Documents disponibles écrits par cet auteur

A closer look at the local responses of twin and grain boundaries in Cu to stress at the nanoscale with possible transition from the P–H to the inverse P–H relation / L. Yue in Acta materialia, Vol. 58 N° 7 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2677–2684 Titre : A closer look at the local responses of twin and grain boundaries in Cu to stress at the nanoscale with possible transition from the P–H to the inverse P–H relation Type de document : texte imprimé Auteurs : L. Yue, Auteur ; H. Zhang, Auteur ; D.Y. Li, Auteur Année de publication : 2011 Article en page(s) : pp. 2677–2684 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Nano-twinning  Nano-grains  Inverse  Petch–Hall  relation  Molecular  dynamics  Simulation Résumé : Nanocrystalline copper is considered to be a candidate for electrical contacts for dynamic systems because of its intrinsic conductivity and enhanced fretting resistance. However, the enhanced electron scattering at high-density grain boundaries significantly deteriorates the overall conductivity of nanocrystalline copper. Recent studies suggest that nanosized twin boundaries in copper might be a solution to such a dilemma. To better understand the general mechanical behavior of nanotwin boundaries, we conducted molecular dynamics simulation studies to investigate responses of both nanotwin and nanograin boundaries in copper to stress at the nanoscale, particularly in the critical range of 5–25 nm where the inverse Petch–Hall relation (P–H) may occur in nanocrystalline copper. The obtained results suggest that the twin boundary blocks dislocation movement more effectively and the degree of emitting dislocations under stress is considerably lower than that of grain boundary, leading to superior mechanical behavior. The inverse P–H relation is not applicable to the nanotwinned system. It is also demonstrated that the inverse P–H relation occurring in nanograined materials does not necessarily result from grain boundary sliding. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000029 [article] A closer look at the local responses of twin and grain boundaries in Cu to stress at the nanoscale with possible transition from the P–H to the inverse P–H relation [texte imprimé] / L. Yue, Auteur ; H. Zhang, Auteur ; D.Y. Li, Auteur . - 2011 . - pp. 2677–2684. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2677–2684 Mots-clés : Nano-twinning  Nano-grains  Inverse  Petch–Hall  relation  Molecular  dynamics  Simulation Résumé : Nanocrystalline copper is considered to be a candidate for electrical contacts for dynamic systems because of its intrinsic conductivity and enhanced fretting resistance. However, the enhanced electron scattering at high-density grain boundaries significantly deteriorates the overall conductivity of nanocrystalline copper. Recent studies suggest that nanosized twin boundaries in copper might be a solution to such a dilemma. To better understand the general mechanical behavior of nanotwin boundaries, we conducted molecular dynamics simulation studies to investigate responses of both nanotwin and nanograin boundaries in copper to stress at the nanoscale, particularly in the critical range of 5–25 nm where the inverse Petch–Hall relation (P–H) may occur in nanocrystalline copper. The obtained results suggest that the twin boundary blocks dislocation movement more effectively and the degree of emitting dislocations under stress is considerably lower than that of grain boundary, leading to superior mechanical behavior. The inverse P–H relation is not applicable to the nanotwinned system. It is also demonstrated that the inverse P–H relation occurring in nanograined materials does not necessarily result from grain boundary sliding. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000029

Plastic deformation of nanocrystalline aluminum at high temperatures and strain rate / A.P. Gerlich in Acta materialia, Vol. 58 N° 6 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2176–2185 Titre : Plastic deformation of nanocrystalline aluminum at high temperatures and strain rate Type de document : texte imprimé Auteurs : A.P. Gerlich, Auteur ; L. Yue, Auteur ; P.F. Mendez, Auteur Année de publication : 2011 Article en page(s) : pp. 2176–2185 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Nanocrystalline  materials  Plastic  deformation  High  temperature  Molecular  dynamics Résumé : The deformation of nanocrystalline aluminum was studied using molecular dynamics simulation at homologous temperatures up to 0.97. The microstructures and stress–strain response were examined in a polycrystalline and bicrystal configuration. The activation energies for dislocation-based deformation as well as grain boundary sliding and migration were quantified by fitting simulation data to temperature using an Arrhenius relation. The activation energy for the flow stress response suggests that deformation is largely accommodated by sliding and migration of grain boundaries. This is in agreement with simulated microstructures, indicating a negligible degree of dislocation interaction within each grain, and microstructural observations from high strain rate processes are also consistent with this result. A steady-state grain size is maintained in the recrystallized structure following yielding due to boundary migration and grain rotation mechanisms, rather than by diffusion-based dislocation climb. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008374 [article] Plastic deformation of nanocrystalline aluminum at high temperatures and strain rate [texte imprimé] / A.P. Gerlich, Auteur ; L. Yue, Auteur ; P.F. Mendez, Auteur . - 2011 . - pp. 2176–2185. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2176–2185 Mots-clés : Nanocrystalline  materials  Plastic  deformation  High  temperature  Molecular  dynamics Résumé : The deformation of nanocrystalline aluminum was studied using molecular dynamics simulation at homologous temperatures up to 0.97. The microstructures and stress–strain response were examined in a polycrystalline and bicrystal configuration. The activation energies for dislocation-based deformation as well as grain boundary sliding and migration were quantified by fitting simulation data to temperature using an Arrhenius relation. The activation energy for the flow stress response suggests that deformation is largely accommodated by sliding and migration of grain boundaries. This is in agreement with simulated microstructures, indicating a negligible degree of dislocation interaction within each grain, and microstructural observations from high strain rate processes are also consistent with this result. A steady-state grain size is maintained in the recrystallized structure following yielding due to boundary migration and grain rotation mechanisms, rather than by diffusion-based dislocation climb. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008374