EBSDt

EBSDt, or electron backscatter diffraction tomography, is a three-dimensional crystallographic orientation mapping technique that combines conventional EBSD with serial sectioning or milling to reconstruct the 3D grain structure of polycrystalline materials. By collecting two-dimensional EBSD maps from successive slices and aligning the datasets, EBSDt yields a volumetric description of grain shapes, boundaries, and orientations.

Procedure: In practice, samples are prepared for sectional removal, typically by focused ion beam milling or mechanical polishing followed by sequential thinning. After each layer is removed, an EBSD map is acquired in an SEM. The orientation data are registered and interpolated to produce a coherent 3D dataset. Grain boundaries are tracked across sections to form a 3D grain network, enabling calculation of grain volume, boundary misorientations, and local texture.

Applications: EBSDt is used to study grain evolution during deformation, annealing, and phase transformations, and to assess texture development in metals, ceramics, and geological materials. It supports investigations of 3D grain topology, grain growth kinetics, and the relationship between processing routes and microstructure.

Advantages and limitations: The technique provides direct 3D microstructural information unattainable with 2D EBSD alone. Limitations include long acquisition times, potential milling artefacts, restricted sampling volume depending on slice thickness and SEM accessibility, and the need for robust alignment and segmentation algorithms.

Variations: EBSDt methods are implemented with FIB-SEM platforms and can be combined with automatic milling and software packages for 3D reconstruction and visualization.