High temperature oxidation enhanced by laser remelted of CoCrFeNiAlx (x = 0.1, 0.5 and 1) high-entropy alloys

In order to further improve the oxidation resistance of CoCrFeNiAlx (x = 0.1, 0.5, and 1) high entropy alloys (HEAs), the surface of CoCrFeNiAlx prepared by vacuum arc melting is controlled by laser surface remelting (LSM) and the high-temperature oxidation properties of CoCrFeNiAlx before and after LSM is systematically studied. The results revealed that, with the increase of Al content, the parabolic velocity constant kp value gradually decreased after LSM treatment. Moreover, CoCrFeNiAl0.1 formed a continuous Cr2O3 oxide layer, CoCrFeNiAl0.5 formed an outer layer of Cr2O3 oxide film and an inner layer of Al2O3 precipitation, and CoCrFeNiAl1 formed a uniform and dense Al2O3 oxide layer on the entire area. After 100 h of oxidation, the oxide film thickness of three alloys is around 5 µm, 4 µm, and 3 µm, respectively. The improvement in oxidation resistance after LSM can be ascribed to the formation of a dense re-melted layer, uniform distribution of the elements, refinement of the re-melted layer.