Design, processing, and characterization of novel high-entropy alloys for biomedical applications by using non-toxic and low-cost alloying elements

High-entropy alloys (HEAs) have emerged as a hotspot for novel biomedical materials, owing to the unique combination of mechanical, corrosion, tribological, and biological properties enabled by the four core effects. However, the currently developed HEAs for high-performance applications are composed of potentially toxic (Ni, Co, and Cr) or refractory elements (Ta, Mo, and Nb), which limit their use in hard tissue replacements, such as orthopedic and dental implants. In this sense, the goal of this study was to design novel multi-component solid solutions by replacing certain alloying elements with Mn, Al, and Fe to meet certain clinical criteria. The chemical composition was designed by using CALPHAD, resulting in the Ti₃₀Nb₃₀Mn₃₀Fe₅Al₅ (at%). After that, the samples were produced by argon arc melting of raw metals, characterized by conventional X-ray and electron-based techniques, and tested in preliminary mechanical, tribo-electrochemical, and cytotoxic assays. The results indicated that the presence of distinct amounts of alloying elements can retain secondary phases (e.g., Laves C14 and C15) in a BCC matrix. As a result, positive effects on hardness (~600 HV) and elastic modulus (~200 GPa) were achieved without compromising corrosion resistance in Hank’s solution or cell interaction with the pre-osteoblast lineage, particularly cell adhesion and proliferation. Therefore, the study sheds light on a new route for developing biomedical materials based on the concept of entropy, especially surgical instruments and bone fixation devices. (Financial support: FAPESP #2024/03148-3 and #2024/01132-2, and CNPq #404020/2023–2 and #304400/2025-4)