The effect of low temperature heat treatment on surface chemistry and corrosion resistance of commercial magnesium alloys AZ31 and AZ61 in 0.6 M NaCl solution

• Surface chemistry of magnesium alloys after short low temperature heat treatments.
• Relation between heat treatment time and aluminium enrichment.
• Relation between surface composition and material degradation.

This paper studies the differences in chemical composition of the oxide surface layers induced by heating in air at 200 °C for time intervals from 5 min up to 60 min on commercial AZ31 and AZ61 magnesium alloys with a view to a better understanding of their protective properties. A strong link was found between the aluminium enrichment observed in the surface of the oxide layer and the decrease in the protective properties of the heat treated AZ31 alloy. In contrast, no significant changes have been observed in the case of the heat treated AZ61 alloy.