The HYTIMOX project, funded by the German Federal Ministry of Education and Research under grant number 03XP0279B, ran from 1 July 2020 to 30 June 2023 and was led by the Fraunhofer Society with project managers Dr. Philipp Imgrund and M.Sc. Jan Johannsen. Its overarching aim was to create a chemically bonded hybrid material that combines oxide ceramics and titanium alloys through a glass‑solder (glosslot) interface, suitable for load‑bearing implants in the musculoskeletal system. A consortium of partners contributed expertise in glass‑solder technology, additive manufacturing, metal injection molding (MIM), and biological evaluation, and the consortium shared test specimens for iterative development and assessment of the hybrid material’s performance.
The technical focus of the subproject was the development and characterization of novel ternary Ti–Nb–Ta alloys for use as the titanium component of the hybrid. Three alloy compositions were investigated: Ti‑20Nb‑6Ta, Ti‑27Nb‑6Ta, and Ti‑35Nb‑6Ta. The powders were produced at a Technical Readiness Level of 4, specifically tailored for additive manufacturing and MIM processes. Laser beam melting (LBM) and MIM routes were optimized to yield reproducible, defect‑free, and fully dense parts. In the LBM process, tensile strengths ranged from 650 MPa for Ti‑35Nb‑6Ta to 820 MPa for Ti‑20Nb‑6Ta, while fracture elongations varied from 17 % (Ti‑20Nb‑6Ta) to 38 % (Ti‑27Nb‑6Ta). Corresponding Young’s moduli spanned 49 GPa (Ti‑35Nb‑6Ta) to 96 GPa (Ti‑27Nb‑6Ta). The MIM route produced slightly higher strengths but lower ductility and a higher modulus, attributed to impurities introduced during the MIM chain. These mechanical data confirm that the alloys meet the requirements for load‑bearing implant applications and provide a solid foundation for further integration with ceramic components.
A critical outcome of the project was the identification of Ti‑35Nb‑6Ta as the most suitable alloy for glass‑solder bonding. Its coefficient of thermal expansion closely matches that of the chosen glass‑solder, enabling a reliable, chemically bonded interface between titanium, glass, and oxide ceramic. This compatibility was demonstrated by fabricating a laboratory‑scale hybrid specimen that successfully combined all three materials. The hybrid’s mechanical integrity and potential for improved bone‑implant contact were confirmed through preliminary biological suitability tests conducted by partner institutions.
Throughout the project, iterative cycles of design, process development, and testing were conducted in close collaboration with consortium partners. Simple test bodies were first produced and then progressively more complex specimens were fabricated to support the development of the glass‑solder technology and to provide material for biological evaluation. The final deliverables included a set of characterized Ti alloy powders, optimized LBM and MIM process recipes, mechanical property data, and a laboratory‑scale hybrid implant prototype. These results lay the groundwork for future scaling and clinical validation of the HYTIMOX hybrid material, advancing the field of biomaterial engineering toward more durable and biologically compatible implant solutions.