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An ab initio study of the structural and mechanical alterations of Ti-Nb alloys
Gutiérrez Moreno, José Julio
Papageorgiou, D. G.
Evangelakis, G. A.
Lekka, Ch. E.
This article describes a systematic theoretical investigation of the role of Nb substitution on the structural and mechanical properties of Ti-Nb alloys. The aim is to understand the origin of the low-rigidity of some of these materials. This quality makes these materials suitable for metallic implants. The mechanical stability conditions in conjunction with the calculated elastic constants of Ti-Nb predict the destabilization of α′ and ω structures, while the β-phase can be stabilized for Nb content above 10 at. %. The evaluated Young's moduli (E) follow the sequence of Eω > Eα′ > Εα″ > Εβ, revealing high Eω and Eα′ values (greater than 120 GPa), while the Eβ value converges to approximately 87 GPa. The averaged E, estimated from a weighted average of Eω, Eα′, Εα″, and Εβ ab initio values, reproduces the experimental Ti-Nb Young's modulus w-shaped curve. Young's modulus surface reveals highly anisotropic E values for all Ti-Nb phases. Eβ exhibits values under 30 GPa along the  direction for Nb compositions larger than 12 at. %, suggesting that the orientational growth of a Ti-Nb alloy is important for the design of low-rigidity alloys, especially at small Nb concentrations. These results can be used as a guide for the design of novel low-rigidity alloys for biomedical applications.
Biomaterials , Titanium alloys , Phase stability , Biomaterials , Polycrystalline material , Titanium , Transition metals , Elastic stiffness , Poisson's ratio , Elastic modulus , Crystal structure , Phase transitions , Crystal orientation
Moreno, J. J. G., Papageorgiou, D. G., Evangelakis, G. A. and Lekka, C. E. (2018) 'An ab initio study of the structural and mechanical alterations of Ti-Nb alloys', Journal of Applied Physics, 124(24), 245102 (7 pp).
© 2018, AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Journal of Applied Physics 2018 124:24and may be found at https://aip.scitation.org/doi/abs/10.1063/1.5025926