Corrosion in Cr-Fe-Co-Ni-Nb hypoeutectic and hypereutectic high entropy alloys

In this paper, corrosion behavior and corresponding mechanism of CrFeCoNiNbx high entropy alloys (HEAs) with hypoeutectic (x = 0.38) and hypereutectic (x = 0.54) structures were systematically investigated. It is found that both HEAs have FCC + Lave dual-phase structure. Similar corrosion behavior could be observed on these HEAs during electrochemical polarization in 3.5 wt% NaCl solution at room temperature, and the hypereutectic HEA shows slightly higher corrosion resistance compared to the hypoeutectic one. Moreover, there are large proportions of Cr+Nb oxides with no significant difference in concentration in the passive films of these HEAs, which has close correlation with their high and similar corrosion resistance. This work provides a novel insight into better understanding of the corrosion mechanism in the Cr-Fe-Co-Ni-Nb HEAs, which is beneficial for their further applications.

Automated summary

This paper systematically investigates the corrosion behavior and mechanism of CrFeCoNiNbx high entropy alloys (HEAs) with hypoeutectic and hypereutectic structures. It is found that both HEAs have a dual-phase structure of FCC + Lave. Similar corrosion behavior is observed during electrochemical polarization in 3.5 wt% NaCl solution at room temperature, and the hypereutectic HEA shows slightly higher corrosion resistance compared to the hypoeutectic one. Large proportions of Cr+Nb oxides are found in the passive films of these HEAs, with no significant difference in concentration, which is closely related to their high and similar corrosion resistance.