Berlin 2015 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 39: Methods in Computational Materials Modelling V: Kinetics and Beyond DFT
MM 39.3: Talk
Wednesday, March 18, 2015, 16:15–16:30, H 0106
Simulation of fractal abnormal grain growth in nanocrystalline materials — •Mingyan Wang1, Jules Dake1, Rainer Birringer2, and Carl Krill1 — 1Ulm University, Germany — 2University of the Saarland, Germany
Despite an implicit rarity in its name, abnormal grain growth (AGG) appears to be a common mode of coarsening in nanocrystalline materials regardless of the specimen's composition or synthesis route. During AGG, a subpopulation of grains manifests rapid growth, leading to grain volumes that not only are much larger than those of their neighbors, but also are sometimes highly irregular in shape. The nature of this irregularity can be described by the geometric concept of fractals. This fractal morphology suggests that, in certain cases, AGG might proceed by some kind of percolation process along the ``grid'' defined by the initial ensemble of grains. We have investigated this possibility by extending a phase field algorithm for simulating grain growth to include selection rules for percolation. For properly chosen parameter values, the abnormal grains generated by simulation can be strikingly similar in shape to their experimental counterparts. Quantifying the comparison between simulation and experiment by fractal dimensionality, we hope to gain insight into at least one of the underlying physical mechanisms behind AGG in nanocrystalline materials.