Abstract
Biomedical Ti-29Nb-13Ta-4.6Zr (TNTZ) has been developed as a structural material for implant devices. Mcrostructural refinement of TNTZ and its effect on mechanical biocompatibility and surface functionality through HPT processing are investigated systematically in this study. Aged TNTZ subjected to HPT processing (TNTZAHPT) has a homogeneous microstructure consisting of nanostructured elongated β grains aligned along the radial direction. The β grains exhibit nanostructured subgrains having non-uniform morphologies distorted by severe torsional deformation. Furthermore, the β grains and subgrains are surrounded by blurred and wavy boundaries in a non-equilibrium state. The needle-like α precipitates are totally refined to a nanostructure with a diameter of approximately 12 nm. TNTZahpt shows an enhanced mechanical biocompatibility, which is a greater tensile strength (1375 MPa) and a higher hardness (450 HV) than those of course-grained solutionized TNTZ (TNTZST), aged TNTZ (TNTZAT), and Ti-6Al-4V (Ti64) ELI while maintaining relatively low Young's modulus. TNTZAHPT exhibits an enhanced combination of a great corrosion performance and improved cellular response in comparison to TNTZST, TNTZat, and Ti64 ELI.