| Dislocation dynamics is of great importance for many physical properties of materials. A dislocation interacting with local obstacles is featured by its jerky motion, which consists of two stages, thermal activation stage in metastable configurations held by local obstacles and viscous motion stage between them. Each stage has been studied separately for long time. Recent experiments have shown that a strong magnetic field and a transition from superconducting to normal conducting state can cause a remarkable reduction of the dislocation velocity in a range of several orders of magnitude. These findings suggest a strong coupling between the two stages and require a new model enabling to unify both of them.; The presenting work describes ways how to derive basic statistical properties of dislocation segments in a metastable configuration, evaluate drag forces acting during the viscous motion, estimate dynamical effect in front of encountered obstacles, and calculate the total dislocation velocity within the newly-developed model. The effect of applied stress, temperature, obstacles strength, strong magnetic field, the SN transition, and temperature-dependent concentration of obstacles on the dislocation velocity are evaluated numerically. The results show good qualitative agreement with available computational and experimental results including both individual dislocations and macroscopic deformation. |
