The T2 phase in the Nb-Si-B system studied by ab initio calculations and synchrotron X-ray diffraction

Joubert Jean Marc (1) , Catherine Colinet (2) , Gilberto Rodrigues (3) , P.A. Suzuki , C. Nunes , G. Coelho , Jean-Claude Tedenac (4)

1 CMTR - Chimie métallurgique des terres rares
2 SIMaP - Science et Ingénierie des Matériaux et Procédés
3 Laboratório de Materiais e Metalurgia
4 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier

The solid solution based on Nb5Si3 (Cr5B3 structure type, D8l, tI32, I4/mcm, No140, a=6.5767 Å, c=11.8967 Å) in the Nb-Si-B system was studied from the structural and thermodynamic point of view both experimentally and by ab initio calculations. Rietveld refinement of powder X-ray synchrotron data allowed to determine the boron to silicon substitution mechanism and the structural parameters. Ab initio calculations of different ordered compounds and selected disordered alloys allowed to obtain in addition to the enthalpy of formation of the solution, substitution mechanism and structural parameters which are in excellent agreement with the experimental data. The stability of the phase is discussed.

Mots clés: Nb-Si-B; Silicide; Boride; Synchrotron; DFT calculations; X-ray powder diffraction

Domaines: Matériaux

Joubert Jean Marc, Catherine Colinet, Gilberto Rodrigues, P.A. Suzuki, C. Nunes, et al.. The T2 phase in the Nb-Si-B system studied by ab initio calculations and synchrotron X-ray diffraction. Journal of Solid State Chemistry, 2012, 190, pp.111-117. ⟨10.1016/j.jssc.2012.02.009⟩. ⟨hal-00756290⟩