Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 22: Focus Session: Magnetism in Materials Science: Thermodynamics, Kinetics and Defects III (joint session MM/MA)

MA 22.1: Topical Talk

Dienstag, 13. März 2018, 11:45–12:15, H 0106

Grain boundary migration and grain growth in non-ferromagnetic metals under the impact of a magnetic field — •Dmitri A. Molodov — Institute of Physical Metallurgy and Metal Physics, RWTH Aachen University, 52056 Aachen, Germany

Grain boundary migration can be induced by a magnetic field, if the anisotropy of the magnetic susceptibility generates a gradient of the magnetic free energy density across the boundary. In contrast to curvature driven boundary motion, a magnetic driving force also acts on planar boundaries so that the motion of crystallographically fully defined boundaries can be investigated. The magnetically driven motion of planar symmetric and asymmetric tilt grain boundaries was studied in high purity bismuth and zinc bicrystals. Boundary migration was measured in-situ by means of a polarization microscopy probe and the corresponding migration activation parameters were obtained. The results revealed that grain boundary mobility essentially depends on the misorientation angle and the inclination of the boundary plane.

As it has been demonstrated in a series of experiments on polycrystalline zinc, titanium and zirconium, as well as by computer simulations, grain growth in magnetically anisotropic non-ferromagnetic materials can be substantially affected by a magnetic field. This manifested itself by significant changes in the development of the grain growth texture during magnetic annealing compared to annealing at zero field. The magnetically induced texture changes are caused by the generation of an additional magnetic driving force for grain growth/shrinkage.