Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures

Area of Science:

• Materials Science
• Crystallography
• Neutron Scattering

Background:

• Polycrystalline material properties are dictated by their complex microstructure.
• Understanding grain shape, phase, orientation, and interfaces is crucial for materials characterization.
• Existing X-ray diffraction techniques have limitations in sample size and material composition.

Purpose of the Study:

• To introduce and validate a novel non-destructive 3D neutron diffraction technique.
• To enable the study of centimeter-sized bulk samples with micrometer spatial resolution.
• To overcome limitations of existing X-ray diffraction methods for larger and heavier samples.

Main Methods:

• Development and implementation of time-of-flight three-dimensional neutron diffraction (ToF 3DND).
• Utilizing an imaging detector with high spatial and temporal resolution at a neutron beamline.
• Testing the technique on an iron sample at the Japan Proton Accelerator Complex (J-PARC).

Main Results:

• Successful reconstruction of the shape and orientation of 108 grains in an iron sample.
• Development of a robust indexing procedure for grain analysis.
• Validation of reconstruction algorithms using stacked Co-Ni-Ga single crystals and comparison with EBSD.

Conclusions:

• Time-of-flight 3D neutron diffraction (ToF 3DND) is a powerful technique for microstructural analysis.
• The method allows for larger sample sizes and heavier elements compared to X-ray methods.
• ToF 3DND is adaptable to complex sample environments, broadening its applicability in materials research.