Dresden 2006 – scientific programme

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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.