Dresden 2006 – wissenschaftliches Programm

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MM: Metall- und Materialphysik

MM 25: Poster Session

MM 25.30: Poster

Mittwoch, 29. März 2006, 15:30–17:30, P4

Grain boundary and triple junction excess energy in nanocrystalline Gadolinium — •Stella Oldenbürger and Rainer Birringer — Universität des Saarlandes, FR 7.3 Technische Physik, Geb.D2.3, D-66123 Saarbrücken

Nanostructured materials are commonly used to investigate the influence of grain boundaries on macroscopic properties of polycrystalline materials. In a recent study on the grain size dependence of the lattice parameters of nanocrystalline Gadolinium it was found that, in addition to the grain boundary stress, a contribution of stress due to triple junctions had to be taken into account at grain sizes smaller than 10 nm. This result indicates that nanostructured Gadolinium is a candidate material to investigate the nature and behaviour of triple junctions. The aim of the present study is to determine the excess energy of the grain boundaries and triple junctions in nanocrystalline Gadolinium prepared by inert gas condensation. The excess energies of the samples are obtained by a sequence of isothermal calorimetric measurements at increasing temperatures. After each heating step, the average grain size is determined by X-ray diffraction. The contributions of the grain boundaries and the triple junctions to the excess energy are separated by a scaling analysis.