Mechanical and tribological evaluation of a biomedical high-entropy alloy reinforced with TiC and TiB

High-entropy alloys (HEAs) are emerging materials that have recently been considered for biomedical applications. However, further adjustments in their properties are still needed to potentialize this application. Thus, research on novel processing routes is interesting for producing such advanced biomedical HEAs. In this study, we synthesized a novel metal–matrix composite (MMC) using an HEA as the matrix, which was reinforced with TiB and TiC particles. The sample was produced by argon arc melting a TiNbZrTaMo ingot with B₄C powder to induce in situ reactions. The resulting sample underwent extensive evaluations, including physical, chemical, structural, microstructural, mechanical, tribological, and biological assessments, and was compared to the unreinforced HEA sample. X-ray diffraction confirmed the in situ reactions, revealing a dual-phase (BCC + HCP) matrix with TiC and TiB peaks. Scanning and transmission electron microscopy showed that the BCC phase was enriched with refractory metals (Ta, Mo, and Nb), while the HCP and carbide precipitate phases were enriched with Ti and Zr. The results demonstrated strong interfacial bonding between the TiC precipitate and the matrix. Mechanical property analysis indicated that the precipitates retained a combination of high microhardness and a relatively low elastic modulus. Despite this, the precipitates enhanced wear resistance without offering any benefits in terms of corrosion resistance. Cytotoxicity tests showed that the precipitates positively influenced cell viability and adhesion. These findings highlight the potential for developing novel biomedical materials by combining HEA and MMC concepts. (Financial support: CNPq and FAPESP grant #2024/03148-3)