Nanoindentation study of mechanical properties of Ti based alloys with Fe and Ta additions

In this work, the effect of Fe and Ta content on the microstructure and β phase stability of as-cast designed Ti-xFe-yTa (x = 8, 9, 10 wt% and y = 0, 5, 8, 9, 10 wt%) alloys was investigated. Additionally, its influence on the resulting mechanical properties including hardness (H), reduced elastic modulus (Er), elastic recovery and wear resistance of the alloys was evaluated using nanoindentation. Microstructural studies and phase analysis showed that all alloys are comprised of body-centered cubic β and orthorhombic α″ phases, the proportion of which depends on their Fe and Ta contents. Nanoindentation measurements indicated that the reduced elastic modulus of the alloys decreases with increase in the Fe and Ta contents owing to increase in their β phase proportion and its stability. It was also observed that the hardness and elastic recovery of the alloys are in the range of 3.38–5.73 GPa and 0.241–0.298, respectively, which are higher than the corresponding ones for the commonly used CP-Ti biomaterial. Additionally, their H/Er and H3/Er2 ratios are higher than those of CP-Ti suggesting a better wear resistance of the designed Ti-Fe-Ta alloys. It is concluded that among the studied alloys, Ti-10Fe-10Ta with dominant β phase microstructure exhibits a good combination of mechanical properties which make it more desirable than CP-Ti for orthopedic application.