Unlocking Nanoscale Microstructural Detail in Aluminum Alloys Through Differential Phase Contrast Segmentation in...

Area of Science:

• Materials Science
• Physics
• Nanotechnology

Background:

• Differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM) typically maps electric/magnetic fields at atomic resolution.
• Its application for rapid materials characterization and nanoscale image segmentation is underexplored.

Purpose of the Study:

• To demonstrate STEM-DPC as a rapid tool for micro and nanoscale image segmentation in advanced aluminum alloys.
• To showcase its capability in identifying and quantifying diverse microstructural features and strain fields.

Main Methods:

• Utilized STEM-DPC imaging with segmented low-angle detectors to map projected electric/magnetic fields.
• Employed hue-saturation-value decomposition of DPC micrographs for feature identification.
• Integrated DPC with neural network segmentation for automated analysis.
• Correlated DPC with STEM-Energy Dispersive X-ray Spectroscopy (EDX) for microstructural analysis.

Main Results:

• Successfully segmented and quantified nanoclusters, GP zones, precipitate phases, dislocation cores, and strain fields in various aluminum alloys.
• Demonstrated phase-variant segmentation in AA7075-T7 and nanopore/nanoparticle detection in AA2024-T3.
• Achieved automated grain boundary delineation in nanocrystalline aluminum thin films via coupled DPC and neural networks.

Conclusions:

• STEM-DPC is a rapid and effective tool for microstructural segmentation and characterization of advanced aluminum alloys.
• It complements existing techniques like SPED and 4D-STEM for correlative analysis.
• The method enables simultaneous identification of multiple nanoscale features and strain fields within a single field of view.