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An amorphous Fe73.5Cu1Nb3Si15.5B7 ribbon was pulse annealed continuously under tensile stress by being passed through in an infrared furnace switched on and off repeatedly for preparation of a nanocrystallized toroidal core with controlled permeability. Optimization of the duty ratio D(=Ton/T) of the furnace enabled us to obtain ribbons with low Hc(<10 A/m) and completely developed anisotropy under a high moving velocity of the ribbon, 50 cm/min. ac magnetic properties of a toroidal core, which is made from the pulse-annealed ribbon, at Bm=0.1 T were measured in the frequency range of 0.1–1 MHz. The loss of the prepared core at f=0.1 MHz is 0.50 J/m3, which is lower than those for a gapped ferrite, sendust powder, and amorphous powder core. The relative permeability of approximately 330 was constant up to 1 MHz. These results suggest that the continuous stress annealing by pulse annealing method is one of the hopeful methods for preparation of a long ribbon with excellent magnetic properties. [ABSTRACT FROM AUTHOR]

Dependence of magnetostrictive and magnetic properties on grain size was calculated numerically for an isotropic giant magnetostrictive material. The model magnet assumed is composed of 8000 cubic (Tb0.3Dy0.7)Fe2 grains. The direction of magnetization and the magnetostriction of each grain was determined for a given applied field under the consideration of the anisotropy, exchange, magnetoelastic, elastic, and Zeeman energies. Subsequently, the hysteresis loop and the magnetostriction versus applied field curve was obtained by varying the applied field. With decreasing the grain size D, the coercivity Hc and dλ/dH, where λ is the magnetostriction, decreased abruptly at D=25 nm. This improvement in soft magnetic properties exceeded the expected improvement from Herzer’s calculation, in which Hc was proportional to D6. In order to study the significant improvement in detail, we calculated magnetic and magnetostrictive properties with varying magnetostriction and anisotropy constants. Resultantly, it was clarified that the critical phenomenon occurs when the total of elastic and magnetoelastic energies exceed the magnetic anisotropy energy in magnitude. [ABSTRACT FROM AUTHOR]

Thin composite bonded magnets, 400 ìm in thickness and 140 kJ/m3 in (BH)max under a low compacting pressure such as 20 MPa, were achieved by using the slip-flow phenomenon for self-organization of binder. The mechanical strength of the prepared composite bonded magnets was not deteriorated by thinning, which enabled the preparation of magnets for transformation into smaller radially anisotropic ones. [ABSTRACT FROM AUTHOR]

Presents information on a study which analyzed the magnetic properties of anisotropic nanocomposite magnets using computer simulation. Methodology of the study; Results and discussion.

Abstract: Continuous stress-annealing process (CSA), in which a ribbon under tensile stress passes through a furnace, was carried out for obtaining long Fe–Cu–Nb–Si–B ribbons with creep-induced anisotropy. It was clarified that the creep-induced anisotropy K uc is almost the same in magnitude for the moving velocity v m range of 1–100cm/min at the annealing temperature of 530°C, which suggests that a remarkable reduction in annealing time can be achieved. Furthermore, an increase in annealing temperature enabled us to increase v m up to 275cm/min. Thus, CSA is an attractive method for applying ribbons with creep-induced anisotropy to mass production. [Copyright &y& Elsevier]

Abstract: When a radially anisotropic rare earth bonded magnet for a rotor with a high (BH)max value is magnetized multi-polarly, its flux distributes rectangularly and increases a cogging torque. In order to overcome this difficulty, we newly developed highly dense Sm2Fe17N3 and Nd2Fe14B-based composite bonded magnets with continuously controlled anisotropy directions by using a viscous deformation technique. [Copyright &y& Elsevier]