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The formation of nanograin structures and accelerated room-temperature theta precipitation in a severely deformed Al–4 wt.% Cu alloy / Y. Huang in Acta materialia, Vol. 58 N° 5 (Mars 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 5 (Mars 2010) . - pp. 1643–1657 Titre : The formation of nanograin structures and accelerated room-temperature theta precipitation in a severely deformed Al–4 wt.% Cu alloy Type de document : texte imprimé Auteurs : Y. Huang, Auteur ; J.D. Robson, Auteur ; P.B. Prangnell, Auteur Année de publication : 2011 Article en page(s) : pp. 1643–1657 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Severe  plastic  deformation  (SPD)  Nanocrystalline  Accelerated  ageing  Theta  phase  Nucleation Résumé : The grain size achievable and long-term stability of a severely deformed aluminium copper alloy have been investigated when copper is used in solution to inhibit recovery. It is shown that copper is more effective than magnesium in inhibiting dynamic recovery. A grain width of only ∼70 nm was obtained in an Al–4 wt.% Cu alloy, after processing by equal-channel angular extrusion to a strain of εeff = 10, resulting in a lamellar nanograin structure. However, post-processing, the severely deformed solid solution was found to be unstable at room temperature and copious precipitation of θ occurred at grain boundaries within the deformed state, leading to recovery of the deformation structure and a loss of strength. The solute level fell to equilibrium within ∼9 months. The precipitation kinetics were shown to occur at many orders of magnitude higher than can be predicted by classical nucleation and growth theory. The reasons for this discrepancy are discussed. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007836 [article] The formation of nanograin structures and accelerated room-temperature theta precipitation in a severely deformed Al–4 wt.% Cu alloy [texte imprimé] / Y. Huang, Auteur ; J.D. Robson, Auteur ; P.B. Prangnell, Auteur . - 2011 . - pp. 1643–1657. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 5 (Mars 2010) . - pp. 1643–1657 Mots-clés : Severe  plastic  deformation  (SPD)  Nanocrystalline  Accelerated  ageing  Theta  phase  Nucleation Résumé : The grain size achievable and long-term stability of a severely deformed aluminium copper alloy have been investigated when copper is used in solution to inhibit recovery. It is shown that copper is more effective than magnesium in inhibiting dynamic recovery. A grain width of only ∼70 nm was obtained in an Al–4 wt.% Cu alloy, after processing by equal-channel angular extrusion to a strain of εeff = 10, resulting in a lamellar nanograin structure. However, post-processing, the severely deformed solid solution was found to be unstable at room temperature and copious precipitation of θ occurred at grain boundaries within the deformed state, leading to recovery of the deformation structure and a loss of strength. The solute level fell to equilibrium within ∼9 months. The precipitation kinetics were shown to occur at many orders of magnitude higher than can be predicted by classical nucleation and growth theory. The reasons for this discrepancy are discussed. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007836