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Atomic transport mechanisms in thin oxide films grown on zirconium by thermal oxidation, as-derived from 18O-tracer experiments / G. Bakradze in Acta materialia, Vol. 59 N° 20 (Décembre 2011) 

Public ISBD [article]  in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7498–7507 Titre : Atomic transport mechanisms in thin oxide films grown on zirconium by thermal oxidation, as-derived from 18O-tracer experiments Type de document : texte imprimé Auteurs : G. Bakradze, Auteur ; L.P.H. Jeurgens, Auteur ; T. Acartürk, Auteur Année de publication : 2012 Article en page(s) : pp. 7498–7507 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Oxidation  Mechanism  Nanocrystalline  films  Zirconium  Time-of-flight  secondary  ion  mass-spectrometry Résumé : Two-stage oxidation experiments using 16O and 18O isotopes were performed to reveal the governing atomic transport mechanism(s) in thin (thickness <10 nm) oxide films grown during the initial stages of dry thermal oxidation of pure Zr at 450 K. To this end, bare (i.e. without a native oxide) Zr(0 0 0 1) and Zr single-crystalline surfaces were prepared under ultra-high vacuum conditions by a cyclic treatment of alternating ion-sputtering and in vacuo annealing steps. Next, the bare Zr surfaces were oxidized at 450 K and at pO2 = 1 × 10−4 Pa, first in 16O2(g) and subsequently in 18O2(g). The 18O-tracer depth distributions in the oxide films were recorded by time-of-flight secondary ion mass spectrometry. It was concluded that the early stage of the oxidation process is governed by oxygen transport to the metal/oxide interface through the lattice and along the grain boundaries of the nanosized oxide grains whereas, on continuing oxidation, only oxygen lattice transport controls the oxidation process. An oxide-film growth mechanism is proposed. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006124 [article] Atomic transport mechanisms in thin oxide films grown on zirconium by thermal oxidation, as-derived from 18O-tracer experiments [texte imprimé] / G. Bakradze, Auteur ; L.P.H. Jeurgens, Auteur ; T. Acartürk, Auteur . - 2012 . - pp. 7498–7507. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7498–7507 Mots-clés : Oxidation  Mechanism  Nanocrystalline  films  Zirconium  Time-of-flight  secondary  ion  mass-spectrometry Résumé : Two-stage oxidation experiments using 16O and 18O isotopes were performed to reveal the governing atomic transport mechanism(s) in thin (thickness <10 nm) oxide films grown during the initial stages of dry thermal oxidation of pure Zr at 450 K. To this end, bare (i.e. without a native oxide) Zr(0 0 0 1) and Zr single-crystalline surfaces were prepared under ultra-high vacuum conditions by a cyclic treatment of alternating ion-sputtering and in vacuo annealing steps. Next, the bare Zr surfaces were oxidized at 450 K and at pO2 = 1 × 10−4 Pa, first in 16O2(g) and subsequently in 18O2(g). The 18O-tracer depth distributions in the oxide films were recorded by time-of-flight secondary ion mass spectrometry. It was concluded that the early stage of the oxidation process is governed by oxygen transport to the metal/oxide interface through the lattice and along the grain boundaries of the nanosized oxide grains whereas, on continuing oxidation, only oxygen lattice transport controls the oxidation process. An oxide-film growth mechanism is proposed. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006124

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