A unified phenomenological model was developed in order to study dislocation glide through weak obstacles in the first stages of plastic deformation. This model took account of the dynamic response of dislocations during flight, and of thermal activation while the dislocations were bound by obstacle arrays. The average thermal activation rate was estimated by using an analytical model that was based upon the generalized Friedel relationships. The average flight velocity after an activation event was then obtained numerically by discrete dislocation dynamics. In order to simulate the dynamic dislocation behavior, an inertia term was implemented into the equation of dislocation motion. The results of the dislocation dynamics simulations, coupled with an analytical model, gave the total dislocation velocity as a function of stress and temperature. Upon choosing parameters which were typical of face centered cubic metals, the model reproduced obstacle control and drag control motion in the low- and high-velocity regimes, respectively. As suggested by other string models, dislocation overshoots of obstacles - caused by dislocation inertia in collisions - were enhanced as the temperature decreased.

Modeling of Thermally Activated Dislocation Glide and Plastic Flow through Local Obstacles. M.Hiratani, H.M.Zbib, M.A.Khaleel: International Journal of Plasticity, 2003, 19[9], 1271-96