Microstructure, corrosion and wear behavior of (AlCu)3.5CoCrNiFe and (AlCu)3.5CoCrNiTi high entropy alloy coatings prepared by laser cladding on AZ91 magnesium alloy

(AlCu)3.5CoCrNiFe and (AlCu)3.5CoCrNiTi high entropy alloy (HEA) coatings were prepared on AZ91 magnesium alloy by using laser cladding technology. The phase constitution, microstructure, microhardness, corrosion resistance and wear resistance of the prepared HEA coatings were investigated. Both the HEA coatings consisted of BCC and FCC phases. The microhardness of the (AlCu)3.5CoCrNiFe coating and (AlCu)3.5CoCrNiTi coating was 642.1 HV and 656.2 HV respectively, and both of them were about 9 times higher than that of the AZ91 substrate (71.9 HV). The addition of Ti element led to the formation of dense TiO2 passivation film, thus improving the corrosion resistance of the (AlCu)3.5CoCrNiTi coating. The wear loss of the (AlCu)3.5CoCrNiFe coating and (AlCu)3.5CoCrNiTi coating was 29% and 20% of that of the AZ91 substrate, respectively. The prepared HEA coatings could significantly improve the surface properties of the AZ91 alloy substrate, and the (AlCu)3.5CoCrNiTi coating showed better performance compared to the (AlCu)3.5CoCrNiFe coating.