AZ31 (UNS M11311) is popular wrought magnesium alloy used in many aerospace and automotive applications. However, its wider use is hindered by the paucity of information regarding its corrosion resistance in highly alkaline environments (pH > 13). Of particular interest is pitting corrosion, which has been reported to cause rapid localized corrosion in aqueous environments.

In this work, KOH-based electrolytes were used to study the corrosion behavior of AZ31 alloy in highly alkaline environment. The effect of dopants and exposure time on pit initiation was studied via scanning electron microscopy (SEM) and optical microscopy. Long-time exposure immersion, Tafel analysis and electrochemical impedance spectroscopy (EIS) were performed to study the stability of the corrosion products and progression of degradation. The results suggest that presence of trace amounts of certain elements (e.g. silicates) resulted in a change of the pitting resistance in AZ31.

Subject
Pits, Scanning electron microscopy, Electrochemical impedance spectroscopy, Metal surfaces, Silicates, Magnesium alloys, Corrosion products, Sodium, Pitting, Immersion, Aluminum alloys, Electrolytes, Samples
Keywords:
Pitting Corrosion, AZ31
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2017
Association for Materials Protection and Performance (AMPP)
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