In situ synchrotron X-ray multimodal experiment to study polycrystal plasticity

Area of Science:

• Materials Science
• Crystallography
• Mechanical Engineering

Background:

• Polycrystalline microstructure significantly impacts structural material performance.
• Advanced characterization methods are crucial for probing microstructural behavior at grain and sub-grain scales.

Purpose of the Study:

• To present and apply in situ diffraction contrast tomography (DCT) and far-field 3D X-ray diffraction (ff-3DXRD) for studying crystal plasticity.
• To analyze the evolution of microstructure and lattice rotations in commercially pure titanium under tensile stress.

Main Methods:

• Utilized in situ DCT and ff-3DXRD at the Psiché beamline (Soleil) with a modified tensile stress rig.
• Performed tensile testing on a titanium specimen up to 1.1% strain, analyzing approximately 2000 grains.
• Employed the 6DTV algorithm for DCT reconstruction and validated results with Electron Backscatter Diffraction (EBSD) and complementary DCT maps.

Main Results:

• Successfully characterized the evolution of lattice rotation across the entire microstructure using DCT reconstructions.
• Validated orientation field measurements in the bulk through comparisons with EBSD and ESRF-ID11 DCT data.
• Identified and discussed challenges at grain boundaries as plastic strain increased during testing.

Conclusions:

• Demonstrated the capability of in situ DCT and ff-3DXRD for detailed microstructural analysis of crystal plasticity.
• Highlighted the potential of ff-3DXRD for acquiring average lattice elastic strain data per grain.
• Proposed future directions including crystal plasticity simulations from DCT data and experimental-simulation comparisons at the grain scale.