Documents disponibles écrits par cet auteur

Dislocation core structure and dynamics in two atomic models of α-zirconium / H.A. Khater in Acta materialia, Vol. 58 N° 8 (Mai 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 8 (Mai 2010) . - pp. 2978–2987 Titre : Dislocation core structure and dynamics in two atomic models of α-zirconium Type de document : texte imprimé Auteurs : H.A. Khater, Auteur ; D. J. Bacon, Auteur Année de publication : 2011 Article en page(s) : pp. 2978–2987 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Dislocation  dynamics  Dislocation  structure  Stacking  faults  Molecular  dynamics  simulations  Zirconium Résumé : Properties of basal and first order prism plane dislocations with Burgers vector 1/3 〈View the MathML source〉 in α-Zr have been investigated by computer simulation. Results for a recent interatomic potential (MA07) are assessed and compared with an older one (AWB95). The elastic constants have been calculated with the inner relaxations allowed for and the energy and vector of metastable stacking faults have been determined and compared with published ab initio estimates. The core of the screw dislocation spreads principally in the prism plane in the MA07 model, in contrast to basal plane dissociation in the AWB95 model, and the prism-to-basal ratio of the Peierls stress for the screw is 0.28 with the MA07 model, compared with 3.31 with the AWB95 model. Simulation of the dynamics of dislocation motion under applied stress reveal how the drag coefficient varies with slip system and temperature. The results for the MA07 model are consistent with the known slip geometry of Zr, suggesting that it offers significant advantages for large-scale atomic simulation of dislocation behaviour. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964541000042X [article] Dislocation core structure and dynamics in two atomic models of α-zirconium [texte imprimé] / H.A. Khater, Auteur ; D. J. Bacon, Auteur . - 2011 . - pp. 2978–2987. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 8 (Mai 2010) . - pp. 2978–2987 Mots-clés : Dislocation  dynamics  Dislocation  structure  Stacking  faults  Molecular  dynamics  simulations  Zirconium Résumé : Properties of basal and first order prism plane dislocations with Burgers vector 1/3 〈View the MathML source〉 in α-Zr have been investigated by computer simulation. Results for a recent interatomic potential (MA07) are assessed and compared with an older one (AWB95). The elastic constants have been calculated with the inner relaxations allowed for and the energy and vector of metastable stacking faults have been determined and compared with published ab initio estimates. The core of the screw dislocation spreads principally in the prism plane in the MA07 model, in contrast to basal plane dissociation in the AWB95 model, and the prism-to-basal ratio of the Peierls stress for the screw is 0.28 with the MA07 model, compared with 3.31 with the AWB95 model. Simulation of the dynamics of dislocation motion under applied stress reveal how the drag coefficient varies with slip system and temperature. The results for the MA07 model are consistent with the known slip geometry of Zr, suggesting that it offers significant advantages for large-scale atomic simulation of dislocation behaviour. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964541000042X

Effects of temperature on structure and mobility of the 〈1 0 0〉 edge dislocation in body-centred cubic iron / D.A. Terentyev in Acta materialia, Vol. 58 N° 7 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2477–2482 Titre : Effects of temperature on structure and mobility of the 〈1 0 0〉 edge dislocation in body-centred cubic iron Type de document : texte imprimé Auteurs : D.A. Terentyev, Auteur ; Yu. N. Osetsky, Auteur ; D. J. Bacon, Auteur Année de publication : 2011 Article en page(s) : pp. 2477–2482 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Bcc  metals  Dislocation  loops  Hardening  〈1  0〉  dislocation Résumé : Dislocation segments with Burgers vector b = 〈1 0 0〉 are formed during deformation of body-centred-cubic (bcc) metals by the interaction between dislocations with b = 1/2〈1 1 1〉. Such segments are also created by reactions between dislocations and dislocation loops in irradiated bcc metals. The obstacle resistance produced by these segments on gliding dislocations is controlled by their mobility, which is determined in turn by the atomic structure of their cores. The core structure of a straight 〈1 0 0〉 edge dislocation is investigated here by atomic-scale computer simulation for α-iron using three different interatomic potentials. At low temperature the dislocation has a non-planar core consisting of two 1/2〈1 1 1〉 fractional dislocations with atomic disregistry spread on planes inclined to the main glide plane. Increasing temperature modifies this core structure and so reduces the critical applied shear stress for glide of the 〈1 0 0〉 dislocation. It is concluded that the response of the 〈1 0 0〉 edge dislocation to temperature or applied stress determines specific reaction pathways occurring between a moving dislocation and 1/2〈1 1 1〉 dislocation loops. The implications of this for plastic flow in unirradiated and irradiated ferritic materials are discussed and demonstrated by examples. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008817 [article] Effects of temperature on structure and mobility of the 〈1 0 0〉 edge dislocation in body-centred cubic iron [texte imprimé] / D.A. Terentyev, Auteur ; Yu. N. Osetsky, Auteur ; D. J. Bacon, Auteur . - 2011 . - pp. 2477–2482. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2477–2482 Mots-clés : Bcc  metals  Dislocation  loops  Hardening  〈1  0〉  dislocation Résumé : Dislocation segments with Burgers vector b = 〈1 0 0〉 are formed during deformation of body-centred-cubic (bcc) metals by the interaction between dislocations with b = 1/2〈1 1 1〉. Such segments are also created by reactions between dislocations and dislocation loops in irradiated bcc metals. The obstacle resistance produced by these segments on gliding dislocations is controlled by their mobility, which is determined in turn by the atomic structure of their cores. The core structure of a straight 〈1 0 0〉 edge dislocation is investigated here by atomic-scale computer simulation for α-iron using three different interatomic potentials. At low temperature the dislocation has a non-planar core consisting of two 1/2〈1 1 1〉 fractional dislocations with atomic disregistry spread on planes inclined to the main glide plane. Increasing temperature modifies this core structure and so reduces the critical applied shear stress for glide of the 〈1 0 0〉 dislocation. It is concluded that the response of the 〈1 0 0〉 edge dislocation to temperature or applied stress determines specific reaction pathways occurring between a moving dislocation and 1/2〈1 1 1〉 dislocation loops. The implications of this for plastic flow in unirradiated and irradiated ferritic materials are discussed and demonstrated by examples. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008817