Microstructure, Texture and Mechanical Properties after Cold Working and Annealing in a Biomedical Ti-Nb-Ta Alloy

Abstract

β titanium alloys, comprising alloying elements such as Nb, Ta, Zr, are considered promising materials for use in orthopedic applications, as the lower elastic modulus of these alloys, reduces the chance of implant failure caused by stress shielding. The mechanical behavior of these alloys depend on the composition as well as the stability of the phases. In the present study, the effect of cold rolling and subsequent annealing on the microstructure, texture and mechanical behavior of a Ti-Nb-Ta-O alloy has been investigated. Structural characterization was done using x-ray diffraction (XRD) and optical microscopy. Mechanical properties were evaluated by estimation of hardness and elastic modulus. The results show that, (1) the alloy contains single-phase β microstructure in both deformed as well as annealed condition with no evidence of deformation induced phase transformation, (2) the microstructures of cold worked alloy become increasingly inhomogeneous with dominance of shear bands at higher rolling strains, (3) high value of hardness to modulus ratio could be obtained in the present alloy due to stability of β phase and interstitial strengthening.