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MA: Magnetismus
MA 17: Magnetic Materials II
MA 17.11: Talk
Tuesday, March 28, 2006, 12:45–13:00, HSZ 401
Influence of texture on corrosion behaviour of highly anisotropic sintered magnets — •Mihaela Rada1, Annett Gebert1, Irina Mazilu1, Kirill Khlopkov1, Oliver Gutfleisch1, Ludwig Schultz1, and Werner Rodewald2 — 1Leibniz-Institute for Solid State and Materials Research IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany — 2Vacuumschmelze GmbH & Co KG, P.O. Box, D-63412 Hanau, Germany
The anisotropic corrosion behaviour of highly textured sintered Nd-Fe-B magnets in weakly acidic solutions has been evaluated by investigations of magnet surfaces, which are parallel or perpendicular to the crystallographic c-axis of the aligned ferromagnetic grains. The total corrosion process progresses more pronouncedly at the perpendicular magnets surfaces (the pole faces). Under free corrosion and anodic polarization conditions the parallel magnet surfaces exhibit a stronger active dissolution tendency due to an enhanced reactivity of grain surfaces parallel to the (100) plane of the Nd2Fe14B crystals. Single misoriented grains dissolve preferentially at both magnet sides. Under cathodic conditions the hydrogenation process progresses more rapidly at the perpendicular sides, suggesting a local preferential penetration of atomic hydrogen into the material.