Ab-initio and experimental study of phase stability of Ti-Nb alloys
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Accepted Version
Date
2016-11-18
Authors
Gutiérrez Moreno, José Julio
Bönisch, M.
Panagiotopoulos, N. T.
Calin, M.
Papageorgiou, D. G.
Gebert, A.
Eckert, J.
Evangelakis, G. A.
Lekka, Ch. E.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Published Version
Abstract
A systematic theoretical and experimental study concerning the crystallographic structure and electronic properties of Ti-xNb (x < 50 at%) alloys is presented, aiming to enlighten the electronic origins of the β-phase stability which is of high interest for the development of novel β stabilized Ti-based alloys for biomedical applications. Both quantum-mechanical calculations and X-ray diffraction found several structural phases depending on Nb concentration. The ab-initio total energy results reveal that at low Nb contents the α′ and ω phases are favoured while at Nb content >18.75 at% the β-phase is favoured against all other crystallographic structures in line with the experimental results. Interestingly, at high Nb content the α′ and ω hexagonal phases become unstable due to the electronic band filling close to the Fermi level EF, which is mainly due to Nb-p and Ti-d antibonding hybridizations. On the contrary, in the cubic β-Ti-25Nb (at%) the depletion of the occupied electronic states at the EF occurs mainly due to Nb-d and Ti-d bonding interactions, resulting in a stable β-TiNb structure. These data could enlighten the electronic origin of the Ti-Nb phase stability, thus, may contribute to the design of β stabilized low moduli Ti-based alloys suitable for load-bearing biomedical applications.
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Keywords
Biomaterials , Titanium alloys , Phase stability
Citation
Gutiérrez Moreno, J. J., Bönisch, M., Panagiotopoulos, N. T., Calin, M., Papageorgiou, D. G., Gebert, A., Eckert, J., Evangelakis, G. A. and Lekka, C. E. (2017) 'Ab-initio and experimental study of phase stability of Ti-Nb alloys', Journal of Alloys and Compounds, 696, pp. 481-489. 10.1016/j.jallcom.2016.11.231