Dresden 2006 – wissenschaftliches Programm

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MM: Metall- und Materialphysik

MM 34: Symposium Materials Modelling III

MM 34.3: Vortrag

Donnerstag, 30. März 2006, 17:30–17:45, IFW A

Using the phase-field method to treat large scale grain growth problems — •Frank Wendler and Britta Nestler — University of Applied Sciences Karlsruhe, Moltkestr. 30, 76133 Karlsruhe

A multi-phase-field model formerly introduced allows the treatment of free boundary problems with complex interface morphologies, where the phase-fields (order parameters) define diffuse interfaces between adjacent phases. Anisotropy in surface energies and kinetic coefficients of the crystalline phases enable the modelling of polycrystals where each grain is represented by a different phase. In the talk special attention is given to grain structures and polycrystals, with applications in alloy solidification as well as geology. Correctly choosen thermophysical and numerical parameters for the binary Ni-Cu alloy system allow for quantitative simulations, initiated with a high number of differently oriented seed crystals growing into an undercooled melt. When starting from a domain wall, selection processes depending on undercooling and distribution of crystal orientations were found and compared for 2D and 3D simulations. Secondly, the seeds are randomly distributed in the simulation domain to mimic homogeneous nucleation. In each case after a complete solidification the resulting polycrystal shows characteristic morphologies, directed by selection processes and grain orientation relationships. Additionally, the influence of a convective melt flow is shown. As a final processing step, grain coarsening at increased temperature is simulated and characteristic relations for grain size and orientational evolution were found.