铸态 Mg-2Nd-0.2Zn-0.4Zr-xY 镁合金组织及力学性能

摘要

The effects of Y addition on the microstructure and mechanical properties of Mg-2%Nd-0.2%Zn-0.4%Zr cast alloys were studied by optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffractometry(XRD) and mechanical properties test. The results show that the grain size is greatly refined by the addition of Y. Especially, with the addition of 6% Y, the grain size is refined from 100 μm to 35 urn. The main phase of as-cast Mg-2%Nd-0.2%Zn-0.4%Zr alloy without addition of Y is Mg12Nd, whereas, the element Nd and Y exist as Mg41Nd5 and Mg24Y5 in alloys containing Y. With the addition of Y, the mechanical properties of the alloys are enhanced. Especially, with the content of 6% Y, the alloy displays excellent mechanical properties, i.e. the tensile strength and yield strength are increased to 245 MPa and 150 MPa, respectively, and the elongation is greatly increased to 16%, which is increased by 191%, compared with the alloy without addition of Y. The mechanical properties of the alloy are descended when the content of Y reaches 8%.%采用光学显微镜(OM)、扫描电子显微镜(SEM)、X线衍射分析(XRD)及力学性能测试等手段,研究不同含量稀土元素Y(4％,6％,8％,质量分数)对Mg-2％Nd-0.2％Zn-0.4％Zr镁合金铸态显微组织及力学性能的影响.结果表明:在Mg-2％Nd-0.2％Zn-0.4％Zr镁合金中添加Y可以明显细化合金晶粒,其中加入6％Y时效果最佳;合金晶粒粒径由100μm细化至35 μm.未添加稀土元素的Mg-2％Nd-0.2％Zn-0.4Zr铸态合金中主要存在Mg12Nd相;加入稀土元素Y后,Nd和Y分别以Mg41Nd5和Mg24Y5化合物形式存在,合金的力学性能得到提高.其中加入6％Y的合金综合力学性能最好,抗拉强度和屈服强度分别提高至245 MPa和150 MPa,而伸长率大幅提高至16％,较未加稀土元素Y的合金提高191％;当Y含量达到8％时,合金综合力学性能下降.