Evaluation of mechanical and wear properties of Ti-xNb-7Fe alloys designed for biomedical applications

A group of Ti-xNb-7Fe (x= 0, 1, 4, 6, 9, 11 wt.%) alloys was designed and produced by cold crucible levitation melting process. The microstructural characteristic of the alloys with Nb addition and its effect on theirmechanical properties as well as wear resistance were investigated. Microscopic and phase analysis results showthat all the alloys, except for the Ti-11Nb-7Fe, exhibit orthorhombic alpha" and body-centred cubic beta phases, while Ti-11Nb-7Fe alloy consists of only beta phase. It is proposed that increasing the Nb content enhances beta phase stability and its proportion in the microstructure of the designed alloys. Depending on the proportion of beta and alpha" phases, Ti-xNb-7Fe alloys show varied hardness (3.57- 5.92 GPa) and compressive strength (1990-2093 MPa). Additionally, they present wear rates in the range of 3 x 10(-15)-1 x 10(-13) m(3)/m which correlates well with the changes in the corresponding microstructures and mechanical properties. Among the studied alloys, Ti-11Nb-7Fe with beta phase microstructure, presents the lowest elastic modulus (86 GPa) and the highest compressive strain (41.5%) along with high compressive strength, hardness and wear resistance. Therefore, it is suggested that this beta-type Ti-11Nb-7Fe alloy is a promising candidate, more suitable than the commercially used CP-Ti and Ti-6Al-4V, for orthopedic applications. (C) 2016 Elsevier Ltd. All rights reserved.