Electron backscattered diffraction (EBSD) is a unique technique that can identify the phase and orientation of crystalline materials. EBSD uses a highly focused electron beam to interact with crystalline planes, resulting interference patterns, similar to X-ray diffraction, in the elastically rebounding electrons. The EBSD diffraction patterns are commonly known as Kikuchi patterns. Since the interactions involve backscattered electrons, the sampling depth of EBSD is on the order of 10s to 100s of nanometers, dependent on experimental and sample parameters. The shallow sampling volume necessitates pristine surface finish to the samples, which can require extensive work to achieve.
FIB for local site preparation #
FIBs are frequently used to prepare small precise sites for subsequent EBSD analysis. Because the FIB is coupled with a SEM in a FIB-SEM, the combination allows accurate selection of areas of interest.
Broad beam ion milling #
If site selective preparation is not necesssary, broad beam ion mills excel at preparing samples for EBSD. Many broad beam ion mills use Ar-ion beams and include systems to mill the surface with low incidence angles and rotation of the sample to average the beam over large areas. Results for many materials are of high quality.
Ion-beam created issues for EBSD #
While focused and broad ion beams can provide excellent polishes for areas, one needs to be aware that ion beams can induce defects and phase changes in materials. Ion implantation from beams can cause changes in the observed crystallite size and stress.
