Electron Backscatter Diffraction

What is Electron Backscatter Diffraction (EBSD)?

Electron Backscatter Diffraction (EBSD) is a scanning electron microscope (SEM) based technique, which enables a sample’s microstructure to be analysed, visualised and quantified.

Although EBSD is the most common acronym to describe the technique, it is also sometimes referred to as “EBSP” (strictly meaning the electron backscatter diffraction pattern) or “BKD” (backscatter Kikuchi diffraction).

This website describes the principles of EBSD, highlights ways in which EBSD and associated techniques are used, covers the main applications of EBSD and provides useful information to help researchers use an EBSD system and to interpret their results. The tabs below introduce you to various aspects of the EBSD technique.

EBSD map of a partially recrystallised Ni sample, showing deformation within grains and the CSL boundary distribution

Typical EBSD Map, showing the internal deformation within grains in a partially recrystallised Ni sample, as well as the distribution of coincident site lattice (CSL) boundaries. This dataset took 15 minutes to collect, containing >3 million individual measurements.

Microstructure is the internal structure of a material investigated on the microscopic scale. It is of interest because a material’s internal features (or structure) will influence its properties and behaviour. The term ‘microstructure’ includes the identification and characterisation of grain populations, the investigation of the different phases or compounds in the material, the characterisation of the spatial distribution of elements and the analysis of the nature of interfaces between and within grains.

Characterising microstructure is fundamental for a complete understanding of a material and its performance. Material processing will govern the creation of the microstructure, which in turn influences the properties of the material. Therefore, understanding the microstructure of a material is increasingly important in a large range of industries and research areas; this includes metals research and processing, advanced manufacturing techniques, renewable energy and solar cell development, developments in microelectronics and geological research.

EBSD is a well-established accessory for the SEM, which is used for characterising microstructure. The data collected with EBSD are spatially distributed and can be visualised in maps and images, enabling detailed examination of localised features in heterogeneous samples. EBSD is a highly automated technique with modern commercial systems capable of analysing many 1000s of diffraction patterns every second: this makes it possible to scan, with high spatial resolution, across the surface of a sample and to collect all the necessary data for a full microstructural characterisation.

EBSD provides detailed information about the crystallographic nature of the sample at the point at which the electron beam strikes the sample surface; the technique is often integrated with energy dispersive X-ray spectrometry (EDS), a complementary analytical tool that measures sample composition, so integrated EBSD and EDS measurements provide a comprehensive characterisation of the microstructure, including:

Phase identification
Phase distribution
Grain size data
Boundary characterisation
Texture (degree of crystallographic preferred orientation)
Local strain variation

All of this can be derived from a single EBSD dataset, with a spatial resolution down to the nm scale and with sample analysis areas covering many mm². More details about the information provided by EBSD and associated applications can be found here.

In EBSD, a stationary electron beam interacts with a tilted crystalline sample and the diffracted electrons form a pattern that can be detected with a fluorescent screen (the full details of EBSD pattern formation can be found here). The diffraction pattern is characteristic of the crystal structure and orientation at the point (or volume) where the electron beam interacts with the sample. Hence the diffraction pattern can be used to determine the crystal orientation, discriminate between crystallographically different phases, characterise grain boundaries and provide information about the local crystalline perfection.

When the electron beam is scanned in a grid across a polycrystalline sample and the crystal orientation is measured at each point, the resulting map reveals the grain morphology, orientations and boundaries. These data can also be used to show the preferred crystal orientation (i.e. texture) within the sample. Thus a complete and quantitative representation of the microstructure can be readily established with EBSD.

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