Title :

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

Author(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]

Journal title :

Computational Materials Science

Volume number :

201

Pages :

110933

Publisher :

Elsevier

Publication date :

2022-01

ISSN :

0927-0256

English keyword(s) :

TiAl
Intermetallic
DFT
Thermodynamic
Intrinsic defects
Oxygen

HAL domain(s) :

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

English abstract : [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 ...
Show more >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.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

Administrative institution(s) :

Université de Lille
CNRS
INRA
ENSCL

Collections :

• Unité Matériaux et Transformations (UMET) - UMR 8207

Research team(s) :

Métallurgie Physique et Génie des Matériaux

Submission date :

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