Preparation And Properties Of CoCrFeNiTiAl_? High Entropy Alloy Coatings

High-entropy alloys have attracted extensive attention due to their high strength,high hardness,excellent corrosion resistance and wear resistance.High-entropy alloy coatings can effectively improve the surface properties of metal materials,and can further expand the use of metal materials.In this study,45#steel was used as the matrix,and the CoCrFeNiTiAl_? high-entropy alloy coatings were prepared by laser cladding method.The influence of the change of Al content on the microstructure and properties of the coatings were studied.The enhancement effect of the high-entropy coating on the matrix was discussed.In this paper,CoCrFeNiTiAl_???=0,0.25,0.5,0.75,1,1.5,2,x is mole fraction?high-entropy alloy blocks were prepared by vacuum arc melting method.The effects of Al element changes on microstructure,phase composition,microhardness and compression properties were investigated.On this basis,high-entropy alloy coatings of CoCrFeNiTiAl_???=0,0.5,1,1.5,2,? is mole fraction?were prepared on the surface of 45#steel by laser cladding.The microstructure and composition of the alloys and the coatings were analyzed by SEM.The phase composition of the alloys and the coatings were characterized by XRD;The compression property of the alloy were studied.The wear resistance and corrosion resistance of the high entropy alloy coatings were studied.The study of high-entropy alloys prepared by arc melting found that Al₀ alloy is a single-phase FCC crystal structure.With the increase of Al content,the alloy changes from FCC to BCC,except that Al₀ and Al₂ alloys are uniform single-phase structure,other alloy microstructures are dendrites.The Al_0.5 high-entropy alloy has the best compression resistance,compressive strength of 2023 MPa and plastic strain of 9.56%.The research on laser cladding high-entropy alloy coatings found that:?1?Al₀ coating is a single-phase FCC crystal structure.When x is 0.5¹.5,the alloy consists of BCC1 and BCC2 phases,and the microstructure is petal-like dendrites.The Al₂ alloy is a single BCC1phase.?2?The corrosion resistance of the Al_0.5 coating is obviously stronger than that of the base 45#steel,and as the Al content increases,the corrosion resistance of the coating increases firstly and then decreases.?3?With the increases of Al content,the average friction coefficient of the coatings decrease firstly and then increases.The average friction coefficient of Al_0.5 high-entropy alloy coating is the lowest,which is 0.2854.At the same time,this study also discussed the wear mechanism of the coatings.