Influence of aluminium enrichment in the near-surface region of commercial twin-roll cast AZ31 alloys on their corrosion behaviour

The effect of increasing the Al concentration to a value between 0.5 and 0.8 wt.% within the 10-μm thick surface layer of a commercial AZ31 alloy sheet manufactured by twin-cast rolling method on its corrosion behaviour was investigated. In long term exposure, both the uniformity of the double layered Mg-Al hydroxide (LDH) formed in the inner layer of the corrosion product on the aluminium-rich surface AZ31 specimen and the precipitation of a significant amount of aluminium hydroxide contributed to enhancing the corrosion resistance significantly.We would like to express our gratitude to Professor S. Feliu for numerous clarifying and stimulating discussions during the course of this research. The authors also gratefully acknowledge the financial support for this project from the Spanish Ministry of Economy and Competitiveness (MAT2015-65445-C2-1-R).Peer Reviewe