Local electrochemical behavior of 2A12 aluminium alloy in the initial stage of atmospheric corrosion under Cl^- conditions

Scanning Kelvin probe (SKP) and localized electrochemical impedance spectroscopy (LEIS) were employed to investigate the corrosion process and electrochemical behavior of 2A12 aluminium alloy during the initial corrosion period. It is shown that Cl^- accelerates the atmospheric corrosion of 2A12 aluminum alloy and pitting expands with exposure time during the initial stage. SKP results indicated that anodic and cathodic areas on the surface changed constantly with distinct characters of localized corrosion in the initial corrosion period. When the corrosion process continued, the surface potential of 2A12 aluminium alloy moved positively, while the anodic and cathodic fields distinguished evidently from each other. LEIS results showed that the surface localized electrochemical impedance in the initial stage increased with time, but distributed dispersively. During the initial stage of the corrosion process, corrosion products formed on the surface of 2A12 aluminium alloy constantly, which could restrict the corrosion process.