Nanoindentation studies and analysis of the mechanical properties of Ti-Nb2O5 based composites

In this study, nanoindentation tests were used to evaluate the mechanical properties of spark plasma sintered Ti based composites containing 5, 10 and 15 wt.% Nb2O5, targeted for potential use as biomedical material. Nanoindentation tests were performed on the samples using indenter loads of 20 and 100 mN, while the microstructures were characterized using scanning electron microscopy. It was noted that with increasing Nb2O5 wt.%, there is transition from the lamellar structure of pure Ti to fully bimodal structures for the Ti-10 wt.% Nb2O5 and Ti-15 wt.% Nb2O5 composites. The hardness (6.0-40.67 GPa (20 mN) and 2.4-12.03 GPa (100 mN)) and reduced elastic modulus (115-266.91 GPa (20 mN) and (28.05-96.873 GPa (100 mN)) of the composites increases with increase in the Nb2O5 content, attributed to contributions of load transfer from the Ti matrix to the relatively harder Nb2O5 particles, particle and dispersion strengthening mechanisms. The elastic recovery index also improved with increase in Nb2O5 content, while the inverse was noted with respect to plasticity index. The elastic strain to failure and yield pressure both improved with increase in Nb2O5 content, which suggests that the antiwear properties and resistance to impact loading equally improves with Nb2O5 addition.