Zn添加对挤压态Mg-Zn-Ce-Zr合金微观组织及力学性能的影响

Effects of Zn addition on microstructures and mechanical properties of as-extruded Mg-Zn-Ce-Zr alloys

通过光学显微镜(OM)、扫描电镜(SEM)、背散射电子衍射(EBSD)和力学性能检测,研究不同Zn含量(0.5%、1.5%和2.0%(质量分数))的Mg-Zn-Ce-Zr合金在温度为350℃,挤压比为9,挤压速率为10 mm/s条件下挤压后的微观组织和力学性能。结果表明:随着Zn含量的增加,铸态下晶间析出相明显增多;挤压后,Zn含量对合金晶粒度的影响不大,但棒材的丝织构随Zn含量增加而增强。由于第二相粒子的强化作用,随Zn含量增加,合金的拉伸屈服强度从158 MPa增加到192 MPa,而抗拉强度从219 MPa提高到246 MPa。由于丝织构强度增加,合金塑性随Zn含量增加从33%降低至18%,添加0.5%Zn合金的伸长率和拉压对称性最好。

The microstructures and mechanical properties of Mg-Zn-Ce-Zr alloys with different Zn contents（0.5%,1.5%,2.0%（mass fraction）） were investigated.These alloys were extruded with an extrusion ratio（λ） of 9 at temperature of 350 ℃ and run speed of 10 mm/s.The microstructures were observed by optical microscope（OM）,scan electron microscope（SEM） and electron back scan diffraction（EBSD）.The mechanical properties were tested by tensile test and compressive test at room temperature.The results show that more particles appear in the alloy with the increase of Zn content,and after extrusion,there are similar grain sizes in three alloys,and the intensity of ring basal textures increases with Zn content increasing.The tensile yield strength（TYS） increases from 158 to 192 MPa and the ultimate tensile strength（UTS） is enhanced from 219 MPa to 246 MPa with Zn addition increasing due to the second phase particles strengthening.However,the elongation decreases from 33% to 18% with Zn content increasing due to the variation of texture.The alloy with 0.5% Zn has highest ductility and lowest yield asymmetry in mechanical property.