Inertial motion and multi-kink pair formation of dislocations on the Peierls potential

The motion of a dislocation overcoming the Peierls potential is investigated by integrating the equation of motion. The behaviour of the segment following the nucleation of the first pair of kinks changes drastically from overdamping to underdamping at a critical value of the applied stress τ. When τ is smaller than a critical value τ*, the migration of kinks is dominant and the whole segment falls into the next valley of the Peierls relief to complete single kink pair formation. On the contrary, when τ, due to inertia the centre part of the bowed out segment overcomes the second maximum of the Peierls relief, and continues to overcome the succeeding maxima dynamically, resulting in multi-kink pair formation. The critical stress τ* is about 0τ7τp in the absence of friction, τp being the Peierls stress. It increases with increasing friction. The possibility to observe the multi-kink pair formation is discussed for f.c.c. metals, b.c.c. metals and ionic crystals.