High entropy alloys have been extensively paid attention in the coating industry due to their excellent mechanical properties and corrosion resistance. CoCrFeNiMox high-entropy alloy coatings were prepared on the surface of Q235 steel by laser cladding with synchronous powder feeding. The microstructure, microhardness and corrosion resistance of the coatings were studied. The corrosion mechanism of the alloys was analyzed and the strengthening mechanism of their corrosion resistance was revealed combined with the first-principle calculation. The results show that CoCrFeNiMo0.1 and CoCrFeNiMo0.2 are composed of the fcc phase. The fcc phase and tetragonal CrMo phase are both observed in the CoCrFeNiMo0.3 high-entropy alloy layer. The microstructure of the alloys is composed of dendrites. Cr and Mo elements are enriched in the interdendritic, and Co and Fe elements are enriched in the dendrites. CoCrFeNiMox high-entropy alloys have excellent comprehensive corrosion resistance in 3.5% (mass fraction) NaCl solution. As the content of Mo increases, the corrosion potential shifts to more positive potentials, the corrosion current density decreases, the length of polarization region increases, the impedance arc radius increases, and the electrode reaction resistance increases. It is found via the first-principle calculation that the higher corrosion resistance of the coating is related to its dense passivation film.

Keywords： metallic materials ; corrosion resistance ; first principle ; high entropy alloy ; laser cladding coating