DISLOCATION STRUCTURES PRODUCED BY CROSS-SLIP

ABSTRACT The cross-slip of single dislocations has often been discussed. However, plastic deformation is usually inhomogeneous, and it is probable that dislocations frequently move in groups rather than glide singly. We argue that this may affect the process of cross-slip. We consider the successive cross-slip of a procession of dislocations and describe a mechanism which produces dislocation structures like those observed in crystals which work-harden in three stages. Evidence for the operation of this mechanism is found in neutron irradiated copper crystals, where similar structures are clearly linked to cross-slip (1,2). We propose a re-interpretation of the role of cross-slip in three-stage hardening; namely, that cross-slip occurs throughout deformation, that it induces secondary slip, and that it is responsible for the growth of structures known as ‘carpets’ (3) or ‘versetzungsschichten’ (A). We attribute Stage III to the onset of primary dislocation multiplication by cross-slip, rather than to the onset of cross-slip itself.