JP3374981B2 - Nanocrystalline soft magnetic alloy and magnetic core with excellent short pulse characteristics - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nanocrystalline alloy suitable for pulse power and exhibiting excellent characteristics under a short pulse magnetization, that is, a high magnetization rate, and a magnetic core using the same.

[0002]

2. Description of the Related Art One of the applications of soft magnetic materials is for pulse power. In these applications, a very rapid reversal of magnetization of 100 MT / s occurs in the soft magnetic material that is the magnetic core material in order to generate electric energy of high power pulse. Examples of short pulse applications include magnetic pulse compression of lasers such as excimer lasers, saturable reactors for protecting circuit elements, pulse transformers, particle accelerators, etc., but the operating magnetic flux density is twice the saturation magnetic flux density. A very large loss occurs in the magnetic core material due to the rapid reversal of magnetization close to.

Therefore, for these applications, a material having a small magnetic core loss is used when magnetized with a short pulse, that is, under a high-speed magnetization condition. Also, saturation characteristics are important,
It is also important that the BH curve has a good squareness to some extent.
This is because in an application for pulse power, an appropriate external magnetic field is applied to the magnetic core material in order to reset the magnetic material, but if the squareness is poor and the saturation characteristics are poor, it is necessary to increase the reset magnetic field and energy loss. This is because not only the size of the device but also the size of the device increases. Further, in these applications, since the operation is performed from the negative residual magnetic flux density to the positive saturated magnetic flux density, it is preferable that the squareness is good because the operating magnetic flux density can be increased. Further, it is also important that the saturation magnetic flux density is large in order to increase the operating magnetic flux density and downsize the magnetic core.

For these applications, ferrite having a high specific resistance and excellent high frequency characteristics, and a class of metal materials having a high specific resistance, are described in Japanese Patent Publication No. 4-502649. An amorphous material having a higher magnetic flux density is used. Further, an Fe-based ultrafine crystal material as described in JP-B-4-4393 is also suitable for these applications.

[0005]

However, since ferrite has a low saturation magnetic flux density of about 5000 G, the magnetic core becomes large, and since the squareness of the BH curve is not sufficient, there is a problem that the operating magnetic flux density cannot be sufficiently obtained. . Co-based amorphous materials have very low magnetic core loss and good squareness, but the saturation magnetic flux density is less than 9000 G and the problem that the magnetic core becomes large like ferrite and expensive Co-based materials are the main materials. There is a problem that the price is extremely high. In the case of Fe-based amorphous material, the saturation magnetic flux density is as large as 15000 G or more, but the core loss under the high-speed magnetization condition, that is, when magnetized with a short pulse is smaller than that of other materials, but it was not sufficient. In addition, the Fe-based amorphous material has a large magnetostriction, and an insulating tape is sandwiched between layers for interlayer insulation.
When ceramics insulation is used, the saturation characteristic deteriorates due to the influence of strain, the squareness ratio also decreases, and it is necessary to apply a large reset magnetic field in order to increase the operating magnetic flux density. Further, the magnetic core loss is not sufficiently low and there is a problem that the efficiency is reduced. FIG. 1 shows a schematic diagram of the operating magnetization curve. In the figure, ΔB is the operating magnetic flux density, and Ha is the applied magnetic field. Ha increases in the area 1 and then takes the maximum value in the area 2. Further, in the region 3, Ha decreases once and shows a substantially constant value. Ha increases again in the region 4 and reaches saturation in the region 5. The area surrounded by the magnetization curve and the vertical axis in FIG. 1 corresponds to the core loss.

By the way, it is disclosed in the above Japanese Patent Publication No. 4-4393.
Fe-based ultra-fine crystal alloys represented by Fe-Cu-Nb-Si-B are 10000
Since it has a high magnetic flux density exceeding G and a low core loss, it is suitable for the above applications. However, the magnetic core loss is low when the magnetization speed is low, and particularly under short pulse magnetization conditions where the magnetization speed is high such as exceeding 1 MT / s, the magnetic core loss increases and the difference from the amorphous material becomes small. Not enough characteristics. For this reason, the appearance of ultrafine crystalline soft magnetic alloys and magnetic cores that exhibit excellent properties under conditions of high magnetization speed, that is, when magnetized with a short pulse, is desired.

[0007]

As a result of extensive studies to solve the above problems, Mn is an extremely effective element for improving short pulse characteristics, and Co is effective for improving short pulse characteristics and saturated. We have found that it is also effective in improving the magnetic flux density. The present invention has been made based on this finding, and at least 50% of the structure is fine crystal grains having a grain size of 500 angstroms or less.
_{100-a-b-c-d-e-f} ( Co _100-x Ni.
_{x) a X b M 'c} Si d B e Mn f ( atomic percent)
Where X is at least one element selected from Cu and Au, M ′ is Ti, Zr, Hf, V, N
at least one element selected from b, Ta, Mo and W, and 0.1 ≦ a ≦ 0.8, 0 < b ≦ 3, 0.1 ≦ c
≦ 10,0 < d ≦ 20, 2 ≦ e ≦ 15, 0 <f ≦ 5, c
+ E ≦ 20 , 0 ≦ x <100, which is a nanocrystalline soft magnetic alloy excellent in short pulse characteristics.

The present invention will be described in detail below. Mn is an element having an effect of improving short pulse characteristics as described above,
It is a feature of the alloy of the present invention together with Co described later. If the amount of Mn exceeds 5 at%, the saturation magnetic flux density is lowered, which is not preferable, so that 0 <f ≦ 5. A particularly preferred range is f of 0.1 to 5. Like Mn, Co has the effect of increasing the saturation magnetic flux density and increasing the operating magnetic flux density as well as improving the short pulse characteristics. On the contrary, when the Co amount exceeds 10 at%, the short pulse characteristic is significantly deteriorated, so that 0 <
Let a ≦ 10. A particularly preferable range of Co is 0.1 ≦ a
≦ 0.8, and particularly excellent short pulse characteristics are obtained in this range. Note that part of Co may be replaced with Ni.
In the present invention, Mn having an effect of improving short pulse characteristics
And Co are added in combination, but when comparing Mn and Co, Mn is superior in the effect of improving the short pulse characteristics, but Mn lowers the saturation magnetic flux density of the alloy. The effect compensates. X is C
It is at least one element selected from u and Au and has the effect of making the crystal grains finer and facilitating the formation of the bcc phase. The X amount b is 0 to 3 at%. b is 3 at%
This is because if the value exceeds 1.0, brittleness is remarkable and it is difficult to form a magnetic core. A particularly preferable range of b is 0.1 to 2 at%. In this range, the short pulse characteristic is particularly excellent. M ′ is at least one element selected from Ti, Zr, Hf, V, Nb, Ta, Mo and W, and has the effect of refining the crystal grains and improving the soft magnetic properties. M'amount c
Is less than 0.1 at%, there is no effect of grain refinement, and 1
If it exceeds 0 at%, the saturation magnetic flux density is remarkably reduced, and the operating magnetic flux density cannot be increased, which is not preferable. Si has the effect of increasing the specific resistance and improving the high frequency characteristics. S
If the i amount d exceeds 20 at%, the magnetic flux density is significantly lowered, which is not preferable. A particularly preferred range of d is 5 to 18 at%. B has the effect of refining the crystal grains, and B
If the amount e is less than 2 at%, there is no effect of refining the crystal grains, and 1
If it exceeds 2 at%, the soft magnetic properties deteriorate, which is not preferable.
A particularly preferred range of e is 5 to 12 at%. Further, the sum c + e of M ′ and B needs to be 20 at% or less. This is because when the sum of M ′ and B exceeds 20 at%, the saturation magnetic flux density is remarkably reduced, and it is difficult to increase the operating magnetic flux density. Further, the alloy of the present invention may contain oxygen, carbon, nitrogen, sulfur, aluminum and the like which are inevitable impurities from the raw materials and atmosphere. The fine crystal grains must have a grain size of 500 angstroms or less. This is because the short pulse characteristics are remarkably deteriorated when the particle size exceeds 500 angstroms. Also, fine crystal grains must occupy at least 50% of the structure. This is because when the fine crystal grains are less than 50%, the magnetostriction increases, and in the case of a large magnetic core, there is a problem that the squareness ratio does not become sufficiently high, which is not preferable.

The alloy of the present invention is usually manufactured as follows. First, a Fe-based amorphous alloy ribbon or film having the above composition is formed by a known liquid quenching method such as a single roll method or a twin roll method, or a vapor phase quenching method such as a sputtering method or a vapor deposition method. Next, this alloy is heat-treated in an atmosphere of an inert gas such as argon gas or nitrogen gas or in vacuum to produce the nanocrystalline soft magnetic alloy of the present invention in which at least 50% of the structure is composed of crystal grains having an average grain size of 500 angstroms or less. . Crystal grains are mainly bcc
It is a phase. Although the alloy of the present invention can be used as a thin film, it is mainly used as a ribbon for ordinary applications. In the case of thin strip, the plate thickness is 25
μm or less is desirable. Within this range, excellent short pulse characteristics can be easily obtained. A particularly preferred range is 2 to 15 μm. Particularly excellent short pulse characteristics can be obtained in this range.
The width of the ribbon is usually 1 mm or more, but for the use according to the present invention, the width is 10 mm or more, preferably 20 mm or more, more preferably 40 mm or more because the influence of the edge portion is reduced, so that the space factor is improved. It is suitable considering Among the alloys of the present invention, the alloy having a specific resistance of 120 μΩ · cm or more is particularly excellent in short pulse characteristics.

Another aspect of the present invention is a magnetic core made of the nanocrystalline alloy. The alloy ribbon of the above composition is then wound, cut, punched, photo-etched, etc., laminated, and then heat-treated in an atmosphere of an inert gas such as argon gas or nitrogen gas or in a vacuum. Then, an alloy ribbon magnetic core made of the fine crystal grains is manufactured. The heat treatment is performed without a magnetic field or while applying a magnetic field in the magnetic path direction.
By performing the heat treatment in the magnetic field, the operating magnetic flux density can be increased without applying a reset magnetic field too much. The magnetic field is not limited to the DC magnetic field, and may be an AC magnetic field or a pulse magnetic field. In this case, it is possible to obtain the heat treatment effect by heat generation due to the magnetic core loss of the magnetic core. It is also possible to energize the magnetic core material and generate heat by Joule heat to obtain a heat treatment effect.

At this time, if the surface of the alloy ribbon is covered with an oxide such as SiO ₂ or Al ₂ O ₃ to perform interlayer insulation, short pulse characteristics are improved especially in a wide material. In particular, in applications where a high voltage is applied, it is necessary to perform interlayer insulation. As the method of interlayer insulation,
A method of adhering oxides such as MgO and Al ₂ O ₃ by electrophoretic method, applying a metal alkoxide solution on the surface and heat-treating it.
There are a method of forming an oxide such as SiO2, a method of performing a phosphate or chromate treatment to coat the surface with an oxide, a method of forming an insulating film on the surface by a CVD method, a sputtering method, or the like.
It is also possible to carry out re-rolling after the heat treatment, in which case an insulating tape is overlapped with the ribbon and wound to perform interlayer insulation. As the insulating tape, organic tape such as polyimide or polyester,
Inorganic materials such as mica tape, ceramic fiber tape and glass fiber tape may be used. If necessary, the magnetic core may be immersed in an inorganic varnish or an organic varnish for impregnation. The space factor of the alloy ribbon of the magnetic core of the present invention is
It is around 50% to 85%. If it exceeds 85%, the squareness is deteriorated, which is not preferable. If it is less than 50%, the operating magnetic flux density cannot be made large, and the apparent magnetic permeability after saturation becomes large, which is not preferable. Further, a magnetic core using a thin film technique such as a sputtering method is also included in the present invention. In this case, it is difficult to manufacture a large magnetic core, but it is possible to obtain a small-sized and high-performance magnetic core in an extremely short pulse region.

[0012]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 An amorphous alloy having a composition shown in Table 1 and having a width of 25 mm and a thickness of 18 μm was prepared by a single roll method. Next, apply a metal alkoxide solution on the surface of the ribbon and wind it while rolling it
A toroidal wound magnetic core having a diameter of 35 mm and an inner diameter of 25 mm was produced. This magnetic core was placed in a furnace in a nitrogen gas atmosphere and heat-treated while applying a magnetic field of 5 Oe in the magnetic path direction. The heat treatment conditions are a temperature rising rate of 5 ° C / min, a holding temperature of 550 ° C, a holding time of 1 hour, and a cooling rate of 2 ° C / min. After the heat treatment, a film containing SiO ₂ as a main component was formed on the surface of the ribbon. As a result of microstructure observation, the ribbon was mainly composed of bcc phase with a grain size of 500 angstroms or less.

Next, the saturation magnetic flux density and the magnetization speed dB of this alloy
The core loss was measured when / dt was 1 MT / s. The results obtained are shown in Table 1.

[0015]

[Table 1]

Example 2 The magnetic core loss of the Fe _bal. Co _0.8 Cu ₁ Nb ₃ Si ₁₄ B ₈ Mn _0.8 alloy when the plate thickness was changed and the magnetization speed dB / dt was 1 MT / s was measured.
The obtained results are shown in Table 2. The thinner the plate thickness is, the lower the core loss is, and the lower value is obtained at 25 μm or less. Especially at 15 μm or less, a particularly low magnetic core loss can be obtained. Thus, when the plate thickness is 25 μm or less, more preferably 15 μm or less, the core loss is
Excellent short pulse characteristics at 300 J / m ³ or less.

[0017]

[Table 2]

Example 3 A molten alloy having the composition shown in Table 3 was quenched by the single roll method,
An amorphous alloy ribbon having a width of 15 mm and a thickness of 15 μm was produced. Next, a wound magnetic core was produced by winding the alloy ribbon with the surface in contact with the roll being the outside while performing interlayer insulation of SiO ₂ . Next, this magnetic core was heat-treated at 550 ° C for 1 hour while applying an alternating magnetic field of 50 Hz with a maximum magnetic field of 5 Oe in the magnetic path direction. After the heat treatment, the bcc phase having a grain size of 500 angstroms or less was formed in 50% or more of the structure in the magnetic core material.

Next, the magnetic core loss and the specific resistance at a magnetization speed dB / dt of 1 MT / s were measured. The results obtained are shown in Table 3.

[0020]

[Table 3]

Example 4 An amorphous alloy having a composition of Fe _bal. Co _a Cu ₁ Nb ₂ Zr _0.5 Si ₁₄ B ₆ Mn _{1 having} a width of 25 mm and a thickness of 18 μm was prepared by a single roll method. Next, a metal alkoxide solution was applied to the surface of the ribbon and the ribbon was wound while being dried to produce a toroidal wound magnetic core having an outer diameter of 35 mm and an inner diameter of 25 mm. This magnetic core was placed in a furnace in a nitrogen gas atmosphere and heat-treated while applying a magnetic field of 5 Oe in the magnetic path direction. The heat treatment conditions are: temperature rising rate 5 ° C / min, holding temperature 550 ° C,
The holding time is 1 hour, and the cooling rate is 2 ° C / min. After the heat treatment, a film containing SiO ₂ as a main component was formed on the surface of the ribbon.
As a result of microstructure observation, the ribbon was mainly composed of bcc phase with a grain size of 500 angstroms or less. Next, the saturation magnetic flux density of this alloy and the magnetic core loss at a magnetization speed dB / dt of 1 MT / s were measured. The obtained results are shown in Table 4, and both the saturation magnetic flux density and the magnetic core loss show good values when the Co amount is in the range of 0.1 to 10. Especially, the core loss is low when the Co amount is in the range of 0.1 to 0.8. Further, when Co is not added, the saturation magnetic flux density is poor.

[0022]

[Table 4]

(Example 5 ) Fe _bal. Co _0.8 Cu ₁ Nb ₂ Ta _0.5 Si _13.5 B _6.5 Mn _f Composition width 25 mm,
An amorphous alloy with a thickness of 18 μm was prepared by the single roll method. Next, a metal alkoxide solution was applied to the surface of the ribbon and the ribbon was wound while being dried to produce a toroidal wound magnetic core having an outer diameter of 35 mm and an inner diameter of 25 mm. This magnetic core was placed in a furnace in a nitrogen gas atmosphere and heat-treated while applying a magnetic field of 5 Oe in the magnetic path direction. The heat treatment conditions are a heating rate of 5 ° C / min and a holding temperature of 550 °.
C, holding time 1 hour, and cooling rate 2 ° C / min. After the heat treatment, a film containing SiO ₂ as a main component was formed on the surface of the ribbon. As a result of microstructure observation, the ribbon was mainly composed of bcc phase having a grain size of 500 Å or less. Next, the saturation magnetic flux density of this alloy and the magnetic core loss at a magnetization speed dB / dt of 1 MT / s were measured. The obtained results are shown in Table 5, which shows that the core loss can be reduced by adding Mn. Moreover, when the Mn amount is increased, the saturation magnetic flux density tends to decrease. Therefore, in order to combine both characteristics of the saturation magnetic flux density and the core loss, it is necessary to add Co and Mn in combination. On the other hand, if the Mn content exceeds 5%, not only is the saturation magnetic flux density significantly reduced, but the core loss tends to increase, which is not preferable.

[0024]

[Table 5]

[0025]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a nanocrystalline alloy suitable for pulsed power and a magnetic core using the same, which exhibits excellent characteristics under conditions of short pulse magnetization, that is, high magnetization rate. Therefore, the effect is remarkable.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an operating magnetization curve.

[Explanation of symbols]

Region 1 of the operating magnetization curve 2 Region 2 of the operating magnetization curve Area 3 of the operating magnetization curve 4 Area 4 of the operating magnetization curve Area 5 of the operating magnetization curve

Continuation of front page (56) References JP-A-3-78215 (JP, A) JP-A-1-110707 (JP, A) JP-A-59-96700 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) C22C 38/00-45/10 H01F 1/14

Claims (10)

(57) [Claims] 1. At least 50% of the structure is fine crystal grains having a grain size of 500 angstroms or less, and the composition formula: F
e _{100-a-b-c-d-e-f} ( Co _100-x N
_{i x) a X b M '} c Si d B e Mn is represented by _f (atomic percent), wherein X is at least one element selected from Cu and Au, M' is Ti, Zr, Hf, V ,
At least one element selected from Nb, Ta, Mo, and W, and 0.1 ≦ a ≦ 0.8, 0 < b ≦ 3, 0.1 ≦
c ≦ 10, 0 < d ≦ 20, 2 ≦ e ≦ 15, 0 <f ≦ 5,
A nanocrystalline soft magnetic alloy excellent in short pulse characteristics, characterized in that c + e ≦ 20 and 0 ≦ x <100 . 2. The nanocrystalline soft magnetic alloy having excellent short pulse characteristics according to claim 1, wherein 0.1 ≦ f ≦ 5. 3. The nanocrystalline soft magnetic alloy excellent in short pulse characteristics according to claim 1, wherein the magnetic core loss at a magnetization rate db / dt of 1 MT / s is 400 J / m ³ or less. 4. 0.1 ≦ b ≦ 2, 5 ≦ d ≦ 18, 5 ≦ e
The nanocrystalline soft magnetic alloy having excellent short pulse characteristics according to any one of claims 1 to 3, wherein ≤12. 5. The nanocrystalline soft magnetic alloy excellent in short pulse characteristics according to claim 1, wherein the plate thickness is 25 μm or less. 6. The nanocrystalline soft magnetic alloy excellent in short pulse characteristics according to claim 5, wherein the plate thickness is in the range of 2 μm to 15 μm. 7. The nanocrystalline soft magnetic alloy excellent in short pulse characteristics according to claim 1, which has a specific resistance of 120 μΩ · cm or more. 8. A magnetic core comprising the nanocrystalline soft magnetic alloy excellent in short pulse characteristics according to any one of claims 1 to 7. 9. The magnetic core according to claim 8, wherein an insulating layer is formed on the surface of the nanocrystalline soft magnetic alloy having excellent short pulse characteristics. 10. The magnetic core according to claim 9, wherein the magnetic core has a structure in which an insulating film is inserted between the nanocrystalline soft magnetic alloy ribbons having excellent short pulse characteristics.