Microstructure and corrosion characterization of the interfacial region in dissimilar friction stir welded AA5083 to AA7023

Microstructure and the corrosion behaviour of friction stir weld region in an aluminium AA5083/AA7023 dissimilar joint was studied using SEM/EDS, potentiodynamic polarization, EIS and AFM/SKPFM techniques. In the presence of an inhomogeneous borderline consisting of Al-Mg-Zn precipitates, a galvanic cell was formed at the interfacial region. Corrosion tests showed that the corrosion resistance of FSW region is in between that of AA5083 and AA7023. AA5083 possesses lower Volta potential compared to AA7023, however, corrosion initiates from both the FSW borderline and areas around intermetallic particles, particularly in AA7023 side