Copper Redistribution during Corrosion of Aluminum Alloys

Abstract

We describe a new quantitative electrochemical technique for measuring the copper redistribution that occurs during corrosion and pretreatment of high‐strength copper‐containing aluminum alloys. Underpotential deposition (upd) of Pb on Cu was used to assay the surface coverage of Cu. Model experiments using samples of known Al‐Cu ratios were used to evaluate the accuracy of the technique and develop a calibration curve. The results demonstrated the accuracy of the method to within 2%. The elemental copper remaining on the surface of Al 2024-T3 samples after various pretreatment/corrosion procedures was determined using the upd technique. A simple treatment involving open‐circuit etching of the alloy surface in 3 M was found to be most efficient for the removal of Cu from the Al alloy surface. In accord with a recent observation of Bucheit et al., convection was found to enhance copper redistribution on an Al 2024-T3 sample in 0.5 M NaCl solution. © 1999 The Electrochemical Society. All rights reserved.