Anomalous Dissolution of Copper in Al-Cu alloys
Résumé
During galvanic coupling between copper and aluminium, copper can undergo anomalous dissolution and replating onto the surface of aluminium. This observation has often been made on 2024-T3 alloys at a micrometric scale, at the interface between the aluminium-rich matrix and the intermetallic particles, as well as at a more macroscopic scale, in the vicinity of the interface between a 2024 sheet and a rivet with similar composition. The aim of this work is to show that anomalous copper dissolution has to be correlated with the presence of a confined medium, rather than with galvanic coupling. A confined medium was simulated using a thin-layer electrochemical cell and copper replating at the mouth of the crevice was followed using EDS analysis. A mechanism is suggested involving local acidification in the crevice, due to Al dissolution. Furthermore pH variations between the inner acidic zone and the more alkaline zone at the mouth of the crevice have also to be taken into account.
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Sutter_Joma_Tran_ASST 2012_Anomalous Dissolution of Copper in Al-Cu alloys.pdf (18.02 Mo)
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