Effect of heat treatment on corrosion behavior of AZ63 magnesium alloy in 3.5 wt.% sodium chloride solution

• Precipitates and films synergistically determine the corrosion of AZ63 alloy.
• An independent variable ξ proposed to characterize the corrosion trends.
• Two models for interpreting the corrosion of AZ 63 alloys are proposed.

The as-cast, homogenized, and peak-aged AZ63 alloys are investigated via microstructure observation, EDS analysis, hydrogen evolution, and electrochemical tests. The results suggest that the heat treatments exert an influence on the corrosion behavior of AZ63 alloy via the microstructure transformation. The corrosion of homogenized alloy is retarded by protective oxide layer at first, but achieves highest corrosion rate among the three alloys owing to the less protective products film. The micro-galvanic couples endow the as-cast and peak-aged alloys high dissolution activity, but the adhesive products alleviate the corrosion. Two models are proposed to interpret the dissolution mechanism for these alloys.

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