Corrosion mechanism of the modified casting Al–Cu alloy by the nano-scale PrxOy

The corrosion resistance of the casting Al–Cu alloys was investigated by both the immersion test and electrochemical measurements. The results showed that the modified Al–Cu alloy by the nano-scale PrxOy had better corrosion resistance than the unmodified Al–Cu alloy. A proposed mechanism for this phenomenon could be described as follows: the dominated existence of continuous and compact protective Al2O3 and Pr2O3 films enhanced the corrosion resistance of the modified Al–Cu alloy during corrosion, while no continuous and compact protective Al2O3 films led to the poor corrosion resistance of the unmodified Al–Cu alloy.