Dynamic Aging of Dislocations in Materials with a High Crystalline Relief: Competition of Diffusion and Dragging Impurities

Abstract

A model of the dynamic interaction of dislocations with the impurity subsystem of crystals that have a high lattice potential relief (Peierls barriers) has been developed. Such materials include metals with a body-centered cubic structure, semiconductors, and many others. The constructed theory of the dynamic interaction of dislocations with the impurity subsystem of the crystal takes into account the inverse effect of impurities entrained by moving dislocations on the dynamics of the dislocations themselves. It is justified that the impurity kinetics during atmosphere formation includes two stages. The first (initial) stage is fast and substantially nonequilibrium; it is followed by the second stage, characterized by a slower approach to equilibrium. The initial stage manifests itself at a sufficiently fast dislocation motion and may lead to an anomalous increase in the driving force (or the yield strength of the material) with an increase in the temperature in some range. The consequences of the self-consistent nature of the process are the occurrence of instability of the movement of dislocations in a certain speed range and immobilization of dislocations at stresses with values below a certain threshold. Blocking of the dislocation motion by impurities may cause inverse brittle–ductile transition, which is observed in some materials with an increase (rather than the usual decrease) in temperature.