JPH01247556A - Fe-base magnetic alloy excellent in iso-permeability characteristic - Google Patents

Abstract

PURPOSE:To manufacture an Fe-base magnetic alloy excellent in iso-permeability characteristic by forming a layer having a structure of crystalline grains larger than those in the inner part on the part in the vicinity of the surface of an Fe-base magnetic alloy having a specific composition and containing crystalline grains under specific conditions. CONSTITUTION:In an Fe-base magnetic alloy having a composition represented by a general formula (Fe1-aMa)100-x-y-z-alpha-beta-gammaCuxSiyBzMalpha'Mbeta''X (atomic%) (where M means Co and Ni, M' means Nb, W, etc., M'' means V, Cr, etc., X means C, P, etc., the symbols (a), (x), (y), (z), alpha, beta and gamma stand for 0-0.5, 0.1-3, 0-30, 0-25, 0.1-30, 0-10 and 0-10, respectively, and y+z=5-30 is satisfied) and also having a structure in which uniformly dispersed fine crystalline grains comprise at least 50% and the average grain size measured by the maximum sizes of respective crystals is regulated to <=1000Angstrom , a layer having a structure of crystalline grains with an average grain size larger than that of the crystalline grains in the inner part is formed on the part in the vicinity of the alloy surface and also crystals which is composed principally of bccFe solid solution and in which the <100> direction is oriented in the thickness direction are formed on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an Fe-based magnetic alloy with excellent constant magnetic permeability suitable for high-frequency transformers, various choke coils, etc., and a method for producing the same.

[Conventional technology] Conventionally, alloys for common mode chokes and high frequency transformers used for noise removal in various electronic devices and switching power supplies have a low squareness ratio, a flat B-8 curve shape, and constant magnetic permeability. Superior alloys are preferred and used.

Examples of such alloys include permalloy that is heat-treated in a magnetic field while applying a magnetic field perpendicular to the magnetic path, amorphous alloy that is heat-treated in a magnetic field while applying a magnetic field perpendicular to the magnetic path, and Fe-based amorphous that has an oxidized surface. Alloys etc. are known.

Such examples are disclosed in Japanese Patent Application Laid-Open No. 57-202709, Japanese Patent Publication No. 59-34781, and the like.

[Problems to be Solved by the Invention] However, the above alloys have various problems.

For example, an Fe-based amorphous alloy whose surface is oxidized has a magnetic permeability of around 5000, which is comparable to ferrite. In addition, the magnetostriction is large and the characteristics deteriorate due to impregnation, etc.
Depending on the frequency, there are problems such as resonance due to magnetostriction. Since permalloy has a low specific resistance, there are problems in that the magnetic permeability at high frequencies tends to decrease, and there is also a problem in that the characteristics deteriorate due to imaging, deformation, etc.

Furthermore, in the case of an amorphous alloy that is heat-treated in a magnetic field while applying a magnetic field in a direction perpendicular to the magnetic path, there is a problem in that the alloy changes significantly over time. In addition, the saturation magnetic flux density is 10K in the case of GO system.
(It is low at 3 or less, and in the case of Fe-based materials, the saturation magnetic flux density is high, but there are problems such as characteristic deterioration due to impregnation and magnetostrictive resonance.

In order to solve these problems, we first filed a patent application in 1986.
No. 2-58577 etc., FeM has an ultra-fine grain structure that exhibits high frequency magnetic properties with low squareness and excellent constant magnetic permeability.
It was shown that a ii-type alloy can be obtained.

Such characteristics can be obtained by heat treatment in a magnetic field while applying a magnetic field in a direction perpendicular to the magnetic field, but such treatment is disadvantageous in terms of mass production, and even without applying a magnetic field, it is difficult to maintain a constant squareness with a low squareness ratio. The appearance of a Fe-based magnetic alloy layered with magnetic permeability has been desired.

An object of the present invention is to provide a Fe-based magnetic alloy that is mass-producible, has a low squareness ratio, and exhibits excellent constant magnetic permeability, and a method for producing the same.

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors have developed the general formula: % formula % (where M is GO and/or N1, and M' is Nb
, W, Ta, Zr, Hf, Ti, and Mo; M LJ is V;
Cr, Mn, AI, white metal element, Sc, Y.

At least one element selected from the group consisting of AU, Zn, Sn, Re, A (+, XG, tC, P, G
e.

At least one element selected from the group consisting of Ga, Sb, In, 3e, and As, and a, x, and y.

Z, α, β, and γ are each 0≦a≦0.5゜0.1
≦×≦ 3.0≦y≦30, 0≦Z≦25.5≦y+7
≦30. 0.1≦α≦30.0≦β≦10. and 0≦
γ≦10 is satisfied. ) and at least 50% of the tissue
F is composed of fine, uniformly distributed crystal grains, and the average grain size measured at the maximum dimension of each crystal grain is 1000 Å or less.
The inventors have discovered that an e-based magnetic alloy in which a layer having a crystal grain structure with a larger average grain size than the inside of the alloy is formed near the alloy surface has excellent constant magnetic permeability, and has conceived the present invention.

In the present invention, C1 is an essential element, and Nb, W, Ta, Zr, and Hf are also essential elements.

The combined effect of adding at least one element selected from the group consisting of Ti and MO has the effect of making crystal grains finer and improving soft magnetic properties.

The preferable amount of C1 added is 0.1 to 3 atomic %.

A particularly preferred range is 0.5 to 2 atomic %.

The additive elements M' are Nb, W, Ta, Zr, and Hf.

It is at least one element selected from the group consisting of Ti and MO, and the amount added is 0.1 to 30 atomic %.

A more preferable range is 0.1 to 10 at%, and a particularly preferable range is 2. ~8 atom%.

3i and B are elements useful for refining the alloy structure and adjusting magnetostriction. The alloy of the present invention can usually be obtained by heat treating an amorphous alloy after its preparation, and 3i and B are the most suitable elements for this purpose.

3i and B addition amount V, z G, to≦y≦3
0. O≦7≦25.5≦y+z≦30.

More preferably 6≦y≦25.3≦2≦15.14≦y
+z≦30.

Mll is V, Cr, Mn, AI, and a platinum metal element.

Sc, Y, Au, Zn, Sn, Re, A(+
At least one element selected from the group consisting of
Improvements in corrosion resistance, magnetic properties, magnetostriction adjustment effects, etc. can be obtained.

The amount β of M I+ added is preferably 0≦β≦10.

X is C, P, Ge, Ga, Sb, In, Be.

It is at least one element selected from the group consisting of AS, and has effects such as assisting amorphization and adjusting magnetostriction and Curie temperature.

The addition amount γ of X is preferably 0≦γ≦10.

The remainder is essentially l"e excluding impurities, but a part of Fe may be replaced by component M (Co and/or Ni). The content a of M is 0≦a ≦ 0.
5 A particularly preferred range is 0≦a≦0.3.

In addition, the alloy of the present invention is an alloy mainly composed of Fe solid solution with a bcc structure, and at least 50% of the structure consists of fine, uniformly distributed crystal grains, and the grain size measured by the maximum dimension of each crystal grain is A Fe-based magnetic alloy having an average grain size of 1000 Å or less is characterized in that a layer having a crystal grain structure with a larger average grain size than the inside of the alloy is formed near the alloy surface.

With such an alloy structure, an alloy with excellent constant magnetic permeability, a low squareness ratio, and a relatively flat -H curve can be obtained.

Particularly preferable soft magnetic properties are easily obtained when the grain size of the crystal inside is 500 Å or less.

The surface grains of an alloy that exhibits these characteristics are larger than the grains formed inside, and have a diameter of <100 mm in the thickness direction.
>The direction tends to be oriented. The internal crystal grains are hardly oriented.

Furthermore, the crystal grain structure formed near the alloy surface is often a columnar structure.

Next, a method for producing the alloy, which is another invention, will be explained.

One method is to first rapidly cool a molten alloy having the above alloy composition by a liquid quenching method such as a single roll method to produce an amorphous alloy ribbon. At this time, a crystalline phase is formed near the alloy surface by controlling the cooling rate. In the case of the single roll method, a crystal phase is formed in the film on the free solidification surface side, and the inside and the roll contact surface side are amorphous. In the present invention, the crystals formed on the surface account for less than 50% of the total volume. Preferably it is 20% or less. Note that the crystals formed on the surface must be larger than those inside, and may have a grain size exceeding 1000A.

Next, the alloy in which crystals have formed near the surface is heated and heat-treated to crystallize the remaining amorphous portion, and heat-treated so that at least 50% of the structure becomes fine, uniformly distributed crystal grains. The above-mentioned Fen magnetic alloy is manufactured by performing the following steps. Further, it may be made into a substantially 100% cohesive phase by heat treatment.

In the above roll method, for example, heating the roll,
A crystalline phase may be formed on the surface of the ribbon by, for example, heating the surface of the ribbon during production of the ribbon.

Further, the heat treatment can be performed in various atmospheres such as air, vacuum, and inert gas atmosphere, and may be performed in Ishikawa. When a thin ribbon is used as a magnetic core, it is usually wound into a toroidal shape and then heat treated.

Another method is to first quench a molten alloy having the above alloy composition using a liquid quenching method such as a single roll method to produce an amorphous alloy ribbon, then heat it to first crystallize near the alloy surface, and then This is a manufacturing method in which heat treatment is performed to crystallize the inside so that at least 50% of the structure becomes fine, uniformly distributed crystal grains.

In this manufacturing method, unlike the above-mentioned method, during the liquid quenching method, the cooling rate is increased to prevent crystal formation on the surface, and the amorphous alloy is rapidly quenched to produce an amorphous alloy, followed by heat treatment.

This heat treatment is divided into two steps: first, heat treatment is performed to crystallize the vicinity of the surface. This heat treatment is performed by heating only the surface by applying a laser beam or the like to the surface, or by adjusting the heat treatment atmosphere to crystallize only the surface. The crystal grains on the surface may be thicker than those inside and may have a grain size exceeding 1000 grains.

The second heat treatment is a heat treatment for crystallizing the inside of the alloy ribbon, and extremely fine crystals are formed due to the combined effect of adding CII, Nb, Mo, and the like. On the other hand, in the case of crystals formed on the surface, the contribution of the crystal nucleation effect of C1 is small, unlike in the case of internal crystallization, and the crystal grains tend to be large and non-uniform.

Since the two types of crystal phases exist in a two-layer state in this way, characteristics with a low squareness ratio and excellent constant magnetic permeability can be obtained.

In this manufacturing method, heat treatment can also be performed in the same atmosphere as in the above manufacturing method, or in a magnetic field.

[Examples] Hereinafter, the present invention will be explained according to Examples, but the present invention is not limited thereto.

Support fi1M1 atomic% Cu1%, Nb2.8%, Si7%, 89%,
The molten alloy having a composition consisting essentially of Fe and the remainder was rapidly cooled by the first roll method to produce an amorphous alloy ribbon with a thickness of 18 μm and a width of 5I.

The X-ray diffraction pattern of the free solidifying surface side of the obtained alloy is
As shown in the figure.

Amorphous halo pattern and bccFe solid solution (20
It can be seen that only the crystal peak corresponding to 0) is observed, and the formed crystals have <100> orientation in the thickness direction. When the next X-ray diffraction peak of this alloy was measured on the roll contact surface side, only a few crystal peaks corresponding to (200) were observed, indicating that crystals are mainly formed on the free solidification surface side of this amorphous alloy. It was confirmed that there is. As a result of cross-sectional observation, it was confirmed that crystals were formed on the free solidification surface side and occupied 20% of the cross section.

Next, this alloy was coated with an outer diameter of 19ml1. It was wound into a toroidal shape with an inner diameter of 15 mm, heated to 570°C in a nitrogen gas atmosphere at a rate of 10°C/sin, held in a non-magnetic field for 1 hour, and then cooled to room temperature at a rate of 5°C/min for heat treatment. .

Next, a portion of the heat-treated alloy was removed from the core and subjected to X-ray diffraction on the free solidification surface side. The results obtained are not shown in Figure 2.

The halo pattern peculiar to amorphous is almost no longer observed, and in addition to the bccFe solid solution (200) crystal peak, (1
00) and (211) peaks are now observed, indicating that most of them are crystallized.

Moreover, not only the (200) peak but also the (110) and (21)
1) The presence of peaks indicates that the crystals formed by heat treatment exhibit a fairly random orientation.

Next, we used a transmission electron microscope to examine the microstructure near the surface and inside the alloy. I guessed it. A schematic diagram of the internal structure is shown in Figure 3(a), and a schematic diagram of the tissue near the surface is shown in Figure 3(b).

The crystals on the surface have a fairly non-uniform shape and have a columnar structure, whereas the crystals inside have a uniform structure with smaller grain sizes compared to the surface.

FIG. 4 shows the DC B-H curve of the toroidal core made of the alloy after heat treatment.

For comparison, FIG. 5 shows a DC B-H curve of an alloy whose surface was etched to remove the surface crystalline phase.

The DC B-1 curve of the alloy of the present invention is slanted and shows a flat shape with a low squareness ratio, whereas the alloy from which the surface crystalline phase has been removed shows a round B-H curve.

Next, excite the magnetic permeability of these two types of cores at 1 kl-IZ! The i magnetic field Hn dependence was measured.

The results obtained are shown in FIG. In the case of the core of the alloy of the present invention, which is made of an alloy with large grain size crystals on the surface, the dependence of the magnetic permeability on the excitation magnetic field is smaller than that in the case where the surface crystals are removed by etching, and the constant magnetic permeability is excellent. .

Example 2 Atomic %T”CU1%, Nb3%, St2%, 813%,
A molten alloy having a composition of 15% Co and the remainder substantially Fe was rapidly cooled by a single roll method to a thickness of 17 μm.

An amorphous alloy ribbon with a width of 5 ml was produced in the air. As a result of performing X-ray diffraction on the obtained alloy, it was confirmed that crystals were present on the free solidification surface side as in Example 1.

Next, this alloy was wound with the free-solidifying surface facing outward to an outer diameter of 131 mm and an inner diameter of 10 mm, and was rapidly heated to 550°C in Ar gas.
After being heated for 1 hour, it was taken out of the furnace and cooled in the air. The alloy after heat treatment had a microstructure similar to that of Example 1. A DC B-H curve of this wound core is shown in FIG.

It was a flat DC curve similar to that of Example 1. Next, the dependence of the magnetic permeability μe lk on the excitation magnetic field Hm at 1 kHz was investigated.

tl m! In the case of JOe, Fe1 has 2000, Hr
When A was 50 m0e, μe 1 was 2050, and the constant magnetic permeability was excellent. This alloy is considered suitable for normal mode chokes and the like.

C1I O, 5%, Nb 3.2%, 3i 2% in atomic%
.

A molten alloy having a composition of 313% and the remainder substantially consisting of Fe was rapidly cooled by a single roll method to form a molten alloy having a thickness of 13 μm, a width of 5 m, and a thickness of 11 mm.
An amorphous alloy ribbon was produced in an Hc gas atmosphere. tS
As a result of X-ray diffraction of the resulting alloy, a halo pattern peculiar to amorphous was observed, and no crystalline peaks were observed, confirming that the alloy was almost an amorphous single phase.

Next, this alloy was wound to an outer diameter of 19 mm and an inner diameter of 15 m1 to form a toroidal core using 90% nitrogen gas.

The temperature was raised to 550° C. at a rate of 10° C./sin in an atmosphere of 10% oxygen, held for 1 hour, and then cooled to room temperature at a cooling rate of 2° C. and 7 mtn.

As a result of microstructural observation of the alloy after heat treatment, it was confirmed that the alloy had a similar structure to that of Example 1.

Next, the DC BH curve of this alloy core was measured. The results obtained are shown in FIG.

Nothing! Although it was an in-situ heat treatment, it was confirmed that a flat direct current B-Ll could be obtained.

Next, the dependence of the magnetic permeability μe lk at 1k) (Z) of this core on the excitation!1 magnetic field t-1++ was investigated.

If t1m+ is 5111Oe, μelk is 1600
0. When Hll goes to 50II, μe 1 has 170
00, and it was confirmed that the constant magnetic permeability was excellent.

Example 4 A molten alloy having the composition shown in Table 1 was rapidly cooled by a single roll method to produce an amorphous alloy ribbon having a thickness of 15 μm and a width of 5 mm. The resulting alloy was subjected to X-ray diffraction and microstructure observation to examine the presence or absence of a crystalline phase formed on the free solidification surface.

Next, this alloy was wound to an outer diameter of 25 au++ and an inner diameter of 20 mm to produce an i~roidal core, and after heat treatment, X-ray diffraction was performed.

Micro II observation, DC B-H curve, magnetic permeability μe1k at 1 kHz, and core loss Pc at 100 kHz and 2 KG were measured. The results obtained are shown in Table 1.

(Hereinafter, blank space) As can be seen from the table, the alloy of the present invention has a squareness ratio of 3r/B
T. is low and μ 1 k/μ5 1k is small, so it has excellent constant magnetic permeability. Therefore, it is ideal for common mode chokes, etc.

Furthermore, the core loss pc is close enough for practical use, making it suitable for high-frequency transformers such as pulse transformers.

Effects of the Invention] According to the present invention, it is possible to provide an Fe-based magnetic alloy with excellent constant magnetic permeability suitable for high-frequency transformers, various choke coils, etc., and a manufacturing method suitable for mass production, so the effects are remarkable.

[Brief explanation of the drawing]

Figure 1 shows the X-ray diffraction pattern of the amorphous alloy produced during the process of manufacturing the alloy of the present invention, and Figure 2 shows the X-ray diffraction pattern of the alloy of the present invention.
Linear diffraction pattern, Figure 3(a) is a schematic diagram of the internal microstructure of the alloy of the present invention, Figure 3(h) is a schematic diagram of the microstructure of the surface of the alloy of the present invention, Figure 4 is the DC B-1 of the alloy of the present invention. -1 curve, Figure 5 shows the DC B-' of the alloy with the surface crystal layer removed.
H curve, Figure 6 shows the excitation of magnetic permeability of the alloy of the present invention from which the surface crystal phase has been removed! Figures 7 and 8 are diagrams showing the direct current B-H curve of the alloy of the present invention.

Claims (5)

[Claims] (1) General formula: (Fe_1_-_aM_a)_1_0_0_-_x_-
＿y＿−＿z＿−＿α＿−＿β＿−＿γCu_xSi_
yB_zM′_αM″_βX (atomic %) (However, M is Co and/or Ni, M′ is Nb,
At least one element selected from the group consisting of W, Ta, Zr, Hf, Ti and Mo, M'' is V, Cr, Mn,
Al, platinum metal element, Sc, Y, Au, Zn, Sn, Re
, at least one element selected from the group consisting of Ag,
X is at least one element selected from the group consisting of C, P, Ge, Ga, Sb, In, Be, and As;
x, y, z, α, β, and γ are each 0≦a≦0.5
, 0.1≦x≦3, 0≦y≦30, 0≦z≦25, 5≦
y+z≦30, 0.1≦α≦30, 0≦β≦10, and 0≦γ≦10. ) and at least 50% of the tissue
F is composed of fine, uniformly distributed crystal grains, and the average grain size measured at the maximum dimension of each crystal grain is 1000 Å or less.
An Fe-based magnetic alloy having excellent constant magnetic permeability, characterized in that a layer having a crystal grain structure with a larger average grain size than the inside of the alloy is formed near the alloy surface. (2) The crystal grains formed near the alloy surface are bccF
e It is mainly composed of solid solution and has a thickness of <100 in the thickness direction.
The Fe-based magnetic alloy with excellent constant magnetic permeability according to claim 1, wherein crystals with oriented orientations are formed on the surface of the alloy. (3) Fe-based magnetism with excellent constant magnetic permeability according to claim 1 or 2, characterized in that the crystal grain structure formed near the alloy surface is a columnar structure. alloy. (4) The process of rapidly cooling the molten alloy using the liquid quenching method to produce an amorphous alloy in which a crystalline phase exists near the alloy surface, and heating this to produce an amorphous alloy in which at least 50% of the structure has fine, uniformly distributed crystal grains. 1. A method for producing a Fe-based magnetic alloy having excellent constant magnetic permeability, the method comprising the step of heat-treating the alloy so that the alloy comprises: (5) The process of rapidly cooling the molten alloy to produce an amorphous alloy using the liquid quenching method, the first heat treatment process of heating this to crystallize the vicinity of the alloy surface, and the process of crystallizing the inside of the alloy to reduce the structure. A method for producing an Fe-based magnetic alloy having excellent constant magnetic permeability, the method comprising a second heat treatment step in which 50% of each grain forms fine, uniformly distributed crystal grains.