Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 26: Poster Session

MM 26.70: Poster

Dienstag, 23. März 2010, 14:45–16:30, Poster C

A phase-field model for polycrystalline grain growth on thin films — •Christian Mennerich, Frank Wendler, and Britta Nestler — Karlsruhe University of Applied Sciences, Karlsruhe, Germany

Polycrystalline grain growth on thin films is of high interest for catalytic active supports or molecular sieves (e.g. zeolites of the MFI-type). Growth competition between the grains determines the final structure of the film and therefore its properties. It is essential to understand the basic principles controlling the selection mechanisms. A phase-field model is presented to describe competitive grain growth on thin films in 2D and 3D. The model is derived from a free energy functional of Ginzburg-Landau type and supports different anisotropy functions to represent various crystal symmetries. The anisotropy is based either on surface energetic or kinetic considerations. As an example, we show results from coffin shaped crystal structures with a fixed aspect ratio competing on thin films. We focus on mechanisms related to the deviation of grain orientations from the film normal. This leads to the outgrowth and extinction of disadvantageously oriented grains, depending on their neighbourhood.