Thermally activated transport of a dislocation loop within an elastic model

We report thermally activated transport of a dislocation loop in terms of a line tension model, where the dislocation line is assumed to be a flexible string. According to conventional rate theory, the features of thermal activation are determined by the saddle-point geometry in high dimensional configuration space. If the circumference of a dislocation loop L is longer than a critical length Lc, the selected saddle-point configuration is the well known double-kink type solution. On the other hand, the manner of the thermal activation of a dislocation loop shorter than Lc is rather point-defect-like. In the present work, we pay attention to the temperature dependence of transition rate which is represented such as ν 0 ∗ exp ( - E / k B T ) . The pre-exponential factor depends on temperature like ν 0 ∗ ∼ T - 1 / 2 for sufficiently long dislocation loops on the basis of the analysis.