Study on Corrosion Behavior of CoCrNi Medium-Entropy Alloy in Acidified Coastal Seawater Environment

This article aims to research the corrosion behavior of CoCrNi medium-entropy alloy (MEA) in acidified coastal seawater environment. The results show that alternating current and HSO 3 − are destructive to the protective ability of passive film and weaken the anti-corrosion property of the MEA. AC causes damage to the passivation film by promoting HCO 3 − and HSO 3 − ionizing extra large amounts of H + , and enhancing the adsorption of corrosive ions (H + and Cl − ). Moreover, the synergistic effect of AC and HSO 3 − significantly facilitates the development of metastable pitting corrosion. As a result of AC imposition, the cathodic reaction transforms from the co-occurrence of hydrogen evolution and oxygen absorption to hydrogen evolution, which reveals that AC is a critical factor in destroying the corrosion resistance of the MEA.