Corrosion Behavior of Al-Mg alloy in 3.5% NaCl + 5 mmol/L KI Solution In-situ Tested by SECM

The corrosion behavior of Al-Mg alloy in 3.5wt.% NaCl + 5 mmol/L KI solution was investigated by scanning electrochemical microscopy (SECM). The surface morphology of the samples was observed by optical microscopy. The component of intermetallic compound was analyzed by scanning electron microscopy and energy dispersive spectroscopy. The corrosion mechanism of Al-Mg alloy was studied preliminarily. The results show that the dissolution was different in different regions of the surface of Al-Mg alloy, and the corrosion mainly occurred in the interface between intermetallic compounds and Al matrix. The quantity and value of oxidation peak current on the surface of Al-Mg alloy changed with prolongation of corrosion time, indicating that the surface dissolution was uneven in corrosion process. The intermetallic compounds were dissolved by corrosion first, and the corrosion pits appeared obviously after corrosion for 144 hours.