Burgers vector determination of decorated dislocations in γ-TiAl by diffraction contrast and large-angle convergent-beam electron diffraction
- 1 February 1994
- journal article
- research article
- Published by Taylor & Francis in Philosophical Magazine A
- Vol. 69 (2) , 285-299
- https://doi.org/10.1080/01418619408244344
Abstract
Decorated and undecorated dislocations in γ-TiAl have been studied by conventional transmission electron microscopy using diffraction contrast and by large-angle convergent-beam electron diffraction (LACBED). The results of the Burgers vector determination for undecorated and decorated dislocations using the different techniques have been compared. For the decorated dislocations the contrast from the decorating particles and the underlying dislocation have been separated and the misfit introduced by the precipitates has been determined. Computer simulations of the contrast from decorated dislocations in LACBED patterns have been performed. The rules governing the dislocation contrast in LACBED patterns have been discussed and extended to the case of decorated dislocations. A new fringe-counting rule to determine the Burgers vectors of dislocations decorated by misfitting precipitates has been proposed. Remarkably good agreement of the computer-simulated LACBED contrast with experimental observations has been achieved.Keywords
This publication has 15 references indexed in Scilit:
- Dislocation contrast in large angle convergent-beam electron diffraction patternsPhilosophical Magazine A, 1992
- Elastic constants, fault energies, and dislocation reactions in TiAl: A first-principles total-energy investigationPhilosophical Magazine Letters, 1990
- Convergent beam diffraction studies of interfaces, defects, and multilayersJournal of Electron Microscopy Technique, 1989
- Observation of Berry's Geometrical Phase in Electron Diffraction from a Screw DislocationPhysical Review Letters, 1988
- An analytical electron microscopy study of the recently reported “Ti2Al phase” in γ-TiAl alloysScripta Metallurgica, 1986
- Diffraction contrast from misfitting spherical particles precipitated close together on a dislocation I. Individual spheres close together on a straight linePhysica Status Solidi (a), 1976
- Electron diffraction contrast of small coherent particles II. Spherical inclusion in a cubic crystalPhysica Status Solidi (a), 1974
- Diffraction contrast from coherent precipitates in elastically-anisotropic materialsPhilosophical Magazine, 1972
- Diffraction contrast from spherically symmetrical coherency strainsPhilosophical Magazine, 1963
- Diffraction contrast of electron microscope images of crystal lattice defects - II. The development of a dynamical theoryProceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1961