Reverse engineering the kinetics of grain growth using time-resolved 3DXRD microscopy

14:00 - 15:00
Prof. Carl E. Krill III
Institute of Functional Nanosystems, Universität Ulm
Kerstin Höllerer
Although grain growth has been studied in polycrystalline materials for nearly a
century, our understanding of the underlying mechanisms remains incomplete. Even
in the case of normal grain growth, computer simulations of this phenomenon differ
significantly from experimental findings. For example, grain size distributions
observed in real materials tend to be less symmetric than those predicted by
simulations operating under the assumption of isotropic boundary properties, and
discrepancies between the measured and simulated evolution of individual grains can
be particularly pronounced. Instead of modeling grain growth in the conventional
manner using boundary parameters derived from physical principles, we elected to
try the opposite approach: i.e., to work backwards from experimental measurements
to the kinetics of individual grain boundaries. Employing 3D x-ray diffraction (3DXRD)
microscopy, we investigated thermally induced grain growth in two different Al alloys.
In a series of microstructural snapshots taken between isothermal annealing steps,
we followed the morphology, misorientation and migration of thousands of
boundaries in a single sample, acquiring the basis for a robust statistical analysis of
local growth kinetics. The results make it feasible to extract dependencies of reduced
mobility (the product of boundary mobility and energy) on grain boundary
misorientation and inclination. In one particular specimen, these dependencies are
consistent with expectations for normal grain growth, but, in the other case, we find
evidence for abnormal kinetics that do not fit standard models.

Letztmalig verändert: 16.08.2019, 22:06:23


Leibniz Institut für Festkörper- und Werkstoffforschung Dresden (A1E.10, Hörsaal, IFW Dresden)Helmholtzstraße2001069Dresden


Leibniz Institut für Festkörper- und Werkstoffforschung DresdenHelmholtzstraße2001069Dresden
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