Disconnections in simple and complex structures

Abstract

Disconnections are interfacial defects with dislocation and step character; for example, twinning dislocations in homo-phase and transformation dislocations in hetero-phase materials. They play important structural roles and are classified as either ‘perfect’, separating energetically degenerate regions of interface, or ‘partial’, bounding a faulted region. In kinetic mechanisms, disconnection motion can be glissile, by conservative climb or climb. In the present paper, disconnection mobility is analyzed in terms of shear and shuffle-type atomic displacements and diffusional flux. This is applied to a sequence of hetero-phase materials with increasing structural complexity, namely the β to α transformation in Ti, θ′ precipitation in Al(Cu) and the orthorhombic to monoclinic martensitic transformation in ZrO₂. A disconnection source mechanism in Ti, involving conservative climb, is also described.

¹Recently moved to Institute of Science and Technology, School of Mechanical Engineering, South China University of Technology, Guangzhou 510640, China.

Acknowledgment

The authors are grateful for helpful input from I-Wei Chen and H. Khater.

Notes

¹Recently moved to Institute of Science and Technology, School of Mechanical Engineering, South China University of Technology, Guangzhou 510640, China.