稀土元素Sm对Mg-Zn-Y合金组织结构和力学性能的影响

Influence of Sm on Microstructure and Mechanical Properties of Mg-Zn-Y Alloys

制备了Mg-6Zn-1.5Y-0.8Zr-xSm(x=0,1,2,3)系列合金,研究了稀土元素Sm对Mg-6Zn-1.5Y-0.8Zr合金组织结构和力学性能的影响。通过金相显微镜、扫描电镜、EDS、XRD等观察和分析了合金的微观形貌和组织结构,测量了合金抗拉强度、屈服强度和伸长率等力学性能。结果表明:合金中添加稀土元素Sm后晶粒有了明显的细化,随着Sm元素含量的增加,晶粒细化效果更为明显;通过XRD分析,添加Sm元素后,合金中并没有出现新的含Sm的物相,通过扫描电镜和EDS分析表明,合金中加入的Sm置换了部分Y,形成了Mg3(SmY)2Zn3,Mg3(SmY)Zn6的相结构,Sm元素对Y的置换主要出现在Mg3(SmY)Zn6结构当中,在Mg3(SmY)Zn6相结构出现较少;力学性能测试结果表明,随着Sm含量增多,合金晶粒细化,细晶强化作用明显,合金屈服强度逐渐增大,而抗拉强度和伸长率在Sm含量为2%时达到最大,比未添加Sm元素时提高约15%以上。

The Mg-6Zn-1.5Y-0.8Zr-xSm （x = 0, 1, 2, 3） series alloys were prepared and the influence of Sm on microstructure and properties of Mg-6Zn-1.5Y-0.8Zr alloys was investigated. The morphology and microstructure of the alloy were researched through microscope, SEM, EDS and XRD methods. The mechanical properties such as ultimate tensile strength（ UTS）, yield strength（YS） and elongation（EL） were measured. The results showed that Sm could refine as-cast mierostructure of Mg-Zn-Y alloy and refinement effect was more apparent when the content of Sm was increased. The phase contained Sm was not found during XRD analysis and it was found that some Y was replaced by Sm and recreated new phase structure like Mg3 （StaY） 2 Zn3 and Mg3 （StaY） Zn6 in the alloy. Sm replaced Y mainly in Mg3 （StaY）2Zn3 phase structure and rarely existed in Mg3 （StaY）Zn6 phase structure. The results of mechanic property test showed that the refined grains caused refinement effect, and the YS of the alloy increased slowly as the content of Sm increasing. The UTS and EL both reached maximum when the content of Sm was 2%, which increased about 15% compare to the alloy has none samarium.