Corrosion behaviors and mechanism of CrFeNi2 based high-entropy alloys

Herein, a novel CrFeNi2-based multi-component alloy system was designed and the corrosion behaviors were investigated in 3.5 wt% NaCl solution. The single-phase FCC solid solution was observed in CrFeNi2 and CoCrFeNi2 alloys, while the lamellar eutectic structure composed of dual-phase formed in the AlCoCrFeNi2 alloy. The electrochemical results showed that the CrFeNi2-based alloys, with higher Epit and lower Icorr, displayed better corrosion resistance, outperforming previously reported conventional alloys and some other high entropy alloys, due to the compact and stable oxide films composing of protective oxide/hydroxide. In the CrFeNi2-based alloy system, all examined specimens were suffered localized corrosion. The Co-free CrFeNi2 alloy possessed the best corrosion resistance, demonstrating the widest passivation region (approximately 1035 mVAg/AgCl), the highest pitting potential (954 mVAg/AgCl), and an outstanding repassivation ability. In addition, the corrosion mechanism was investigated and discussed. This research will sight light on the comprehending of corrosion behaviors through different phases and the effect of element on corrosion resistance.