Increasing strength of a biomedical Ti-Nb-Ta-Zr alloy by alloying with Fe, Si and O

Low-modulus biomedical beta titanium alloys often suffer from low strength which limits their use as load bearing orthopaedic implants. In this study, twelve different Ti-Nb-Zr-Ta based alloys alloyed with Fe, Si and 0 additions were prepared by arc melting and hot forging. The lowest elastic modulus (65 GPa) was achieved in the benchmark TNTZ alloy consisting only of pure beta phase with low stability due to the 'proximity' to the beta to alpha martensitic transformation. Alloying by Fe and O significantly increased elastic modulus, which correlates with the electrons per atom ratio (e/a). Sufficient amount of Fe/O leads to increased yield stress, increased elongation to fracture and also to work hardening during deformation. A 20% increase in strength and a 20% decrease in the elastic modulus when compared to the common Ti-6Al-4V alloy was achieved in TNTZ-Fe-Si-O alloys, which proved to be suitable for biomedical use due to their favorable mechanical properties.