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MA: Fachverband Magnetismus

MA 25: Micro- and Nanostructured Magnetic Materials II

MA 25.12: Talk

Wednesday, March 25, 2009, 17:45–18:00, HSZ 403

Magnetic single-phase behaviour of die-upset magnets made from µm-sized Nd₂Fe₁₄B and Fe-particles — •Juliane Thielsch, Dietrich Hinz, Konrad Gueth, Oliver Gutfleisch, and Ludwig Schultz — IFW Dresden, Institute for Metallic Materials, P.O. Box 27 01 16, D-01171 Dresden, Germany

Textured composite magnets containing hard magnetic NdFeB and soft magnetic α-Fe were produced by hot pressing and subsequent die upsetting. As starting material NdFeB melt spun ribbons (MQU-F) and µm-sized Fe-particles were blended in varying compositions from a NdFeB:Fe-weight ratio of 100:0 to 70:30. The addition of Fe leads to a drastic decrease in coercivity from 13.20 kOe for pure NdFeB ribbons to 1.54 kOe for a sample with 30 wt-% Fe but has surprisingly almost no influence on the remanence. In contrast values for saturation magnetisation increase with larger amounts of Fe. The diameter of the Fe-particles exceeds by far the maximum length of effective exchange interactions. Therefore magnetostatic coupling between the two phases is proposed to explain the magnetic single-phase hysteresis behaviour when measured along the nominal easy direction of magnetisation. Measurements along the hard direction of magnetisation show two-step curves. SEM and Kerr investigations were carried out to investigate phase distribution and coupling.