3-DIMENSIONAL NANOANALYSIS WITH THE TOMOGRAPHIC ATOM-PROBE

The tomographic atom-probe is a nanoanalytical instrument which provid es three-dimensional maps of chemical heterogeneities in a metallic ma terial on a subnanometric scale. The basic principle of this new gener ation of apparatus relies on the field evaporation and ionisation of m aterial atoms and the localization of generated ions on a position-sen sitive multidetector. Chemical species are identified by time-of-fligh t mass spectrometry. Local chemical composition in a small selected re gion of the reconstructed volume (10 x 10 x 1000 nm(3)) may be therefo re quantitatively measured. Illustrations of performance of this new g eneration of apparatus are given (GP zones in Al Cu, precipitation and ordering in two-phase gamma/gamma' NiCrAl single crystal alloys).