(1. 中南大学 材料科学与工程学院，长沙 410083； 2. 中南大学 轻合金研究院，长沙 410083； 3. 中南大学 有色金属先进结构材料与制造协同创新中心，长沙 410083)
摘 要: 通过金相观察、X射线衍射、透射电镜、硬度测试和拉伸性能测试等实验方法，研究添加不同含量的Nd元素对Mg-6Gd-2.5Y-0.5Zr合金的显微组织、时效硬化行为以及峰值时效下力学性能的影响。结果表明：随着Nd含量的增加，铸态合金中第二相Mg5(Gd/Y)和Mg24(Gd/Y)5 的含量显著增加，合金经固溶淬火后，时效强化现象越来越显著，峰值时效时间缩短，峰值时效硬度明显增加。当Nd元素的含量为1.0%(质量分数)，合金的力学性能最佳，Mg-6Gd-2.5Y-1Nd-0.5Zr的抗拉强度为289 MPa，屈服强度为241 MPa。时效硬化行为和峰值时效力学性能得到改善，其主要是因为加入Nd元素后，在α-Mg基体中形成大量的β′相，且β′相明显细化，β′相的形貌也发生改变。
关键字: Nd元素；镁合金；显微组织；力学性能
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China; 2. Light Alloy Research Institute, Central South University, Changsha 410083, China; 3. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Central South University, Changsha 410083, China）
Abstract:The effects of Nd addition on microstructure, age-hardening behavior and mechanical properties of Mg-6Gd-2.5Y-0.5Zr alloy were investigated by optical microscopy (OM), X-ray diffractometry (XRD), transmission electron microscopy (TEM), hardness test and tensile tests. The results show that the amount of second phase (Mg5(Gd/Y) and Mg24(Gd/Y)5) increase significantly in the as-cast alloys, and the age hardening response after quenched is improved apparently with the addition of Nd, the hardness is enhanced and time to peak ageing is shortened. The Mg-6Gd-2.5Y-1Nd-0.5Zr alloy exhibits the maximum yield strength of 241 MPa and ultimate tensile strength of 289 MPa. The reason for the improvement of age-hardening behavior and mechanical properties is the higher number density and finer β′ precipitates in the α-Mg matrix, and morphologies of β′ precipitates also change with Nd addition.
Key words: neodymium; magnesium alloy; microstructure; mechanical property
