Fabrication and characterization of highly porous Ti6Al4V/xTa composites for orthopedic applications

This paper presents the processing and properties of Ti6Al4V/xTa porous materials for potential use as bone implants. The processing route includes powder mixing, die pressing and solid state sintering. The porosity was created by 30 or 40 vol.% of salt particles with controlled volume fraction and size distribution, acting as space holders. The microstructure of the sintered materials was characterized by SEM and microtomography. Mechanical properties were deduced from simple compression tests, and permeability was evaluated by numerical simulations performed with real 3D microstructures. The obtained results showed various advantages of the fabricated materials. Their weight densities of the materials processed with 40 vol.% of salt particles were in the range of those of human bones. As a consequence of Ta diffusion, the final microstructures included Ta-stabilized β-Ti phase, conventional α-Ti phase, martensitic α′-Ti phase, and small residual Ta particles. Also, it was found that both Ta and salt additions reduced the Young’s modulus and the yield stress, while the permeability strongly increased with increasing vol.% of salt particles. Notably, the properties of the material processed with 30 vol.% of Ta particles and 40 vol.% of salt particles were close to those required for trabecular bone implants.