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MM: Fachverband Metall- und Materialphysik

MM 21: Topical Session: Thermodynamics at the nano scale I - Kinetics, nucleation, grain growth, segregation

MM 21.2: Vortrag

Dienstag, 1. April 2014, 10:45–11:00, BAR 205

Observing steady-state coarsening: From nanocrystalline to normal grain growth — •Dana Zöllner and Peter Streitenberger — Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany

It is well-known that normal grain growth is characterized by a parabolic growth law and self-similar scaling resulting in a universal, time-independent grain size distribution as well as in a self-similar topology of the polycrystalline grain microstructure. In the present work we show by theoretical considerations and modified Potts model simulations that self-similarity is also a feature of junction controlled grain growth as it can be found in nanocrystalline materials.

To this aim, the influence of the grain junctions - boundary faces, triple lines and quadruple points - on the growth kinetics is analyzed by attributing each type of boundary junction an own specific energy and mobility. This strategy results in nine size-dependent types of growth kinetics, each characterized by a self-similar scaling form of the growth law and corresponding self-similar grain size distributions. For the three limiting cases of grain growth controlled by the specific grain boundary energy in conjunction with the mobility of grain boundaries, triple lines or quadruple points the analytical results are in good agreement with those obtained by Potts model simulations. In particular, we show that triple and quadruple junction controlled coarsening is characterized by a series of quasi-steady-states reaching for long-time annealing the characteristics of normal grain growth.