Documents disponibles écrits par cet auteur

Reversible–irreversible plasticity transition in twinned copper nanopillars / J. A. Brown in Acta materialia, Vol. 58 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 886-894 Titre : Reversible–irreversible plasticity transition in twinned copper nanopillars Type de document : texte imprimé Auteurs : J. A. Brown, Auteur ; N. M. Ghoniem, Auteur Article en page(s) : pp. 886-894 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Copper  MD  simulations  Twin  boundary  Nanopillars  Plasticity Index. décimale : 669 Métallurgie Résumé : Through computer simulations, we show that plasticity in twinned copper nanopillars can be either reversible or irreversible depending on the applied stress state. Copper nanopillars, containing twinned crystals, are subjected to both compression and tension, and the ratio of the resolved shear (σR) to the normal stress (σN), R, is adjusted through variation of the orientation of the twin boundary plane with respect to the loading axis. It is found that the yield locus on the σR–σN plane for twinned nanopillars is asymmetric with respect to the sign of R. For a 9 nm diameter copper nanopillar under compression, plastic deformation can be totally reversed when σR is in the range View the MathML source, with a corresponding increase in the compressive normal stress, up to ≈2.5 GPa. It is shown that these conditions are achieved for axial strains <3.3%, and that the transition to plastic irreversibility takes place at larger strains or normal stresses. The mechanism responsible for the plastic reversible–irreversible transition is shown to be a competition between the nucleation of Shockley partial dislocations at the nanopillar surface for irreversible plasticity vs. twinning dislocations for reversible plasticity. Furthermore, the speed of Shockley partials at twin boundaries is subsonic when there is either tension or compression acting on the twin boundary, and slightly supersonic when only shear is applied. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Reversible–irreversible plasticity transition in twinned copper nanopillars [texte imprimé] / J. A. Brown, Auteur ; N. M. Ghoniem, Auteur . - pp. 886-894. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 886-894 Mots-clés : Copper  MD  simulations  Twin  boundary  Nanopillars  Plasticity Index. décimale : 669 Métallurgie Résumé : Through computer simulations, we show that plasticity in twinned copper nanopillars can be either reversible or irreversible depending on the applied stress state. Copper nanopillars, containing twinned crystals, are subjected to both compression and tension, and the ratio of the resolved shear (σR) to the normal stress (σN), R, is adjusted through variation of the orientation of the twin boundary plane with respect to the loading axis. It is found that the yield locus on the σR–σN plane for twinned nanopillars is asymmetric with respect to the sign of R. For a 9 nm diameter copper nanopillar under compression, plastic deformation can be totally reversed when σR is in the range View the MathML source, with a corresponding increase in the compressive normal stress, up to ≈2.5 GPa. It is shown that these conditions are achieved for axial strains <3.3%, and that the transition to plastic irreversibility takes place at larger strains or normal stresses. The mechanism responsible for the plastic reversible–irreversible transition is shown to be a competition between the nucleation of Shockley partial dislocations at the nanopillar surface for irreversible plasticity vs. twinning dislocations for reversible plasticity. Furthermore, the speed of Shockley partials at twin boundaries is subsonic when there is either tension or compression acting on the twin boundary, and slightly supersonic when only shear is applied. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]

Reversible–irreversible plasticity transition in twinned copper nanopillars / J. A. Brown in Acta materialia, Vol. 58 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 886–894 Titre : Reversible–irreversible plasticity transition in twinned copper nanopillars Type de document : texte imprimé Auteurs : J. A. Brown, Auteur ; N. M. Ghoniem, Auteur Année de publication : 2011 Article en page(s) : pp. 886–894 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Copper  MD  simulations  Twin  boundary  Nanopillars  Plasticity Résumé : Through computer simulations, we show that plasticity in twinned copper nanopillars can be either reversible or irreversible depending on the applied stress state. Copper nanopillars, containing twinned crystals, are subjected to both compression and tension, and the ratio of the resolved shear (σR) to the normal stress (σN), R, is adjusted through variation of the orientation of the twin boundary plane with respect to the loading axis. It is found that the yield locus on the σR–σN plane for twinned nanopillars is asymmetric with respect to the sign of R. For a 9 nm diameter copper nanopillar under compression, plastic deformation can be totally reversed when σR is in the range View the MathML source, with a corresponding increase in the compressive normal stress, up to ≈2.5 GPa. It is shown that these conditions are achieved for axial strains <3.3%, and that the transition to plastic irreversibility takes place at larger strains or normal stresses. The mechanism responsible for the plastic reversible–irreversible transition is shown to be a competition between the nucleation of Shockley partial dislocations at the nanopillar surface for irreversible plasticity vs. twinning dislocations for reversible plasticity. Furthermore, the speed of Shockley partials at twin boundaries is subsonic when there is either tension or compression acting on the twin boundary, and slightly supersonic when only shear is applied. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964540900682X [article] Reversible–irreversible plasticity transition in twinned copper nanopillars [texte imprimé] / J. A. Brown, Auteur ; N. M. Ghoniem, Auteur . - 2011 . - pp. 886–894. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 886–894 Mots-clés : Copper  MD  simulations  Twin  boundary  Nanopillars  Plasticity Résumé : Through computer simulations, we show that plasticity in twinned copper nanopillars can be either reversible or irreversible depending on the applied stress state. Copper nanopillars, containing twinned crystals, are subjected to both compression and tension, and the ratio of the resolved shear (σR) to the normal stress (σN), R, is adjusted through variation of the orientation of the twin boundary plane with respect to the loading axis. It is found that the yield locus on the σR–σN plane for twinned nanopillars is asymmetric with respect to the sign of R. For a 9 nm diameter copper nanopillar under compression, plastic deformation can be totally reversed when σR is in the range View the MathML source, with a corresponding increase in the compressive normal stress, up to ≈2.5 GPa. It is shown that these conditions are achieved for axial strains <3.3%, and that the transition to plastic irreversibility takes place at larger strains or normal stresses. The mechanism responsible for the plastic reversible–irreversible transition is shown to be a competition between the nucleation of Shockley partial dislocations at the nanopillar surface for irreversible plasticity vs. twinning dislocations for reversible plasticity. Furthermore, the speed of Shockley partials at twin boundaries is subsonic when there is either tension or compression acting on the twin boundary, and slightly supersonic when only shear is applied. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964540900682X