Carbon-Induced Structural Evolution and Synergistic Enhancement of Wear and Corrosion Resistance in (AlFeCoNi)C High-Entropy Alloy Carbide Films

The (AlFeCoNi)C high-entropy alloy carbide films (HECFs) with tunable carbon contents were fabricated by magnetron sputtering to investigate the carbon-driven structural evolution and its coupling effects on mechanical and chemical properties. With increasing carbon incorporation (0-47.6 at.%), the HECFs formed a composite structure of amorphous phase and BCC nanocrystalline phase, as evidenced by XRD and TEM. Atom probe tomography (APT) reveals Al segregation in the film. Remarkably, the wear rate decreases exponentially from 4.8 × 10^-5 to 6.7 × 10^-6 mm³/N·m, attributed to the amorphous carbon phase acting as solid lubricant. Simultaneously, the corrosion current density reduces by two orders of magnitude (7.2 × 10^-8 A/cm² in 3.5% NaCl), benefiting from the amorphous network inhibiting ion diffusion pathways. This work establishes a carbon-content-property correlation paradigm for designing multifunctional HEA films in extreme environments.