JPWO2015046140A1 - Method for producing Fe-based nanocrystalline alloy and method for producing Fe-based nanocrystalline alloy magnetic core - Google Patents

Abstract

The method for producing an Fe-based nanocrystalline alloy ribbon includes a heat treatment step of heating and cooling a nanocrystallizable Fe-based amorphous alloy ribbon to a crystallization temperature region, and in the heat treatment step, a differential scanning calorimeter is used. An alloy having a temperature range including at least a part of a temperature range from a low crystallization start temperature of 50 ° C. to a high crystallization start temperature of 20 ° C. and not exceeding a high crystallization start temperature of 50 ° C. A magnetic field is applied in the width direction of the ribbon.

Description

  The present invention relates to a Fe-based nanocrystalline alloy and a method for manufacturing a magnetic core in which an Fe-based nanocrystalline alloy is wound or laminated.

  Fe-based nanocrystalline alloys have excellent soft magnetic properties that can achieve both a high saturation magnetic flux density and a high relative permeability μ, and are therefore used in magnetic cores such as common mode choke coils and high-frequency transformers.

  A typical example of the composition system of the Fe-based nanocrystalline alloy is the Fe—Cu—Nb—Si—B system described in Patent Document 1.

  An Fe-based nanocrystalline alloy is produced by microcrystalline (nanocrystallizing) an amorphous alloy obtained by rapid solidification of a liquid phase alloy heated to a temperature equal to or higher than the melting point. . As a method for rapid solidification from the liquid phase, for example, a single roll method excellent in productivity is adopted.

  Fe-based nanocrystalline alloys have different magnetic properties such as relative permeability μ and squareness ratio by applying a temperature profile during heat treatment and applying a magnetic field in a specific direction during heat treatment.

  For example, in Patent Document 2, in order to obtain an Fe-based nanocrystalline alloy having an initial relative permeability of 70,000 or more and a squareness ratio of 30% or less, a magnetic field is applied in the ribbon width direction (magnetic core height direction). It has been proposed to heat-treat while. Although there are various patterns as specific examples of the heat treatment in Patent Document 2, it is roughly divided to hold while applying a magnetic field in the highest temperature range of the heat treatment, cooling process from the temperature rising process to the highest temperature range And holding while applying a magnetic field, and holding while applying a magnetic field from the highest temperature range to the cooling process.

Japanese Patent Publication No. 4-4393 Japanese Patent Laid-Open No. 7-278774

  The heat treatment method disclosed in Patent Document 2 is considered effective as a means for reducing the squareness ratio.

  By the way, in recent years, the frequency band used as a common mode choke or the like has become a high frequency band near 100 kHz, and there is an increasing demand for downsizing of magnetic components in such a high frequency band. That is, a nanocrystalline alloy having a high relative permeability μ in a high frequency range is desired.

  The inventor has made various studies in order to obtain a high relative permeability μ at a high frequency in the vicinity of a frequency of 100 kHz. As a result, it has been recognized that it may be difficult to obtain a high relative permeability μ in the high frequency region in the heat treatment patterns described in Patent Document 1 and Patent Document 2.

  The present invention has been made in view of the above, and provides a method for producing an Fe-based nanocrystalline alloy and a method for producing an Fe-based nanocrystalline alloy magnetic core in which a high relative permeability μ can be easily obtained in the vicinity of a frequency of 100 kHz. For the purpose.

  When the present inventors microcrystallize (nanocrystallize) an Fe-based amorphous alloy by heat treatment, for example, by applying a magnetic field in a specific temperature region during the temperature rising period, a high ratio in a high frequency band of, for example, 100 kHz It has been found that a magnetic permeability μ can be obtained.

<1> Method for Producing Fe-Based Nanocrystalline Alloy A method for producing an Fe-based nanocrystalline alloy according to an embodiment of the present invention comprises heating a nanocrystallizable Fe-based amorphous alloy ribbon to a crystallization temperature region and cooling it. And includes at least part of a temperature range from a low crystallization start temperature of 50 ° C. to a high crystallization start temperature of 20 ° C. in the differential scanning calorimeter. A magnetic field is selectively applied in the width direction of the alloy ribbon in a temperature range during a temperature rising period not exceeding 50 ° C. of the temperature, that is, in a temperature range during the temperature rising period.

  In one embodiment, a magnetic field strength of 50 kA / m or more and 300 kA / m or less is applied in the width direction of the alloy ribbon.

  In one embodiment, the magnetic field is not applied when the maximum temperature is reached in the heat treatment step.

  In one embodiment, a method for producing an Fe-based nanocrystalline alloy ribbon includes a step of preparing a nano-crystallizable Fe-based amorphous alloy ribbon, and the Fe-based amorphous alloy ribbon in a crystallization temperature range. A heat treatment step of heating and cooling; and a step of applying a magnetic field to the Fe-based amorphous alloy ribbon during the heat treatment step, wherein the step of applying the magnetic field is a temperature increase of the heat treatment step. During a period, a predetermined intensity (for example, 50 kA / m) or more in at least a part of a temperature range from a low crystallization start temperature of 50 ° C. to a high crystallization start temperature of 20 ° C. indicated by the differential scanning calorimeter Is applied along the width direction of the alloy ribbon, and a magnetic field of the predetermined strength or higher is not applied during a part of the temperature raising period. Typically, a magnetic field of the predetermined strength or higher is not applied during a temperature rising period exceeding the crystallization start temperature of 50 ° C. or higher. Further, it is not necessary to apply a magnetic field having the predetermined strength or more even during a temperature rising period below the crystallization start temperature of 50 ° C.

<2> Method for Producing Fe-Based Nanocrystalline Alloy Core The method for producing a magnetic core according to an embodiment of the present invention includes heating or laminating a nano-crystallizable Fe-based amorphous alloy ribbon to a crystallization temperature region. A magnetic core comprising an Fe-based nanocrystalline alloy ribbon wound or laminated by a heat treatment step for cooling, wherein in the heat treatment step, a crystallization start temperature of a differential scanning calorimeter is measured. The temperature range includes at least a part of the temperature range from a low temperature of 50 ° C. to a high temperature of 20 ° C. of the crystallization start temperature and does not exceed the high temperature of 50 ° C. of the crystallization start temperature. A magnetic field is selectively applied in the height direction of the magnetic core in a temperature range during the warm period.

  In one embodiment, a magnetic field having a magnetic field strength of 50 kA / m or more and 300 kA / m or less is applied in the height direction of the magnetic core.

  In one embodiment, the Fe-based nanocrystalline alloy ribbon has a thickness of 15 μm or less and a width of 250 mm or less.

  According to the manufacturing method of the Fe-based nanocrystalline alloy or the manufacturing method of the Fe-based nanocrystalline alloy core according to the embodiment of the present invention, for example, a high relative magnetic permeability μ can be easily realized at a high frequency near 100 kHz. Therefore, it is possible to provide an Fe-based nanocrystalline alloy or an Fe-based nanocrystalline alloy magnetic core that is suitably used for a common mode choke or the like in which high-frequency characteristics are important.

It is a figure explaining the profile of the heat processing of this invention Example 1, and the application of a magnetic field. It is a figure explaining the profile of the heat processing of this invention Example 2, and the application of a magnetic field. It is a figure explaining the profile of the heat processing of this invention Example 3, and the application of a magnetic field. It is a figure explaining the profile of the heat processing of this invention Example 4, and the application of a magnetic field. It is a figure explaining the profile of the heat processing of the comparative example 1, and application of a magnetic field (no magnetic field). It is a figure explaining the profile of the heat processing of the comparative example 2, and the application of a magnetic field. It is a figure explaining the profile of the heat processing of the comparative example 3, and the application of a magnetic field.

  Hereinafter, embodiments of the present invention will be described in detail.

  One of the features of the method for manufacturing an Fe-based nanocrystalline alloy and a magnetic core according to an embodiment of the present invention is that when an Fe-based nanocrystalline alloy is obtained by performing a heat treatment while applying a magnetic field to an amorphous alloy. Unlike the case, it is possible to selectively apply a magnetic field in a specific temperature range during the temperature rising period. The magnetic field is applied along the width direction of the ribbon and the height direction as the magnetic core.

  Specifically, in the temperature rising period of the heat treatment step, at least a part of the temperature range from a low crystallization start temperature specified by using a differential scanning calorimeter to a high crystallization start temperature of 50 ° C. to a high crystallization start temperature of 20 ° C. A magnetic field is selectively applied along the width direction of the alloy ribbon during the heat treatment in a temperature rising period that includes a period and does not exceed the 50 ° C. crystallization start temperature.

  Thus, in the embodiment of the present invention, for example, the magnetic field is applied in the period during the temperature rising period without applying the magnetic field in the vicinity of the highest temperature of the heat treatment or in the cooling process after the highest temperature is reached. . However, the present inventor confirmed that the relative permeability μ at a frequency of 100 kHz does not substantially decrease even if the magnetic field is relatively weak (for example, less than 50 kA / m) even when applied near the maximum temperature of heat treatment. Has been. Therefore, in the embodiment of the present invention, a relatively weak magnetic field may be applied temporarily or continuously in any period of the heat treatment step. In the embodiment of the present invention, application of a weak magnetic field of less than 50 kA / m may be regarded as not applying a magnetic field. In the following, unless otherwise specified, application of a magnetic field having a magnitude (typically 50 kA / m or more and 300 kA / m or less) that can affect the magnetic properties of the nanocrystalline alloy will be described.

  According to the inventor's study, as a result of experiments, when a magnetic field is applied at a maximum temperature that is typically 50 ° C. higher than the crystallization start temperature indicated by the differential scanning calorimeter, a large induced magnetic anisotropy is imparted. The Therefore, the relative permeability μ from the low frequency region to the high frequency region decreases as a whole, and the relative permeability μ at the target frequency of 100 kHz is lowered.

  On the other hand, application of a magnetic field in the vicinity of the crystallization start temperature confirmed by a differential scanning calorimeter imparts weak induced magnetic anisotropy, and the permeability at a required frequency of 100 kHz tends to be improved without decreasing. It is confirmed. In addition, in the application of the magnetic field in the vicinity of the crystallization start temperature, the degree of fluctuation of the relative permeability μ is small with respect to the strength of the magnetic field to be applied and the fluctuation of the temperature region to which the magnetic field is applied, and the required frequency. It was found that the relative permeability μ at 100 kHz can be easily adjusted.

  The reason why the relative permeability μ in the high frequency band can be easily adjusted by applying the magnetic field during the temperature rising period in this way is estimated as follows.

  The alloy having an amorphous structure before the heat treatment has a Curie temperature lower than the crystallization start temperature. On the other hand, when nanocrystallization is performed, the Curie temperature greatly exceeds the crystallization start temperature. In other words, if a magnetic field is applied during the crystallization period, the magnetic domain is fixed with the crystallization, and it is estimated that the same effect as that obtained by cooling from the Curie temperature or higher is obtained.

  However, the induced magnetic anisotropy as strong as when cooling from near the Curie temperature is not given during the temperature rising period in which the structure continues to change. It is estimated that this makes it easy to control the degree of induced magnetic anisotropy.

  As described above, in the heat treatment step according to the embodiment of the present invention, at least a partial temperature increase within a temperature range from a low crystallization start temperature of 50 ° C. to a high crystallization start temperature of 20 ° C. in the differential scanning calorimeter. Apply a magnetic field for a period of time. In the present embodiment, the magnetic field is applied during a temperature rising period that does not exceed 50 ° C., which is the crystallization start temperature.

  Application of a magnetic field only in a temperature range lower than the crystallization start temperature lower than 50 ° C. does not cause substantial crystallization, and application of a magnetic field while maintaining an amorphous state with a low Curie temperature Therefore, the above effects cannot be obtained. On the other hand, in the application of a magnetic field only in a temperature range higher than the temperature of 20 ° C., which is the crystallization start temperature, this time approaches the Curie temperature of the nanocrystalline alloy, so that induced magnetic anisotropy is added too much, It becomes difficult to adjust the permeability μ.

  More preferably, the temperature range to which the magnetic field is applied includes at least a part of the temperature range from a low crystallization start temperature of 20 ° C. to a high crystallization start temperature of 10 ° C. in the differential scanning calorimeter.

  In addition, if a magnetic field is continuously applied from a low temperature range to a remarkably high temperature range during the temperature raising period, too much induction magnetic anisotropy is imparted, and also in this case, it is difficult to adjust the relative permeability μ. Therefore, in the embodiment of the present invention, the upper limit of the temperature at which the magnetic field is applied is 50 ° C. higher than the crystallization start temperature. More preferably, the upper limit of the temperature at which the magnetic field is applied is a temperature 40 ° C. higher than the crystallization start temperature.

  As can be seen from the above description, in the embodiment of the present invention, the application of an effective magnetic field of a predetermined intensity or higher (for example, 50 kA / m or higher) is performed during a part of the temperature rising period. It does not take place over the entire period. That is, there is a period during which no effective magnetic field is applied during the temperature raising period. In this way, an effective magnetic field is selectively applied in a temperature range near the crystallization start temperature. For example, a temperature range of 50 ° C. and a temperature range higher than 50 ° C. By adopting a method that does not apply an effective magnetic field (in the vicinity of the maximum temperature), a nanocrystalline alloy imparted with moderate induced magnetic anisotropy can be efficiently obtained.

  In the present specification, the “temperature increase period” means a period before the maximum temperature is reached, and before reaching the maximum temperature, the temperature is increased, the temperature is decreased, and a certain temperature is reached. It may be in a holding state.

  In the embodiment of the present invention, the crystallization start temperature is determined by a differential scanning calorimeter. It is difficult to accurately measure the true crystallization onset temperature, and identification by a differential scanning calorimeter (DSC) is effective. The temperature at which an exothermic reaction due to the start of nanocrystallization was detected during the temperature rise was defined as the crystallization start temperature. The measurement conditions of the differential scanning calorimeter in the present invention are set at a heating rate of 10 ° C./min.

  In the embodiment of the present invention, the heat treatment temperature is controlled by taking into consideration the capacity of the heat treatment furnace and the amount of heat generated by the crystallization of the amorphous alloy ribbon to be heat treated while the actual temperature distribution in the heat treatment furnace is positive. It is preferable to control so that it may become minus 5 degrees C or less. By performing such control, the magnetic properties of the alloy after heat treatment can be stabilized.

  In the embodiment of the present invention, the strength of the applied magnetic field is preferably 50 kA / m or more and 300 kA / m or less. If the applied magnetic field is too weak, it is difficult to impart induced magnetic anisotropy under actual working conditions. If it is too high, induced magnetic anisotropy tends to be imparted too much.

  A more preferable range is 60 kA / m or more and 240 kA / m.

  The time for applying the magnetic field is not particularly limited as long as it is in the first half temperature range, but about 1 to 180 minutes is practical.

In an embodiment of the present invention, the nano-crystallizable Fe-based amorphous alloy, for example, the general _{formula: (Fe 1-a M a} ) 100-xyz- α - β - γCu x Si y B z M ' αM ″ βXγ (atomic%) (where M is Co and / or Ni, and M ′ is at least selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V, Cr, Mn and W) One element, M ″ is at least one element selected from the group consisting of Al, platinum group elements, Sc, rare earth elements, Zn, Sn, Re, X is C, Ge, P, Ga, Sb, In , Be, As, and at least one element selected from the group consisting of a, x, y, z, α, β, and γ is 0 ≦ a ≦ 0.5, 0.1 ≦ x ≦ 3, respectively. 0 ≦ y ≦ 30, 0 ≦ z ≦ 25, 5 ≦ y + z ≦ 30, 0 ≦ α ≦ 20, 0 ≦ β ≦ 20 and 0 ≦ γ ≦ 20). It can be an alloy composition represented.

  A long amorphous alloy ribbon (strip) can be obtained by melting an alloy having the above composition to a melting point or higher and rapidly solidifying it by a single roll method.

  The thickness of the amorphous alloy ribbon is preferably 10 to 30 μm. If it is less than 10 μm, the mechanical strength of the ribbon is insufficient and the ribbon is easily broken during handling. When it exceeds 30 μm, it is difficult to stably obtain an amorphous state. When the amorphous alloy ribbon is nanocrystallized and used as a magnetic core for high-frequency applications, an eddy current is generated in the ribbon, but the loss due to the eddy current increases as the ribbon becomes thicker. Therefore, a more preferable thickness is 10 to 20 μm.

  Furthermore, since the relative permeability μ at a high frequency near 100 kHz can be increased as the thickness is reduced, a thickness of 15 μm or less is more preferable.

  The width of the amorphous alloy ribbon is preferably 10 mm or more in consideration of a practical magnetic core shape. Since it is possible to reduce the cost by slitting a wide alloy ribbon, it is preferably wide at the stage after quenching, but is preferably 250 mm or less for stable production of the alloy ribbon. In order to manufacture more stably, 70 mm width or less is more preferable.

  The heat treatment for nanocrystallization is preferably performed in an inert gas such as nitrogen, and the maximum temperature reached is preferably set to 550 to 600 ° C. When the temperature is less than 550 ° C. or exceeds 600 ° C., the magnetostriction is increased, which is not preferable. Even if the holding time at the highest temperature is not specifically set and is 0 minute (no holding time), nanocrystallization can be performed. In consideration of the heat capacity of the entire amount of the alloy to be heat-treated and the stability of the characteristics, the alloy may be held at the maximum temperature for more than 0 minutes and not more than 3 hours.

  The temperature profile in the heat treatment is, for example, from a room temperature to a temperature near the temperature at which nanocrystallization starts, with a temperature increase rate of 2 to 4 ° C./min relatively rapidly, and the temperature at which nanocrystallization starts at 50 ° C. From the low temperature to the highest temperature, the temperature may be increased at a moderate temperature increase rate of 0.2 to 1 ° C./min on average. By doing in this way, nanocrystallization can be performed efficiently and stably. In the cooling process after nanocrystallization, it is preferable to cool at a cooling rate of 2 to 5 ° C./min in the temperature range from the highest temperature to 200 ° C. Usually, after cooling to below 100 ° C., the alloy can be taken out into the atmosphere.

  In the case of manufacturing a magnetic core in the embodiment of the present invention, a heat treatment step of heating and cooling to a crystallization temperature region may be performed after a nano-crystallizable Fe-based amorphous alloy ribbon is wound or laminated. In the process of heating to the crystallization temperature region (temperature increase period), the magnetic field is applied as described above. By making the direction of the applied magnetic field the height direction of the magnetic core, a desired induced magnetic anisotropy can be imparted.

Example 1
Atomic%, Cu: 1%, Nb: 3%, Si: 15.5%, B: 6.5%, the remaining molten alloy consisting of Fe and unavoidable impurities was quenched by a single roll method, A Fe-based amorphous alloy ribbon having a thickness of 13 μm was obtained. After slitting this Fe-based amorphous alloy ribbon to a width of 3 mm, it was wound to an outer diameter of 20 mm and an inner diameter of 10 mm to produce 10 toroidal magnetic cores. When measured with a differential scanning calorimeter (DSC), the crystallization onset temperature of this alloy was 500 ° C.

  The produced magnetic core was subjected to heat treatment and magnetic field application with the temperature and magnetic field application profiles shown in FIG. The application of the magnetic field was continuously performed over a temperature range of 440 to 480 ° C. (temperature range from a low crystallization start temperature of 60 ° C. to a crystallization start temperature of 20 ° C.) during the temperature rising period. The magnetic field application direction was the width direction of the alloy ribbon, that is, the height direction of the magnetic core. The magnetic field strength was 120 kA / m. The maximum temperature reached in the heat treatment is 580 ° C.

  The relative magnetic permeability μ at 100 kHz of the 10 magnetic cores (alloys) after the heat treatment was in the range of 27,000 to 30,000.

  The measurement was performed under the conditions of an oscillation level of 0.5 V and an average of 16 using HP4194A manufactured by Agilent Technologies. The insulation coated conductor was passed through the center of the toroidal magnetic core and connected to an input / output terminal for measurement.

(Comparative Example 1)
Ten toroidal magnetic cores were similarly produced using an Fe-based amorphous alloy ribbon having the same composition and size as in Example 1. As shown in FIG. 5, the manufactured magnetic core was heat-treated according to the same profile as the temperature profile of Example 1 shown in FIG. 1 without applying a magnetic field (without a magnetic field).

  The relative permeability μ at 100 kHz of the 10 magnetic cores (alloys) after the heat treatment was in the range of 20,000 to 24,000.

  Comparing Comparative Example 1 and Example 1 in which no magnetic field is applied, even when the temperature range is lower than the crystallization start temperature by DSC, when the magnetic field is applied within the temperature range defined by the present invention, It can be confirmed that the relative permeability μ is clearly increased.

(Example 2)
Using the same Fe-based amorphous alloy ribbon as in Example 1, ten toroidal magnetic cores were similarly produced. The produced magnetic core was subjected to heat treatment and magnetic field application with the temperature and magnetic field application profiles shown in FIG. Only the temperature range of the magnetic field application is different from that of the first embodiment (FIG. 1), and other conditions are the same as those of the first embodiment. The application of the magnetic field is in a temperature range of 480 to 520 ° C. (temperature range from 20 ° C. lower than the crystallization start temperature to 20 ° C. higher than the crystallization start temperature).

  The relative permeability μ at 100 kHz of the 10 magnetic cores (alloys) after heat treatment was in the range of 31,000-32,000.

  In Example 2, a higher relative magnetic permeability μ can be obtained at 100 kHz than in Example 1. This indicates that if a magnetic field is applied in a temperature range including the crystallization start temperature by DSC, the relative permeability μ at 100 kHz can be further improved even when the magnetic field is applied at the same magnetic field strength. ing.

(Example 3)
Using the same Fe-based amorphous alloy ribbon as in Example 1, ten toroidal magnetic cores were similarly produced. The manufactured magnetic core was subjected to heat treatment and magnetic field application with the temperature and magnetic field application profiles shown in FIG. Only the magnetic field strength of the applied magnetic field is different from that of the second embodiment (FIG. 2), and other conditions are the same as those of the second embodiment. A magnetic field strength of 60 kA / m was applied as the magnetic field was raised.

  The relative permeability μ at 100 kHz of the 10 magnetic cores (alloys) after the heat treatment was in the range of 28,000 to 30,000.

Example 4
Using the same Fe-based amorphous alloy as in Example 1, ten toroidal magnetic cores were similarly produced. The produced magnetic core was subjected to heat treatment and magnetic field application with the temperature and magnetic field application profiles shown in FIG. Only the magnetic field strength of the applied magnetic field is different from that of the second embodiment (FIG. 2), and other conditions are the same as those of the second embodiment. A magnetic field was applied at a magnetic field strength of 240 kA / m when the temperature was raised.

  The relative magnetic permeability μ at 100 kHz of the 10 magnetic cores (alloys) after the heat treatment was in the range of 27,000 to 29,000.

  In Examples 2 to 4 described above, only the magnetic field strength of the applied magnetic field is greatly different. However, in contrast to Comparative Example 1 in which no magnetic field is applied, in any of Examples 2 to 4, Comparative Example 1 is different. In comparison, it can be confirmed that the relative permeability μ at 100 kHz is greatly increased.

(Comparative Example 2)
Using the same Fe-based amorphous alloy ribbon as in Example 1, ten toroidal magnetic cores were similarly produced. The produced magnetic core was subjected to heat treatment and magnetic field application with the temperature and magnetic field application profiles shown in FIG. In Comparative Example 2, the magnetic field strength and the application time in the magnetic field application are the same as in Examples 1 and 2 (FIGS. 1 and 2), but the temperature range of the magnetic field application is from 560 ° C. to the highest equivalent temperature 580 ° C. This leads to cooling. In this temperature range, the magnetic field application start temperature is 60 ° C. higher than the crystallization start temperature.

  The relative permeability μ at 100 kHz of the 10 magnetic cores (alloys) after the heat treatment was in the range of 24,000 to 25,000.

  In the comparative example 2, the relative permeability μ at 100 kHz is only 4000 higher than that in the comparative example 1 in which no magnetic field is applied. By the way, when the relative permeability μ at a frequency of 10 kHz was evaluated in Comparative Example 1 and Comparative Example 2, it was about 80,000 in Comparative Example 1 and about 35,000 in Comparative Example 2. Was a high relative permeability μ. This is because, when a magnetic field is applied in a high temperature region that is higher by 50 ° C. than the crystallization start temperature, the magnetic anisotropy imparted to the magnetic core becomes too large, and the relative permeability μ at 100 kHz decreases. It is estimated that this occurred.

(Comparative Example 3)
Using the same Fe-based amorphous alloy ribbon as in Example 1, ten toroidal magnetic cores were similarly produced. A magnetic field was applied to the manufactured magnetic core for the entire period of the heat treatment step with the temperature and magnetic field application profiles shown in FIG. The applied magnetic field strength was 290 kA / m.

  The relative permeability μ at 100 kHz of the 10 magnetic cores (alloys) after the heat treatment was in the range of 14,000 to 15,000.

(Example 5)
At 1%, Cu: 1%, Nb: 2.5%, Si: 13.5%, B: 7.2%, the molten alloy consisting of the balance Fe and unavoidable impurities is rapidly cooled by a single roll method. A Fe-based amorphous alloy ribbon having a thickness of 60 mm and a thickness of 18 μm was obtained. After slitting this Fe-based amorphous alloy ribbon to a width of 3 mm, it was wound to an outer diameter of 20 mm and an inner diameter of 10 mm to produce 10 toroidal magnetic cores. The crystallization start temperature of this alloy was measured and found to be 480 ° C.

  The manufactured magnetic core was heat-treated with the heat treatment profile shown in FIG. The holding temperature was 580 ° C. The magnetic field was applied in the temperature range of 480 to 520 ° C. (temperature range from the crystallization start temperature to the crystallization start temperature 40 ° C.) during the temperature increase. The magnetic field application direction was the width direction of the alloy ribbon, that is, the height direction of the magnetic core. The magnetic field strength was 120 kA / m.

  As a result of evaluating 10 magnetic cores (alloys) after the heat treatment, the relative magnetic permeability μ at 100 kHz was in the range of 19,000 to 22,000.

(Comparative Example 4)
Using the same Fe-based amorphous alloy ribbon as in Example 5, ten toroidal magnetic cores were similarly produced. The manufactured magnetic core was heat-treated without applying a magnetic field (with no magnetic field) using the temperature and magnetic field application profiles shown in FIG.

  The relative magnetic permeability μ at 100 kHz of the 10 magnetic cores (alloys) after the heat treatment was in the range of 17,000 to 18,000.

  When Example 5 is compared with Comparative Example 4 in which no magnetic field is applied, it is confirmed that the relative permeability μ at 100 kHz is clearly improved by applying the magnetic field in the temperature range near the crystallization start temperature. it can.

(Example 6)
An alloy melt consisting of Ni: 5%, Cu: 0.8%, Nb: 2.8%, Si: 11%, B: 9.8%, the balance Fe and unavoidable impurities by atomic roll method. Quenching was performed to obtain a Fe-based amorphous alloy ribbon having a width of 50 mm and a thickness of 13 μm. After slitting this Fe-based amorphous alloy ribbon to a width of 3 mm, it was wound to an outer diameter of 20 mm and an inner diameter of 10 mm to produce 10 toroidal magnetic cores. The crystallization start temperature of this alloy was measured and found to be 480 ° C.

  The manufactured magnetic core was heat-treated with the heat treatment profile shown in FIG. The holding temperature was 580 ° C. The magnetic field was applied in the temperature range of 480 to 520 ° C. (temperature range from the crystallization start temperature to the crystallization start temperature 40 ° C.) during the temperature increase. The magnetic field application direction was the width direction of the alloy ribbon, that is, the height direction of the magnetic core. The magnetic field strength was 120 kA / m.

  As a result of evaluating 10 magnetic cores (alloys) after the heat treatment, the relative magnetic permeability μ at 100 kHz was in the range of 15,000 to 17,000.

(Comparative Example 5)
Using the same Fe-based amorphous alloy as in Example 6, ten toroidal magnetic cores were similarly produced. The manufactured magnetic core was heat-treated without applying a magnetic field (with no magnetic field) using the temperature and magnetic field application profiles shown in FIG.

  The relative permeability μ at 100 kHz of the 10 magnetic cores (alloys) after the heat treatment was in the range of 9,000 to 12,000.

  When Example 6 is compared with Comparative Example 5 in which no magnetic field is applied, the relative permeability μ at 100 kHz can be clearly increased by applying a magnetic field in the temperature range near the crystallization start temperature. I can confirm.

(Example 7)
A molten alloy having the same alloy composition (crystallization start temperature: 500 ° C.) as in Example 1 was rapidly cooled by a single roll method to obtain a Fe-based amorphous alloy ribbon having a width of 50 mm and a thickness of 18 μm. After slitting this Fe-based amorphous alloy ribbon to a width of 15 mm, it was wound to an outer diameter of 31 mm and an inner diameter of 21 mm to produce four toroidal magnetic cores.

  The manufactured magnetic core was heat-treated with the heat treatment profile shown in FIG. The magnetic field was applied in the temperature range of 480 to 520 ° C. when the temperature was raised. The magnetic field application direction was the width direction of the alloy ribbon, that is, the height direction of the magnetic core. The magnetic field strength was 120 kA / m.

  As a result of evaluating four magnetic cores (alloys) after the heat treatment, the relative magnetic permeability μ at 100 kHz was in the range of 28,000 to 29,000.

  As can be seen from a comparison between Example 2 and Example 7, Example 2 in which the thickness of the Fe-based amorphous alloy ribbon is 15 μm or less is more than Example 7 in which the thickness exceeds 15 μm. Also, it was confirmed that the relative permeability μ at 100 kHz was slightly increased.

  The method for producing an Fe-based nanocrystalline alloy according to an embodiment of the present invention can be applied to the production of a magnetic core such as a common mode choke coil or a high-frequency transformer.

Claims (7)

A method for producing an Fe-based nanocrystalline alloy comprising a heat treatment step of heating and cooling a nano-crystallizable Fe-based amorphous alloy ribbon to a crystallization temperature region,
In the heat treatment step,
A temperature rising period including at least part of a temperature range from a low crystallization start temperature of 50 ° C. to a high crystallization start temperature of 20 ° C. in the differential scanning calorimeter and not exceeding the high crystallization start temperature of 50 ° C. A method for producing an Fe-based nanocrystalline alloy, wherein a magnetic field is applied in the width direction of the alloy ribbon in a medium temperature range.   The manufacturing method according to claim 1, wherein a magnetic field having a magnetic field strength of 50 kA / m or more and 300 kA / m or less is applied in the width direction of the alloy ribbon.   The manufacturing method according to claim 1 or 2, wherein the magnetic field is not applied when the maximum temperature is reached in the heat treatment step. Manufacture of a magnetic core in which a Fe-based nanocrystalline alloy ribbon is wound or laminated, including a heat treatment step in which a nanocrystallizable Fe-based amorphous alloy ribbon is wound or laminated and then heated to a crystallization temperature region and cooled. A method,
In the heat treatment step,
A temperature rising period including at least a part of a temperature range from a low crystallization start temperature of 50 ° C. to a high crystallization start temperature of 20 ° C. in the differential scanning calorimeter and not exceeding the high crystallization start temperature of 50 ° C. A method for producing an Fe-based nanocrystalline alloy magnetic core, wherein a magnetic field is applied in a height direction of the magnetic core in a medium temperature range.   The manufacturing method according to claim 4, wherein a magnetic field having a magnetic field strength of 50 kA / m or more and 300 kA / m or less is applied in a height direction of the magnetic core. The Fe-based nanocrystalline alloy ribbon is
The manufacturing method according to claim 4 or 5, wherein the thickness is 15 µm or less and the width is 250 mm or less.   The manufacturing method according to claim 4, wherein the magnetic field is not applied when the maximum temperature is reached in the heat treatment step.

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