Anodic dissolution pattern of magnesium alloy in different media: Effects of solution treatment on its microstructure and corrosion behaviour

Abstract

Magnesium (Mg) alloys may be formidable structural metals for automobile and biomedical applications, but their applications are heavily challenged due to the chemical reactivity of Mg and its susceptible to corrosion. Efficient mitigation control toward Mg corrosion can only be proposed if its degradation kinetics are properly understood in various media. In this work, we have investigated the degradation pattern of Mg alloy in different corrosive media at room temperature. Mg alloy demonstrated varying rates of corrosion and passivation within a range of pH in corrosion media. The effects of solution treatment on its corrosion behavior have been vividly examined; the trend of increasing metal corrosion is low pH > saline pH > high pH. Localized corrosion behavior has been observed by SEM evidence while potentiodynamic polarization and electrochemical impedance spectroscopy techniques reveal increased changes in anodic polarization and charge transfer, respectively. The chemistry and diffraction phases of adhering corrosion products as well as their surface morphologies have also been identified. The metal mass must have uniformly corroded within each corrodent over an extended duration; however, the early corrosion stages reveal localized passivation of oxide films at grain boundaries.