Effect of aging on corrosion property, electrochemical behavior and microstructure of Al-Zn-Mg-Cu alloy

摘要

The effect of aging treatment on corrosion behavior of Al-Zn-Mg-Cu alloy was investigated by means of intergranular corrosion test, exfoliation corrosion test, electrochemical analysis, and transmission electron microscope. The results show that intergranular and exfoliation corrosion susceptibility of the studied alloy decrease gradually with increasing aging time. This is further confirmed by potentiodynamic polarization and electrochemical impedance spectroscopy tests, which show the corrosion resistance increased and corrosion density decreased with prolonging aging time. Moreover, the variation of impedance parameters simulated in terms of an equivalent electrical circuit present better reflection to the corrosion process, thus give valuable information to evaluate the corrosion property. According to microstructural observation, the morphology and distribution of grain boundary precipitate varied with aging treatment have decisive influence to the corrosion behavior.