Why CoCrFeMnNi HEA could not passivate in chloride solution? – A novel strategy to significantly improve corrosion resistance of CoCrFeMnNi HEA by N-alloying

This work elaborated the underlying mechanism for the non-passivation of CoCrFeMnNi HEA in chloride solution based on the dissolution-diffusion-deposition model. A novel N-alloying strategy was proposed to significantly improve the corrosion resistance of CoCrFeMnNi HEA. Modelling results indicated that N could consume H+ and relieve the acidification on the surface of HEA, thus accelerating deposition of Cr and Fe oxides and hydroxides. Thereby, the nucleation rate and growth rate of passive film were apparently enhanced after N-alloying, which agreed well with the less defective and thinner passive film. Finally, the element selection for designing corrosion resistant HEAs was recommended. [Display omitted] •The model describing passive film formation on CoCrFeMnNi HEA was established.•The non-passivation of CoCrFeMnNi HEA in chloride solution was interpreted.•N accelerated passive film deposition and dramatically enhanced corrosion resistance.•The model gave recommendation for designing corrosion resistant HEAs.