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SYWS: Simulation von Wachstum und Strukturbildung
SYWS 1: Fachsitzung I
SYWS 1.1: Fachvortrag
Thursday, March 29, 2001, 15:15–15:30, S12
The importance of size correlations to grain growth as revealed by phase-field simulation in 3D — •C. E. Krill1, R. Birringer1, L.-Q. Chen2, and D. T. Wu3 — 1FR 7.3 Technische Physik, Universität des Saarlandes, Geb. 43B, Postfach 151150, D-66041 Saarbrücken — 2Dept. of Materials Science and Eng., The Pennsylvania State University, University Park, PA 16802, USA — 3Dept. of Mechanical Eng., Yale University, P.O. Box 208284, New Haven, CT 06520, USA
Normal grain growth in polycrystalline materials is characterized by an increase in the average grain size R according to a power law of the annealing time t and by the establishment of a stationary grain-size distribution f(R/R). Analytic models for grain growth correctly predict the experimental value for the exponent in the dependence of R on t, but they fail to account for the lognormal shape of f. This discrepancy between theory and experiment may arise from the mean-field nature of the analytic models, which ignores the presence of significant nearest-neighbor size correlations in growth-induced microstructures. By extending the phase-field method for simulating grain growth to three dimensions, we were able to generate realistic microstructures for which the size correlations could be quantified. Combined with a recently developed non-mean-field theory for grain growth, the size correlations found by simulation account for the difference between the mean-field and simulated shapes of f(R/R). Surprisingly, the form of the grain-size distribution in simulation deviates strongly from that of experiment, suggesting that current methods for simulating grain growth fail to capture the full richness of the physics underlying this process.