Étude par simulations à l'échelle atomique de la formation de boucles de dislocation à partir d'irrégularités de surface d'un métal contraint

Abstract : In this PhD thesis, we studied the nucleation of dislocations from a surface in a fcc metal under stress, using atomic-scale simulations as well as models based on elastic theory of dislocations. Nucleation from surfaces, which initiate plasticity in nanometer-scale materials, requires the crossing of an energy barrier ; this is possible through thermal activation. We were able to determine the role of different factors, such as temperature or the surface condition, on the nucleation event. Several atomistic methods were used to determine the activation parameters associated with the energy barrier : the critical radius the dislocations has to overcome in order to become stable and propagate, and the activation energy and volume. Finally, some information concerning dislocations dynamics and plastic phenomena subsequent to the nucleation process were obtained.
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Submitted on : Thursday, June 25, 2009 - 3:17:32 PM
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Pierre Hirel. Étude par simulations à l'échelle atomique de la formation de boucles de dislocation à partir d'irrégularités de surface d'un métal contraint. Matière Condensée [cond-mat]. Université de Poitiers, 2008. Français. ⟨tel-00399038⟩

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