SKM 2023 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 26: Interface Controlled Properties and Nanomaterials: Grain Boundaries and Stability, Spectroscopy and Interatomic Potentials
MM 26.2: Talk
Wednesday, March 29, 2023, 10:30–10:45, SCH A 216
When grains go wild! Tracing microstructural outcomes back to possible mechanisms for abnormal grain growth — •Carl E. Krill III1, Elizabeth A. Holm2, Jules M. Dake1, Ryan Cohn2, Karolína Holíková1, and Fabian Andorfer1 — 1Ulm University, Ulm, Germany — 2Carnegie Mellon University, Pittsburgh, PA, USA
Usually, the coarsening of a polycrystalline material is a civilized affair, with adjacent grains swiping atoms so surreptitiously that relative growth rates remain moderate, and the mutual boundary stays smooth. In some cases, however, certain participants in this competition give free rein to an innate hunger for growth! The result is a subpopulation of large, “abnormal” crystallites embedded in a matrix of much smaller grains, whereby the abnormal/matrix interface can be anywhere from perfectly flat to fractally convoluted. The formation of such a microstructure is the telltale signature of abnormal grain growth (AGG). Although the most prominent feature of AGG is the shape of the abnormal grains, simulations indicate that the mechanism of AGG is encoded to a greater extent in the morphology of the interfaces between abnormal and matrix grains. Based on this finding, we propose a scheme for inferring the possible mechanism(s) underlying any experimentally observed case of (sufficiently extreme) AGG, and we illustrate our phenomenological method with experimental examples taken from the literature. Surprisingly, in the most clear-cut cases of AGG we have encountered, microstructural outcomes point to boundary-to-boundary mobility variation as the sole governing factor.