Unveiling the Degradation Mechanism of Sulfide Concentration on the Corrosion Behavior of CoCrFeNiTiMo0.1 High‐Entropy Alloy in Acidified NaCl Solution

Abstract In this work, the effect of sulfide concentration on the passivation behavior and film chemistry of CoCrFeNiTiMo 0.1 high‐entropy alloy (HEA) is systematically investigated by electrochemical measurements and XPS methods. Electrochemical results elucidate that sulfide can tremendously exacerbate the passive film degradation kinetics as reflected by the raised dissolution current. The main reason that sulfide has a detrimental influence on the passivation behavior and the anti‐corrosion behavior is also discussed in detail. The sulfide can exhibit preferential adsorption in the passive film, which can prevent the passivation process by competitively occupying the coordination sites for hydroxyl ion adsorption that are hydroxylation precursors. Moreover, due to the adsorbed responses, the composition, thickness, defect density, and compactness of the passive film are altered, triggering in distinct differences in the structural changes of the passive film. This results in a significantly aggravating effect on its corrosion behavior consequently.