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.