Ab-initio and experimental study of phase stability of Ti-Nb alloys

作者：Moreno J J Gutierrez; Boenisch M; Panagiotopoulos N T; Calin M; Papageorgiou D G; Gebert A; Eckert J; Evangelakis G A; Lekka Ch E^*

来源：Journal of Alloys and Compounds, 2017, 696: 481-489.

DOI：10.1016/j.jallcom.2016.11.231

• Biomaterials
• Titanium alloys
• Phase stability

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 beta-phase stability which is of high interest for the development of novel beta 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 alpha' and omega phases are favoured while at Nb content > 18.75 at% the beta-phase is favoured against all other crystallographic structures in line with the experimental results. Interestingly, at high Nb content the alpha' and omega hexagonal phases become unstable due to the electronic band filling close to the Fermi level E-F, which is mainly due to Nb-p and Ti-d antibonding hybridizations. On the contrary, in the cubic beta-Ti-25Nb (at%) the depletion of the occupied electronic states at the EF occurs mainly due to Nbd and Ti-d bonding interactions, resulting in a stable beta-TiNb structure. These data could enlighten the electronic origin of the Ti-Nb phase stability, thus, may contribute to the design of beta stabilized low moduli Ti-based alloys suitable for load-bearing biomedical applications.

• 出版日期2017-3-5