Microstructure and Properties of Al_xCoCrFeNi_2.1 High Entropy Alloy Coating by Laser Cladding

Al_xCoCrFeNi_2.1（x =1.0, 1.2, 1.4） high entropy alloy coatings were prepared on 304 stainless steel by laser cladding technology. The phase structure, microstructure, microhardness and wear resistance of the high-entropy alloy coatings were investigated by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, microhardness tester and friction/wear testing machine. The results show that Al_xCoCrFeNi_2.1high entropy alloy coatings are composed of face-centered cubic（FCC） phase and body-centered cubic（BCC） phase. When x=1.0, the microstructure of the coating is columnar dendrites;when x=1.2, the central region of the coatings exhibits hypereutectic structure, while the bottom region of the coatings exhibits complete eutectic structure; when x=1.4, the microstructure of the coating is cellular crystals. The microhardness of the coating increases with the increase of Al content, and the maximum is 444.1 HV0.2. With the increase of Al element, the wear resistance of Al_xCoCrFeNi_2.1high entropy alloy coatings improves, and the dominant wear mechanism of the coatings changes from adhesive wear to abrasive wear.