Effect of 0.3 at. % Ce on the corrosion resistance of Fe40Ni20Co20Cr20 high-entropy alloy in 3.5 wt% NaCl solution

Abstract

The impact of trace Ce doping on the pitting behavior of Fe40Ni20Co20Cr20 high-entropy alloy in a 3.5 wt% NaCl solution was examined. The results indicate that the addition of trace Ce elements leads to a notable reduction in grain size and improved corrosion resistance of the alloy, the critical pitting potential of the alloy increased to 428 mv, and the corrosion resistance of the passivation film was significantly enhanced. This improvement can be mainly attributed to the strong surface activity of Ce, which promotes the formation of Cr2O3 in the passivation film, resulting in a more stable and protective film layer. The ΔE (difference between corrosion potential and zero charge potential) of the high-entropy alloys (HEAs) was negative, indicating a decrease in the adsorption capacity of the electrochemical interface for Cl−. This reduction helps to mitigate pitting corrosion on the surface of the passivation film caused by Cl− erosion.