Characterization of Dislocation Core Structures in BCC Metals
Abstract
The scientific aim of this study was to use state-of-the-art TEM techniques to experimentally describe dislocation core structures in bcc metals through experimental characterization of screw dislocations in single-crystalline Mo. Methods were developed for deriving localized electron structure data from electron energy loss spectra (EELS) taken from perfect lattice regions and along dislocations and low angle boundaries in ordered NiAl. Significant changes in the fine structure of the NiL edge were associated with <001> dislocations in NiAl and comparisons with first-principles were used to characterize localized electronic structure and bonding in the vicinity of this dislocation. However, difficulties associated with the position of the energy edges for Mo precluded application of this technique to the study of 1/2<111> screw dislocations in single-crystalline Mo. For this reason, the majority of this study focused on: direct HREM observations of the atomic columns surrounding 1/2<111> screw dislocations in Mo, characterization of the displacement fields associated with these dislocations, mitigation of experimental noise, and comparison of the experimental observations with theoretically predicted dislocation structures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 30, 2004
- Accession Number
- ADA443132
Entities
People
- Kevin J. Hemker
Organizations
- Johns Hopkins University