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Phase separation mediated devitrification of Al88Y7Fe5 glasses / K.K. Sahu in Acta materialia, Vol. 58 N° 12 (Juillet 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 12 (Juillet 2010) . - pp. 4199–4206 Titre : Phase separation mediated devitrification of Al88Y7Fe5 glasses Type de document : texte imprimé Auteurs : K.K. Sahu, Auteur ; N.A. Mauro, Auteur ; L. Longstreth-Spoor, Auteur Année de publication : 2011 Article en page(s) : pp. 4199–4206 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Coarsening  Aluminum  alloys  Phase  separation  Nucleation  and  growth  Metallic  glass Résumé : The mechanisms responsible for the nanoscale devitrification of Al-based metallic glasses are unclear. A particularly well-studied case is Al88Y7Fe5, where non-isothermal differential scanning calorimetry (DSC) measurements show an exothermic peak that is consistent with glass devitrification to α-Al, but with no glass transition. Additionally, isothermal DSC studies show a monotonic decrease in enthalpy release with annealing, a feature generally taken to indicate grain coarsening. The results of coordinated DSC, bright field transmission electron microscopy, in situ electrical resistivity and atom probe tomography (APT) studies of Al88Y7Fe5 support a nucleation/growth-based crystallization process. The APT data indicate the presence of sub-nanometer pure Al zones and coarser scale (separation distance ∼74–126 nm) Al-rich regions in the glass. The pure Al zones dispersed in the Al-rich regions appear to catalyze α-Al nucleation, explaining the high nucleation rates. The solute-rich regions between the Al-rich regions inhibit long-range diffusion, explaining the low growth rates. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964541000217X [article] Phase separation mediated devitrification of Al88Y7Fe5 glasses [texte imprimé] / K.K. Sahu, Auteur ; N.A. Mauro, Auteur ; L. Longstreth-Spoor, Auteur . - 2011 . - pp. 4199–4206. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 12 (Juillet 2010) . - pp. 4199–4206 Mots-clés : Coarsening  Aluminum  alloys  Phase  separation  Nucleation  and  growth  Metallic  glass Résumé : The mechanisms responsible for the nanoscale devitrification of Al-based metallic glasses are unclear. A particularly well-studied case is Al88Y7Fe5, where non-isothermal differential scanning calorimetry (DSC) measurements show an exothermic peak that is consistent with glass devitrification to α-Al, but with no glass transition. Additionally, isothermal DSC studies show a monotonic decrease in enthalpy release with annealing, a feature generally taken to indicate grain coarsening. The results of coordinated DSC, bright field transmission electron microscopy, in situ electrical resistivity and atom probe tomography (APT) studies of Al88Y7Fe5 support a nucleation/growth-based crystallization process. The APT data indicate the presence of sub-nanometer pure Al zones and coarser scale (separation distance ∼74–126 nm) Al-rich regions in the glass. The pure Al zones dispersed in the Al-rich regions appear to catalyze α-Al nucleation, explaining the high nucleation rates. The solute-rich regions between the Al-rich regions inhibit long-range diffusion, explaining the low growth rates. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964541000217X