The role of precipitates enriched with copper on the susceptibility to pitting corrosion of the 2024 aluminium alloy

Abstract The susceptibility to pitting corrosion of pure aluminium and 2024 T351 alloy in 0.1 mol l −1 Na 2 SO 4 solutions containing chloride ions was investigated by a statistical approach. At high concentrations of chloride ions, the logarithm of the pit germination rate, A, varied linearly with concentration for both materials. The 2024 alloy was less resistant to chloride ion attack than pure aluminium. The influence of the polarization potential on the susceptibility to pitting of the two materials was also determined. For the 2024 alloy, a considerable peak of pitting susceptibility appeared in the low potential range which can be related to the copper content of the alloy. Observations by Scanning Electron Microscopy (SEM) confirmed these results.