ZEISS Lunch and Learn at Microscopy & Microanalysis (M&M) 2019

Monday, August 5, 2019 – 12:00 pm - 1:00 pm

Non-destructive 3D Grain Mapping by Laboratory X-ray Diffraction Contrast Tomography
Hrishi Bale, ZEISS

Determining crystallographic microstructure of a given material in 2D can be challenging. Further extending such an investigation to 3D on meaningful volumes (and without sample sectioning) can be even more so. Yet reaching this insight holds tremendous value for 3D materials science since the properties and performance of materials are intricately linked to microstructural morphology including crystal orientation. Achieving direct visualization of 3D crystallographic structure is possible by diffraction contrast tomography (DCT), which was for a long time only available at a limited number of synchrotron X-ray facilities around the world.

Laboratory diffraction contrast tomography (LabDCT) technique with a ZEISS Xradia Versa X-ray microscope opens up a whole new range of possibilities for studies of the effect of 3D crystallography on materials performance in the laboratory. Using a polychromatic X-ray source, LabDCT takes advantage of the Laue focusing effect, improving diffraction signal detection and allows handling of many and closely spaced reflections. Grain morphology, orientation and boundaries of metals, alloys or ceramics can be characterized fully in 3D.

LabDCT opens the way for routine, non-destructive and time-evolution studies of grain structure to complement electron backscatter diffraction (EBSD). Crystallographic imaging is performed routinely by EBSD for metallurgy, functional ceramics, semi-conductors, geology etc. However, in most cases it is difficult for EBSD to investigate microstructure evolution when subject to either mechanical, thermal or other environmental conditions.

The non-destructive nature of LabDCT enables the observation and characterization of microstructural response to stimuli (stress, thermal, radiation) of one and the same sample over time. Combination of LabDCT with conventional absorption contrast imaging enables a wide range of microstructural features to be characterized simultaneously and provides complementary information about the observed microstructure. Aside from introducing the fundamentals of the technique and its implementation on a laboratory scale, we will present a selection of LabDCT applications with particular emphasis on how its non-destructive operation can facilitate a better understanding of the relation between structure and property for polycrystalline materials.

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