Study on corrosion behavior and mechanism of CoCrFeMnNi HEA interfered by AC current in simulated alkaline soil environment

The corrosion behavior and mechanism of CoCrFeMnNi HEA interfered by AC current was investigated in carbonate/bicarbonate solution. AC application can destroy the structure of passive film, generate a change in the content of constitutes, and decrease the stability and protective ability of passive film, especially at higher iAC. With increasing iAC, the corrosion form of HEA is evolved from pitting corrosion occurred at low iAC to intergranular corrosion generated at high iAC. At the interference of 200 A/m2, more H atoms are distributed at grain boundaries and interior of grains, resulting in the occurrence of severe corrosion. Moreover, the selective dissolution of Co/Mn occurs in the interior of corroded grains of HEA sample. However, selective dissolution of Fe, Co and Cr is occurred at pits and grain boundaries. [Display omitted] •AC corrosion behavior of CoCrFeMnNi HEA was investigated in CO32−/HCO3− solution.•AC application damaged the structure of passive film, and changed its composition.•An increased iAC reduced the stability and protective ability of passive film.•Corrosion form of the HEA was evolved from pitting corrosion to intergranular corrosion.•Selective dissolution of Fe, Co and Cr was occurred at pit and grain boundary.