Corrosion susceptibility of Al-Cu and Al-Cu-Si films

The susceptibility to chlorine-induced corrosion of Al-Cu and Al-Cu-Si films has been measured. The adverse impact of Cu on the corrosion susceptibility of unsintered films is clearly evident at 0.3% and increases sharply between 1.0% and 2.0% with the latter being 6 times more corrosive than the former. Adding 1.0% Si to the Al-Cu (2%) alloys tends to lower the corrosion susceptibility of unannealed films by a factor of 9. This effect is shown to be caused by higher quality native aluminum oxide resulting in a delay in the onset of the corrosion rather than a slower rate once corrosion has begun. Annealing (30 min at 450 degrees C) the copper containing films also has a beneficial effect on corrosion susceptibility.<>