Berlin 2005 – wissenschaftliches Programm

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M: Metallphysik

M 32: Poster TU B (Symposium Tomographic Methods in Materials Research M-32.32-55)

M 32.40: Poster

Montag, 7. März 2005, 14:30–16:30, Poster TU B

New aspects of the decomposition in CuCo observed with different field ionisation-based tomographic techniques — •Alexander Heinrich, Talaat Al-Kassab und Reiner Kirchheim — Institut für Materialphysik, Friedrich-Hund-Platz 1, 37077 Göttingen

CuCo has been of great interest as an ideal model system for decomposition in binary alloys. Specimen of Cu2at.%Co have been examined using the Tomographic Atom Probe (TAP), Field Ion Microscopy (FIM) and a recently developed method for Field Ion Image Tomography (FIIT). In this method sequences of field evaporation images are digitally registered. A three dimensional reconstruction of the imaged volume is followed via an advanced algorithm. This enables the examination of large analysis volumes with respect to the volume analysed in the TAP. New aspects of the decomposition behaviour at lower annealing temperatures (703K and 763K) could be observed with this technique. Nucleation is observed initially along the elastic soft direction in Cu, forming needle-shaped precipitates which are subsequently subject to coarsening reactions. In contrast to this phase separation at higher annealing temperatures (853K) was observed to take a different path of decomposition. Small agglomerates of atoms form which then coarsen to larger precipitates. The results will be discussed in terms of phase decomposition theory.