Microstructure, wear and corrosion resistance of (CrFeNiAl)_100–xMo_x high-entropy alloy coatings by laser cladding

For the corrosion and wear failure of materials used in the marine environment, the (CrFeNiAl)_100–xMo_x high-entropy alloy coatings were prepared on 304 stainless steel (304 ss) by laser cladding. The phase composition, microstructure, hardness, wear resistance and corrosion resistance of the coatings were analyzed. The results show that the coatings are composed of body-centered cubic (BCC)+B2 phases. With the increase of Mo, the content of B2 phase gradually increases, and nano scale B2 phase precipitates in the dendrite. The hardness of the coating increases with the increase of Mo content, the highest hardness reaches HV_0.2 636.6, and the wear resistance increases gradually. The corrosion current density firstly decreases and then increases with the increase of Mo, indicating that the corrosion resistance of the coating firstly increases and then decreases in 3.5wt%NaCl solution. The results of immersion corrosion show that the coatings are selectively dissolved in the interdendritic region. The corrosion current density and passivation current density of (CrFeNiAl)₉₂Mo₈ coating are lower than 304 ss, and the corrosion resistance is the best with good wear resistance. Adding appropriate Mo element can improve the wear resistance and corrosion resistance of (CrFeNiAl)_100–xMo_x coatings.