Simulating the galvanic coupling between S-Al2CuMg phase particles and the matrix of 2024 aerospace aluminium alloy

Study of the corrosion behaviour of a magnetron sputtered Al–Cu/Al–Cu–Mg model alloy couple in sulphate solutions has been undertaken to gain insight into the galvanic coupling between the matrix and S-Al2CuMg particles in the 2024 aluminium alloy (AA2024). Polarisation curves and local electrochemical impedance spectroscopy measurements (LEIS) were performed on the individual alloys and on the model alloy couple. SEM enabled correlation of electrochemical phenomena to the observed damage. The corrosion behaviour of the sputtered alloys was shown to be representative of the AA2024, with the Al–Cu–Mg alloy part undergoing localised corrosion and the Al–Cu alloy part remaining passive.

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► The Al–Cu and Al–Cu–Mg model alloys were shown to be representative of AA2024 alloy.
► LEIS showed a capacitive behaviour of the Al–Cu alloy part of the couple.
► LEIS showed that the Al–Cu–Mg alloy part appeared to be the location of strong reactivity.
► Model couples constitute an original and efficient way to study galvanic coupling.
► The macroscopic model systems were shown to be representative of submicron phenomena.