Regensburg 2007 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 36: Nano structured materials IV
MM 36.1: Vortrag
Donnerstag, 29. März 2007, 14:45–15:00, H4
Intrinsic Microstrain in Nanocrystalline Metals — •Jürgen Markmann1, Vesselin Yamakov2, and Jörg Weissmüller1,3 — 1Universität des Saarlandes, FR 7.3 Technische Physik, 66123 Saarbrücken — 2National Institute of Aerospace, Hampton, Virginia 23666, USA — 3Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, Institut für Nanotechnologie, 76344 Eggenstein-Leopoldshafen
Microstrain is often observed as a consequence of plastic deformation of metals and its appearance is usually contributed to the increase of dislocation density after deformation. Interestingly almost all nanocrystalline metals show already a high amount of microstrain in their as-prepared state independent of their synthesis route. This leads to the assumption that microstrain could be an intrinsic property of nanocrystalline metals. To investigate this, defect-free nanocrystalline 3-dimensional microstructures containing between 16 and 1024 grains were thermally relaxed at 300 K by molecular dynamics simulation. X-ray diffractograms were calculated out of the atom positions and the x-ray peak broadening was analysed to determine the average grain size and microstrain. The evaluated grain size is in excellent agreement with the grain size of the starting microstructure. Nevertheless there is a large the amount of microstrain in the relaxed samples. These findings support an intrinsic nature of microstrain in nanocrystalline metals because no extrinsic sources for microstrain in these "samples" exist. A simple model will be presented which can explain this intrinsic microstrain as a function of the grain size.