Documents disponibles écrits par cet auteur

Dislocation cross-slip in heteroepitaxial multilayer films / S.S. Quek in Acta materialia, Vol. 58 N° 1 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 226–234 Titre : Dislocation cross-slip in heteroepitaxial multilayer films Type de document : texte imprimé Auteurs : S.S. Quek, Auteur ; Y.W. Zhang, Auteur Année de publication : 2010 Article en page(s) : pp. 226–234 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Dislocation  dynamics  Thin  film  Heteroepitaxy  Multilayers  Cross-slip Résumé : We simulated dislocation dynamics in heteroepitaxial multilayer thin film systems, considering the case where threading dislocations emerging from the substrate replicate themselves into the thin film during the film growth process. In the regime where the thin film layer thickness is tens of nanometers, the strain hardening mechanism involves the glide of single threading dislocation segments in the thin film instead of by dislocation pile-ups. We studied the dislocations’ evolution behavior and their interactions since these then became significant to the strain hardening of the multilayer structure. Cross-slip of threading dislocation segments in multilayer structure was found to be more prevalent compared to a single-layered thin film. This can result in a more complex pattern of interfacial dislocations and may have a significant contribution to the interactions between threading and interfacial dislocations. The simulation was carried out using the level set method incorporating thin film growth. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005965 [article] Dislocation cross-slip in heteroepitaxial multilayer films [texte imprimé] / S.S. Quek, Auteur ; Y.W. Zhang, Auteur . - 2010 . - pp. 226–234. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 226–234 Mots-clés : Dislocation  dynamics  Thin  film  Heteroepitaxy  Multilayers  Cross-slip Résumé : We simulated dislocation dynamics in heteroepitaxial multilayer thin film systems, considering the case where threading dislocations emerging from the substrate replicate themselves into the thin film during the film growth process. In the regime where the thin film layer thickness is tens of nanometers, the strain hardening mechanism involves the glide of single threading dislocation segments in the thin film instead of by dislocation pile-ups. We studied the dislocations’ evolution behavior and their interactions since these then became significant to the strain hardening of the multilayer structure. Cross-slip of threading dislocation segments in multilayer structure was found to be more prevalent compared to a single-layered thin film. This can result in a more complex pattern of interfacial dislocations and may have a significant contribution to the interactions between threading and interfacial dislocations. The simulation was carried out using the level set method incorporating thin film growth. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005965

On intrinsic brittleness and ductility of intergranular fracture along symmetrical tilt grain boundaries in copper / Y. Cheng in Acta materialia, Vol. 58 N° 7 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2293–2299 Titre : On intrinsic brittleness and ductility of intergranular fracture along symmetrical tilt grain boundaries in copper Type de document : texte imprimé Auteurs : Y. Cheng, Auteur ; Z.-H. Jin, Auteur ; Y.W. Zhang, Auteur Année de publication : 2011 Article en page(s) : pp. 2293–2299 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Fracture  Grain  boundary  Dislocation  Atomistic  simulation Résumé : The intrinsic brittleness and ductility of intergranular fracture along a number of symmetrical [1 1 0] tilt grain boundaries (GBs) in Cu are investigated via combined atomistic and continuum studies of dislocation nucleation from an atomically sharp crack tip. In all cases investigated, the classical model of Rice predicts a directional anisotropy in that, along a given GB, brittle cleavage is favored for crack propagation in one direction while dislocation emission from the crack tip is preferred in the opposite direction. This prediction is validated by atomistic simulations of crack propagation along coherent GBs, including View the MathML source and View the MathML source. However, for incoherent GBs such as View the MathML source and View the MathML source, such directional anisotropy in intrinsic ductility is not observed; instead, we show that dislocation emission is favored in both crack propagation directions. The reason for this discrepancy is shown to be dislocation emission at a distance ahead of the crack tip along an incoherent GB, which violates the assumption in Rice’s model that dislocation emission occurs directly at the crack tip. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964540900812X [article] On intrinsic brittleness and ductility of intergranular fracture along symmetrical tilt grain boundaries in copper [texte imprimé] / Y. Cheng, Auteur ; Z.-H. Jin, Auteur ; Y.W. Zhang, Auteur . - 2011 . - pp. 2293–2299. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2293–2299 Mots-clés : Fracture  Grain  boundary  Dislocation  Atomistic  simulation Résumé : The intrinsic brittleness and ductility of intergranular fracture along a number of symmetrical [1 1 0] tilt grain boundaries (GBs) in Cu are investigated via combined atomistic and continuum studies of dislocation nucleation from an atomically sharp crack tip. In all cases investigated, the classical model of Rice predicts a directional anisotropy in that, along a given GB, brittle cleavage is favored for crack propagation in one direction while dislocation emission from the crack tip is preferred in the opposite direction. This prediction is validated by atomistic simulations of crack propagation along coherent GBs, including View the MathML source and View the MathML source. However, for incoherent GBs such as View the MathML source and View the MathML source, such directional anisotropy in intrinsic ductility is not observed; instead, we show that dislocation emission is favored in both crack propagation directions. The reason for this discrepancy is shown to be dislocation emission at a distance ahead of the crack tip along an incoherent GB, which violates the assumption in Rice’s model that dislocation emission occurs directly at the crack tip. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964540900812X