Influence of pH value on corrosion behavior of non-equiatomic Fe₄₀Mn₂₀Cr₂₀Ni₂₀ high-entropy alloy

The electrochemical performance and corrosion properties of Fe₄₀Mn₂₀Cr₂₀Ni₂₀ high-entropy alloys (HEAs) in a 3.5% NaCl solution with various pH values were thoroughly investigated. The results revealed a close correlation between the corrosion properties of HEAs and the pH value. On the one hand, the pH value can affect the semiconducting properties of the passive film on the alloy surfaces, thereby further influencing the protective capacity of the passive film. On the other hand, an excess of H⁺ or OH⁻ promotes the growth of localized corrosion, facilitating the formation of a larger number of larger-sized localized corrosion pits. Ultimately, the corrosion of HEAs is most severe in acidic solutions.