微量Er对Mg-Nd-Zn-Zr合金显微组织与力学性能的影响
Effects of trace Er addition on the Microstructure and Mechanical Properties of As-cast Mg-Nd-Zn-Zr Alloy
梁叔全，陈亮，官迪凯，陈涛
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作者单位：中南大学材料科学与工程学院
中文关键字：稀土Er；Mg-Nd-Zn-Zr合金；显微组织；力学性能
英文关键字： rare earth Er; Mg-Nd-Zn-Zr alloy; microstructure; mechanical properties
中文摘要：利用光学显微镜、扫描电子显微镜、透射电子显微镜、能谱仪、X射线衍射分析及力学性能测试，研究稀土元素Er对Mg-Nd-Zn-Zr合金铸态显微组织及力学性能的影响。研究结果表明：在Mg-Nd-Zn-Zr合金镁中添加质量分数为0.5wt.%的Er后，元素Er主要以白色小颗粒形貌分布在晶间，合金达到峰值时效的时间更短，且有大量细小的相均匀析出，时效强化效果更好。加入Er后，合金抗拉强度和屈服强度升高，而延伸率几乎不变；它的抗拉强度、屈服强度和延伸率分别达到为283.4MPa、170.2MPa和4%。Mg-Nd-Zn-Zr-Er合金室温拉伸断口形貌中有高度不一的解理台,撕裂棱和少量的韧窝，韧窝中的颗粒物主要含Er,Nd，说明合金具有较好的塑性。Er的加入并没有改变合金的断裂方式，两种合金时效态都以准解理断裂为主。
英文摘要：The effects of trace Er addition on microstructure and mechanical properties of as-cast Mg-Nd-Zn-Zr alloy were investigated by optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscope(TEM) ,energy-dispersive spectroscopy(EDS) , X-ray diffractometry (XRD) , mechanical properties test. The results show that Mg-Nd-Zn-Zr alloy with addition of Er 0.5%(wt.%) has small white particles consisted of Er mostly dispersed in the grain boundaries.The alloy with Er reaches the peak-aged hardness sooner than that without Er with lots of uniform fine precipitates,so its aging strengthening response is better with Er . As Er is added to Mg-Nd-Zn-Zr alloy,its ultimate tensile strength(UTS) and Yield strength(YS) increases while its elongation(E.I.) is almost at the same.And its UTS, YS and E.I. reaches 283.4MPa, 170.2MPa and 4% respectively. There are some rugged cleavage plates,tear ridges and a few dimples in the room temperature fracture surface images of Mg-Nd-Zn-Zr-Er alloy.The particles in the dimples mainly include Er,Nd.This shows the alloy with Er has a good plasticity. Er addition does not change the fracture behavior of Mg-Nd-Zn-Zr alloy and the fracture modes of both alloys after age-treatment are majorly quasi-cleavage.