Influence of Fe Content on Corrosion Resistance of FeCrMnAlCu High-Entropy Alloys in 3.5％NaCl Solution
FexCrMnAlCu(x=0,0.5,1,1.5,2)high-entropy alloys were prepared by vacuum arc melting.The phase structure and microstructure of the alloys before and after corrosion were characterized by XRD,SEM,and EDS.The corrosion behavior and oxide film composition of the alloys in 3.5％NaCl solution were investigated by potentiodynamic polarization curves,EIS,XPS,and immersion tests.The results indicate that FexCrMnAlCu high-entropy alloys exhibit a dual-phase structure of bcc+fcc.The addition of Fe enhances the intensity of the bcc phase diffraction peaks.As the Fe content increases,the alloy's corrosion resistance initially improves and then deteriorates.The alloys with Fe addition exhibit superior corrosion resistance compared with those without Fe.This is attributed to the change in grain size caused by the addition of Fe,which alters the number of grain boundaries per unit area,consequently affecting the corrosion resistance.The primary type of corrosion observed in FexCrMnAlCu alloys is intergranular corrosion.After corrosion,an oxide film composed of various elemental oxides forms on the alloy surface.The Fe1.5CrMnAlCu alloy exhibits the lowest self-corrosion current density(1.75× 10-6 A/cm2),the most positive self-corrosion potential(-0.589 V),and the largest impedance arc radius.
high-entropy alloysvacuum arc meltingmicrostructureoxide film
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