Phase-field-crystal study on the reaction mechanisms of opposite sign edge dislocations appearing in the deformation processes of asymmetric tilt sub-grain boundary system

摘要

With phase-field-crystal method, the microscopic movement processes of asymmetric tilt sub-grain boundary system under applied stresses at high temperature are investigated. Reactions of opposite sign edge dislocations (OSEDs) gliding on the same and different slip planes are observed during the deformation processes. The reaction mechanisms of OSEDs are explored from the microstructure and energy perspectives. The simulation results show that OSEDs gliding on different slip planes can either annihilate or react into new perpendicular OSEDs. If the internal stress caused by the extra half-planes of edge dislocations in the region between different slip planes is in direction opposite to the applied stress, the free energy density (FED) curve has an obvious peak structure during the approaching process of dislocations. When FED achieves its maximum, new perpendicular OSEDs are generated. On the contrary, if the internal and applied stresses have the same direction, the FED curve changes gently without forming obvious peak structure. OSEDs annihilate. (C) 2016 Elsevier B.V. All rights reserved.