Experimental data and models for non-compact glide (Peierls, locking-unlocking) were reviewed. It was pointed out that a key factor was the differing mobilities of the screw and edge dislocations. This implied that an indication of non-compact glide in the structure was the observation of longer straight dislocation sections; especially screw sections. For most of these sections, it was assumed that there was an effect of the higher friction force in the non-compact plane, and that only screw sections were capable of cross-glide between the compact and non-compact plane, as proposed in the models. Non-compact glide in the pure form could be achieved in the hexagonal close-packed structure, and pyramidal glide was possible by selecting an axis of loading which was parallel to the basal plane. However, this was not possible in the face-centered cubic structure. Glide of the non-compact planes, {001}, {110} and {11x}, x = 2, 3 …, took place; together with favourably oriented glide on the {111} planes, and was often replaced by this type of glide. This factor complicated the analysis (determination of activation parameters, etc.) of non-compact glide as a thermally activated process. The experimental data showed that the activation energy of non-compact glide clearly exceeded the activation energy for lattice self-diffusion, but did not attain the theoretically predicted values. The properties of non-compact glide in various materials were the result of the specific behaviours of the dislocation cores. In pure metals, this was reflected by a dependence of the activation conditions upon the stacking-fault energy. In materials having a more complicated structure (intermetallics), it was also reflected by a dependence upon other parameters (energy of antiphase boundary). The change in the structure of the dislocation cores with increasing temperature was suggested to be a possible reason for the high-temperature anomaly in the flow stress of certain materials.

Dislocation Glide in Non-Compact Crystal Planes. H.Kvapilova, A.Orlova: Metallic Materials, 2000, 38[3], 142-52