Corrosion resistance of anodised single-phase Mg alloys

This work studied the effect of the impurity iron and the alloying elements aluminium and zinc in single-phase substrate magnesium alloys on the corrosion resistance of the alloys after anodisation. It was found that increasing zinc content (0–2%) led to increased corrosion resistance of an anodised single-phase Mg–Zn alloy. The addition of Al lowered the corrosion resistance of an anodised commercial purity Mg–Al single-phase alloy, whereas the same addition was found to be beneficial to the corrosion resistance of an anodised high purity Mg–Al single-phase alloy. Heat-treatment made the substrate Mg–Al and Mg–Zn alloys more uniform and hence improved the corrosion resistance of the alloys after anodisation. The detrimental effect of iron impurity on corrosion performance of the unanodised substrate single-phase magnesium alloys was inherited by the anodised alloys. The corrosion resistance of the anodised Mg alloys was found to be closely correlated with the corrosion performance of the unanodised as-cast Mg alloys.