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MM: Fachverband Metall- und Materialphysik

MM 11: Growth

MM 11.6: Vortrag

Montag, 23. März 2009, 16:00–16:15, IFW D

Theory of dendritic growth in the presence of lattice strain — Efim A. Brener, •Claas Hüter, and Denis Pilipenko — Institut für Festkörperforschung, Forschungszentrum 52425 Jülich

The need to understand the dominating phenomena during solid-solid transitions as they occur in various processes of industrial relevance is apparent.

Elastic effects as they occur due to lattice strain modify the local equilibrium condition at the solid-solid interface compared to classical dendritic growth. Both, the thermal and the elastic fields are eliminated by Green's function techniques and a closed nonlinear integro-differential equation for the interface is derived. In the case of pure dilatation, the elastic effects lead only to a trivial shift of the transition temperature while in the case of the discussed shear transitions and superposition of these basic lattice strains, dendritic patterns are found even for isotropic surface energy. Of course, the discussed elastic effects also introduce an "effective anisotropy`` of the system. However, the physics and structure of selection theory for the two mechanisms, anisotropy of surface energy and elastic effects, are fundamentally different. Elastic effects lead to a much more robust selection mechanism compared to tiny effects of anisotropy of surface energy. Moreover, the growth velocities for the same effective driving force can reach appreciably larger values than in the case of selection via anisotropy of surface energy.