Dresden 2011 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 29: Topical Session TEM VIII

MM 29.3: Vortrag

Mittwoch, 16. März 2011, 16:15–16:30, IFW B

Quantitative local profile analysis of nanomaterials based on TEM diffraction — •Christoph Gammer, Clemens Mangler, Hans-Peter Karnthaler, and Christian Rentenberger — University of Vienna, Physics of Nanostructured Materials, Boltzmanngasse 5, 1090 Wien, Austria

A method yielding a quantitative profile analysis from selected area electron diffraction patterns (PASAD, www.univie.ac.at/pasad) has been worked out. The results gained by PASAD can be combined with the local information from TEM images to study various nanomaterials. It can be used for the analysis of inhomogeneous materials, ultrathin nanocrystalline films, nanoparticles and nanosized ordered domains. As an example the grain size reduction by thermal annealing in nanocrystalline FeAl is shown in the present study. Nanocrystalline FeAl was made by severe plastic deformation resulting in the loss of the long-range order. Thermal annealing leads to the recurrence of the B2 superstructure, the recovery of dislocations, the sharpening of grain boundaries and an unexpected reduction in grain size. To study these processes, both the coherently scattering domain (CSD) size and the grain size were monitored during annealing by TEM methods. The CSD size was determined using PASAD and the grain size was determined from analysing dark field images: the CSD size increases by a factor of 2 while the grain size is reduced by a factor of 2. It is concluded that the decrease of the grain size during annealing is caused by the re-arrangement of dislocations forming new boundaries, that is linked to the recurrence of the long-range order.