Microstructure and corrosion resistance of Al₂CrFeCoCuNi_xTi high entropy alloy coatings prepared by laser cladding

The Al2CrFeCoCuNixTi high entropy alloy coating was prepared by laser cladding on Q235 steel surface. The microstructure of Al2CrFeCoCuNixTi high entropy alloy coatings were analyzed, and the corrosion resistance of Al2CrFeCoCuNixTi high entropy alloy coatings in 0.5 mol/L HNO3 solution and 0.5 mol/L HCl solution were tested. The experimental results show that the Al2CrFeCoCuNixTi high entropy alloy coating can be divided into cladding zone, bonding zone and heat affected zone. The microstructure of cladding zone is mainly composed of equiaxed grain, with micron-grade particles distributed on it, the phase structure of Ni1.0 high entropy alloy coating was simple for FCC and BCC structure. Due to the passivation effect of Cr and Ni elements and formation of Al2O3 and Al2O3H2O films by Al element, the Al2CrFeCoCuNixTi high entropy alloy coating exhibits good corrosion resistance in 0.5 mol/L HNO3 solution and 0.5 mol/L HCl solution. Compared with Q235 steel, the corrosion current density decreases 1-2 orders of magnitude. Pitting corrosion appears because of Cl- in 0.5 mol/L HCl solution can penetrate the passive film on the Ni0.5 high entropy alloy coating surface.