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First-principles prediction of partitioning of alloying elements between cementite and ferrite / Chaitanya Krishna Ande in Acta materialia, Vol. 58 N° 19 (Novembre 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6276–6281 Titre : First-principles prediction of partitioning of alloying elements between cementite and ferrite Type de document : texte imprimé Auteurs : Chaitanya Krishna Ande, Auteur ; Marcel H.F. Sluiter, Auteur Année de publication : 2011 Article en page(s) : pp. 6276–6281 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Iron  Carbides  Steels  First-principles  electron  theory  Partitioning Résumé : At long tempering times in steels when both cementite (Fe3C) and ferrite (body-centered cubic (bcc) Fe-rich solid solution) phases are present, alloying elements tend to segregate to either of the two phases. The elements V, Cr, Mn, Mo and W are found to partition to the cementite phase, while Al, Si, P, Co, Ni and Cu partition to ferrite. We show that partitioning of alloying elements and cementite (de)stabilization by alloying in mixtures of bcc Fe and cementite are intimately related through the introduction of a partitioning enthalpy. The formation enthalpy of alloying-element-substituted cementite is shown not to be a proper gauge for addressing these questions. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410004933 [article] First-principles prediction of partitioning of alloying elements between cementite and ferrite [texte imprimé] / Chaitanya Krishna Ande, Auteur ; Marcel H.F. Sluiter, Auteur . - 2011 . - pp. 6276–6281. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6276–6281 Mots-clés : Iron  Carbides  Steels  First-principles  electron  theory  Partitioning Résumé : At long tempering times in steels when both cementite (Fe3C) and ferrite (body-centered cubic (bcc) Fe-rich solid solution) phases are present, alloying elements tend to segregate to either of the two phases. The elements V, Cr, Mn, Mo and W are found to partition to the cementite phase, while Al, Si, P, Co, Ni and Cu partition to ferrite. We show that partitioning of alloying elements and cementite (de)stabilization by alloying in mixtures of bcc Fe and cementite are intimately related through the introduction of a partitioning enthalpy. The formation enthalpy of alloying-element-substituted cementite is shown not to be a proper gauge for addressing these questions. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410004933

Liquid structure as a guide for phase stability in the solid state / Emre S. Tasci in Acta materialia, Vol. 58 N° 2 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 449-456 Titre : Liquid structure as a guide for phase stability in the solid state : discovery of a stable compound in the Au–Si alloy system Type de document : texte imprimé Auteurs : Emre S. Tasci, Auteur ; Marcel H.F. Sluiter, Auteur ; Alain Pasturel, Auteur Article en page(s) : pp. 449-456 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Crystal  structure  Modelling  Amorphous  materials  Metallic  glasses  Datamining Index. décimale : 669 Métallurgie Résumé : A new crystalline ground state was discovered in the Au–Si system through first-principles electronic structure calculations. The new structure was found using the experimentally and theoretically determined local atomic structure in the liquid as a guide for the solid state. Local atomic structure in the liquid was matched with that for all known crystal structures as compiled in the Pauling File structural database. The best matching crystalline structures were then explicitly calculated using first-principles methods. Most candidate crystal structures were found to be close, but above the enthalpy of a composition weighted average of the face-centered cubic Au and diamond structure Si terminal phases, but one crystal structure was more stable than the terminal phases by about 10 meV atom–1 at T = 0 K. As first-principles simulations of local structure are feasible for most liquid alloys, the present methodology is applicable to other alloys lying near a eutectic composition. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Liquid structure as a guide for phase stability in the solid state : discovery of a stable compound in the Au–Si alloy system [texte imprimé] / Emre S. Tasci, Auteur ; Marcel H.F. Sluiter, Auteur ; Alain Pasturel, Auteur . - pp. 449-456. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 449-456 Mots-clés : Crystal  structure  Modelling  Amorphous  materials  Metallic  glasses  Datamining Index. décimale : 669 Métallurgie Résumé : A new crystalline ground state was discovered in the Au–Si system through first-principles electronic structure calculations. The new structure was found using the experimentally and theoretically determined local atomic structure in the liquid as a guide for the solid state. Local atomic structure in the liquid was matched with that for all known crystal structures as compiled in the Pauling File structural database. The best matching crystalline structures were then explicitly calculated using first-principles methods. Most candidate crystal structures were found to be close, but above the enthalpy of a composition weighted average of the face-centered cubic Au and diamond structure Si terminal phases, but one crystal structure was more stable than the terminal phases by about 10 meV atom–1 at T = 0 K. As first-principles simulations of local structure are feasible for most liquid alloys, the present methodology is applicable to other alloys lying near a eutectic composition. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]