High-temperature oxidation behavior of FeCoCrNiAl_x high-entropy alloy coatings

Abstract

Laser cladding was applied to fabricate FeCoCrNiAlx high-entropy alloy coatings. Scanning electron microscopy, optical microscopy, and XRD analysis were used to investigate the evolution of phases and microstructures in the coatings. The addition of Al could promote the formation of BCC solid solutions. The solidification pattern of the coatings changed from columnar to equiaxed crystals. Furthermore, characterization of the oxidation films (using XRD, SEM, and EDS) after high-temperature oxidation test indicates that Al element could lead to the formation of a dense oxide layer on the surface of the coatings. This layer significantly improved the resistance of the coatings to high-temperature oxidation.