In-situ production of a biomedical metal-matrix composite based on a high entropy alloy reinforced with TiC and TiB

This study developed a novel metal-matrix composite (MMC) composed of a high entropy alloy (HEA) as a matrix and TiB and TiC particles as reinforcement. The sample was produced by argon arc-melting of a TiNbZrTaMo ingot with the addition of B4C powder to induce in-situ reactions. Then, the sample was submitted to physical, chemical, structural, microstructural, mechanical, tribological, and biological evaluation to uncover the effects of TiB and TiC precipitates on the solid solution. X-ray diffraction measurements confirmed the in-situ reactions, exhibiting a dual phase (BCC + HCP) for the matrix coexisting with the TiC and TiB precipitates. The scanning and transmission electron microscopy revealed that the BCC phase was preferentially enriched by refractory metals (Ta, Mo, and Nb), while the HCP and carbide precipitate by Ti and Zr. The results also highlighted a great interfacial bonding between the TiC precipitate and the matrix. The selected mechanical properties indicated that the precipitates unaffected the microhardness values but had a smooth influence on the elastic modulus. The precipitates mostly enhanced wear resistance despite the corrosion one. The cytotoxicity test indicated that the precipitates positively influenced the cell viability and adhesion. Our results shed light on developing the next generation of biomedical materials by joining the HEA and MMC concepts.