atom

micro

macro

A

B

C
EBSD

EBSD: Electron BackScatter Diffraction
Definition:An electron diffraction technique in scanning electron microscopy (→SEM), which is used to obtain information about crystallographic phase, crystal orientation, and defect densities
Explanation:Fig. 1a shows a typical EBSD pattern. The pattern consists of straight bright bands, so called Kikuchi bands, which have a direct relation to the lattice planes of the diffracting crystal: the centre line of each band directly corresponds to the gnomonic projection of the lattice planes. The width of the Kikuchi band is approximately proportional to the Bragg angle of electron diffraction on the related lattice plane. The band intensity profile corresponds to the dynamic electron diffraction intensity obtained in a rocking experiment across the related lattice plane.

From the geometry of the Kikuchi bands in the pattern, the crystallographic phase and orientation can be determined. The band profiles contain information on the local defect densities (particularly on dislocation densities). These information can be obtained in a highly automated manner by computer software which displays the basis of so called EBSD-based orientation microscopy (→ORM).

To obtain EBSD patterns, a crystalline sample with planar and artefact free surface is placed in the SEM, and typically tilted to 70° as shown in Fig. 1b. An EBSD detector, consisting of a phosphor screen observed by a highly light sensitive camera, is placed close to the sample. When a stationary electron beam is placed on a single crystalline area of the sample surface, an EBSD pattern appears on the detector.
Picture /
Figure /
Diagram:

Figure 1: (a) EBSD pattern of Nb (15 kV). (b) Geometric setup of EBSD.
SFB-Link:EBSD is the basis of ORM which is one of the most comprehensive microstructure characterization methods for bulk materials. It allows characterization of microstructure morphology, lattice defects, crystallographic texture, phase distributions, and residual stresses.
References:Schwartz, A.J. et al.: Electron Backscatter Diffraction in Materials Science, 2nd ed., Springer Verlag, Berlin, 2009
Zaefferer, S. (2007), On the formation mechanisms, spatial resolution and intensity of backscatter Kikuchi patterns, Ultramicroscopy 107, 254 – 266.