Zr和Si对Al-Zn-Mg-Cu铝合金再结晶行为和性能的影响

Effects of Zr and Si additions on the recrystallization behavior of Al-Zn-Mg-Cu aluminum alloys

采用力学拉伸、金相、扫描电镜、透射电子显微镜和高角环形暗场扫描透射电子显微镜等测试分析方法,研究了Zr和Si对Al-Zn-Mg-Cu系铝合金再结晶行为和性能的影响。结果表明:在合金中添加质量分数为0.17%的Zr和0.05%的Si后,合金保留了其原始的纤维组织结构,其强度和塑性的各向异性显著增大。随Zr、Si含量的升高,合金横向主要断裂模式从穿晶断裂向沿晶断裂转变。与合金纵向强度变化程度相比较,Zr、Si含量对合金横向强度的影响更加显著。其主要原因是复合添加Zr和Si形成(Al,Si)3Zr弥散相,抑制再结晶作用更明显,引起合金L向和T向的晶粒形态差异增大及粗大的残余相粒子沿晶界分布。

In the present work,the effects of Zr and Si additions on the recrystallization behavior and performance of Al-Zn-Mg-Cu alloys were investigated by mechanical tensile testing,optical microscopy,Electron Scanning Microscopy(ESM),Transmission Electron Microscopy(TEM),and High-angle Annular Dark-field Scanning Transmission Electron Microscopy(HAADF-STEM),respectively.The results suggest that the alloys retain the original fibrous structure after addition of0.17% Zr and 0.05% Si,but the aniscotropy of the strength and plasticity of the alloys increase significantly.As the contents of Zr and Si increase,a transition in fracture mode is observed frompredominantly transgranular dimpled rupture to predominantly intergranular dimpled rupture transverse.Compared with the change in longitudinal strength,the Zr and Si contents have greater impact on the transverse strength of the alloys.The main reason is that the additions of Zr and Si can form the precipitation of(Al,Si)3 Zr in the alloy,which inhibits the recrystallization of the alloy effectively,increases the difference of grain morphology between L and T directions of alloy,and leads to the distribution of coarse residual particles along the grain boundary.