Dresden 2009 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 35: Poster Session II
MM 35.30: Poster
Mittwoch, 25. März 2009, 16:30–18:30, P4
Experimental determination of excess energy contributions in nanocrystalline Pd — •Matthias Wegner1, Markus Ames2, Jürgen Markmann2, Jörg Schmauch2, Gerhard Wilde1, and Rainer Birringer2 — 1Universität Münster, Institut für Materialphysik, 48149 Münster, Germany — 2Universität des Saarlandes, Technische Physik, 66041 Saarbrücken, Germany
Nanocrystalline materials with grain sizes considerably below 100nm are characterized by significant contributions of grain boundaries and triple lines to the overall energetics. Until today, the magnitude of triple line energies is unknown and even the sign of their excess energy contribution is discussed. In this contribution, a method is indicated that investigates the excess contributions of grain boundaries and triple junctions for inert gas condensed (IGC) Palladium (Pd) with an average grain size of about 10 nm by micro calorimetric and micro structural investigations. Measurements were done simultaneously at room temperature (23 °C) on two identical halves of the same sample in order to correlate both experiments. A reduction of microstrain and grain coarsening accompanied by annihilation of grain interfaces are observed, which lead to a reduction of free energy. The results and the influence of different geometric grain models underlying the analysis are also discussed in the presented work.