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Thermodynamic and experimental study on phase stability in nanocrystalline alloys / Wenwu Xu in Acta materialia, Vol. 58 N° 2 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 396-407 Titre : Thermodynamic and experimental study on phase stability in nanocrystalline alloys Type de document : texte imprimé Auteurs : Wenwu Xu, Auteur ; Xiaoyan Song, Auteur ; Nianduan Lu, Auteur Article en page(s) : pp. 396-407 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Nanocrystalline  materials  Thermodynamics  Phase  transformations  Grain  boundary  energy  Grain  boundary  structure Index. décimale : 669 Métallurgie Résumé : Nanocrystalline alloys exhibit apparently different phase transformation characteristics in comparison to the conventional polycrystalline alloys. The special phase stability and phase transformation behavior, as well as the essential mechanisms of the nanocrystalline alloys, were described quantitatively in a nanothermodynamic point of view. By introducing the relationship between the excess volume at the grain boundary and the nanograin size, the Gibbs free energy was determined distinctly as a function of temperature and the nanograin size. Accordingly, the grain-size-dependence of the phase stability and phase transformation characteristics of the nanocrystalline alloy were calculated systematically, and the correlations between the phase constitution, the phase transformation temperature and the critical nanograin size were predicted. A series of experiments was performed to investigate the phase transformations at room temperature and high temperatures using the nanocrystalline Sm2Co17 alloy as an example. The phase constitution and phase transformation sequence found in nanocrystalline Sm2Co17 alloys with various grain-size levels agree well with the calculations by the nanothermodynamic model. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Thermodynamic and experimental study on phase stability in nanocrystalline alloys [texte imprimé] / Wenwu Xu, Auteur ; Xiaoyan Song, Auteur ; Nianduan Lu, Auteur . - pp. 396-407. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 396-407 Mots-clés : Nanocrystalline  materials  Thermodynamics  Phase  transformations  Grain  boundary  energy  Grain  boundary  structure Index. décimale : 669 Métallurgie Résumé : Nanocrystalline alloys exhibit apparently different phase transformation characteristics in comparison to the conventional polycrystalline alloys. The special phase stability and phase transformation behavior, as well as the essential mechanisms of the nanocrystalline alloys, were described quantitatively in a nanothermodynamic point of view. By introducing the relationship between the excess volume at the grain boundary and the nanograin size, the Gibbs free energy was determined distinctly as a function of temperature and the nanograin size. Accordingly, the grain-size-dependence of the phase stability and phase transformation characteristics of the nanocrystalline alloy were calculated systematically, and the correlations between the phase constitution, the phase transformation temperature and the critical nanograin size were predicted. A series of experiments was performed to investigate the phase transformations at room temperature and high temperatures using the nanocrystalline Sm2Co17 alloy as an example. The phase constitution and phase transformation sequence found in nanocrystalline Sm2Co17 alloys with various grain-size levels agree well with the calculations by the nanothermodynamic model. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]