It was recalled that disconnections were interfacial defects with dislocation and step character: for example, twinning dislocations in homo-phase materials and transformation dislocations in hetero-phase materials. They played important structural roles and were classified as being either perfect (separating energetically degenerate regions of interface) or partial (bounding a faulted region). In kinetic mechanisms, disconnection motion could be glissile; via conservative climb or climb. Here, disconnection mobility was analyzed in terms of shear and shuffle-type atomic displacements and diffusional flux. This was applied to a sequence of hetero-phase materials of increasing structural complexity: the β-to-α transformation in Ti and θ’-precipitation in Al-Cu. There was also a disconnection source mechanism, in Ti, which involved conservative climb.

Disconnections in Simple and Complex Structures. R.C.Pond, X.Ma, J.P.Hirth, T.E.Mitchell: Philosophical Magazine, 2007, 87[33], 5289-307