Effect of iron content on microstructure and properties of FexNi2Co2CrTiNb high-entropy alloy coating

Abstract

FexNi2Co2CrTiNb (x = 0, 0.5, 1, 2) high-entropy alloy coatings were fabricated on 45 steel by laser cladding. The phase, microstructure, hardness and wear resistance of FexNi2Co2CrTiNb coatings are studied systematically. The results behave that FexNi2Co2CrTiNb (x = 0, 0.5, 1, 2) coatings are composed of FCC and BCC solid solutions. When the Fe content increases from 0 to 2, the BCC phase in the coating increases significantly while the FCC phase decreases notably, the microstructure of FexNi2Co2CrTiNb coating evolves from coarse dendrites to the fine dendritic clusters in the general form of columnar or equiaxed crystals. The hardness of each FexNi2Co2CrTiNb (x = 0, 0.5, 1, 2) coating is much higher than that of the substrate. The highest hardness measured reaches up to 873.40 HV, which is about 3 times the hardness of the substrate. The average hardness of the FexNi2Co2CrTiNb coating presents an increasing trend with the increase of Fe content, the average hardness of Fe2Ni2Co2CrTiNb coating is 40.74 % higher than that of the Fe0Ni2Co2CrTiNb coating. Correspondingly, Fe2Ni2Co2CrTiNb coating with the highest hardness has the best wear resistance. The Fe2Ni2Co2CrTiNb coating with excellent wear resistance can be fully applied to various tools, molds and mechanical parts that require high hardness and superior wear resistance.