Dresden 2006 – wissenschaftliches Programm

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MM: Metall- und Materialphysik

MM 15: Hydrogen in Metals II

MM 15.1: Vortrag

Dienstag, 28. März 2006, 11:45–12:00, IFW D

Surface morphology changes and time dependency of hydride formation in thin epitaxial Nb-films — •Kai Nörthemann, Reiner Kirchheim, and Astrid Pundt — Institut für Materialphysik, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen

The growth and arrangement of precipitates in thin epitaxial films is presented in this contribution, using the model system Niobium-Hydrogen.

With the surface sensitive scanning tunneling microscopy (STM) it is possible to distinguish between matrix and precipitates because of the different lattice parameter of niobium and niobium hydride. The STM measurements of thin epitaxial niobium films are taken during hydrogen loading, therefore the time dependency of the hydride formation and the orientation of the hydride can be examined. Two different types of hydride precipitates were found. Their appearance will be discussed. Their expansion is fitted to a Johnson-Mehl-Avrami kinetic. The stability of the α-phase and the hydride in the two phase field will be discussed.

This work is financially supported by the DFG via SFB 602.