THE KINK PICTURE OF DISLOCATION MOBILITY AND DISLOCATION-POINT-DEFECT INTERACTIONS

Abstract

The paper gives a coherent account of the theory of dislocation mobility in terms of kink-pair formation and kink migration. Three levels of description arise in a natural way, namely those of the motion of straight dislocations, of kink-pair formation on dislocations, and of kink migration. The interrelationships between these levels (hierarchies) are discussed. The interaction with phonons and foreign atoms (impurities) is treated on the third level, that of the kink mobility. Experimental information on the properties of kinks may be obtained from measurements of dislocation velocities, of flow stress, and of internal friction and modulus effect. The comparison between theory and experiment is illustrated by examples from valence crystals (dislocation velocity in Ge) and from body-centred cubic transition metals (γ relaxation = kink-pair formation on screw dislocations ; dislocation-enhanced Snoek effect ; Snoek- Koster relaxation in Nb and Ta).