(1. 中南大学 材料科学与工程学院，长沙 410083;
2. 钢铁研究总院 安泰科技股份有限公司， 北京 100039;
3. 北京工业大学 材料科学与工程学院， 北京 100022)
摘 要: 采用铸锭冶金法， 制备含不同量稀土元素Er的Al-5Mg合金。 利用拉伸力学性能测试、 OM、 XRD、 SEM、 TEM及EDS分析等分析测试手段， 研究微量Er对Al-5Mg合金微观组织与力学性能的影响。 结果表明： Er可以明显提高Al-5Mg合金的强度， 添加0.4%Er(质量分数)的Al-5Mg合金的冷轧态屈服强度(σ0.2)提高了81 MPa， 而延伸率变化不大； Er的加入还能减少Al-5Mg合金的枝晶偏析， 并可显著细化合金的晶粒组织； Er对晶粒的细化机理与其添加量有关， 当Er含量较低时， 符合传统的稀土细化机理； 当Er含量较高时， 由于在熔体中形成了初生Al3Er质点， 在结晶形核时可以作为非均质形核核心， 从而可显著细化晶粒组织； Er对合金的强化效应主要来自于晶粒细化及在晶内形成的细小二次Al3Er质点。 根据实验结果可知， 添加0.4%Er可使合金具有较为优异的综合性能。
关键字: Er; Al-5Mg合金; Al3Er; 微观组织; 力学性能
（ 1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Central Iron and Steel Research Institute, Beijing 100039, China;
3. School of Materials Science and Engineering, Beijing University of Technology, Beijing 100022, China）
Abstract: Al-5Mg alloys containing different content of Er were prepared by cast metallurgy. The effect of trace Er on the microstructure and properties of Al-5Mg alloy was studied with tensile properties measurement, OM, XRD, SEM, TEM and EDS. The results show that the addition of Er to Al-5Mg alloy can improve the strength remarkably, and the yield strength of the cold-rolled alloy is improved by 81 MPa when the content of Er is 0.4%(mass fraction), while the ductility keeps stable or decreases slightly. The addition of Er can reduce the dendritical arm space of the alloy, and the grains are refined obviously. The refinement mechanism of Er addition on the grain depends on the quantity of Er added. The refinement mechanism of the alloy containing less Er conforms to be traditional refining theory on rare-earth aluminum alloy. The grain of the alloy containing more Er is refined due to the formation of primary Al3Er, and the primary Al3Er shall be able to act as nucleus. The strengthing effect of Er on Al-5Mg alloy is caused by grain refinement and the fine secondary Al3Er particles. The results indicate that the alloys with 0.4%Er have more excellent properties.
Key words: Er; Al-5Mg alloy; Al3Er; microstructure; mechanical properties
