Preparing high-entropy ceramic films from high-entropy alloy substrate

High-entropy ceramic films with good anti-wear, anti-radiation, anti-corrosion and anti-oxidation performance are attractive for the application in extreme environments such as high temperature, high strength and strong radiation. This paper reported an alternative way to produce high-entropy ceramic films by in-situ nitridation or oxidation of high-entropy alloy substrates. Nitride and oxide high-entropy ceramic films of (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)N and (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)O2 were prepared by heat treatment of high-entropy alloy (Ti0.2Zr0.2V0.2Nb0.2Ta0.2) in 0.1 MPa N2 and air atmosphere, respectively. For the high-entropy ceramic films, except for a small amount of oxides impurity, the solid solutions (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)N and (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)O2 with a simple face-centered cubic and tetragonal crystal structure were the major products and showed homogeneous element distribution. The porous (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)O2 film about 5.5 μm thick has a hardness of 19.8 GPa, modulus of 378 GPa and critical load value of 55.3 mN. And (Ti0.2Zr0.2V0.2Nb0.2Ta0.2)N film about 850 nm thick is relatively dense and exhibits a hardness of 36.7 GPa, modulus of 635 GPa and critical load value of 90.8 mN.