© oxford instruments analytical limited 2001 module 4 - introduction to ebsd crystallographic...
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© Oxford Instruments Analytical Limited 2001
MODULE 4 - Introduction to EBSD
• Crystallographic Orientations
• Misorientations
• Texture trends• Grain size and boundary types
• Phases
EBSD = Electron Backscatter Diffraction
EBSD is a technique that allows:
To be characterised and quantified on a sub-micron scale
© Oxford Instruments Analytical Limited 2001
Introduction to EBSD - History
• 1928 Kikuchi lines observed in TEM• 1954 Alam: patterns obtained in TEM• 1973 Venebles: patterns recorded on film in SEM• 1980 Patterns imaged with low light TV cameras• 1990 Automatic pattern solving using Hough transform• Present day
– Local orientation and misorientation measurements – Crystal Orientation Mapping (COM)– Special grain boundaries imaged– Special textures revealed – Grain sizing
© Oxford Instruments Analytical Limited 2001
Introduction to EBSD - Hardware
• Schematic layout of components
© Oxford Instruments Analytical Limited 2001
Introduction to EBSD - Collection Geometry
• 70.5 deg tilt
• Approx. 70 steradian of pattern detected
• Distances shown are arbitrary
© Oxford Instruments Analytical Limited 2001
Introduction to EBSD - Forward Scattered Electron Imaging (FSE)
• FSE greatly enhances diffraction contrast in imaging
• Grains and grain boundaries are clearly revealed
© Oxford Instruments Analytical Limited 2001
Introduction to EBSD - FSE Examples
• Nickel
• Austenitic Stainless Steel
© Oxford Instruments Analytical Limited 2001
Introduction to EBSD - Crystal Orientation Mapping (COM)
• Crystal uses reference electron image• Orientation obtained at every pixel• Color derived from inverse Pole Figure
color key• Hough transform for every pixel stored
for post acquistion reprocessing
© Oxford Instruments Analytical Limited 2001
Introduction to EBSD - Color Key for COMs
• COM with Inverse Pole Figure color key for cubic material
• Red = 100• Green = 110• Blue = 111
planes parallel to the surface
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