Optimizing pitting corrosion resistance of Fe40Mn20Cr20Ni20 high entropy alloy through acid treatment
The corrosion resistance of the Fe40 Mn20Cr20 Ni20 high-entropy alloy(HEA)was systematically investigated by electrochemical tests in various solutions,including 10 wt.％H2SO4,3.5 wt.％NaCl,and 3.7 wt.％HCl solution.The HEA exhibited outstanding corrosion resistance and passivation behavior in the 10 wt.％H2SO4 solution.Nevertheless,the Mn content in the matrix adversely affected its resistance to pitting corrosion.X-ray photoelectron spectroscopy(XPS)analysis reveals that the passivation film formed on the Fe40 Mn20Cr20 Ni20 HEA after anodic polarization in the 10 wt.％H2 SO4 solution predominantly consists of Cr and its oxides,with Cr(OH)3 being the primary compound.The electrochemical impedance spectroscopy(EIS)results revealed a noteworthy enhancement in the corrosion resistance of the Fe40 Mn20Cr20 Ni20 HEA when exposed to a 3.7 wt.％HCl solution,achieved through anodic polarization.This treatment resulted in a remarkable 1.7-fold increase in the charge transfer resistance(Rct)value.The findings strongly suggest that utilizing anodic polarization in the H2SO4 solution to establish a stable passivation film is an effective strategy for improving the resistance of FeMnCrNi HEAs to pitting corrosion.This method holds significant research significance and possesses broad potential applications.
high entropy alloyanodic polarizationpittingelectrochemical impedance spectroscopypassivity
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