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Updated: Feb 8, 2026
13:15
Quantitative and Qualitative Examination of Particle-particle Interactions Using Colloidal Probe Nanoscopy
Published on: July 18, 2014
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An Examination of the Composition and Microstructure of Coarse Intermetallic Particles in AA2099-T8, Including Li
Colin M MacRae1, Anthony E Hughes1, James S Laird1
11CSIRO,Mineral Resources,Bayview Ave,Clayton,3169, Victoria,Australia.
Summary
This study characterized the Al-Cu-Li alloy AA2099-T8 microstructure using advanced electron and proton microprobe techniques. Researchers identified seven intermetallic particle types and mapped lithium distribution, revealing insights into alloy deformation.
Area of Science:
- Materials Science
- Metallurgy
- Solid State Physics
Background:
- Al-Cu-Li alloys are critical in aerospace for their high strength-to-weight ratio.
- Understanding the microstructure of alloys like AA2099-T8 is key to optimizing their performance.
- Intermetallic (IM) particles significantly influence alloy properties and processing behavior.
Purpose of the Study:
- To comprehensively characterize the microstructure of the Al-Cu-Li alloy AA2099-T8.
- To identify and classify the various intermetallic (IM) particles present within the alloy.
- To investigate the distribution of elements, particularly Lithium (Li), and its correlation with microstructure and deformation.
Main Methods:
- Electron probe microanalysis (EPMA) using wavelength-dispersive (WDS) and energy-dispersive X-ray spectrometry (EDS).
- Soft X-ray emission spectroscopy (SXES) for elemental analysis, including light elements like Li.
- Electron backscatter diffraction (EBSD) for crystallographic orientation and misorientation mapping.
- Proton-induced X-ray emission (PIXE) for elemental distribution analysis.
Main Results:
- Seven distinct types of intermetallic (IM) particles were identified, containing combinations of Al, Cu, Fe, Mn, Zn, Ti, B, and Si.
- EBSD confirmed five IM particle types were isomorphous with known phases in 2xxx series aluminum alloys.
- SXES and Al mapping revealed Li presence in some IM particles and an Al-enriched, Cu/Li-depleted zone at grain boundaries.
- EBSD misorientation maps indicated localized deformation or stored energy in the grain boundary regions.
- PIXE analysis showed banding of TiB2 IM particles and copper enrichment between these bands.
Conclusions:
- The study provides a detailed microstructural characterization of AA2099-T8, identifying key intermetallic phases and their elemental compositions.
- The findings highlight the complex distribution of elements and the presence of Li within IM particles.
- Correlations between microstructural features, elemental distribution, and localized deformation suggest implications for alloy performance and failure mechanisms.
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