Enhancement of mechanical properties of biocompatible Ti-45Nb alloy by hydrostatic extrusion

Author(s)
K. Ozaltin, W. Chrominski, M. Kulczyk, A. Panigrahi, J. Horky, M. Zehetbauer, M. Lewandowska
Abstract

β-Type titanium alloys are promising materials for orthopaedic implants due to their relatively low Young’s modulus and excellent biocompatibility. However, their strength is lower than those of α- or α + β-type titanium alloys. Grain refinement by severe plastic deformation (SPD) techniques provides a unique opportunity to enhance mechanical properties to prolong the lifetime of orthopaedic implants without changing their chemical composition. In this study, β-type Ti–45Nb (wt%) biomedical alloy in the form of 30 mm rod was subjected to hydrostatic extrusion (HE) to refine the microstructure and improve its mechanical properties. HE processing was carried out at room temperature without intermediate annealing in a multi-step process, up to an accumulative true strain of 3.5. Significant microstructure refinement from a coarse-grained region to an ultrafine-grained one was observed by optical and transmission electron microscopy. Vickers hardness measurements (HV0.2) demonstrated that the strength of the alloy increased from about 150 to 210 HV0.2. Nevertheless, the measurements of Young’s modulus by nanoindentation showed no significant changes. This finding is substantiated by X-ray diffraction analyses which did not exhibit any phase transformation out of the bcc phase being present still before processing by HE. These results thus indicate that HE is a promising SPD method to obtain significant grain refinement and enhance strength of β-type Ti–45Nb alloy without changing its low Young’s modulus, being one prerequisite for biomedical application.

Organisation(s)
Physics of Nanostructured Materials
External organisation(s)
Warsaw University of Technology, Polish Academy of Sciences (PAS)
Journal
Journal of Materials Science
Volume
49
Pages
6930-6936
No. of pages
7
ISSN
0022-2461
DOI
https://doi.org/10.1007/s10853-014-8397-7
Publication date
10-2014
Peer reviewed
Yes
Austrian Fields of Science 2012
103018 Materials physics
Keywords
ASJC Scopus subject areas
Mechanics of Materials, Mechanical Engineering, Materials Science(all)
Portal url
https://ucris.univie.ac.at/portal/en/publications/enhancement-of-mechanical-properties-of-biocompatible-ti45nb-alloy-by-hydrostatic-extrusion(13bae434-009c-4ef6-af91-7df9400162ac).html