Corrosion performance of Al2CrFeCoxCuNiTi high-entropy alloy coatings in acid liquids

Abstract The Al 2 CrFeCo x CuNiTi high-entropy alloy coatings were prepared by laser cladding on Q235 steel surface. The microstructure was characterized by scanning electron microscopy with spectroscopy (SEM/EDS). Electrochemical workstation was used to test the corrosion resistance of Al 2 CrFeCo x CuNiTi high-entropy alloy coatings and Q235 steel in H 2 SO 4 and HCl solutions. Experimental results show that the coating and its substrate are well combined. The cladding zone is mainly composed of equiaxed grains, as well as “cat foot shaped” grains and “snowflake” grains distributed in the matrix grains. Cracks appear in the coatings due to thermal stress. The corrosion resistance of Al 2 Co x CrCuFeNiTi coatings is excellent in H 2 SO 4 and HCl solutions, which can be attributed to three factors: the formability of Co element, passivation film formed on the alloy surface and the microstructure of the alloy. Increasing Co content can lead to an enhancement of the corrosion resistance of high-entropy alloy coatings in 0.5 mol/L HCl solution. Cyclic polarization curve shows no pitting corrosion in the 0.5 mol/L H 2 SO 4 solution for the Co 2.0 high-entropy alloy coating, but slight pitting corrosion in 0.5 mol/L HCl solution for the Co 0.5 high-entropy alloy coating due to the Cl − in the medium.