Electron backscatter diffraction (ebsd)
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The document discusses electron backscatter diffraction (EBSD), including a brief history, the principal system components, how patterns are formed, operating conditions, and uses. EBSD allows determining crystallographic orientations, misorientations, texture trends, grain size, boundary types, and phases. It works by detecting Kikuchi patterns formed by elastic backscatter of electrons from tilted crystalline samples, and analyzing the patterns to determine crystallographic data. EBSD is now widely used to quantitatively characterize microstructures and textures in materials.
Electron backscatter diffraction (ebsd)
- 1. Presenter: Imtiaz Ali Registration No. : 400360
- 2. Introduction to EBSD Brief History Principal system components How the Pattern is Formed? EBSP - Electron Backscatter Diffraction Patterns Operating conditions Uses of EBSD Summary
- 3. EBSD is a technique that allows: Crystallographic Orientations Misorientations Texture trends Grain size and boundary types Phases
- 4. 1928 Kikuchi lines observed inTEM 1954 Alam: patterns obtained inTEM 1973Venebles: patterns recorded on film in SEM 1980 Patterns imaged with low lightTV cameras 1990 Automatic pattern solving using Hough transform Present day Local orientation and misorientations measurements Crystal Orientation Mapping (COM) Special grain boundaries imaged Special textures revealed Grain sizing
- 5. Sample tilted at 70° from the horizontal. A phosphor screen. A sensitive CCD video camera A vacuum interface for mounting the phosphor and camera in an SEM port. Electronic hardware that controls the SEM, including the beam position, stage, focus, and magnification. A computer to control EBSD experiments, analyze the EBSD pattern and process and display the results.
- 7. High energy electrons are elastically scattered by atomic planes in a crystallographic sample.
- 8. Accelerating Voltage : 15-30 kV Beam current : 1-15 nA Collection angle : 70° Working distance : 10-25 mm
- 9. Si single crystal As the sample is rotated, the pattern changes to reflect the new orientaion
- 10. Quantitative micro structural data Phase identification Strain analysis Maps
- 11. EBSD has become a well established micro structural analytical technique. EBSD mapping can be used to explore the processing microstructure – properties relationships. EBSD can be used on most crystalline materials Grain size, sample tilt, and sample preparation are the primary limitations of the technique.