Corrosion behavior of CoCrNi medium-entropy alloy compared with 304 stainless steel in H2SO4 and NaOH solutions

The corrosion resistance and passive film properties of the CoCrNi medium-entropy alloy were investigated. Experimental results show that selective dissolution of elements in the CoCrNi is evident compared with the 304 SS. The passive film formed on the CoCrNi is enriched in Cr but depleted in Co and Ni, and the high content of Cr and thicker passive film are responsible for the higher anti-corrosion of the CoCrNi in H2SO4 solution; the surface is enriched in Co while depleted in Cr and Ni, and the higher dissolution rate of Cr is responsible for the lower anti-corrosion in NaOH solution.