High temperature oxidation behavior of CoCrFeNiMo 0.2 high-entropy alloy coatings produced by laser cladding

The oxidation behavior of CoCrFeNiMo 0.2 high-entropy alloy laser cladding coatings at 700 degrees C and 900 degrees C was investigated. The oxidation kinetics of the alloys at all temperatures followed a parabolic behavior, with the oxidation rates increasing significantly with increasing temperature. The alloy exhibits excellent oxidation resistance at 700 degrees C. Compared with the original alloy structure, the segregation of Mo element in the alloy is more serious after high-temperature treatment. Compared with 700 degrees C, the oxidation degree of the alloy is more intense at 900 degrees C. The reaction between iron and chromium oxides forms a chromite layer, and the rapid diffusion of iron ions in the layer forms an outer layer of iron oxides. As the oxidation proceeds, the oxide film is separated from the metal, and the chromium oxide layer grows between the spinel layer and the metal. The thermodynamics of the reaction was calculated, the oxidation mechanism of the alloy was explored, and a hightemperature model of the alloy was developed. This study expands the potential applications of high entropy alloys in surface engineering.