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MM: Fachverband Metall- und Materialphysik

MM 12: Postersitzung I

MM 12.47: Poster

Monday, March 14, 2011, 17:30–19:00, P5

Growth of nanosized ordered domains in nanocrystalline intermetallic FeAl studied by TEM methods — •Christoph Gammer, Clemens Mangler, Hans-Peter Karnthaler, and Christian Rentenberger — University of Vienna, Physics of Nanostructured Materials, Boltzmanngasse 5, 1090 Wien, Austria

Severe plastic deformation of intermetallic compounds leads to the formation of a nanocrystalline structure that is frequently accompanied by a loss of the long range order. Up till now this has been monitored by X-ray methods; here it is shown that Transmission Electron Microscopy (TEM) is able to give additional insight. In this study TEM methods are used to reveal that high pressure torsion deformation of FeAl does not lead to a complete destruction of the chemical order B2. It leads to the formation of a structure of a medium range chemical order, composed by nanosized ordered domains of B2 structure (about 2 nm in size). Upon heating the long-range order is recurring by coarsening of the ordered nanodomains until they reach the grain size. The growth of the nanosized ordered domains is studied by using both TEM dark field images and TEM diffraction patterns. The quantitative evaluation of the diffraction ring patterns is carried out with the PASAD method (www.univie.ac.at/pasad). The results deduced from the images and those achieved by PASAD complement each other very well. Furthermore the present example shows that due to the strong scattering factor electron diffraction patterns can be used to evaluate very weak superlattice reflections.