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The effect of platinum on Al diffusion kinetics in β-NiAl / Kristen A. Marino in Acta materialia, Vol. 58 N° 7 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2726–2737 Titre : The effect of platinum on Al diffusion kinetics in β-NiAl : Implications for thermal barrier coating lifetime Type de document : texte imprimé Auteurs : Kristen A. Marino, Auteur ; Emily A. Carter, Auteur Année de publication : 2011 Article en page(s) : pp. 2726–2737 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Diffusion  Nickel  aluminides  Platinum  Kinetics  Density  functional  theory Résumé : First-principles density functional theory calculations are used to study Al diffusion in β-NiAl. The activation energy and diffusion constant pre-exponential factors are calculated for five previously postulated Al diffusion mechanisms: next-nearest-neighbor Al jumps, the triple defect mechanism and three variants of the six-jump cycle mechanism beginning with an Al vacancy. We predict that the triple defect mechanism has the lowest activation energy and is the mechanism by which Al diffusion occurs in NiAl. In order to elucidate why Pt has a beneficial effect on thermal barrier coating lifetime, the effect of Pt on each of these mechanisms is also examined. In all cases, Pt decreases the diffusion activation energy, which should enhance Al diffusion in the coatings. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964541000011X [article] The effect of platinum on Al diffusion kinetics in β-NiAl : Implications for thermal barrier coating lifetime [texte imprimé] / Kristen A. Marino, Auteur ; Emily A. Carter, Auteur . - 2011 . - pp. 2726–2737. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2726–2737 Mots-clés : Diffusion  Nickel  aluminides  Platinum  Kinetics  Density  functional  theory Résumé : First-principles density functional theory calculations are used to study Al diffusion in β-NiAl. The activation energy and diffusion constant pre-exponential factors are calculated for five previously postulated Al diffusion mechanisms: next-nearest-neighbor Al jumps, the triple defect mechanism and three variants of the six-jump cycle mechanism beginning with an Al vacancy. We predict that the triple defect mechanism has the lowest activation energy and is the mechanism by which Al diffusion occurs in NiAl. In order to elucidate why Pt has a beneficial effect on thermal barrier coating lifetime, the effect of Pt on each of these mechanisms is also examined. In all cases, Pt decreases the diffusion activation energy, which should enhance Al diffusion in the coatings. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964541000011X