Advancing characterisation with statistics from correlative electron diffraction and X-ray spectroscopy, in the...

Area of Science:

• Materials Science
• Metallurgy
• Microstructure Characterization

Background:

• Accurate identification of minor phases is crucial for alloy development and understanding material degradation.
• Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) are key characterization techniques.
• Principal component analysis (PCA) is an emerging 'big data' approach for analyzing complex material datasets.

Purpose of the Study:

• To develop an advanced correlative method for routine and unique determination of minor phases in microstructures.
• To enhance the signal-to-noise ratio for identifying very small phases, especially when individual EDS or EBSD signals are ambiguous.
• To improve the characterization of carbide phase shape, size, location, and distribution in superalloys.

Main Methods:

• Utilizing a scanning electron microscope (SEM) for simultaneous energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) data acquisition.
• Applying a novel weighted principal component analysis (PCA) approach to concurrently analyze EDS (chemistry) and EBSD (crystal structure) signals.
• Rotating principal components to control variance distribution for physically meaningful signal interpretation.

Main Results:

• The weighted PCA method successfully integrates EDS and EBSD data for phase labeling.
• The technique amplifies signal-to-noise, enabling the classification of previously difficult-to-identify small phases.
• Improved characterization of microstructural features, including carbide phases in superalloys, was achieved.

Conclusions:

• The developed weighted PCA method offers a significant advancement in microstructure analysis.
• Concurrent use of EDS and EBSD data provides a more robust and accurate approach to phase identification.
• This correlative technique is vital for materials science, impacting alloy design and performance assessment.