Electronic Component of Dislocation Drag in Metals

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Abstract
The energy dissipation produced by the electric fields and currents associated with a dislocation moving through a metal is calculated from the Boltzmann equation. The applied stress required for steady motion is found to be proportional to the dislocation velocity divided by the electrical resistivity, in good agreement with low-temperature yield-and flow-stress measurements on bcc metals. The forms of the electric fields and currents are derived, and these are found to exhibit Friedel oscillations and to depend in a unique way on the dislocation velocity. The displacement field of a dislocation is believed to be significantly wider and more gradual in an fcc than in a bcc lattice, and this feature can be taken into account either by (1) inserting dislocation widths into the calculation, or (2) assuming perfect electronic screening of the dislocation deformation potential. The stress or drag coefficient obtained from the width calculation shows a very small temperature dependence, while the perfect-screening result is temperature-independent. The problem of a dislocation moving in a magnetic field applied along its length and perpendicular to its direction of motion is also considered. Under suitable conditions, it is found that oscillatory effects of the cyclotron-resonance type may occur in the stress or drag coefficients.

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