Phase constitution, surface chemistry and corrosion behavior of electrodeposited MnFeCoNiCu high entropy alloy-graphene oxide composite coatings

MnFeCoNiCu high entropy alloy (HEA) coatings with and without graphene oxide (GO) incorporation was deposited onto a mild steel substrate by the electrodeposition method. Coating morphology, phase constitution, corrosion properties, and coatings surface chemistry before and after corrosion in a 3.5 wt% NaCl solution was investigated. A predominantly body-centered cubic (BCC) phase with a minor fraction of face-centered cubic (FCC) phase was obtained in the pristine coating. Whereas a nearly equal volume fraction of FCC and BCC phases formed in coatings with increasing GO content. Corrosion characteristics of the MnFeCoNiCu HEA coatings with different GO content were studied. All the GO containing coatings exhibited higher corrosion resistance than the coating without GO in 3.5 wt% NaCl solution. The corrosion resistance of the coatings increased with increasing GO content. The surface chemistry of the coatings before and after exposure was studied by X-ray photoelectron spectroscopy (XPS). These results showed that the GO incorporation into the MnFeCoNiCu matrix enhanced the formation of stable oxides, which can reduce ionic diffusion, thus improving the corrosion resistance of the MnFeCoNiCu HEA-GO coatings when compared to the MnFeCoNiCu HEA coating without GO.