Dislocation motion in a random solid solution

The thermally activated motion of a dislocation through an array of randomly distributed solute atoms is studied. The influence of fluctuations in the solute density on the activation energy for dislocation motion is investigated, and the stress dependences of the effective activation energy and the activation volume are determined. It is shown that, in creep deformation, fluctuations in the activation energies may lead to a creep strain which increases with time according to a power law, with an exponent that increases linearly with increasing temperature. Implications of the calculated activation energy spectrum for low-frequency internal friction are discussed.