[SY-N4] Symposium N-4

[SY-N4] Multiscale diffusion method for simulations of long-time defect evolution with application to dislocation climb

Invited

^○Kristopher Baker¹, William Curtin² (1.Knolls Atomic Power Laboratory, United States of America, 2.Swiss Federal Institute of Technology, Switzerland)

In many problems of interest to materials scientists and engineers, the evolution of crystalline extended defects (dislocations, cracks, grain boundaries, interfaces, voids, precipitates) is controlled by the flow of point defects (interstitials/substitutional atoms and/or vacancies) through the crystal into the extended defect. Accurate modeling of this process requires atomistic methods in and around the extended defect, but the flow of point defects into and out of the extended defect region can be treated by coarse-grained methods. This talk presents a multiscale algorithm to provide this coupling, which was first documented in the manuscript "Multiscale diffusion method for simulations of long-time defect evolution with application to dislocation climb," published in 2016 in the Journal of the Mechanics and Physics of Solids, Number 92, pages 297-312. Specifically, direct accelerated molecluar dynamics (AMD) of extended defect evolution is coupled to a diffusing point defect concentration field that captures the long spatial and temporal scales of point defect motion in the presence of the internal stress fields generated by the evolving extended defect. The algorithm is applied to study vacancy absorption into an edge dislocation in aluminum where vacancy accumulation in the core leads to nucleation of a double-jog that then operates as a sink for additional vacancies; this corresponds to the intial stages of dislocation climb modeled with explicit atomistic resolution. The method is general, so it can be applied to many other problems associated with nucleation, growth, and reactions due to accumulation of point defects in crystalline materials.