Regensburg 2004 – wissenschaftliches Programm

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M: Metallphysik

M 4: Flüssige und amorphe Metalle II

M 4.4: Vortrag

Montag, 8. März 2004, 12:30–12:45, H16

A Multiscale 3D Simulator for Dendritic and Eutectic Structure Formation — •Frank Wendler and Britta Nestler — University of Applied Sciences Karlsruhe, Germany

Diffuse interface models allow for an effective computational treatment of free boundary problems with complicated interface morphology. Here different solidification phenomena of pure metals, binary and ternary alloys are studied relying upon the formerly introduced multi-phase-field model [1,2].

After an appropriate choice of thermophysical and numerical parameters, quantitative 2D and 3D calculations of dendritic solidification in a pure melt (Ni) and in binary (Ni-Cu) and ternary alloys were performed. The following analysis of the simulation data provides the dynamical and geometrical parameters. For the dendritic phases these quantities are the tip speed, the tip radius and the primary arm spacing, which are compared with theoretical and experimental data. Also, a strong influence of the interplay between kinetic and surface anisotropy on the dendrite morphology is observed. Smooth anisotropic and facetted patterns are simulated and compared. For the examined binary and ternary eutectic systems, characteristic lamellae spacings are found and related to the classical theory of Jackson and Hunt and to a new analytical extensions of this theory for ternary systems.

[1] B. Nestler, A.A. Wheeler, Physica D 138 (2000) 114-133

[2] H. Garcke, B. Nestler und B. Stinner, SIAM J. on Appl. Math., in print