摘要
In this study, Al5SiCo22Cr22Ni44NbMo5 high entropy alloy (HEA) thin films with nanotwinned structure were prepared using a magnetron sputtering on the nickel-metal substrate and the high-temperature oxidation behavior of the films was investigated in air atmosphere at 600–800 ℃. The results show that HEA films exhibit good oxidation resistance and significantly reduce the oxidation mass gain of pure Ni. The oxidized HEA films exhibit a flat surface with no pores or cracks. Cr2O3 particles are found to precipitate on the surface after long-term oxidation at 800 ℃. The surface oxide on the films consists of an internal Al-rich oxide and an external Cr-rich oxide at 600 ℃, and the oxidation is dominated by the inward diffusion of oxygen. However, the oxide layer changed to a three-layer structure with Al-rich/Cr-rich/Al-rich oxide at 700 ℃ and 800 ℃, and the oxide changes to an island-type structure with discontinuous thickness when the oxidation time increases. After long-term oxidation at 800 ℃, chromium diffuses through the outer Al-rich oxide layer, forming Cr2O3 on the surface.
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•Nanotwinned Al₅SiCo₂₂Cr₂₂Ni₄₄NbMo₅ HEA films were engineered via magnetron sputtering.•HEA films provide excpetional oxidation resistance to Ni at elevated temperature.•HEA films retain dense, void-free surfaces after oxidation due to thermal stability.•Oxidation mechanism of HEA films at high temperatures is discussed in detail.•Films show strong potential as functionl coatings for high-temperature applications.