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Shearing of γ′ precipitates by a〈1 1 2〉 dislocation ribbons in Ni-base superalloys / V.A. Vorontsov in Acta materialia, Vol. 58 N° 12 (Juillet 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 12 (Juillet 2010) . - pp. 4110–4119 Titre : Shearing of γ′ precipitates by a〈1 1 2〉 dislocation ribbons in Ni-base superalloys : A phase field approach Type de document : texte imprimé Auteurs : V.A. Vorontsov, Auteur ; C. Shen, Auteur ; Y. Wang, Auteur Année de publication : 2011 Article en page(s) : pp. 4110–4119 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Primary  creep  Dislocation  dissociation  Phase  field  Shockley  partials  Stacking  faults Résumé : The phase field model of dislocations has been used to study the propagation of dislocation ribbons with an overall Burgers vector of a〈1 1 2〉 through a simulated Ni-base superalloy. The driving force for dislocation dissociation reactions and formation of planar faults is incorporated into the free energy functional using periodic functions specially fitted to ab initio γ-surface data. The model shows that the mechanism of cutting of the γ′ precipitates by these ribbons exhibits significant dependence on stress magnitude, orientation and precipitate shape. In the case of mixed screw–edge ribbons a change of shearing mode is observed, from stacking fault shear to anti-phase boundary shear, when the applied stress approaches the yield of the material. This transition is absent in pure edge ribbons. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001990 [article] Shearing of γ′ precipitates by a〈1 1 2〉 dislocation ribbons in Ni-base superalloys : A phase field approach [texte imprimé] / V.A. Vorontsov, Auteur ; C. Shen, Auteur ; Y. Wang, Auteur . - 2011 . - pp. 4110–4119. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 12 (Juillet 2010) . - pp. 4110–4119 Mots-clés : Primary  creep  Dislocation  dissociation  Phase  field  Shockley  partials  Stacking  faults Résumé : The phase field model of dislocations has been used to study the propagation of dislocation ribbons with an overall Burgers vector of a〈1 1 2〉 through a simulated Ni-base superalloy. The driving force for dislocation dissociation reactions and formation of planar faults is incorporated into the free energy functional using periodic functions specially fitted to ab initio γ-surface data. The model shows that the mechanism of cutting of the γ′ precipitates by these ribbons exhibits significant dependence on stress magnitude, orientation and precipitate shape. In the case of mixed screw–edge ribbons a change of shearing mode is observed, from stacking fault shear to anti-phase boundary shear, when the applied stress approaches the yield of the material. This transition is absent in pure edge ribbons. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001990