Corrosion behavior of CoCrNi medium-entropy alloy in a mixed HF and HCl medium

The corrosion behavior of CoCrNi MEA in a mixed HF and HCl medium was investigated by immersion tests. The alloy exhibits superior corrosion resistance compared to Ni-based alloys, including enhanced passivation capability and insensitive to temperature variations. The underlying mechanisms are closely associated with the protective barrier provided by the Cr and Co oxide films that form during corrosion, attributed to their higher work function and lower binding energy. Co element shortens bond length between adsorbate and surface atoms, enhancing adsorption of the adsorbate on both Cr and Ni, which promotes stable oxide layer formation.