Magnetic ribbon

Abstract

This magnetic ribbon has a homogeneous structure rather than a structure in which the surface is partially oxidized or an amorphous layer having a high B concentration is provided at a predetermined depth from the surface. The magnetic domain structure appearing on the ribbon surface of the magnetic ribbon includes stripe domains. The directions of magnetization in the stripe domains are along an orthogonal direction (X direction) orthogonal to a direction (Y direction) in which the stripe domains extend, and the directions of magnetization of the stripe domains adjacent to each other in the orthogonal direction (X direction) are antiparallel to each other. The cross section of the magnetic ribbon is single-layered.

Description

Magnetic band

[0001] This invention relates to a magnetic thin band capable of achieving low loss.

[0002] Patent Document 1 proposes a magnetic thin band made of a nanocrystalline alloy having a specific composition containing B, as an example of a magnetic thin band capable of achieving low loss, wherein the magnetic thin band has an amorphous layer with a high concentration of B at a predetermined depth from the surface.

[0003] Japanese Patent Publication No. 2010-189761

[0004] The present invention aims to provide a magnetic thin band having a novel structure different from that of Patent Document 1, and capable of achieving low loss.

[0005] The present invention provides a first magnetic thin strip in which the magnetic domain structure appearing on the surface of the thin strip is striped, the direction of magnetization in the striped magnetic domains is along an orthogonal direction perpendicular to the direction in which the striped magnetic domains extend, the directions of magnetization of adjacent striped magnetic domains in the orthogonal direction are antiparallel to each other, and the cross-section is a single layer.

[0006] Furthermore, the present invention provides a second magnetic thin band, which is a first magnetic thin band with a thin band thickness t and a saturation magnetostriction constant λ that satisfy the following conditions. ｓ It has 1.3 × 10 －５ I understand ２ ≤ t ２ / λ ｓ ≤ 2.5 × 10 －４ I understand ２ To provide a magnetic thin band.

[0007] Furthermore, the present invention provides a third magnetic thin band, which is the first or second magnetic thin band, comprising an amorphous phase and a crystalline phase having at least one constituent element and formed within the amorphous phase.

[0008] Furthermore, the present invention provides a fourth magnetic thin band, which is the first or second magnetic thin band, and is made of an Fe-based alloy.

[0009] According to the present invention, the magnetic ribbon has a striped magnetic domain structure that satisfies specific requirements. When a magnetic field is applied in the in-plane direction to a magnetic ribbon having such a magnetic domain structure, a change in magnetization can be caused without domain wall movement. Therefore, the magnetic ribbon of the present invention makes it easier to achieve low loss.

[0010] This figure schematically shows the magnetic domain structure of a magnetic ribbon according to an embodiment of the present invention. This is an image showing the magnetic domains on the surface of the magnetic ribbon of Example 7. This is an image showing the magnetic domains on the surface of the magnetic ribbon of Example 8.

[0011] As shown in Figure 1, in the magnetic thin band of the embodiment of the present invention, the magnetic domain structure appearing on the surface of the thin band is striped magnetic domains. In the magnetic thin band of this embodiment, as can be seen from Figure 1, striped magnetic domains can be observed on both the front and back surfaces of the thin band.

[0012] Furthermore, in the magnetic thin band of this embodiment, the direction of magnetization in the striped magnetic domains is along a direction perpendicular to the direction in which the striped magnetic domains extend, and the directions of magnetization of adjacent striped magnetic domains in that perpendicular direction are antiparallel to each other. Specifically, in Figure 1, the direction in which the striped magnetic domains extend is the Y direction, and the perpendicular direction is the X direction. That is, the direction of magnetization in the striped magnetic domains is along the X direction, and the directions of adjacent striped magnetic domains in the X direction are +X and -X directions.

[0013] In addition, the cross-section of the magnetic ribbon of this embodiment is a single layer. In other words, the magnetic ribbon of this embodiment has a homogeneous ribbon structure as a whole. For example, in the magnetic ribbon of this embodiment, surface oxidation hardly occurs, and there is no specific layer at a predetermined depth from the surface. Furthermore, in the magnetic ribbon of this embodiment, crystallization does not occur locally in only specific regions (i.e., partial crystallization does not occur).

[0014] Having such a specific magnetic domain structure allows a magnetization change to occur solely through magnetization rotation without domain wall movement when a magnetic field is applied to the magnetic thin band in the in-plane direction. Therefore, the magnetic thin band of this embodiment can achieve low loss.

[0015] Here, the ribbon thickness t of the magnetic ribbon and the saturation magnetostriction constant λ ｓ preferably satisfy the following conditions. 1.3 × 10 －５ m ２ ≤ t ２ / λ ｓ ≤ 2.5 × 10 －４ m ２ When appropriate heat treatment is performed while satisfying this condition, the possibility of obtaining the specific magnetic domain structure described above is increased. For example, considering the ribbon thickness t of a general ribbon of about 25 μm, it is understood that the saturation magnetostriction constant λ ｓ is a relatively large value. From this, it is also understood that the loss reduction due to the specific magnetic domain structure described above is fundamentally different from the loss reduction in conventional magnetic ribbons.

[0016] As understood from the principle of the above-described loss reduction, it is important that the magnetic ribbon of the present invention has a specific magnetic domain structure. Therefore, the present invention is not limited to a specific composition. For example, the magnetic ribbon may have an amorphous phase composed of an arbitrary and single composition, or may have a homogeneous structure in which a part thereof is microcrystallized and dispersed in the amorphous phase. However, from the viewpoint of easily realizing an appropriate compressive stress for constituting the specific magnetic domain structure described above, the latter is preferable. That is, the magnetic ribbon preferably includes an amorphous phase and a crystal phase having at least one constituent element and formed in the amorphous phase.

[0017] As an inexpensive and industrially realistic example, the magnetic ribbon is preferably made of an Fe-based alloy. Since the Fe-based alloy is a material having a relatively large magnetostriction and a high magnetization material, it is suitable as the material of the magnetic ribbon of the present embodiment. In particular, the magnetic ribbon may be a nanocrystalline alloy ribbon having an amorphous layer and a plurality of Fe-based crystal phases formed in the amorphous layer. The Fe-based crystal phase may be, for example, an α-Fe crystal phase, or an FeSi crystal phase, an FeAl crystal phase, or an FeSiAl crystal phase.

[0018] Hereinafter, embodiments of the present invention will be described in more detail with reference to a plurality of examples.

[0019] (Examples 1-6 and Comparative Examples 1-2) The raw materials were weighed to match the compositions of Examples 1-6 and Comparative Examples 1-2 of the present invention listed in Table 1 below, and then arc-melted. Subsequently, the molten alloys having each respective composition were processed in air using a single-roll liquid quenching method to produce amorphous alloy strips. The roll diameter was 450 mm, the discharge speed from the nozzle was 20 m / s, and the gas blown during peeling from the roll was nitrogen. The produced strips were approximately 60 mm wide and several hundred m long, and had various strip thicknesses t. Furthermore, the amorphous alloy strips of Examples 1-6 and Comparative Examples 1-2 were heat-treated using an infrared lamp furnace (QHC-P616) manufactured by Advance Engineering Co., Ltd., under an Ar atmosphere and under the conditions described in Table 2. After that, all strips were immediately cooled to below the Curie temperature of 295°C within 10 minutes after the holding period was completed. The phase of the magnetic strips after heat treatment was identified by X-ray diffraction. An X-ray diffractometer, a Rigaku Miniflex 600, was used, and the target metal was Cu. The surface of each magnetic threshold was observed using a magneto-optical effect microscope modified from a polarizing microscope, and the magnetic domain structure was identified. The core loss of each magnetic threshold was measured using a B-H analyzer (SY-8219) manufactured by Iwasaki Communication Equipment Co., Ltd. The saturation magnetostriction constant λ of each magnetic threshold was determined. ｓ The measurements were taken using a strain gauge type magnetostrictive measuring instrument manufactured by Toei Kagaku Sangyo Co., Ltd., and the values ​​from each thin strip thickness t to t ２ / λ ｓ The value was calculated. The measurement results are shown in Table 1.

[0020]

[0021]

[0022] In the magnetic domain structure shown in Table 1, the "striped domains" represent the specific magnetic domain structure described above. In contrast, the "striped domains (Note)" in Comparative Example 2 show a structure different from the specific magnetic domain structure described above. Specifically, the magnetic domain structure observed on the surface of the thin band resembles striped domains, but unlike the specific magnetic domain structure, the direction of magnetization in the striped domains is along the direction in which the striped domains extend, and the directions of magnetization of adjacent striped domains in the direction perpendicular to that are antiparallel to each other. To explain this in comparison with the specific magnetic domain structure in Figure 1, in the magnetic thin band of Comparative Example 2, the direction of magnetization in the striped domains is along the Y direction, and the directions of adjacent striped domains in the X direction are +Y and -Y directions.

[0023] As can be seen from Table 1, when the specific magnetic domain structure described above is present, the core loss is 110 or less, whereas in Comparative Examples 1 and 2, which have magnetic domain structures different from the specific magnetic domain structure, the core loss exceeds 110.

[0024] Furthermore, referring to Examples 1 to 6 and Comparative Examples 1 and 2, the thickness t of the magnetic strip and the saturation magnetostriction constant λ ｓ It can be understood that the specific magnetic domain structure described above is easily obtained when the following conditions are met and appropriate heat treatment is performed: 1.3 × 10 －５ I understand ２ ≤ t ２ / λ ｓ ≤ 2.5 × 10 －４ I understand ２

[0025] (Examples 7 and 8) In Examples 7 and 8, the raw materials had the same composition as in Example 2, and magnetic thin strips were produced in the same manner as in Examples 1 to 6 and Comparative Examples 1 and 2 described above, followed by heat treatment to confirm the relationship between the ratio (area ratio) of the striped magnetic domains occupying the thin strip surface and the core loss characteristics. In Examples 7 and 8, an infrared lamp furnace (QHC-P616) manufactured by Advance Institute of Technology Co., Ltd. was used, and under an Ar atmosphere, the amorphous alloy thin strips produced were heat-treated under the conditions shown in Table 3. Then, all the thin strips were immediately cooled so that the temperature would be 295 °C or lower, which is the Curie temperature, within 10 minutes after the holding was completed. The phase identification of the magnetic thin strips after heat treatment, the observation of the surface of each magnetic thin strip, the measurement of the core loss of each magnetic thin strip, and the measurement of the saturation magnetostriction constant were carried out in the same manner as in Examples 1 to 6 and Comparative Examples 1 and 2. The measurement results are shown in Table 4.

[0026]

[0027]

[0028] In the magnetic thin strips of Examples 7 and 8, while specific striped magnetic domains (hereinafter referred to as striped magnetic domains) shown in Fig. 1 were formed on the thin strip surface, a state was obtained in which magnetic domains that are not striped magnetic domains (for example, so-called random magnetic domains) may also coexist. The area ratio of the striped magnetic domains can be obtained by acquiring the magnetic domain image (image) of the thin strip surface with a magneto-optical effect microscope and calculating the area of the striped magnetic domain region in the image by image analysis. As a representative example of the observation field, a magnetic domain image of the thin strip surface was acquired at a scale of about 1 mm.

[0029] Fig. 2 shows the magnetic domain image of the surface of the magnetic thin strip obtained under the conditions of Example 7. In Fig. 2, the region ② of the striped magnetic domain is shown as a stripe pattern with a relatively small pitch, the region ③ of the random magnetic domain is shown as a pattern with a relatively large pitch of white and black, and a mixed state is shown in which the region ③ of the random magnetic domain is scattered while the region ② of the striped magnetic domain occupies most of the area. At the boundary between the region ② of the striped magnetic domain and the region ③ of the random magnetic domain, the striped magnetic domain is interrupted. Fig. 3 shows the magnetic domain image of the surface of the magnetic thin strip obtained under the conditions of Example 8. It can be seen from Fig. 3 that more regions ③ of random magnetic domains are scattered than in the magnetic thin strip of Example 7.

[0030] In the magnetic thin band of Example 7, the area ratio of striped magnetic domains is approximately 70%, ２ / λ ｓ 2.8 x 10 －５ I understand ２ The core loss was 10⁹. In the magnetic thin band of Example 8, the area ratio of striped magnetic domains was approximately 50%, and t ２ / λ ｓ 2.3 × 10 －５ I understand ２ The core loss was 111. As in Examples 7 and 8, even when striped magnetic domains and random magnetic domains are mixed, it was confirmed that samples in which striped magnetic domains occupy about 50% or more of the surface of the thin band can contribute to low loss (reduced core loss). It was also confirmed that the larger the area ratio of striped magnetic domains, the smaller the core loss. Therefore, as one embodiment of a magnetic thin band, a magnetic thin band in which striped magnetic domains are formed on the surface of the thin band and the area ratio occupied by striped magnetic domains on the surface of the thin band is 50% or more is preferred. Furthermore, the area ratio occupied by striped magnetic domains may more preferably be 70% or more.

[0031] In addition to this embodiment, samples of magnetic strips prepared by the same method and subjected to heat treatment were also found to have samples with a small area ratio of striped magnetic domains (for example, about 15%), and samples with an area ratio of nearly 100% striped magnetic domains. The area ratio of striped magnetic domains is affected by temperature control and temperature uniformity during heat treatment, and varies depending on the performance of the heat treatment equipment and the heat treatment environment. If high temperature uniformity can be maintained with a high-performance heat treatment equipment, it is possible to produce samples with an area ratio of nearly 100% striped magnetic domains. However, even with a simple heat treatment equipment and environment where temperature uniformity is somewhat uneven, it is possible to form striped magnetic domains with a certain area ratio.

[0032] As described above, it was confirmed that a state in which specific striped magnetic domains shown in Figure 1 and other magnetic domain patterns coexist can actually occur in a magnetic thin band, and that samples with a large area proportion occupied by striped magnetic domains can exhibit superior core loss characteristics. If at least a portion of the magnetic domain structure appearing on the surface of the thin band is striped magnetic domains, it can contribute to lower loss (reduced core loss) than a magnetic thin band without striped magnetic domains.

[0033] Although the best embodiment of the present invention has been described, it will be obvious to those skilled in the art that the embodiment can be modified without departing from the spirit of the invention, and such embodiments fall within the scope of the present invention.

[0034] 1. Thin magnetic band 2. Region of specific striped magnetic domains shown in Figure 1 3. Region of random magnetic domains

Claims

1. A magnetic thin strip having a magnetic domain structure on its surface that includes striped magnetic domains, wherein the direction of magnetization in the striped magnetic domains is along a direction perpendicular to the direction in which the striped magnetic domains extend, the directions of magnetization of adjacent striped magnetic domains in the perpendicular direction are antiparallel to each other, and the cross-section is a single layer.

2. A magnetic thin band according to claim 1, wherein the thin band thickness t and saturation magnetostriction constant λ satisfy the following conditions. ｓ It has 1.3 × 10 －５ I understand ２ ≤ t ２ / λ ｓ ≤ 2.5 × 10 －４ I understand ２ Magnetic thin band.

3. A magnetic thin strip according to claim 1 or claim 2, comprising an amorphous phase and a crystalline phase having at least one constituent element and formed within the amorphous phase.

4. A magnetic thin strip according to claim 1 or claim 2, wherein the magnetic thin strip is made of an Fe-based alloy.

5. A magnetic thin strip according to claim 1 or claim 2, wherein the striped magnetic domains are magnetic thin strips in which a magnetization change occurs solely by magnetization rotation without magnetic domain wall movement when a magnetic field is applied to the magnetic thin strip in the in-plane direction.

6. A magnetic thin band according to claim 1 or claim 2, wherein the area ratio occupied by the striped magnetic domains on the surface of the magnetic thin band is 50% or more.

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