Titre :

Interactions of oxygen with intrinsic defects in L10 gamma-TiAl in presence of substitutional solutes: Influence on diffusion kinetics

Auteur(s) :

Thenot, Camille [Auteur]
Centre interuniversitaire de recherche et d'ingénierie des matériaux [CIRIMAT]
Centre d'élaboration de matériaux et d'études structurales [CEMES]
Besson, Rémy [Auteur]
Unité Matériaux et Transformations (UMET) - UMR 8207
Sallot, Pierre [Auteur]
Safran Tech
Monchoux, Jean-Philippe [Auteur]
Centre d'élaboration de matériaux et d'études structurales [CEMES]
Connétable, Damien [Auteur]
Centre interuniversitaire de recherche et d'ingénierie des matériaux [CIRIMAT]

Titre de la revue :

Computational Materials Science

Numéro :

201

Pagination :

110933

Éditeur :

Elsevier

Date de publication :

2022-01

ISSN :

0927-0256

Mot(s)-clé(s) en anglais :

TiAl
Intermetallic
DFT
Thermodynamic
Intrinsic defects
Oxygen

Discipline(s) HAL :

Physique [physics]/Matière Condensée [cond-mat]/Science des matériaux [cond-mat.mtrl-sci]
Chimie/Matériaux

Résumé en anglais : [en]

This work reexamines the insertion of O atoms in the L10 gamma-TiAl system using first-principles calculations and thermodynamic modeling in the independent point defect approximation. It includes a study of intrinsic point ...
Lire la suite >This work reexamines the insertion of O atoms in the L10 gamma-TiAl system using first-principles calculations and thermodynamic modeling in the independent point defect approximation. It includes a study of intrinsic point defects, the insertion of many alloying elements (more than twenty were considered), as well as a study of their interaction with oxygen. The formation of complex defects composed of either vacancies, anti-sites or solute elements is then studied. Results at the atomic scale show a high segregation of oxygen in titanium-rich environments: oxygen easily segregates onto Ti anti-sites (TiAl) and alloying elements are located in the vicinity of Al sub-lattices. DFT point-defect energetics shows that there is a clear correlation between the nature and site preference of an alloying element, and the oxygen segregation energy in the vicinity of this solute. The thermodynamic model shows that at equilibrium, oxygen does not occupy isolated interstitial sites but prefers to be located in the vicinity of Ti anti-sites or alloying elements. The effect of this strong segregation on oxygen diffusivity is discussed hereinafter. Results show a strong slowdown in oxygen diffusivity due to intrinsic defects. For Ti/Al > 0.5 ratios, the traps for O diffusion are mainly constituted by Ti anti-sites, and the addition of solutes does not contribute much to the trapping of diffusing O atoms. For Ti/Al < 0.5 ratios however, the contribution of solutes to trapping phenomena can be very important, and a decrease by 1–2 orders of magnitude of effective O diffusion coefficients can be observed for temperatures around 800–1100 K.Lire moins >

Langue :

Anglais

Comité de lecture :

Oui

Audience :

Internationale

Vulgarisation :

Non

Établissement(s) :

Université de Lille
CNRS
INRA
ENSCL

Collections :

• Unité Matériaux et Transformations (UMET) - UMR 8207

Équipe(s) de recherche :

Métallurgie Physique et Génie des Matériaux

Date de dépôt :

2022-01-20T13:48:41Z
2022-01-20T14:50:56Z