Influence of heat treatment on corrosion behaviour of AlZnMgCuZrSc alloy

Corrosion behaviour of different tempers (namely NA, UA, PA and OA) of AlZnMgCuZrSc alloy was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), optical microscopy (OM) and transmission electron microscopy (TEM). Over aged (OA) can decrease the susceptibility to exfoliation due to the discontinuous distribution of the η precipitates at the grain boundaries, cause a negative shift of the corrosion potential (Ecorr), and lead to the prolonging of the time of the appearance of two time constants in impedance diagrams. In addition, AlZnMgCuZrSc alloy with over aged treatment has an enhanced resistance to exfoliation corrosion.