Understanding the impacts of L12 nanoprecipitates on the electrochemical and passive behavior of CoCrNiAlTi-type high-entropy alloys

This work investigated the effects of L12 nanoprecipitates on the electrochemical corrosion behavior and passive film characteristics of CoCrNiAlTi-type high-entropy alloys (HEAs) in chloride-containing solutions. Compared with the single-phase recrystallized alloys, the precipitation of the L12 phase destabilized surface passive films, thus deteriorating the localized corrosion resistance and increasing the metastable pitting activities of the L12-strengthened HEA. Influenced by the L12-induced chemical inhomogeneities, the increase of Cr(OH)3 content in passive films together with the high galvanic corrosion tendency between the two phases was considered as the main reason for the increased susceptibility of the L12-strengthened alloys to localized corrosion attacks.