Structure of misfit dislocations in niobium-sapphire interfaces and strength of interfacial bonding: An atomistic study
The formation of networks of misfit dislocations is investigated at the (0001){sub Al{sub 2}O{sub 3}}{parallel}(111){sub Nb} interface using a recently proposed approach which employs a very simple pair-potential to describe interaction between the metal and the substrate that contains the strength of interfacial adhesion as a parameter. The calculations demonstrate how the strength of bonding between the two materials decides both the form of the network and the atomic structure of the cores of these dislocations. At the same time it reveals that diffusion is essential for the formation of the observed triangular network of 1/2{l{underscore}angle}111{r{underscore}angle} dislocations. The calculated structures are then used to investigate related high resolution electron microscope (HREM) images using a multislice technique. In these simulations translational symmetry along the electron beam was not assumed but for each slice of material along the beam different sub-structures were used. This allowed us to investigate fully the effect of the dislocation intersections upon the images of the dislocation cores. Their effect is, indeed, considerable if an intersection is in the region producing the image but if not, the images of the cores of misfit dislocations are affected only marginally and HREM can capture fine details of the core structure. A direct comparison of an experimental observation in Mayer and co-workers with the present simulations demonstrates this ability.
- Research Organization:
- Max-Planck-Inst. fuer Metallforschung, Stuttgart (DE)
- Sponsoring Organization:
- Department of Energy; Volkswagen Foundation; Hungarian National Science Foundation; Deutsche Akademische Austauschdienst; National Science Foundation (NSF)
- OSTI ID:
- 20005389
- Journal Information:
- Acta Materialia, Vol. 47, Issue 15-16; Conference: Materials Science and Mechanics of Interfaces, La Jolla, CA (US), 10/25/1998--10/30/1998; Other Information: PBD: 12 Nov 1999; ISSN 1359-6454
- Country of Publication:
- United States
- Language:
- English
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