It was recalled that a dislocation, moving in a lattice, accelerated and decelerated due to the lattice periodicity and emitted lattice waves. Simulations of this process were performed for square and triangular lattices. Under a stress of less than 70 to 80% of the Peierls stress, a dislocation moving from an unstable position could not overcome the next Peierls hill because it lost energy by emitting lattice waves. At higher stresses, long-distance motion of a dislocation was possible. When the dislocation moved slowly, lattice waves of dipolar type were emitted in the direction perpendicular to the motion of the dislocation. When the dislocation velocity was equal to about 50% of the shear-wave velocity, a V-shaped pattern of strong lattice vibration formed behind the moving dislocation because of the restricted propagation directions of the excited lattice waves. When the dislocation velocity exceeded 70% of the shear-wave velocity, dislocation-pair creation occurred and led to dislocation cascading. A dislocation could move faster than the shear-wave velocity in the square lattice, and there was no discontinuous change between subsonic and supersonic motions. The dislocation velocity was not proportional to the applied stress. The energy loss of the moving dislocation was about an order of magnitude larger than the theoretical value, as estimated by phonon-scattering mechanisms, even at room temperature.

Lattice Wave Emission from a Moving Dislocation. H.Koizumi, H.O.K.Kirchner, T.Suzuki: Physical Review B, 2002, 65[21], 214104 (9pp)