Corrosion Behaviour of Al-4Mg-1Cu (wt%) Microalloyed with Si and Ag

The microstructure, hardness, and corrosion behavior of Al–4Mg–1Cu–0.5Si and Al–4Mg–1Cu–0.5Si–0.4Ag (wt%) following various aging times is investigated. Potentiodynamic polarisation and immersion tests reveal an apparent insensitivity in corrosion rates for the alloys studied with aging, along with a higher pitting corrosion resistance for the Ag containing alloy. The addition of Ag to the base Al–4Mg–1Cu–0.5Si composition increases the age hardening response and corrosion performance by modifying the morphology, size, and chemical composition of precipitates (from S‐phase to Z‐phase). The mechanical and corrosion properties of Al‐alloys, which depend upon microstructure, can be optimized via the combination of suitable thermomechanical processing and alloy composition. The addition of 0.4 wt% Ag to Al–4Mg–1Cu–0.5Si simultaneously increases the age hardening response and corrosion resistance in the peak aged condition.