稀土Nd对热挤压Mg-Y-Nd-Zr合金组织性能的影响

Effects of Nd on Microstructure and Properties of Extruded Mg-Y-Nd-Zr Alloy

采用光学显微镜(OM)、扫描电镜(SEM)、X射线衍射仪(XRD)和室温拉伸试验研究了稀土Nd对热挤压Mg-5.0Y-xNd-0.6Zr(x=0,1.0,2.6,4.2,质量分数/%,下同)合金微观组织和力学性能的影响。结果表明:随着Nd加入量增大,挤压合金中带状分布的β和Mg24Y5相颗粒增多,促进了动态再结晶的形核,提高了再结晶体积分数,其平均晶粒尺寸由4.5μm细化到2.6μm。挤压合金的抗拉强度和屈服强度随着Nd加入量增大而升高,最高分别达到303 MPa和262 MPa,而延伸率和断面收缩率随Nd加入量增大而降低,其值分别从24.7%和39.9%降低到12%和16.7%。Nd加入量为2.6%时,挤压合金具有较好的综合性能。

Effects of Nd on microstructure and mechanical properties of extruded Mg-5.0Y-xNd-0.6Zr（x=0,1.0,2.6,4.2,mass fraction/ %,the same below） alloy were investigated by optical microscopy（OM）,scanning electron microscopy（SEM）,X-ray diffraction（XRD） and tensile testing.The results showed that with addition of Nd,the banding particles of β and Mg24Y5 phase in the extruded alloy increased,which promoted the nucleation of dynamic recrystallization,the volume fraction of recrystallization advanced,and the average grain size of recrystallization could be refined from 4.5μm to 2.6μm.The tensile strength and yield strength of extruded alloy increased with increment of Nd,the maximum values of them were 303MPa and 262MPa respectively.The elongation and section shrinkage conspicuous decreased from 24.7% and 39.9% to 12% and 16.7% with increasing Nd content.The extruded alloy displayed better strength and plasticity at Nd content of 2.6%.