JPH04362162A - Amorphous alloy thin strip having crystallized layer at inside of sheet thickness and excellent in magnetic property - Google Patents

Abstract

PURPOSE:To offer an amorphous alloy thin strip excellent in magnetic properties by providing the inside of its sheet thickness with at least one crystallized layer. CONSTITUTION:This is an amorphous alloy thin strip in which its compsn. is expressed by TMa Sib, Bc, Cd and Me, having a feature of having at least one crystallized layer at the inside of its sheet thickness, formed by executing jetting via a multiple slit nozzle having plural slit-shaped opening parts and executing rapid cooling by a cooling substrate and excellent in magnetic properties; where TM denotes at least one kind among Fe, Co and Ni, M denotes at least one kink among Al, Ti and Zr as well as, by atom, a satisfies 70 to 85%, b satisfies 4 to 18%, c satisfies 7 to 18%, d satisfies 0 to 4%, e satisfies 0.01 to 0.3% and a+b+c+d+e=100. In this way, because the number of crystallized layers at the inside of the sheet thickness and each thickness can be controlled, its properties can be controlled in a wide range compared to the case of the conventional amorphous alloy thin strip in which crystallization is limited only to its surface layer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous magnetic material used for choke cores, sensors, reactors, etc.

0002

BACKGROUND OF THE INVENTION Amorphous metals produced by liquid quenching have superior electromagnetic properties, mechanical properties, corrosion resistance, etc. compared to crystalline metals, and have therefore been considered for application in a wide range of fields. In particular, regarding electromagnetic properties, the characteristics of low coercive force, high magnetic permeability, and low iron loss are suitable for iron core materials, and practical application in this field is most advanced. For example, for power transformers, Fe-based alloys with high saturation magnetic flux density,
Co-based alloys with a high squareness ratio and high magnetic permeability are used for saturable reactors and common mode chokes.

[0003] All of these uses take full advantage of the characteristics of amorphous alloys, but depending on the application, the characteristics of amorphous alloys may become disadvantageous. For example, in a high-frequency transformer, the iron loss increase rate with respect to frequency is greater than that of ferrite, and above a certain frequency, the magnetic properties are inferior to that of ferrite. In addition, the application of Fe-based amorphous alloys is being considered in order to utilize high saturation magnetic flux density in smooth chokes, but there is a problem that using cut cores will significantly degrade the soft magnetic properties inherent in amorphous alloys due to magnetostriction. There is.

In order to avoid these problems, measures have been taken to somewhat sacrifice the excellent soft magnetic properties of amorphous alloys. It is a method of crystallizing the surface of an amorphous alloy ribbon. The crystals formed on the ribbon surface subdivide the magnetic domains and reduce iron loss at high frequencies. This method is employed in high frequency transformers. Furthermore, in a smooth choke, the crystallized layer on the surface exerts compressive stress and causes the magnetization curve to lie in the direction of the magnetic field axis, so it is expected that the desired DC superimposition characteristics can be obtained even if the cutting step is omitted.

Specific methods for crystallizing the surface layer of an amorphous alloy ribbon include: (1) Annealing under conditions that will crystallize the surface; (2) Adding a small amount of Al and rapidly cooling in an oxidizing atmosphere (
Methods such as Japanese Patent Publication No. 2-26767) are known. However, each of these methods has its own problems. ■In the surface crystallization method, there are difficulties in annealing. In other words, in order to crystallize only the thin layer on the surface, it is necessary to set the annealing conditions strictly, but as the core winding thickness increases, a temperature difference occurs between the inside and outside of the core, narrowing the range of appropriate annealing temperatures. .

[0006] Also, ■Al addition method is described in the above-mentioned Japanese Patent Publication No. 2-2.
According to Japanese Patent No. 6767, in order to provide the constant magnetic permeability required for a smooth choke, it is necessary to add Al in an amount of 0.3 to 5 atomic %. However, when 0.3 to 5 at % of Al was added, a problem arose in ribbon productivity. That is, Al
This causes frequent nozzle clogging, making it impossible to perform continuous casting for long periods of time.

[0007] Even if the amount of Al added is reduced in order to avoid nozzle clogging, there is an effect of making the magnetization curve stale. The effect of creating a magnetization curve tilted in the X-axis direction is 0.03 to 0.1%.
According to H. C. Fiedler et al. (published in 1981, U.S. General
Electric's technical report 81CRD
199). However, a surface crystallized layer made of such a small amount of Al cannot maintain a constant magnetic permeability up to a high magnetic field. For example, the magnetization characteristics after annealing of a Fe-Si-B alloy ribbon containing 0.1% Al are 1
Up to a magnetic field of approximately Oe, the magnetization characteristic exhibits a rectangular linear magnetization characteristic, but when the magnetic field exceeds 1 Oe, the magnetic flux density tends to rise rapidly. That is, it does not exhibit constant magnetic permeability up to high magnetic fields.

As described above, when trying to partially crystallize an amorphous ribbon using the conventional method, crystallization proceeds from the surface layer of the ribbon, so it is difficult to control the properties of the amorphous alloy in various ways. It was difficult to do so. If it were possible to selectively crystallize any thin layer within the thickness of the amorphous ribbon, the degree of freedom in controlling the properties of the amorphous alloy would increase, but from past experience It was thought to be impossible.

[0009]

The present invention provides an amorphous alloy having a thin layer crystallized inside the thickness of an amorphous alloy ribbon obtained by selective crystallization of a thin layer inside the thickness of the amorphous alloy ribbon. The purpose is to provide thin strips.

0010

[Means for Solving the Problems] The gist of the present invention is to provide an alloy whose composition is represented by TMa Sib Bc Cd Me, in which a molten metal of the alloy is passed through a multi-slit nozzle having a plurality of openings. An amorphous alloy ribbon with excellent magnetic properties, characterized by having at least one crystallized layer within the thickness of the plate, is produced by jetting it onto a moving cooling substrate and rapidly solidifying it. be.

[0011] However, TM is at least one of Fe, Co, and Ni, M is at least one of Al, Ti, and Zr,
a, b, c, d, e are each atomic %, a: 70 ~
85, b: 4-18, c: 7-18, d: 0-4, e:
0.01 to 0.3, and a+b+c+d+e=100. The gist of the configuration of the present invention is to rapidly cool an alloy of a specific composition using a multi-slit nozzle method. In other words, we discovered that when an alloy containing a small amount of crystallization-promoting elements is cast into a thin strip by a rapid cooling method using a multi-slit nozzle, a thin crystallized layer is formed within the thickness of the plate, which was previously unknown. The present invention was completed based on this knowledge.

Next, the configuration of the present invention will be explained in detail. The alloy composition consists of F, a ferromagnetic metal element, as the main component.
It contains at least one of e, Co, and Ni, and also contains metalloid elements Si, B, and C, which are amorphous forming elements. moreover,
A trace amount of at least one of Al, Ti, and Zr is added to promote crystallization. The reason for limiting the content of each element is as follows.

The range of the basic composition of ferromagnetic elements and metalloid elements was determined mainly from the viewpoints of amorphous formation ability and magnetic properties. Specifically, if the content of the ferromagnetic element is small, the saturation magnetic flux density becomes low, so the lower limit was set to 70 atomic % (hereinafter expressed in %). The reason why the upper limit is set to 85% is that if it exceeds 85%, the total metalloid content will decrease to less than 15%, making it difficult to form an amorphous phase.

The range of the metalloid content was determined from the viewpoints of amorphous formation ability, thermal stability, manufacturing stability, mechanical properties, etc. Si is mainly necessary to enhance thermal stability and ability to form an amorphous state. If Si is less than 4%, a problem will occur in thermal stability, so the lower limit is set to 4%, and if it exceeds 18%, the ribbon becomes brittle, so the upper limit is set to 18%.

[0015] Furthermore, when B is less than 7%, it becomes difficult to form an amorphous state, and even when it exceeds 18%, there is no effect of increasing the ability to form an amorphous state, so the upper limit was set at 18% in consideration of economic efficiency. . C
is not an essential element, but is added based on the knowledge discovered by the present inventors that when contained in a small amount, manufacturability, magnetic properties, and amorphous formation ability are improved. However, since addition of an excessive amount impairs thermal stability, the upper limit was set at 4%.

Furthermore, for the purpose of improving soft magnetic properties, corrosion resistance, and mechanical properties, 5% or less of Cr and Mo are added to the alloy of the present invention.
, Nb, W, and Ta can be added. Next, regarding the method for manufacturing the amorphous alloy ribbon of the present invention, basically a multiple slit nozzle method is used. This method is
This is disclosed in Japanese Patent No. 40629. The key point is that the mutual distance d is 0.5 to 4.0 mm, as shown in Figure 1.
In this method, a multi-slit nozzle equipped with a plurality of parallel slit-like openings is used to eject molten metal onto a cooling substrate moving in the direction shown by the arrow in FIG. 1 to form a thin ribbon. However, in the present invention, the width W of the slit is 0.
．． 1 to 2.0 mm, and the slit interval d is 0.5 to 6.
．． The range is 0mm.

The number n of slits and the series of slit widths W1, W2, . . . Wn of the multiple nozzle shown in FIG. to be determined. For example, when it is desired to form one crystallized layer at the center of the plate thickness, n=2, that is, a double slit nozzle is used, and the individual slit widths are made the same size. Also, if you want to form a crystallized layer closer to both sides of the ribbon roll, you can make the slit width relatively narrower on the upstream side, and conversely, if you want to get it closer to the free surface, you can make it narrower on the downstream side. . However, even if the slit width is the same, heat transfer tends to be better on the upstream side, so it is necessary to take this into consideration when determining the width of each slit. The heat transfer coefficient depends on factors such as the roll material, roll diameter, and cooling method (water-cooled or non-water-cooled), so it is necessary to understand the characteristics of the equipment used in advance. The size of the slit interval is determined depending on the width of the adjacent upstream slit. Usually, the slit interval is set to become wider as the width of the upstream slit becomes larger. Note that when it is desired to form two or more crystallized layers, the number of slits may be one more than the number of crystallized layers. Further, the thickness of the crystallized layer is controlled by the amount of the crystallization promoting element added. The larger the amount added, the thicker the crystallized layer will be. The thickness of the crystallized layer depends on the slit interval, the slit width, and the cooling capacity of the roll, so it can be controlled using these parameters as well. For example, increasing the slit interval increases the thickness of the crystallized layer.

The cross-sectional structure of the ribbon produced by the method described above is schematically shown in FIG. 2. Figure 2
(a) is a ribbon produced using a double nozzle, and (b) is a ribbon produced using a triple nozzle. In both cases, a crystallized layer thinner than the crystallized layer inside the plate thickness is formed on the free surface. Depending on the application, the crystallized layer on the surface can be harmful. In such a case, the surface crystallized layer is removed by etching. In the present invention, the thickness of the crystallized layer inside the plate thickness is
It is preferable that the amount of each crystallized layer be 20% or less of the board thickness. The reason is that the thicker the crystallized layer, the worse the mechanical properties of the ribbon.

The magnetic properties of the amorphous alloy ribbon of the present invention produced by the method described above will be explained with reference to FIG. Figure 3(a) shows a thickness of 3 μm in the central layer of the plate produced using a double nozzle.
Fe80.5Si6 with a thickness of 40 μm and a crystallized layer of
．． 5B12C0.9 Al0.1 The hysteresis curve of the amorphous alloy ribbon is shown. As shown in the figure, it is linear up to a high external magnetic field and is tilted greatly in the X-axis direction. This property makes it suitable as a gapless choke core material. In addition, since the amorphous alloy ribbon of the present invention exhibits two Curie temperatures, it can be used as a temperature sensor. Also,
It can also be applied to mechanical quantity sensors by utilizing the characteristic stress dependence.

[0020]

[Example] Example 1 Composition is Fe80.5Si6.5 B12C0.9Al0
．． 1 (at%), and this molten metal was jetted onto the outer circumferential surface of a Cu roll with a diameter of 600 mm through a multi-slit nozzle made of quartz having two slit-shaped openings, and then rapidly cooled. A thin strip with a thickness of 40 μm and a width of 25 mm was produced. However, the width of each slit was 0.4 mm, and the interval between the slits was 2 mm. The structural changes in the thickness direction of the obtained ribbon were investigated by X-ray diffraction. Specifically, the roll surface of the thin strip is covered with resin, and while the thickness is reduced by etching from the free surface side with a hydrogen fluoride/hydrogen peroxide aqueous solution, X-ray diffraction is performed to observe changes in the diffraction pattern. According to this, a crystallized layer with a thickness of 0.5 μm is formed on the surface of the free surface, and a crystallized layer with a thickness of about 3 μm is formed almost at the center of the plate thickness.
The rest was found to be amorphous. This thin strip 12
After annealing the sample at 380° C. in N2, the crystallized layer on the free surface was removed by etching, and the magnetic properties of the sample were measured using a single plate tester. The hysteresis curve at 50 Hz was as shown in FIG. 3(a). As is clear from the figure, the amorphous alloy ribbon of the present invention does not saturate even in a high magnetic field of 30 Oe and has excellent linearity.

On the other hand, the hysteresis curve of a 30 μm thick ribbon made of an alloy of the same composition using a conventional single slit nozzle was almost saturated in a magnetic field of 5 Oe, as shown in FIG. 3(b). That is, the amorphous alloy ribbon of the present invention maintains a constant magnetic permeability up to a higher magnetic field than the conventional amorphous alloy ribbon in which only the surface layer is crystallized. Example 2 The composition is ■Fe71.99 Co10Si6 B12Z
r0.01, ■Fe62.9Co6 Ni6 Si16
Quenched ribbons were produced using the same method and equipment as in Example 1 using two types of alloys: B9 Ti0.1. In each ribbon, a crystallized layer of approximately 2 μm was formed approximately at the center of the thickness. The magnetic properties after annealing at 380° C. were such that the magnetic flux density did not saturate even at high magnetic fields and the linearity of magnetic permeability was excellent compared to ribbons produced by the conventional single slit method.

[0022]

According to the present invention, it is possible to provide an amorphous alloy ribbon having a crystallized layer within the thickness, which cannot be obtained by conventional methods. Since the number of crystallized layers and the thickness of each layer can be controlled, the properties can be controlled over a wider range than in conventional structures in which crystallization is limited to only a thin layer on the surface. As a result, a material with characteristics suitable for gapless chokes, stress sensors, etc. can be easily obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of a multi-slit nozzle used in manufacturing the amorphous alloy ribbon of the present invention.

FIG. 2 is a cross-sectional view in the thickness direction of an amorphous alloy ribbon having a crystallized layer within the thickness of the present invention.

FIG. 3 is a diagram comparing the hysteresis curve of the amorphous alloy ribbon of the present invention with that of a conventional material.

Claims (1)

[Claims] [Claim 1] Composition is TMa Sib Bc Cd
An alloy represented by Me, which is manufactured by spouting the molten metal of the alloy onto a moving cooling substrate through a multi-slit nozzle having a plurality of openings and rapidly solidifying it. An amorphous alloy ribbon with excellent magnetic properties characterized by having at least one crystallized layer. However, TM is at least one of Fe, Co, Ni, M
is at least one of Al, Ti, and Zr, and a, b, c,
d and e are respectively atomic %, a: 70-85, b: 4
~18, c: 7-18, d: 0-4, e: 0.01-0
．． 3, and a+b+c+d+e=100.