铸态Mg-12Gd-xZn-0.5Zr合金组织与力学性能研究

Study on Microstructures and Mechanical Properties of As-cast Mg-12Gd-xZn-0.5Zr Alloy

采用X射线衍射仪、光学显微镜、扫描电镜、透射电镜、布氏硬度计和拉伸实验机等研究了Mg-12Gd-xZn-0.5Zr(x=0,0.5%,1.0%,1.5%,质量分数)合金显微组织和力学性能。结果表明:铸态Mg-12Gd-0.5Zr合金主要由α-Mg和沿晶界均匀分布的Mg5Gd相组成;当Zn含量添加到0.5%(Zn/Gd原子比为1∶10),Mg5(Gd,Zn)相形成;当Zn含量添加到1%(Zn/Gd原子比为1∶5),合金中出现少量杂乱分布在基体中的层片状18R-LPSO(Mg_(10)GdZn)相;随着Zn含量的进一步增加(Zn/Gd原子比为1∶3),合金中出现连续分布在晶界处的大块层片状18R-LPSO相。Zn含量为1%时,合金的综合力学性能最佳,Mg-12Gd-1Zn-0.5Zr合金抗拉强度、屈服强度、布氏硬度和伸长率分别达到200.70 MPa、106.42 MPa、73.3 HBW、10.51%。

The microstructures and mechanical properties of the Mg-12Gd-xZn-0.5Zr(x=0,0.5%,1.0%,1.5%,mass fraction)alloy were studied by X-ray diffractometry,OM,SEM,TEM,brinell hardness tester,and tensile test machine.The results show that the as-cast Mg-12Gd-0.5Zr alloy is mainly composed ofα-Mg and Mg5Gd uniformly distributed along the grain boundary.Mg5(Gd,Zn)phase is formed when Zn content is increased to 0.5%and Zn/Gd atom ratio is 1∶10.When Zn content is increased to 1.0%and the atom ratio of Zn/Gd is 1∶5,a small amount of lamellar 18R-LPSO(Mg_(10)GdZn)phase is randomly distributed in the matrix.When the Zn/Gd atom ratio is 1∶3,large lamellar 18R-LPSO phases are continuously distributed at grain boundaries.When Zn content is 1%,the comprehensive mechanical properties of the alloy are the best.The tensile strength,yield strength,Brinell hardness and elongation of Mg-12Gd-1Zn-0.5Zr alloy are 200.70 MPa,106.42 MPa,73.3 HBW and 10.51%,respectively.