Corrosion of heat treated magnesium alloy ZE41

► Heat treatment of ZE41A-T5 significantly altered the Zr-rich regions and T-phase. ► HTZE41 corrosion morphology consisted of grain boundary attack. ► Attack progressed into the α-Mg grain but was arrested by the Zr-rich regions. This paper investigates the effect of heat treatment upon the corrosion morphology and mechanism of ZE41 alloy. The results of optical and scanning electron microscopy (SEM) together with potentiodynamic polarisation reveal the importance of the microstructure in the initiation and propagation of corrosion in an aqueous environment. The corrosion of the heat-treated alloy is significantly altered due to changes in the microstructure, specifically the Zr-rich regions and the grain boundary T-phase.