mg24Y5相,加入0.5%Zn后,合金中出现Mg12YZn相。随Zn含量的增加,Mg12YZn相的体积分数不断增大,合金的力学性能逐渐提高。当Zn含量为1.0%时,合金具有最优的力学性能,其抗拉强度、屈服强度和伸长率分别为(208±5.9),(159±3.9)MPa和(7.5±0.2)%,较未加Zn的合金分别提高了18,42MPa和1.2%。

Effects of Zn on Microstructure and MechanicalProperties of As-cast Mg-Y-Nd-Zr Alloys

Effects of Zn on microstructure and mechanical properties of Mg-Y-Nd-Zr as-cast alloys were investigated by the optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffractometry(XRD) and the mechanical properties test.The results show that the grain size of Mg-Y-Nd-Zr-xZn(x=0.0%, 0.5%, 1.0%, 1.5%,mass fraction)alloys is greatly refined with the increase of Zn content, which is refined from (57±0.8)μm to (30±0.3)μm.The volume fraction of eutectic structure at grain boundary increases gradually.Mg12Nd phase and Mg24Y5 phase exist mainly in Mg-Y-Nd-Zr as-cast alloy.With the addition of 0.5%Zn, Mg12YZn phase appears at the grain boundary.With the increase of Zn, the volume fraction of Mg12YZn phase and the mechanical properties of the alloys increases gradually.The alloy containing 1.0%Zn exhibits the optimal mechanical properties, the ultimate tensile strength, yield strength and elongation are (208±5.9), (159±3.9)MPa and (7.5±0.2)%, respectively;comparing with the alloy without the addition of Zn, the ultimate tensile strength, yield strength and elongation increase by 18, 42MPa and 1.2%.