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A phase field study of strain energy effects on solute–grain boundary interactions / Tae Wook Heo in Acta materialia, Vol. 59 N° 20 (Décembre 2011) 

Public ISBD [article]  in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7800–7815 Titre : A phase field study of strain energy effects on solute–grain boundary interactions Type de document : texte imprimé Auteurs : Tae Wook Heo, Auteur ; Saswata Bhattacharyya, Auteur ; Long-Qing Chen, Auteur Année de publication : 2012 Article en page(s) : pp. 7800–7815 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Grain  boundary  segregation  Solute  drag  effect  Elastic  strain  energy  Phase  field  model Résumé : We have studied strain-induced solute segregation at a grain boundary and the solute drag effect on boundary migration using a phase field model integrating grain boundary segregation and grain structure evolution. The elastic strain energy of a solid solution due to the atomic size mismatch and the coherency elastic strain energy caused by the inhomogeneity of the composition distribution are obtained using Khachaturyan’s microelasticity theory. Strain-induced grain boundary segregation at a static planar boundary is studied numerically and the equilibrium segregation composition profiles are validated using analytical solutions. We then systematically studied the effect of misfit strain on grain boundary migration with solute drag. Our theoretical analysis based on Cahn’s analytical theory shows that enhancement of the drag force with increasing atomic size mismatch stems from both an increase in grain boundary segregation due to the strain energy reduction and misfit strain relaxation near the grain boundary. The results were analyzed based on a theoretical analysis in terms of elastic and chemical drag forces. The optimum condition for solute diffusivity to maximize the drag force under a given driving force was identified. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006227 [article] A phase field study of strain energy effects on solute–grain boundary interactions [texte imprimé] / Tae Wook Heo, Auteur ; Saswata Bhattacharyya, Auteur ; Long-Qing Chen, Auteur . - 2012 . - pp. 7800–7815. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7800–7815 Mots-clés : Grain  boundary  segregation  Solute  drag  effect  Elastic  strain  energy  Phase  field  model Résumé : We have studied strain-induced solute segregation at a grain boundary and the solute drag effect on boundary migration using a phase field model integrating grain boundary segregation and grain structure evolution. The elastic strain energy of a solid solution due to the atomic size mismatch and the coherency elastic strain energy caused by the inhomogeneity of the composition distribution are obtained using Khachaturyan’s microelasticity theory. Strain-induced grain boundary segregation at a static planar boundary is studied numerically and the equilibrium segregation composition profiles are validated using analytical solutions. We then systematically studied the effect of misfit strain on grain boundary migration with solute drag. Our theoretical analysis based on Cahn’s analytical theory shows that enhancement of the drag force with increasing atomic size mismatch stems from both an increase in grain boundary segregation due to the strain energy reduction and misfit strain relaxation near the grain boundary. The results were analyzed based on a theoretical analysis in terms of elastic and chemical drag forces. The optimum condition for solute diffusivity to maximize the drag force under a given driving force was identified. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006227

Simulations of stress-induced twinning and de-twinning / ShenYang Hu in Acta materialia, Vol. 58 N° 19 (Novembre 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6554–6564 Titre : Simulations of stress-induced twinning and de-twinning : A phase field model Type de document : texte imprimé Auteurs : ShenYang Hu, Auteur ; Chuck H. Henager Jr, Auteur ; Long-Qing Chen, Auteur Année de publication : 2011 Article en page(s) : pp. 6554–6564 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Phase  field  method  Partial  dislocation  Deformation  twin  Polycrystal  deformation Résumé : Twinning in certain metals or under certain conditions is a major plastic deformation mode. Here we present a phase field model to describe twin formation and evolution in a polycrystalline fcc metal under loading and unloading. The model assumes that twin nucleation, growth and de-twinning is a process of partial dislocation nucleation and slip on successive habit planes. Stacking fault energies, energy pathways (γ surfaces), critical shear stresses for the formation of stacking faults and dislocation core energies are used to construct the thermodynamic model. The simulation results demonstrate that the model is able to predict the nucleation of twins and partial dislocations, as well as the morphology of the twin nuclei, and to reasonably describe twin growth and interaction. The twin microstructures at grain boundaries are in agreement with experimental observation. It was found that de-twinning occurs during unloading in the simulations, however, a strong dependence of twin structure evolution on loading history was observed. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410005343 [article] Simulations of stress-induced twinning and de-twinning : A phase field model [texte imprimé] / ShenYang Hu, Auteur ; Chuck H. Henager Jr, Auteur ; Long-Qing Chen, Auteur . - 2011 . - pp. 6554–6564. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6554–6564 Mots-clés : Phase  field  method  Partial  dislocation  Deformation  twin  Polycrystal  deformation Résumé : Twinning in certain metals or under certain conditions is a major plastic deformation mode. Here we present a phase field model to describe twin formation and evolution in a polycrystalline fcc metal under loading and unloading. The model assumes that twin nucleation, growth and de-twinning is a process of partial dislocation nucleation and slip on successive habit planes. Stacking fault energies, energy pathways (γ surfaces), critical shear stresses for the formation of stacking faults and dislocation core energies are used to construct the thermodynamic model. The simulation results demonstrate that the model is able to predict the nucleation of twins and partial dislocations, as well as the morphology of the twin nuclei, and to reasonably describe twin growth and interaction. The twin microstructures at grain boundaries are in agreement with experimental observation. It was found that de-twinning occurs during unloading in the simulations, however, a strong dependence of twin structure evolution on loading history was observed. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410005343