Effect of Potential on the Characteristics of Passive Film on a CoCrFeMnNi High-Entropy Alloy in Carbonate/Bicarbonate Solution

Effect of passive potential on the protective capacity of passive film formed on CoCrFeMnNi high-entropy alloy was investigated in carbonate/bicarbonate solution by using electrochemical measurements, atomic force microscopy and x-ray photoelectron spectroscopy (XPS). The results reveal that the protective ability of passive film is sensitive to the applied potential, and the anti-corrosion property of passive film at high potential is significantly enhanced as indicated by the high film resistance and the low donor densities. The Cr2O3 content and the ratios of Mn/Mn-ox as well as O2-/OH- in the secondary passive film are greater than those in the primary passive film. Moreover, increasing the potential facilitates the formation of a homogeneous and thick passive film, which considerably improves the protective ability of the film.

Automated summary

The study found that the protective capacity of the passive film formed on the CoCrFeMnNi high-entropy alloy surface is sensitive to the applied potential, with significantly enhanced anti-corrosion properties at high potential leading to the formation of a thicker and more homogeneous passive film, thereby improving its protective ability.