Documents disponibles écrits par cet auteur

Nucleation and thickening of shear bands in nano-scale twin/matrix lamellae of a Cu–Al alloy processed by dynamic plastic deformation / C.S. Hong in Acta materialia, Vol. 58 N° 8 (Mai 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 8 (Mai 2010) . - pp. 3103–3116 Titre : Nucleation and thickening of shear bands in nano-scale twin/matrix lamellae of a Cu–Al alloy processed by dynamic plastic deformation Type de document : texte imprimé Auteurs : C.S. Hong, Auteur ; N.R. Tao, Auteur ; X. Huang, Auteur Année de publication : 2011 Article en page(s) : pp. 3103–3116 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Dynamic  plastic  deformation  Shear  bands  Nano-scale  twins  Nano-grained  structure  Dislocation  structure Résumé : Microstructural evolution associated with the shear banding in nano-scale twin/matrix (T/M) lamellae of a Cu–Al alloy processed by means of dynamic plastic deformation was investigated using transmission electron microscopy (TEM) and high-resolution TEM. The development of a shear band was found to be a two-stage process, namely a nucleation stage resulting in a narrow band composed of nano-sized (sub)grains intersecting the T/M lamellae, followed by a thickening stage of the narrow band into adjacent T/M lamellae regions. The nucleation stage occurred within a narrow region of an almost constant thickness (100–200 nm thick, referred to as “core” region) and consisted of three steps: (1) initiation of localized deformation (bending, necking, and detwinning) against the T/M lamellae, (2) evolution of a dislocation structure within the detwinned band, and (3) transformation of the detwinned dislocation structure (DDS) into a nano-sized (sub)grain structure (NGS). On the two sides of a core region, two transition layers (TRLs) exist where the T/M lamellae experienced much less shear strain. The interface boundaries separating the core region and the TRLs are characterized by very large shear strain gradients accommodated by high density of dislocations. Increasing shear strains leads to thickening of shear bands at the expense of the adjoining T/M lamellae, which is composed of thickening of the core region by transforming the TRLs into the core region with DDS and NGS, analogous to steps (2) and (3) of the nucleation process, and outward movement of the TRLs by deforming the adjoining T/M lamellae. Grain sizes in the well-developed shear bands are obviously larger than the lamellar thickness of original T/M lamellae. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000790 [article] Nucleation and thickening of shear bands in nano-scale twin/matrix lamellae of a Cu–Al alloy processed by dynamic plastic deformation [texte imprimé] / C.S. Hong, Auteur ; N.R. Tao, Auteur ; X. Huang, Auteur . - 2011 . - pp. 3103–3116. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 8 (Mai 2010) . - pp. 3103–3116 Mots-clés : Dynamic  plastic  deformation  Shear  bands  Nano-scale  twins  Nano-grained  structure  Dislocation  structure Résumé : Microstructural evolution associated with the shear banding in nano-scale twin/matrix (T/M) lamellae of a Cu–Al alloy processed by means of dynamic plastic deformation was investigated using transmission electron microscopy (TEM) and high-resolution TEM. The development of a shear band was found to be a two-stage process, namely a nucleation stage resulting in a narrow band composed of nano-sized (sub)grains intersecting the T/M lamellae, followed by a thickening stage of the narrow band into adjacent T/M lamellae regions. The nucleation stage occurred within a narrow region of an almost constant thickness (100–200 nm thick, referred to as “core” region) and consisted of three steps: (1) initiation of localized deformation (bending, necking, and detwinning) against the T/M lamellae, (2) evolution of a dislocation structure within the detwinned band, and (3) transformation of the detwinned dislocation structure (DDS) into a nano-sized (sub)grain structure (NGS). On the two sides of a core region, two transition layers (TRLs) exist where the T/M lamellae experienced much less shear strain. The interface boundaries separating the core region and the TRLs are characterized by very large shear strain gradients accommodated by high density of dislocations. Increasing shear strains leads to thickening of shear bands at the expense of the adjoining T/M lamellae, which is composed of thickening of the core region by transforming the TRLs into the core region with DDS and NGS, analogous to steps (2) and (3) of the nucleation process, and outward movement of the TRLs by deforming the adjoining T/M lamellae. Grain sizes in the well-developed shear bands are obviously larger than the lamellar thickness of original T/M lamellae. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000790