Disconnections in simple and complex structures |
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| Authors: | R C Pond X Ma J P Hirth T E Mitchell |
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| Institution: | 1. Department of Engineering , University of Liverpool , Brownlow Hill, Liverpool L69 3BX, UK r.c.pond@liverpool.ac.uk;3. Department of Engineering , University of Liverpool , Brownlow Hill, Liverpool L69 3BX, UK;4. 114 E. Ramsey Canyon Rd. , Hereford, AZ, 85615, USA;5. Structure–Property Relations Group, MST-8, Mail Stop G755, Los Alamos National Laboratory , Los Alamos, NM, 87545, USA |
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| 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. |
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