Malashenko V. Interaction of structural defects of different dimensionalities and their influence on inelastic properties of crystals

The dynamic interaction between moving dislocation and point defects, dislocation loops, dislocation dipoles, free surface in metals, alloys and alkali-halide crystals is studied theoretically. For the calculation of the drag force a method of Green's functions was used. The orientation effect for the dynamic interaction between moving edge dislocation and dislocation loops is predicted. A new mechanism of dislocation drag is proposed and analyzed. The motion of a pair of edge dislocations in an elastic potential of point defects is investigated. The effect of the surface on a glide of edge dislocation in the crystal with point defects distributed in bulk and surface is studied. It is shown that the drag force can be reduced by the image forces to several orders of magnitude in nano-scale region. The explanation of the experimentally observed decrease of the yield strength with increase of strain rate at low temperatures is proposed. The anomalous strain rate dependence of the yield point is caused by the dynamic instability of dislocation motion.The effect of high hydrostatic pressure on dislocation drag force is studied. The dynamic drag coefficient for various metals and alloys is estimated. Theoretically found estimates have the same order of magnitude as available experimental values. Motion of the edge dislocation at presence of dislocation loops and point defects is investigated. It is shown that at certain conditions the velocity dependence of the drag force gets two maximums and two minimums.