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MM: Fachverband Metall- und Materialphysik
MM 23: Phase Transformations I
MM 23.6: Vortrag
Mittwoch, 16. März 2011, 12:15–12:30, IFW D
Surface studies of Fe polycrystals with LEEM — •Benjamin Borkenhagen1, Thorsten Franz2, Gerhard Lilienkamp1, and Winfried Daum1 — 1IEPT, TU Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld — 2ELMITEC GmbH, Albrecht-von-Grodeck-Str. 3, 38678 Clausthal-Zellerfeld
Low energy electron microscopy (LEEM) has been proven a versalite tool for studies on single crystal surfaces. In this contribution, we present the application of LEEM to study the microstructure and processes on surfaces of polycrystals. The additional capability of this microscope to acquire low energy electron diffraction patterns of crystallites (µ-LEED) allowed us to distinguish between different crystallographic surface structures. We observed atomically flat terraces separated by monoatomic steps as well as facetted surfaces. Islands with regular shapes were detected at the surfaces of some crystallites. In situ investigations during heating of the polycrystal showed that these islands were bulk impurities which segregated to the surface, or diffused back to the bulk depending on temperature. Parallel imaging of the whole field by LEEM enabled the observation of dynamic processes such as grain boundary motion and segregation processes at elevated temperatures.