Study on the effect and growth mechanism of micro-arc oxidation coating on AlCoCrFeNi high entropy alloy

In this study, a method for preparing micro-arc oxidation (MAO) coating on the surface of AlCoCrFeNi high entropy alloy (HEAs) with low valve metal content was proposed. By adjusting the sintering temperature of HEAs, a high entropy alloy micro-arc oxidation (HEAs-MAO) coating with excellent performance was successfully prepared. The microstructure and composition of the coating were characterized by scanning electron microscopy, X-ray diffractometer and energy dispersive spectrometer. The wear resistance and corrosion resistance of the coating were evaluated by friction test and electrochemical corrosion test. The results show that the coating is mainly composed of Al2O3, and contains a small amount of Co, Fe and Ni oxides on the surface, among which Co3O4 is the main reason for the appearance of blue spots on the coating surface. Compared with the HEA7 sample, the coating of the HEA7-M sample is thicker, has a lower coefficient of friction, higher hardness, and exhibits excellent wear resistance and significantly improved corrosion resistance. In summary, the preparation of MAO coating on the surface of HEAs provides an effective and feasible solution for the further application of HEAs.