Effects of RExOy addition on corrosion behavior of the Al–Cu alloys in 3.5wt.% NaCl solution and pH=4 acid solution

Abstract Immersion tests and electrochemical experiments were performed to study the room temperature corrosion behavior of the unmodified and modified Al–Cu alloys with using RE x O y (Pr x O y and La x O y ) in 3.5 wt.% NaCl solution and pH = 4 acid solution. The results showed that the modified Al–Cu alloys have superior corrosion resistance than the unmodified alloy in both solutions. However, a contrary variation trend of corrosion resistance with increasing RE x O y content was found in these two solutions. In 3.5 wt.% NaCl solution, the corrosion resistance of the modified alloys increases gradually with increasing RE x O y content, but deceases gradually in pH = 4 acid solution. The reason for this contrary trend was discussed.