Dresden 2011 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 7: Surface Dynamics I
O 7.2: Vortrag
Montag, 14. März 2011, 11:30–11:45, WIL C107
LEEM study of segregation and diffusion of impurities at Fe polycrystal surfaces — •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
Surface properties of applied materials are frequently related to microstructural properties such as texture, grain boundaries and stacking faults in polycrystals. The application of methods providing information on surface crystallography and topography with sub-grain lateral resolution is a most promising route for the surface characterization of such materials. Recently we have demonstrated that low energy electron microscopy (LEEM) is well suited to image surfaces of crystallites and grain boundaries intersecting the surface of polycrystals. In this contribution we report on our application of LEEM to monitor segregation and diffusion processes at the surface of polycrystalline Fe samples. During thermal treatment of the Fe polycrystal, we observed formation of islands which consisted of bulk impurities segregated to the surfaces of the crystallites. Depending on temperature ramp and surface orientation of the crystallites, different shapes of these islands were observed. At elevated temperatures Ostwald ripening of the impurity islands occurred. Increasing the temperature even more caused dissolution of these islands via diffusion into the bulk of the polycrystal, mainly along grain boundaries. In the majority of these transformations the polycrystalline texture remained unaffected by segregation and diffusion processes, but we also observed grain boundary motion.