Interactions of oxygen with intrinsic defects in L1<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e1983" altimg="si96.svg"><mml:msub><mml:mrow /><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msub></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e1991" altimg="si48.svg"><mml:mi>γ</mml:mi></mml:math>-TiAl in presence of substitutional solutes: Influence on diffusion kinetics

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