On the localized corrosion of AA5083 in a simulated dynamic seawater/air interface—Part 1: Corrosion initiation mechanism

Localized corrosion of the aluminium alloy AA5083-H111 in a simulated dynamic seawater/air interfacial zone and a full seawater immersion zone was investigated with electrochemical impedance spectroscopy and electrochemical noise. Al-Fe/Ti intermetallic particles (IMPs) on localized corrosion were examined with focused ion beam, transmission electron microscopy and energy dispersive x-ray spectroscopy. As compared with the full immersion zone, the interfacial zone showed higher oxide film resistance and charge transfer resistance, which was attributed to the high oxygen flux in that zone. Localized corrosion arose from IMPs that posessed an Al-Fe phase and a Ti enriched phase.