ABSTRACT
The deformation of crystals by the conservative glide of dislocations on a single set of crystallographic planes causes shear in the direction of the resultant Burgers vector of the dislocations concerned, a direction which lies in the slip plane. The slip plane and slip direction constitute a slip system. The material in the slip plane remains crystalline during slip and since there is no reconstruction of this material during slip (e.g., by localized melting followed by resolidification), there can be no change in the relative positions of atoms in the slip plane. The atomic arrangement on the slip plane is thus completely unaffected by the deformation. Another mode of conservative plastic deformation is mechanical twinning, in which the parent lattice is homogeneously sheared into the twin orientation. The plane on which the twinning shear occurs is again unaffected by the deformation and forms a coherent boundary between the parent and its twin.
