Corrosion Behavior of FeCrxMnAlCu High-Entropy Alloys in 3.5wt% NaCl Solution

Abstract:

In this study, FeCr?MnAlCu (x=0, 0.5, 1.0, 1.5, 2.0) high-entropy alloys were fabricated using vacuum arc melting, and the corrosion behavior of these alloys in 3.5wt% NaCl solution at room temperature was investigated by electrochemical dynamic potential polarization curves and immersion experiments. The microstructure results show that the high-entropy alloy with x=0 has a body-centered cubic phase structure, whereas the high-entropy alloys with x=0.5–2.0 have a mixed face-centered cubic+body-centered cubic dual-phase structure. The corrosion results show that the corrosion resistance of the high-entropy alloy is increased with the increase in Cr content. Among them, the high-entropy alloy with x=2.0 exhibits the optimal corrosion resistance: the highest self-corrosion potential (E_corr=-0.354 V vs. Ag/AgCl), the smallest self-corrosion current density (I_corr=1.991×10^-6 A·cm^-2), and the smallest corrosion rate (0.0292 mm/a). The composite passivation film of oxides and hydroxides is formed on the surface of the corroded high-entropy alloys, and the Cr₂O₃ content is increased with the increase in Cr content, which effectively improves the stability and protective properties of the passivation film.