Optimizing laboratory X-ray diffraction contrast tomography for grain structure characterization of pure iron

Area of Science:

• Materials Science
• Crystallography
• X-ray Physics

Background:

• Laboratory diffraction contrast tomography (LabDCT) is an emerging technique for non-destructive 3D grain mapping.
• It utilizes a laboratory-based X-ray source and a conical polychromatic beam.

Purpose of the Study:

• To quantify the impact of experimental parameters on 3D grain structure characterization using LabDCT.
• To provide recommendations for optimizing LabDCT experiments and 3D volume reconstruction.

Main Methods:

• Experiments were performed on an iron sample using a ZEISS Xradia 520 Versa with a LabDCT module.
• Data analysis involved the GrainMapper3D software for 3D reconstruction from binarized 2D diffraction patterns.
• Forward simulations were used to assess the effect of projection numbers.

Main Results:

• Exposure time critically influences background noise and the detection of small grain diffraction spots.
• As few as 30-40 projections are sufficient for accurate crystallographic orientation indexing and grain shape resolution.
• Electron current is more influential than accelerating voltage for optimizing photon flux in the 20-60 keV range.

Conclusions:

• Optimizing exposure time and projection count enhances 3D grain mapping accuracy.
• Electron current is a key parameter for maximizing photon flux in relevant energy ranges for metals like iron and aluminum.
• The study offers practical guidance for improving LabDCT experimental design and data reconstruction.