Corrosion Behavior of High Corrosion Resistant Fe-Cr-Ni Medium-Entropy Alloy in H₂SO₄ Solution

A low-cost Fe-Cr-Ni medium-entropy alloy was developed. The corrosion resistance of the medium-entropy alloy in a 0.1 mol·L^-1 H₂SO₄ solution was studied by comparing with that of 316L stainless steel, and the protective ability of the surface passive film was analyzed. The results show that comparing with 316L stainless steel, the test alloy had a higher free-corrosion potential and a smaller free-corrosion current density, indicating the stronger corrosion resistance, slower corrosion rates and better corrosion resistance. Comparing with those of 316L stainless steel, the content of chromium and nickel in the passive film on surface of the test alloy was higher, and the content of iron and manganese was lower; the charge transfer resistance was 8.1 times that of 316L stainless steel. This showed that a more protective passive film was formed on surface of the alloy. The test alloy had a stable single-phase face-centered cubic solid solution structure, and the degree of element segregation was low, which improved the passivation ability and reduced the corrosion sensitivity of the alloy, thus ensuring the stability and protection ability of the passive film.