As noted above, intergranular corrosion is a form of localised corrosion that proceeds along grain boundaries and the corrosion rate depends on factors such as the diffusion of chemical species to or from the anodic front that governs the dissolution kinetics. Ref. [7] provides detailed information on intergranular corrosion in aluminium alloys, stainless steels, nickel and nickel alloys, as well as briefly considering ICG in other metals and alloys. Three main mechanisms have been proposed for IGC