Diffraction Contrast Tomography in the Laboratory – Applications and Future Directions

Determining 3D crystallographic information holds tremendous value for 3D materials science because the properties and performance of materials are intricately linked to microstructural morphology. Conventional 2D approaches (for example, metallography) have been extended to 3D through serial methods but still require destructive sectioning of sample material. Achieving direct non-destructive visualization of 3D crystallographic structure was first possible by diffraction contrast tomography (DCT) in the early 2000s at synchrotron X-ray facilities; it is today only available at a limited number of sites around the world. Recent developments, however, have made DCT possible on a laboratory X-ray microscope. The first laboratory-based DCT system (LabDCTTM from Carl Zeiss X-ray Microscopy) for 3D grain imaging is now available and includes advanced reconstruction and analysis capabilities [1]. The establishment of DCT into a laboratory setting opens the way for routine, non-destructive, time-evolution studies of grain structure over meaningful sample volumes up to 8 mm3. This extends DCT access beyond the synchrotron and complements electron backscatter diffraction (EBSD) end-point characterization and other crystallographic imaging techniques at finer scales such as TEM-based orientation imaging microscopy. The combination of grain information with microstructural features such as cracks, porosity, and inclusions, all derived non-destructively in 3D, enables materials characterization of damage, deformation, and growth mechanisms. In this article we introduce the LabDCT technique and demonstrate its capabilities through a selection of application examples in materials science. We also discuss innovative methods to extend the current capabilities of the technology.