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Calculation of impurity diffusivities in α-Fe using first-principles methods / Shenyan Huang in Acta materialia, Vol. 58 N° 6 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 1982–1993 Titre : Calculation of impurity diffusivities in α-Fe using first-principles methods Type de document : texte imprimé Auteurs : Shenyan Huang, Auteur ; Daniel L. Worthington, Auteur ; Mark Asta, Auteur Année de publication : 2011 Article en page(s) : pp. 1982–1993 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Bulk  diffusion  Ab  initio  electron  theory  Kinetics  Iron  alloys Résumé : Self- and impurity diffusivities in body-centered-cubic (bcc) iron have been calculated within the formalisms of harmonic transition-state theory and the Le Claire nine-frequency model for vacancy-mediated diffusion. The approach combines first-principles calculations of vacancy formation, migration, and solute-binding enthalpies and entropies in the ferromagnetic phase, with an empirical relationship for the effect of magnetic disorder on diffusion activation energies. Calculated Fe self-diffusion and Mo and W impurity-diffusion coefficients are shown to agree within a factor of five with the most recent experimental measurements in both the ferromagnetic and paramagnetic phases. Calculated diffusion coefficients for Mo and W impurities are comparable to or larger than that for Fe self-diffusion at all temperatures below the α–γ phase transition. Calculated activation energies for Ta and Hf impurities suggest that these solutes should also display impurity-diffusion coefficients larger than that for self-diffusion in body-centered cubic Fe. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008209 [article] Calculation of impurity diffusivities in α-Fe using first-principles methods [texte imprimé] / Shenyan Huang, Auteur ; Daniel L. Worthington, Auteur ; Mark Asta, Auteur . - 2011 . - pp. 1982–1993. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 1982–1993 Mots-clés : Bulk  diffusion  Ab  initio  electron  theory  Kinetics  Iron  alloys Résumé : Self- and impurity diffusivities in body-centered-cubic (bcc) iron have been calculated within the formalisms of harmonic transition-state theory and the Le Claire nine-frequency model for vacancy-mediated diffusion. The approach combines first-principles calculations of vacancy formation, migration, and solute-binding enthalpies and entropies in the ferromagnetic phase, with an empirical relationship for the effect of magnetic disorder on diffusion activation energies. Calculated Fe self-diffusion and Mo and W impurity-diffusion coefficients are shown to agree within a factor of five with the most recent experimental measurements in both the ferromagnetic and paramagnetic phases. Calculated diffusion coefficients for Mo and W impurities are comparable to or larger than that for Fe self-diffusion at all temperatures below the α–γ phase transition. Calculated activation energies for Ta and Hf impurities suggest that these solutes should also display impurity-diffusion coefficients larger than that for self-diffusion in body-centered cubic Fe. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008209