N. Teshima

Recent researches on high silicon-iron alloys

Recent researches on high silicon iron alloys in our laboratory are presented. In the field of 6.5%Si-Fe alloy sheet, the substitution of 1.5% aluminum for silicon improves the cold workability and retains the good magnetic properties of 6.5%Si-Fe sheet. By a splat cooling technique, XSi.YAl.(100-X-Y). Fe ribbons ( 4.0\leqX\leq6.5, 0\leqY\leq2.5 ) in the crystalline state were prepared. They are remarkably flexible and can be easily cold-rolled, and after annealing are mechanically very soft. The good magnetic properties are obtained after annealing at 1200°C for 1hr in vaccum. The magnetic properties of 6.5%Si-Fe ribbon are improved by the double heat treatment. The initial permeability versus frequency curves for 6.5%Si-Fe ribbon are nearly flat up to 100kHz. The ribbon could be used in high frequency magnetic cores.

Magnetic properties of 6.5 percent silicon-iron ribbon formed by a melt spinning technique

Silicon-iron alloys containing 6.5 percent silicon can be formed into ribbons by a melt spinning technique. The ribbons obtained were 10-40 μm in thickness, 1-2 mm in width, and 5-10 m in length, and after annealing all of them were remarkably flexible so as to be bent 180°. The as-quenched ribbons are crystalline and are not amorphous. Low loss is maintained for frequencies up to 50 kHz for 15-μm thick 6.5 percent silicon-iron ribbons. The values obtained for as-quenched ribbon were relative permeability \mu_{R} = 6000 , and loss per cycle W_{f}/f= 30 mJ/kg, measured at a maximum induction of 0.8 T and frequency of 50 kHz.

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.

Magnetic properties of 6.5% silicon-iron ribbon produced by splat-cooling technique

Abstract It has been found that the silicon-iron ribbons containing up to 6.5% silicon can be prepared by the splat-cooling technique. The obtained ribbons are very pliable in spite of high-silicon—iron alloys. Magnetic properties of this ribbon are discussed.

Thickness dependence of magnetic properties in rapidly quenched 6.5 percent silicon iron thin ribbons

Ribbons of 6.5% Si-Fe alloy were prepared with a rapid quenching single roller method. The thickness was 10 to 90μm. After annealing these samples at 1100°C for one hour in pure hydrogen, the grain structure was observed using a 25 kV-SEM. Mechanical properties were measured with a tensile testing machine. Magnetic properties were measured using an open magnetic circuit apparatus. Thickness dependence of these results were examined. The grain size became abruptly larger with increasing thickness and reached 1.8 mm in diameter at a 90 μm thickness. The tensile strength was about 65 kg/mm2for ribbon with a 60 μm thickness. The coercive force measured at a maximum applied field of 10 Oe decreased with increasing thickness and was 0.27 Oe at a thickness of 90 μm. The coercive force was reduced to 0.24 Oe by a double heat tretment. Initial and maximum permeabilities increased with increasing thickness. The former was 700 and the latter 18000 at a 90 μm thickness. The core loss was much lower than for grain oriented 3% silicon iron steel. It was less than one third the value for the steel when measured at frequencies above 1 kHz.

Magnetic and mechanical properties of rapidly quenched microcrystalline Alfer ribbons

Ribbon‐form 13% Al–Fe alloy was prepared by a rapid quenching single roller method. The ribbon obtained had dimensions of 50–60 μm thick, 1–3 mm wide, and a few meters long. The annealing temperature dependence of magnetic, electrical, and mechanical properties were examined from 900 to 1200 °C. After annealing at 1000 °C for one hour in vacuum of 1×10−5 Torr, the best magnetic properties were obtained: the saturation magnetostriction was 52×10−6, the coercive force was 0.8 Oe, and the initial permeability was about 500. The electric resistivity was as high as 105–110 μΩ cm. The ribbon was notably flexible and could be wound around a rod of 0.5 mm diameter.

Magnetic properties of rapidly quenched Alperm ribbons

Abstract Ribbon-form 16% Al-Fe alloy was prepared by a rapid quenching single-roller method. The ribbon obtained was very pliable and corrosion-resistant. The ribbon dimensions were: 50–60 μm thick, 1–2 mm wide and a few meters long. The magnetic, electrical and mechanical properties of these ribbons are discussed in this paper.

Improvement of mechanical workability and constancy of permeability of Fe-Ni-Si alloy by splat cooling technique

Iron-rich alloy ribbons containing about 15 wt % nickel and 12 wt % silicon, which have been called Senperm, were prepared in the crystalline state using a single roller quenching method. The ribbons were remarkably flexible and had a silver-white lustre. They were not oxidized even if they were left in the air for a few months. They could not be bent 180° the minimum winding diameter was 6 mm. The magnetic properties were measured with an open magnetic circuit apparatus and an LCR-meter. The magnetic properties of the as-prepared ribbons were: initial permeability μi=500 and the range of constant permeability Hi=0.25 Oe for SP-No.1; μi=250 and Hi=1.4 Oe for SP-No.2. After annealing at 900°C for a few hours in a vacumm, the ribbons became more flexible and could be bent 180° easily. The minimum winding diameter decreased to 1.2 mm. The magnetic properties were improved noticeably and were: μi=350, Hi=0.6 Oe for SP-No.1 and μi=50, Hi=2.7 Oe for SP-No.2. It was also confirmed that μi was nearly constant up to 50 kHz. The grain strucrure was observed using a 25 kV scanning electron microscope.

Matteucci effect of rapidly quenched Co-Fe alloy ribbon and its application

Ribbon-shaped 70% Co-Fe and 12-14% A1-2% Co-Fe alloys were formed by a rapid quenching method with a single roller. The Matteucci effect was measured on the ribbon after annealing in a dry hydrogen atmosphere. The ribbon were very flexible. A sharp voltage pulse was induced between both ends of the ribbon when placed in an ac field due to the Matteucci effect. The voltage was sufficiently high and increased with an increase in frequency and/or field strength. The temperature dependence of the pulse voltage was measured in the temperature range from 50 to 200°C. Furthermore, experimental results are shown for an a.c. current sensor as an application of these ribbons.

Magnetic characteristics of highly ductile 70% Co-Fe splat cooled ribbons

Ribbon-shaped 70% Co-Fe alloy was formed by a rapid quenching method with a single roller. Magnetic and mechanical measurements were made on the ribbon after annealing in a dry hydrogen gas atmosphere. The ribbon was very flexible; could be wound around a rod with 1 mm diameter, could put up with repeated bending, and could be bent 180° upon itself. The saturation magnetostriction was as high as 70×10-6, Curietemperature was 875°C and the saturation flux density was as high as 2.2 T. The magnetostriction activity of the ribbon was improved and attained 3×1010. The pulse voltage induced in the ribbon by acexciting was sufficiently high and was linear to frequency and bias field.