How complex is the microstructure of AA2024-T3?

Polished AA2024-T3 was characterised using wavelength and energy dispersive X-ray spectroscopies on an electron microprobe. The hyperspectral datasets were processed by first partitioning the map into distinct chemical phases based on counting statistics and then the phases within the map were sorted into a hierarchical tree, where “chemically-like” phases are in the same branch of the tree. Using this method, nine distinct compositions were identified including the alloy matrix. Many intermetallic particles were “multiphase” in that they contained more than one composition indicating very heterogeneous precipitation processes. Particle size distributions are reported for each composition and clustering behaviour of the intermetallic particles was also examined.