lecture 4

• SEM imaging


  SE, BSE
• Diffraction for orientation measurement

  • XRD
  • Crystallography

  
• Electron backscatter diffraction (EBSD)

  Orientation of grains in polycrystalline sample relative to sample axes

  
• EBSD orientation map


  • X-ray diffraction (bulk texture)

  
• Measure grain orientations


  • Transmission Electron Microscopy
  • Convergent Beam Electron Diffraction
  • Kikuchi Patterns
  • Scanning Electron Microscopy
  • Electron Backscatter Diffraction – EBSD

  
• EBSD


  • Measure the orientation of a given crystal
  • Measure the overall orientation of the material or crystallographic texture
  • Measure the misorientation between two points in a crystal or across grains
  • Identification of unknown crystal phases
  • Identification of multiphase material crystals

  
• EBSD pattern formation


  More electrons undergo diffraction, and escape from the specimen before being absorbed
• EBSD pattern indexing


  1. Collect EBSP

  2. Match to phase & orientation

  3. Verify match: Indexed EBSP

  4. Phase and orientation
• EBSD is a surface technique with the diffraction pattern signal coming from the top few nm

  
• Sample preparation for EBSD

  • Mounting in conductive resin, mechanical grinding, diamond polishing and final polishing with colloidal silica
  • Mounting in conductive resin, mechanical grinding, diamond polishing and electropolishing
  • Fracturing to reveal surfaces immediately suitable for EBSD
  • Ion milling for materials not amenable to conventional metallography