corrosion of a single phase having more than one component, when the ratio of the corrosion rates of the components differs from the ratio of bulk mole fractions. Selective corrosion changes the composition of the material in the interfacial region.
Source:
PAC, 1989, 61, 19. 'Electrochemical corrosion nomenclature (Recommendations 1988)' on page 21 (https://doi.org/10.1351/pac198961010019)