Electrochemical polarization and corrosion behavior of Al–Zn–In based alloy in acidity and alkalinity solutions

The corrosion behavior of Al–5Zn–1Mg−0.02In−0.05Ti−0.1Si (wt %) alloy has been investigated in different pH solutions by cyclic polarization, self-corrosion and scanning electron microscopy. The results show that the alloy undergoes two types of corrosion, including pitting in acidic solutions, relative light pitting in neutral solutions and crystallographic corrosion in alkalinity solutions with a high possibility. The difference of ΔE = (Epit − Ecor) are used as criterion for susceptibility to pitting and the hysteresis loop area as criterion for pitting propagation and repassivation of the alloy. The criterion is discussed. Corrosion morphologies of the alloy are in good agreement with corrosion parameters. •In acidic solutions, pitting is the main corrosion type.•In alkaline solution, the alloy mainly suffers crystallographic corrosion.•The alloy exhibits a notable corrosion resistance in neutral chloride solutions.•Corrosion parameters of ΔE = Epit − Ecor as criterion for susceptibility to pitting.