Tribo-corrosion performances of high-entropy alloy coatings for biomedical applications: A review

High-entropy alloy (HEA) coatings have emerged as a revolutionary alternative to conventional metallic biomaterials, owing to their unique core effects that synergistically optimize biocompatibility, tribo-corrosion resistance, and mechanical compatibility with human tissues. However, their clinical application is severely hindered by tribo-corrosion challenges. Mechanical wear exacerbates electrochemical degradation in chloride-rich physiological environments, causing pitting, passive film breakdown, and structural integrity loss. This review summarizes recent advances in tribo-corrosion mitigation via composition regulation, structural design, and advanced fabrication technologies. Alloying optimizes passive film properties, induces lattice distortion, and refines microstructures. Function-doped HEA coatings achieve tailored performances (e.g., MRI compatibility, antibacterial activity). Technologies like laser cladding and magnetron sputtering enhance coating density and interface bonding. Data-driven design accelerates the development of HEA systems with balanced hardness and corrosion resistance. Despite the progress outlined above, the large-scale clinical translation of HEA coatings remains challenging. The multi-field coupling mechanisms and predictive models for tribo-corrosion have yet to be established. Existing processes suffer from poor uniformity and reproducibility in batch production, making it difficult to meet industrial requirements. The reliance on precious metals results in high costs, necessitating the urgent development of environmentally friendly and low-cost systems. Furthermore, there is a lack of data on long-term in vivo stability and a lack of clinical trials in large animals.