Abstract
Bone fractures and degenerative skeletal conditions drive a growing demand for implants that combine high mechanical strength, long-term biocompatibility, and optimal biomechanical performance. Conventional titanium alloys, such as CP-Titanium Grade 4 and Ti-6Al-4V ELI (Ti64), are widely used in clinical practice but are limited by their high elastic modulus and biological functionality. In contrast, nanostructured β-type titanium alloys, such as Ti-13Nb-13Zr (TNZ), offer reduced stiffness, enhanced osseointegration, and promising antibacterial properties. However, the production of bulk nanostructured β-type titanium alloys has so far been restricted to laboratory-scale severe plastic deformation processes with limited industrial applicability.
This study introduces a novel thermomechanical processing route based on Continuous Multidirectional Swaging (CMDS) for the continuous fabrication of flat, nanostructured titanium semi-finished products for osteosynthesis applications. The CMDS process was specifically designed to enable simultaneous macroscopic shaping and microstructural refinement, supported by dedicated tool development and numerical simulations to ensure homogeneous deformation and controlled strain distribution throughout the semi-finished product.
CMDS processing of TNZ, followed by tailored heat treatment, resulted in a homogeneous nanostructure with grain sizes below 100 nm and tuneable mechanical properties suitable for load-bearing implant applications. In contrast, Ti64 exhibited a significantly reduced nanostructuring capability under comparable processing conditions, highlighting fundamental differences in the deformation and recovery behaviour of α+β and β-type titanium alloys. The presented results demonstrate that CMDS effectively overcomes key scalability limitations associated with conventional severe plastic deformation techniques and underlines the superior suitability of β-type titanium alloys for industrial-scale nanostructuring. Overall, this work establishes CMDS as a promising manufacturing route for advanced, nanostructured titanium semi-finished products for next generation osteosynthesis implants.