We introduce a novel method to add grain position, orientation and size information to absorption 3-D x-ray microscope imaging for poly-crystalline samples. This imaging modality will be available on a commercial x-ray microscope and will open the way for routine, non-destructive studies of time-evolution of grain structure to complement destructive EBSD end-point characterization. Grain sizes down to 40 micrometers can be studied using this non-destructive image modality.
Crystallographic imaging (i.e. imaging of crystallites/grains in polycrystalline materials) are primarily known from electron microscopy, and particularly the introduction of the electron back-scattering diffraction (EBSD) technique in the early 1990’s, has made it a routine tool for research and/or development related to metallurgy, functional ceramics, semi-conductors, geology etc. The ability to image the grain structure in such materials is instrumental for understanding and optimization of material properties and processing. However, the destructive nature of 3D EBSD prevents the technique from directly evaluating the microstructure (and grain-orientation) evolution when subject to either mechanical, thermal or other environmental conditions. Non-destructive x-ray diffraction imaging methods allow for such ‘4D’ time dependent studies, and to date have been primarily the domain of a limited number of synchrotron facilities.
Here, we present a novel method to acquire, reconstruct and analyze grain orientation and related information from polycrystalline samples on a commercial laboratory x-ray microscope (ZEISS Xradia 520 Versa) that utilizes a synchrotron-style detection system. Known as laboratory diffraction contrast tomography (DCT), this technique may be efficiently coupled to in situ environments within the microscope or subject to an extended time evolution experiment (across days, weeks, months), which remains a unique strength of laboratory (non-synchrotron) experiments. Following an evolution experiment, the sample may be sent to the electron microscope or focused ion beam (FIB-SEM) for destructive but complementary investigation of the same volume of interest.
We will show a selection of results of laboratory DCT, discuss the boundary conditions of such a method, and point to the future to discuss ways in which this can be correlatively coupled to related techniques for a better understanding of a materials structure evolution in 3D at multiple length scales.