JPH0343763B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a soft magnetic material used as a magnetic core for high frequency coils and transformers. [Background Art] In conventional soft magnetic materials, the magnetization process is mainly caused by domain wall movement. However, the magnetization process due to domain wall motion becomes irreversible in a large magnetization range, resulting in hysteresis, and when the magnetic field changes at a high frequency, the domain wall motion cannot follow external magnetic field changes, resulting in abnormal eddy current loss. Iron loss was increasing. [Object of the Invention] An object of the present invention is to provide a novel soft magnetic material with low iron loss. [Disclosure of the Invention] The soft magnetic material of the present invention is characterized in that the entire surface layer is crystallized, the inside is in an amorphous state, and the magnetostriction constant is positive. With this configuration, when the surface layer of a soft magnetic material in an amorphous state with a positive magnetostriction constant is crystallized, the contracted surface layer magnetic material becomes a magnetic material in an amorphous state with a positive magnetostriction constant. By applying compressive stress, the direction of the magnetic moment in the absence of an external magnetic field can be made perpendicular to the direction of the magnetic field, eliminating hysteresis in the magnetization curve and reducing iron loss. Crystallization of the surface layer of the soft magnetic material is obtained by heat-treating an amorphous soft magnetic ribbon having a positive magnetostriction constant under certain conditions. By crystallizing the entire surface layer in this way, the same effect as applying compressive stress in the plane in the direction of the external magnetic field can be obtained, and the direction of the magnetic moment in the absence of an external magnetic field can be made perpendicular to the direction of the magnetic field. can. In other words, according to well-known magnetic theory, when the axis of easy magnetization is perpendicular to the external magnetic field,
The magnetization curve becomes as shown in FIG. 1, and there is no hysteresis. The magnetization process at this time occurs only by the rotation of the magnetic moment, so even if the external magnetic field changes at a high frequency, the magnetization changes can be easily tracked.
Since no abnormal eddy current loss occurs, iron loss is reduced. For soft magnetic materials with positive magnetostriction, such as iron-based amorphous magnetic materials, if compressive stress A is applied in the plane direction of the ribbon 1, as shown in Figure 2, the so-called Villari effect (the inverse phenomenon of magnetostriction) will occur. The magnetic moment B is therefore perpendicular to the plane. It is practically difficult to apply compressive stress A parallel to the surface of a ribbon material such as amorphous amorphous, but if an amorphous amorphous magnetic material of a given composition is heat-treated under certain conditions, the result shown in Figure 3 is as follows. In this way, only the surface layer 2 is crystallized, and an effect similar to that obtained by applying compressive stress A parallel to the surface of the ribbon 1 can be obtained. Example Each amorphous magnetic ribbon having the composition shown in the following table was used as the core 3 (a: 20
mm, b: 8 mm, c: 3 mm, R: 4 mm). The ribbon used had a thickness of 25 to 30 μm and a width of 1 cm, and was wound 100 times. After heat treating each core 3 under the conditions shown in the table, 20KHz, 3KG
Iron loss was measured. The results are shown in the table.

〔Effect of the invention〕

In this invention, the entire surface layer of a soft magnetic material in an amorphous state with a positive magnetostriction constant is crystallized, so compressive pressure parallel to the surface of the soft magnetic material acts, and the magnetic moment is perpendicular to the surface. Then,
This has the effect of reducing iron loss.

[Brief explanation of drawings]

Figure 1 is the magnetization curve when the axis of easy magnetization and the magnetic field direction are perpendicular, Figure 2 is an explanatory diagram showing the direction of the magnetic moment when compressive stress is applied to a soft magnetic material with positive magnetostriction, and Figure 3 The figure is an explanatory diagram showing the direction of the magnetic moment due to surface crystallization of the soft magnetic material in this invention, Figure 4 is a plan view of the sample core used in the example of this invention, and Figure 5 is the sample No. The graphs of Mössbauer spectra before and after heat treatment in .1 and FIGS. 6A to 6C are cross-sectional views of sample thin sections used for transmission electron microscopy. 1... Thin ribbon (soft magnetic material), 2... Surface layer.

Claims (1)

[Claims] 1 A soft magnetic material with a positive magnetostriction constant, with the entire surface crystallized and the inside in an amorphous state.