Si对Al-Zn-Mg-Cu合金组织、断裂和局部腐蚀行为的影响

采用光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)以及室温拉伸、剥落腐蚀等测试方法,研究了微量的Si对Al-Zn-Mg-Cu铝合金组织、性能和局部腐蚀的影响.研究表明:随着Si含量增加,合金的强度先增加再减小,0.040%Si(质量分数)时合金的强度出现峰值;合金的力学性能各向异性随Si含量的增加,先减小再增大,0.025%Si时,力学性能各向异性最小;随着Si含量的升高,合金横向断裂模式从以穿晶断裂为主向沿晶断裂转变.与合金纵向强度变化幅度比较,Si含量对合金横向强度影响显著.

Microstructure, Fracture and Localized Corrosion Behaviors of Al-Zn-Mg-Cu Alloy with Si Additions

The effect of Si additions on microstructure, mechanical properties and localized corrosion behaviors of Al-Zn-Mg-Cu alloy was investigated by means of mechanical tensile and exfoliation corrosion testing combined with optical microscopy(OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the strength of the alloys first increases and then decreases with the increase of Si contents, when Si content is 0.040% (mass fraction), the strength of the alloy reaches the peak value; The anisotropic mechanical properties of the alloys first decreases and then increases with the increase of Si contents, when Si content is 0.025%, the alloy has the minimum anisotropy. Concomitant with this increase in Si contents, a transition in fracture mode was observed from predominantly transgranular dimpled rupture to predominantly intergranular dimpled rupture of transverse. Compared with the change of the longitudinal strength of the alloys, the Si contents have a significant effect on the transverse strength of the alloys.