Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 56: Phase Transformations II

MM 56.5: Talk

Thursday, March 14, 2013, 12:45–13:00, H26

Impact of the inclination dependence of grain boundary energy on faceting and kinetics of grain boundaries in Aluminum — •Jann-Erik Brandenburg, Dmitri A. Molodov, and Luis A. Barrales-Mora — Institute of Physical Metallurgy and Metal Physics, RWTH-Aachen University

The motion and faceting behaviour of <100> tilt and mixed tilt-twist grain boundaries with misorientations in the range between 4° and 23° were investigated in situ in a scanning electron microscope at elevated temperatures. The results revealed that tilt boundaries with misorientations lower than 15° did not assume a curved shape and did not move under a capillary driving force at any temperature. In contrast, all investigated low angle boundaries with mixed tilt-twist geometry (20° twist component) were observed to attain a smoothly curved shape and moved under a curvature force. Molecular static simulations provided evidence that the experimentally observed behaviour is due to the inclination dependence of grain boundary energy, which is very pronounced for pure tilt (low angle) boundaries but becomes nearly isotropic for mixed boundaries with the same rotation angle. The influence of the energy anisotropy on grain boundary migration during grain growth was investigated by molecular dynamic simulations of shrinking initially circular grains encircled by tilt and mixed boundaries. The results showed an influence of the inclination dependent energy on the shape of the grains during shrinking as well as on the shrinking rate itself.