The 9th International Conference on Multiscale Materials Modeling

講演情報

Symposium

C. Crystal Plasticity: From Electrons to Dislocation Microstructure

[SY-C3] Symposium C-3

2018年10月30日(火) 09:45 〜 11:00 Room1

Chair: Francois Willaime(DEN-Departement des Materiaux pour le Nucleaire, CEA, Universite Paris-Saclay, France)

[SY-C3] Dislocation climb models from atomistic scheme to dislocation dynamics

Yang Xiang1, Xiaohua Niu2 (1.Department of Mathematics, Hong Kong University of Science and Technology, Hong Kong, 2.Department of Mathematics, Jimei University, China)

We develop a mesoscopic dislocation dynamics model for vacancy-assisted dislocation climb by upscalings from a stochastic model on the atomistic scale. Our models incorporate microscopic mechanisms of (i) bulk diffusion of vacancies, (ii) vacancy exchange dynamics between bulk and dislocation core, (iii) vacancy pipe diffusion along the dislocation core, and (iv) vacancy attachment-detachment kinetics at jogs leading to the motion of jogs. Our mesoscopic model consists of the vacancy bulk diffusion equation and a dislocation climb velocity formula. The effects of these microscopic mechanisms are incorporated by a Robin boundary condition near the dislocations for the bulk diffusion equation and a new contribution in the dislocation climb velocity due to vacancy pipe diffusion driven by the stress variation along the dislocation. Our climb formulation is able to quantitatively describe the self-climb of prismatic loops at low temperatures when the bulk diffusion is negligible. Simulations performed show evolution, translation, coalescence of prismatic loops by self-climb that agree with the experimental observations.