Elemental electron energy loss mapping of a precipitate in a multi-component aluminium alloy

• Atomistic characterization of precipitates for industrially important Al alloys.
• The investigations were executed by combining EELS and HAADF-STEM.
• Atomic columns of mixed elements within the precipitate were discovered.
• The hexagonal ordering of Si and Mg columns was verified.
• The Al fcc lattice could be resolved by both methods.

The elemental distribution of a precipitate cross section, situated in a lean Al-Mg-Si-Cu-Ag-Ge alloy, has been investigated in detail by electron energy loss spectroscopy (EELS) and aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). A correlative analysis of the EELS data is connected to the results and discussed in detail. The energy loss maps for all relevant elements were recorded simultaneously. The good spatial resolution allows elemental distribution to be evaluated, such as by correlation functions, in addition to being compared with the HAADF image.The fcc-Al lattice and the hexagonal Si-network within the precipitates were resolved by EELS. The combination of EELS and HAADF-STEM demonstrated that some atomic columns consist of mixed elements, a result that would be very uncertain based on one of the techniques alone. EELS elemental mapping combined with a correlative analysis have great potential for identification and quantification of small amounts of elements at the atomic scale.