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Interface thermodynamics of ultra-thin, amorphous oxide overgrowths on AlMg alloys / E. Panda in Acta materialia, Vol. 58 N° 5 (Mars 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 5 (Mars 2010) . - pp. 1770–1781 Titre : Interface thermodynamics of ultra-thin, amorphous oxide overgrowths on AlMg alloys Type de document : texte imprimé Auteurs : E. Panda, Auteur ; L.P.H. Jeurgens, Auteur ; E. J. Mittemeijer, Auteur Année de publication : 2011 Article en page(s) : pp. 1770–1781 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Interface  energy  Thermodynamics  Alloy  oxidation  Amorphous  oxides  Ultra-thin  oxide  films Résumé : A thermodynamic model has been presented for the prediction of the type of initial, amorphous oxide overgrowth (i.e. am-Al2O3, am-MgO or am-MgAl2O4) on bare AlMg substrates as a function of the Mg alloying element content at the substrate/oxide interface, the growth temperature and the oxide-film thickness (up to 5 nm). On the basis of the macroscopic atom approach, expressions have been derived for the estimation of the energies of the interfaces between the AlMg substrate and the competing am-Al2O3, am-MgO and am-MgAl2O4 overgrowths. For all cases a strong driving force has been revealed for the interfacial (chemical) segregation of Mg. am-Al2O3 was found to be the most stable amorphous oxide phase on the AlMg substrate for T < 610 K; its relatively high stability is governed by a relatively low interface energy. The model predictions are in good agreement with corresponding experimental results on the chemical constitution of ultra-thin amorphous oxide films grown on Al- and Mg-based alloy substrates in the temperature range of 300–400 K. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007988 [article] Interface thermodynamics of ultra-thin, amorphous oxide overgrowths on AlMg alloys [texte imprimé] / E. Panda, Auteur ; L.P.H. Jeurgens, Auteur ; E. J. Mittemeijer, Auteur . - 2011 . - pp. 1770–1781. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 5 (Mars 2010) . - pp. 1770–1781 Mots-clés : Interface  energy  Thermodynamics  Alloy  oxidation  Amorphous  oxides  Ultra-thin  oxide  films Résumé : A thermodynamic model has been presented for the prediction of the type of initial, amorphous oxide overgrowth (i.e. am-Al2O3, am-MgO or am-MgAl2O4) on bare AlMg substrates as a function of the Mg alloying element content at the substrate/oxide interface, the growth temperature and the oxide-film thickness (up to 5 nm). On the basis of the macroscopic atom approach, expressions have been derived for the estimation of the energies of the interfaces between the AlMg substrate and the competing am-Al2O3, am-MgO and am-MgAl2O4 overgrowths. For all cases a strong driving force has been revealed for the interfacial (chemical) segregation of Mg. am-Al2O3 was found to be the most stable amorphous oxide phase on the AlMg substrate for T < 610 K; its relatively high stability is governed by a relatively low interface energy. The model predictions are in good agreement with corresponding experimental results on the chemical constitution of ultra-thin amorphous oxide films grown on Al- and Mg-based alloy substrates in the temperature range of 300–400 K. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007988

Kinetics of austenitization under uniaxial compressive stress in Fe–2.96 at.% Ni alloy / Y. C. Liu in Acta materialia, Vol. 58 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 753-763 Titre : Kinetics of austenitization under uniaxial compressive stress in Fe–2.96 at.% Ni alloy Type de document : texte imprimé Auteurs : Y. C. Liu, Auteur ; F. Sommer, Auteur ; E. J. Mittemeijer, Auteur Article en page(s) : pp. 753-763 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Ferrite–austenite  transformation  Substitutional  Fe-based  alloys  Applied  compressive  stress  Annealing  Dilatometer Index. décimale : 669 Métallurgie Résumé : Differential dilatometry has been employed to study the kinetics of the massive ferrite (α) → austenite (γ) transformation upon isochronal heating (i.e. austenitization) of the substitutional Fe–2.96 at.% Ni alloy subjected to a range of applied constant uniaxial compressive stresses. A phase-transformation model, involving site saturation, interface-controlled (continuous) growth and incorporating an impingement correction for an intermediate of the cases of ideally periodically and of ideally randomly dispersed growing particles, has been employed to extract the interface-migration velocity of the α/γ interface and the transformation-induced deformation energy taken up by the specimen. The value obtained for the energy corresponding with the elastic and plastic deformation associated with the accommodation of the α/γ volume misfit depends on the austenite fraction and increases distinctly with an increase in the applied uniaxial compressive stress, which is compensated by, in particular, an increase in the chemical driving force corresponding to an increase in the onset temperature. The opposite effects of an applied uniaxial compressive stress on the α → γ transformation and on the γ → α transformation can be discussed as the outcome of constrained plastic deformation due to transformation-induced strain. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Kinetics of austenitization under uniaxial compressive stress in Fe–2.96 at.% Ni alloy [texte imprimé] / Y. C. Liu, Auteur ; F. Sommer, Auteur ; E. J. Mittemeijer, Auteur . - pp. 753-763. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 753-763 Mots-clés : Ferrite–austenite  transformation  Substitutional  Fe-based  alloys  Applied  compressive  stress  Annealing  Dilatometer Index. décimale : 669 Métallurgie Résumé : Differential dilatometry has been employed to study the kinetics of the massive ferrite (α) → austenite (γ) transformation upon isochronal heating (i.e. austenitization) of the substitutional Fe–2.96 at.% Ni alloy subjected to a range of applied constant uniaxial compressive stresses. A phase-transformation model, involving site saturation, interface-controlled (continuous) growth and incorporating an impingement correction for an intermediate of the cases of ideally periodically and of ideally randomly dispersed growing particles, has been employed to extract the interface-migration velocity of the α/γ interface and the transformation-induced deformation energy taken up by the specimen. The value obtained for the energy corresponding with the elastic and plastic deformation associated with the accommodation of the α/γ volume misfit depends on the austenite fraction and increases distinctly with an increase in the applied uniaxial compressive stress, which is compensated by, in particular, an increase in the chemical driving force corresponding to an increase in the onset temperature. The opposite effects of an applied uniaxial compressive stress on the α → γ transformation and on the γ → α transformation can be discussed as the outcome of constrained plastic deformation due to transformation-induced strain. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]

Kinetics of austenitization under uniaxial compressive stress in Fe–2.96 at.% Ni alloy / Y. C. Liu in Acta materialia, Vol. 58 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 753–763 Titre : Kinetics of austenitization under uniaxial compressive stress in Fe–2.96 at.% Ni alloy Type de document : texte imprimé Auteurs : Y. C. Liu, Auteur ; F. Sommer, Auteur ; E. J. Mittemeijer, Auteur Année de publication : 2011 Article en page(s) : pp. 753–763 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Ferrite–austenite  transformation  Substitutional  Fe-based  alloys  Applied  compressive  stress  Annealing  Dilatometer Résumé : Differential dilatometry has been employed to study the kinetics of the massive ferrite (α) → austenite (γ) transformation upon isochronal heating (i.e. austenitization) of the substitutional Fe–2.96 at.% Ni alloy subjected to a range of applied constant uniaxial compressive stresses. A phase-transformation model, involving site saturation, interface-controlled (continuous) growth and incorporating an impingement correction for an intermediate of the cases of ideally periodically and of ideally randomly dispersed growing particles, has been employed to extract the interface-migration velocity of the α/γ interface and the transformation-induced deformation energy taken up by the specimen. The value obtained for the energy corresponding with the elastic and plastic deformation associated with the accommodation of the α/γ volume misfit depends on the austenite fraction and increases distinctly with an increase in the applied uniaxial compressive stress, which is compensated by, in particular, an increase in the chemical driving force corresponding to an increase in the onset temperature. The opposite effects of an applied uniaxial compressive stress on the α → γ transformation and on the γ → α transformation can be discussed as the outcome of constrained plastic deformation due to transformation-induced strain. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409006545 [article] Kinetics of austenitization under uniaxial compressive stress in Fe–2.96 at.% Ni alloy [texte imprimé] / Y. C. Liu, Auteur ; F. Sommer, Auteur ; E. J. Mittemeijer, Auteur . - 2011 . - pp. 753–763. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 753–763 Mots-clés : Ferrite–austenite  transformation  Substitutional  Fe-based  alloys  Applied  compressive  stress  Annealing  Dilatometer Résumé : Differential dilatometry has been employed to study the kinetics of the massive ferrite (α) → austenite (γ) transformation upon isochronal heating (i.e. austenitization) of the substitutional Fe–2.96 at.% Ni alloy subjected to a range of applied constant uniaxial compressive stresses. A phase-transformation model, involving site saturation, interface-controlled (continuous) growth and incorporating an impingement correction for an intermediate of the cases of ideally periodically and of ideally randomly dispersed growing particles, has been employed to extract the interface-migration velocity of the α/γ interface and the transformation-induced deformation energy taken up by the specimen. The value obtained for the energy corresponding with the elastic and plastic deformation associated with the accommodation of the α/γ volume misfit depends on the austenite fraction and increases distinctly with an increase in the applied uniaxial compressive stress, which is compensated by, in particular, an increase in the chemical driving force corresponding to an increase in the onset temperature. The opposite effects of an applied uniaxial compressive stress on the α → γ transformation and on the γ → α transformation can be discussed as the outcome of constrained plastic deformation due to transformation-induced strain. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409006545