Y. Yamashiro

Magnetic properties of rapidly quenched silicon-iron ribbons

Abstract Preparation conditions and magnetic properties of rapidly quenched silicon-iron ribbons containing 4.5–6.5% Si have been investigated. The tensile strength and ductility of high silicon-iron alloys are improved by forming them into ribbons. The maximum permeability of 18 000 and the minimum coercive force of 0.27 Oe can be obtained for the specimen of 6.5% Si-Fe with 90 μm thickness. The magnetic properties are improved by oil-quenching at 700°C after annealing at 1100°C for 1 h at the air pressure of 10-5 Torr.

Microstructure and some magnetic properties of amorphous and nanocrystalline Fe-Cu-Nb-Si-B alloys

Abstract The microstructure and magnetic properties, i.e. saturation magnetic polarization, initial magnetic susceptibility and its disaccommodation, for the amorphous and the partially crystallized Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 ribbons aged at 733 K were studied. After accumulative annealing of the samples at 733 K, the decrease of the initial susceptibility and increase of the disaccommodation intensities were observed. These are connected with the annealing out of ‘free volumes’ in the amorphous matrix, which is the main source of the magnetic after-effect in all investigated samples.

Study on the deformation of 3%Si-Fe single crystal with magnetic field being deviated from [001]

We have investigated the magnetostriction and the magnetization process of 3%Si-Fe single crystal with (110) parallel to the surface, when the direction of magnetization is deviated from [001]. It was found that large contraction and expansion occurred as a result of magnetostriction in the magnetization process, even if the deviation angle was small. Complicated magnetic domain structures were observed with external field being applied. The behavior of magnetostriction corresponds to changes of magnetic domain structure. On the basis of the principle that no magnetic pole appears at domain walls, a model of domain structure is proposed. Using the model, the deformation behavior was explained well.

Effect of compressive stress on hysteresis loss of Terfenol-D

Changes in hysteresis loss of Terfenol-D rods due to compressive stress have been investigated to clarify its characteristics. The hysteresis loss monotonically increases owing to compressive stress, and its increment is in proportional to mechanical work of magnetostriction under compressive stress. The proportionality ratio between them relates to the increment of non-180° walls due to compressive stress in magnetization process.

Annealing effect on grain texture of cold‐rolled 4.5% Si‐Fe ribbons prepared by a rapid quenching method

4.5% Si‐Fe ribbons with 280‐μm thickness were cold rolled to 60‐μm thickness with high thickness reduction rate about 30% per pass. In the ribbon the secondary recrystallization of (110)[001] orientation was sufficiently promoted and covered the whole ribbon surface after annealing at 1150 °C. In addition, misorientation angles of all grains were under 5° and the average grain misorientation from (110)[001] was 1.5°. The magnetic properties in the grain‐oriented 4.5% Si‐Fe ribbon were excellent: the maximum B8 was 1.86 T, and the minimum Hc was 2.2 A/m.

Magnetization change due to stress change in a constant magnetic field on amorphous ribbons

Magnetization changes due to stress change in a constant magnetic field on amorphous ribbons are investigated. The magnetization change due to stress is divided into reversible and irreversible components. These occur simultaneously, and can be observed in the domain structure. The reversible magnetization change occurs with rotations in the magnetization vector due to stress, and a corresponding change in the domain structure. The irreversible magnetization change occurs mainly in the small stress regime. The magnetization change results from a stress induced anisotropy field which is calculated from the magnetoelastic energy, which was reduced by an amount of energy associated with the reversible magnetization change. Calculated values show good agreement with experimental results.

Ultra-low iron loss in new non-oriented silicon steel sheets

We report a new method of preparing 30 μm-thick non-oriented 3% silicon steel sheets covered with only (1 0 0) grains. The iron loss at 1.0 T, 50 Hz, was 0.61 W/kg. This value is less than the iron loss of the highest grade conventional non-oriented 3% silicon steels with the thickness 350 μm (Nippon Steel Corporation 35H270) by approximately 40%.

The effect of cold-rolling on the magnetic properties of non-oriented silicon steel sheets

Non-oriented 3% silicon steel sheets were cold-rolled to 0.1 mm thick by various methods, and then they were finally annealed in an argon atmosphere for 1.5 hours at 900/spl deg/C with a cooling rate of 0.025/spl deg/C/s. Their magnetic properties changed depending on cold-rolling method used. A sample which had magnetic two-easy-directions with strong [100] cubic texture was obtained in the following way. The sample was alternately cold-rolled in two perpendicular directions L and T, and was also subjected to an intermediate anneal. The average grain diameter of the sample was 57 /spl mu/m. Its magnetic induction at 800 A/m was 1.65 T in the L direction, and 1.62 T in T direction, respectively.

Effect of compressive stress on hysteresis loss and magnetostriction of grain oriented Si–Fe sheets

Changes in hysteresis loss and magnetostriction λ due to compressive stress σ are discussed for grain oriented Si–Fe sheets. L and T samples are prepared for each kind of sheets, where the longitudinal direction of the L/T sample is parallel/transverse to the rolling direction of the sheets. Hysteresis loss of all samples increases owing to compressive stress σ, and the increased value is in proportion to λσ. The proportional ratio between them varies depending on the conditions of the sample and measuring maximum flux density.

Very low core loss high silicon-iron ribbons

Rapidly quenched 4.5wt% silicon-iron ribbons 280/μm thick were cold-rolled with large thickness reduction in each rolling pass for a total thickness reduction of 70% or more. After annealing at high temperatures in a vacuum, they had highly oriented