Electrochemical corrosion behavior and passive film properties of Fe2Ni2CrV0.5Nbx (x=0.2, 0.4, 0.6, 0.8) eutectic high-entropy alloy coating prepared by laser cladding

The phase composition, microstructure morphology, and corrosion behavior of Fe2Ni2CrV0.5Nbx (x = 0.2, 0.4, 0.6, 0.8) eutectic high-entropy alloy (EHEA) coatings produced via laser cladding were investigated. The research delved into discerning the phase structures and microstructural variations of the EHEA coatings concerning differing Nb compositions. The findings highlighted a direct correlation between Nb content and the volume fraction of the eutectic structure, specifically the FCC/Laves phases. Electrochemical evaluations, including diverse tests such as potentiodynamic polarization, electrochemical impedance spectroscopy, cyclic polarization, Mott-Schottky measurements, and X-ray photoelectron spectroscopy, revealed distinct corrosion behaviors among the EHEA variants. Notably, the Fe2Ni2CrV0.5Nb0.2 coating exhibited relatively superior corrosion resistance compared with Fe2Ni2CrV0.5Nbx (x = 0.4,0.6,0.8) coatings, attributed to its lower corrosion current density (I corr ) and the formation of a thicker passive film with prolonged passivation duration. Conversely, the Fe2Ni2CrV0.5Nb0.8 coating, characterized by increased eutectic structures and grain boundary density, yielded a thicker yet non-uniform passive film with higher vacancy defects. This comprehensive exploration into the corrosion behavior and passive film properties of these EHEA coatings provides a reference for designing materials that hold promising implications for future corrosion-resistant material development in industrial parts repair applications.