Research Article

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

¹ Materials Design and Structural Integrity Research Group, Department of Metallurgical and Materials Engineering, Federal University of Technology Akure, PMB 704, Nigeria
² Center for Nanoengineering and Tribocorrosion, School of Mining, Metallurgy and Chemical Engineering, University of Johannesburg, Johannesburg, South Africa

^* e-mail: kalanemek@yahoo.co.uk

Received: 2 April 2020
Accepted: 22 May 2020

Abstract

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.