Electron backscatter diffraction

Electron backscatter diffraction (EBSD) is a microstructural-crystallographic characterisation technique to study any crystalline or polycrystalline material. The technique involves understanding the structure, crystal orientation and phase of materials in the Scanning Electron Microscope (SEM). Typically it is used to explore microstructures, revealing texture, defects, grain morphology and deformation. It can be combined with complementary techniques within the SEM for phase discrimination. Traditionally these types of studies have been carried out using X-ray diffraction (XRD), neutron diffraction and/or electron diffraction in a TEM.

Experimentally EBSD is conducted using a SEM equipped with an EBSD detector containing at least a phosphor screen, compact lens and low light CCD camera. Commercially available EBSD systems typically come with one of two different CCD cameras: for fast measurements the CCD chip has a native resolution of 640×480 pixels; for slower, and more sensitive measurements, the CCD chip resolution can go up to 1600×1200 pixels. The biggest advantage of the high-resolution detectors is their higher sensitivity and therefore the information within each diffraction pattern can be analysed in more detail. For texture and orientation measurements, the diffraction patterns are binned in order to reduce their size and reduce computational times. Modern EBSD systems can index patterns at up to 1800 patterns / second. This enables very rapid and rich microstructural maps to be generated.