JP6137408B2 - Fe-based nanocrystalline alloy core and method for producing Fe-based nanocrystalline alloy core - Google Patents

Description

  The present invention relates to an Fe-based nanocrystalline alloy core wound with an Fe-based nanocrystalline alloy and a method for producing an Fe-based nanocrystalline alloy core.

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

  As the composition of the Fe-based nanocrystalline alloy, Fe—Cu—M′—Si—B (M ′ is a group consisting of Nb, W, Ta, Zr, Hf, Ti, and Mo described in Patent Document 1). The composition of the (at least one element selected) system is representative.

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

  The Fe-based nanocrystalline alloy has different magnetic characteristics 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 μi of 70,000 or more and a squareness ratio of 30% or less, a magnetic field is applied in the width direction of the alloy ribbon (core height direction). It has been proposed to heat-treat while applying. As specific examples of the heat treatment in Patent Document 2, various profiles have been proposed. Generally, the heat treatment is held while applying a magnetic field in the highest temperature range of the heat treatment. There are those that hold while applying a magnetic field over the cooling process and those that hold while applying the 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, as a frequency band used as a common mode choke, there is a demand for an application that can correspond to a low frequency to a high frequency, specifically, an application that can correspond to a 10 kHz band to a 1 MHz band.

As a characteristic index as a common mode choke, impedance relative permeability μrz is often used. The impedance relative permeability μrz is described in, for example, JIS standard C2531 (revised in 1999). The impedance relative permeability μrz can be considered as being equal to the absolute value of the complex relative permeability (μr′−iμr ″), as shown in the following equation (for example, “Point of Magnetic Material Selection”, 1989). Issued on November 10, 2011, edited by Keizo Ota).
μrz = (μr ′ ² + μr ″ ² ) ^1/2

  The real part μr ′ of the complex relative permeability in the above formula represents a magnetic flux density component having no phase lag with respect to the magnetic field, and generally corresponds to the magnitude of the impedance relative permeability μrz in the low frequency range. On the other hand, the imaginary part μr ″ represents a magnetic flux density component including a phase lag with respect to the magnetic field and corresponds to a loss of magnetic energy. In a high frequency range (for example, 50 kHz or more), the noise suppression effect becomes higher as the imaginary part μr ″ is higher.

  The impedance relative permeability μrz expressed by the above formula is used as an index for evaluating the noise suppression effect for a wide frequency band. If the impedance relative permeability μrz is a high value in a wide frequency band, it is excellent in the ability to absorb and remove common mode noise.

  The present inventor has studied to increase the impedance relative permeability μrz in a wide band of frequencies from 10 kHz to 1 MHz. As a result, it has been recognized that it is difficult to obtain a high impedance relative permeability μrz in a wide frequency band with the heat treatment profiles described in Patent Document 1 and Patent Document 2.

  The present invention has been made in view of the above, and an Fe-based nanocrystalline alloy core having a high impedance relative permeability μrz in a wide frequency band from 10 kHz to 1 MHz, and a method for producing the Fe-based nanocrystalline alloy core. The purpose is to provide.

  When the present inventors microcrystallize (nanocrystallize) an Fe-based amorphous alloy by heat treatment, the frequency is 10 kHz to 1 MHz by applying a magnetic field only within a specific temperature range during the temperature rising period. The present inventors have found that an Fe-based nanocrystalline alloy core having a high impedance relative permeability μrz can be obtained in a wide band of the present invention.

<1> Fe-based nanocrystalline alloy core The core according to the embodiment of the present invention includes a heat treatment step in which a nano-crystallizable Fe-based amorphous alloy ribbon is wound and then heated to a crystallization temperature region and cooled. A core produced through
The impedance relative permeability μrz of the core is
More than 90,000 at a frequency of 10 kHz
40,000 or more at a frequency of 100 kHz, and
More than 8,500 at 1MHz frequency
It is.

In an embodiment of the present invention,
The impedance relative permeability μrz of the core is
105,000 or more at a frequency of 10 kHz,
45,000 or more at a frequency of 100 kHz, and
More than 9,000 at 1MHz frequency
It is preferable that

  In one embodiment of the present invention, the thickness of the Fe-based nanocrystalline alloy ribbon is preferably 9 μm or more and 20 μm or less.

<2> Method for Producing Fe-Based Nanocrystalline Alloy Core A method for producing a core according to an embodiment of the present invention comprises heating a nano-crystallizable Fe-based amorphous alloy ribbon and then heating to a crystallization temperature region, A heat treatment step of cooling, wherein the heat treatment step is within a temperature range during a temperature rise period corresponding to a temperature from a high crystallization start temperature of 25 ° C. to a high temperature of 60 ° C. of the crystallization start temperature in a differential scanning calorimeter. Limiting, it has a magnetic field application process which applies a magnetic field to the height direction of the core in 10 minutes or more and 60 minutes or less.

  In the manufacturing method according to an embodiment of the present invention, the heat treatment step is performed within a temperature range during the temperature increase period from a high crystallization start temperature of 30 ° C. to a high crystallization start temperature of 50 ° C. in a differential scanning calorimeter. It is preferable to include a magnetic field applying step of applying a magnetic field in the height direction of the core in 15 to 40 minutes.

  In the manufacturing method according to the embodiment of the present invention, it is preferable that in the magnetic field application step, 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 core.

  In the manufacturing method according to the embodiment of the present invention, it is preferable to use an Fe-based nanocrystalline alloy ribbon having a thickness of 9 μm or more and 20 μm or less.

  In an embodiment of the present invention, a method for producing an Fe-based nanocrystalline alloy ribbon includes a step of preparing an Fe-based amorphous alloy ribbon capable of nanocrystallization, and winding the Fe-based amorphous alloy ribbon. Including a step of forming a wound body, a heat treatment step of heating and cooling the wound body to a crystallization temperature region, and a step of applying a magnetic field to the wound body during the heat treatment step. The step of applying the magnetic field is at least one in a temperature range from a high crystallization start temperature of 25 ° C. to a high crystallization start temperature of 60 ° C. indicated by the differential scanning calorimeter during the temperature rising period of the heat treatment step. A magnetic field of a predetermined strength (for example, 50 kA / m) or more is applied along the height direction of the wound body (the width direction of the alloy ribbon) during the period of the portion, and a part of the temperature rise period A magnetic field greater than the predetermined intensity in a period Not applied to the Kimaki times body. More specifically, the magnetic field is applied within a time range of 10 minutes or more and 60 minutes or less, limited to a temperature range from 25 ° C. as the crystallization start temperature to 60 ° C. as the crystallization start temperature. The magnetic field is not applied in a temperature range other than the above temperature range during the temperature rising period. In this step, a magnetic field having a predetermined strength or higher is not applied during a temperature rising period equal to or lower than the crystallization start temperature or when reaching the maximum temperature of the heat treatment step (a temperature higher than 60 ° C. than the crystallization start temperature). .

  According to the embodiment of the present invention, an Fe-based nanocrystalline alloy core having a high impedance relative permeability μrz can be obtained in a wide frequency band from 10 kHz to 1 MHz. In addition, the Fe-based nanocrystalline alloy core can be manufactured. For this reason, it is optimal for a common mode choke or the like in which characteristics in a wide frequency band from 10 kHz to 1 MHz 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 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. FIG. 3 is a diagram showing a measurement result of a Fe-based amorphous alloy ribbon described in Example 1 using a differential scanning calorimeter (DSC). It is a graph which shows that the frequency characteristic of impedance relative permeability (micro | micron | mu) rz changes by the aspect of the magnetic field application during heat processing changing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In the embodiment of the present invention, when a magnetic field is applied in the width direction of the wound ribbon (the height direction as the core) to obtain the Fe-based nanocrystalline alloy, it is limited to a specific temperature range of the temperature rising period. A heat treatment step is performed while applying a magnetic field.

  Specifically, in the heat treatment step according to the embodiment of the present invention, the temperature is limited to a temperature range during a temperature rising period from a high crystallization start temperature of 25 ° C. to a high crystallization start temperature of 60 ° C. in the differential scanning calorimeter. Then, a magnetic field application step is performed in which a magnetic field is applied in the height direction of the core for a time of 10 minutes to 60 minutes.

  As described above, in the manufacture of the core according to the embodiment of the present invention, the magnetic field is applied only during a specific period of the temperature rising period, and when the maximum temperature of the heat treatment is reached or during the period of the cooling process after reaching the maximum temperature. Does not apply a magnetic field. In the embodiment of the present invention, the maximum temperature of the heat treatment is typically higher than the temperature of 60 ° C. higher than the crystallization start temperature.

  In this specification, the “temperature increase period” means a period before the maximum temperature is reached, and before reaching the maximum temperature, the temperature is increased, decreased, and maintained at a constant temperature. The state may be included. For example, in the case where the temperature is in the temperature range during the temperature rising period from 25 ° C. higher than the crystallization start temperature to 60 ° C. higher than the crystallization start temperature, the heat treatment is held for a certain time at a specific temperature within the temperature range May be done to do. Further, the temperature may be monotonously increased at a constant temperature increase rate, or the temperature increase rate may be changed in the middle.

  Here, the reason why the inventor has come to recall that the magnetic field is applied only within the specific temperature range during the temperature rising period in the heat treatment step as described above will be described.

  FIG. 6 is a graph showing the frequency characteristic of the impedance relative permeability obtained by the experiment of the present inventor, and the frequency of the impedance relative permeability of the core (core C1) when no magnetic field is applied during the heat treatment. The characteristics and the frequency characteristics of the impedance relative permeability of the core (core C2) when a magnetic field is applied throughout the heat treatment period are shown.

  As can be seen from FIG. 6, in a low frequency range of 100 kHz or less, for example, the impedance relative permeability μrz of the core C1 (no magnetic field applied) greatly exceeds the impedance permeability μrz of the core C2 (always magnetic field applied). On the other hand, in a high frequency region exceeding 1 MHz, it is observed that the impedance permeability μrz of the core C2 is higher than the impedance permeability μrz of the core C1. From this, when magnetic anisotropy is imparted to the core by applying a magnetic field during the heat treatment, the impedance relative permeability μrz in the low frequency region (according to the experiments by the present inventor, in particular, the real part μr of the complex relative permeability). It was confirmed that the impedance ratio permeability μrz in the high frequency range tends to be improved.

  Thus, the present inventor has recognized that the improvement of the impedance relative permeability μrz on the low frequency side is contradictory to the improvement of the impedance relative permeability μrz on the high frequency side. However, as the present inventors repeated various experiments on heat treatment in a magnetic field, we confirmed the existence of conditions with little decrease in impedance relative permeability on the low frequency side in heat treatment at low temperature for a short time, and conducted further diligent studies. I did it.

  As a result, in the heat treatment step, it is limited to a temperature range during the temperature rising period corresponding to from the high crystallization start temperature of 25 ° C. in the differential scanning calorimeter to the high crystallization start temperature of 60 ° C. Improving the impedance relative permeability μrz in the high frequency range while suppressing the decrease in the impedance relative permeability μrz in the low frequency range by applying a magnetic field in the height direction of the core for a time of 60 minutes or less. I found out that I can. In particular, if a magnetic field is applied for the above time within the above temperature range, not only can a decrease in impedance permeability μrz in the low frequency region be suppressed, but also there is a possibility of improvement over the case where no magnetic field is applied. I found. As a result, a core having a high impedance relative permeability μrz could be obtained in a wide frequency band from 10 kHz to 1 MHz.

  As described above, according to the heat treatment method in which a magnetic field is applied only for a specific time within a specific temperature range during the temperature rising period, μrz at a frequency of 10 kHz is 90,000 to 115,000 and μrz at a frequency of 100 kHz. Of 40,000 to 49,000 and a μrz of 8500 to 15,000 at a frequency of 1 MHz can be obtained.

  In addition, it is presumed that the impedance relative permeability μrz can be maximized in a wide frequency band from a frequency of 10 kHz to 1 MHz by applying a magnetic field limited within a certain temperature range of the temperature raising period. However, the mechanism of how the magnetic field application limited to a certain temperature range of the temperature rising period contributes to each of μ ′ and μ ″ has not been elucidated.

  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 (see FIG. 5). In the present specification, the crystallization start temperature means a value obtained when the measurement conditions of the differential scanning calorimeter are performed at a heating rate of 10 ° C./min.

  The heat treatment temperature is controlled so that the temperature distribution in the actual heat treatment furnace becomes plus or minus 5 ° C. or less, taking into consideration the capacity of the heat treatment furnace and the amount of heat generated by crystallization of the amorphous alloy ribbon to be heat treated. It is preferable to control. Thereby, the magnetic properties of the alloy after heat treatment can be stabilized.

  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 280 kA / m.

  In addition, if the magnetic field to be applied is a relatively weak magnetic field of less than 50 kA / m, it was confirmed by the present inventor that even if it is applied during an arbitrary period of the heat treatment step, the impedance relative permeability is hardly affected. . Therefore, in an 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.

Examples of the Fe-based amorphous alloy that can be nanocrystallized include, for example, the general formula: (Fe _1-a M _a ) _100-xyz- α _- β _- γ Cu _x Si _y B _z M′α M ″ βXγ (atomic%) (Where M is Co and / or Ni, and M ′ is at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V, Cr, Mn and W, M ″) Is at least one element selected from the group consisting of Al, platinum group elements, Sc, rare earth elements, Zn, Sn, Re, and X is a group consisting of C, Ge, P, Ga, Sb, In, Be, As At least one element selected from a, x, y, z, α, β, and γ is 0 ≦ a ≦ 0.5, 0.1 ≦ x ≦ 3, 0 ≦ y ≦ 30, and 0 ≦ z, respectively. ≦ 25, 5 ≦ y + z ≦ 30, 0 ≦ α ≦ 20, 0 ≦ β ≦ 20 and 0 ≦ γ ≦ 20). Can.

  A long amorphous alloy ribbon (strip) can be obtained by melting the 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 9 μm or more and 30 μm or less. If it is less than 9 μm, the mechanical strength of the ribbon is insufficient, and it is easy to break during handling. When it exceeds 30 μm, it is difficult to stably obtain an amorphous state. In addition, when the amorphous alloy ribbon is nanocrystallized and used as a core for high frequency applications, an eddy current is generated in the ribbon, and the loss due to the eddy current increases as the ribbon becomes thicker. Therefore, a more preferable thickness is 9 μm to 20 μm, and a thickness of 15 μm or less is further preferable.

  The width of the amorphous alloy ribbon is preferably 10 mm or more from the practical shape of the core. Since a cost can be reduced by slitting (cutting) a wide alloy ribbon, a wide width is preferable, but a width of 250 mm or less is preferable 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 more than 560 ° C. and 600 ° C. or less. When the temperature is 560 ° C. or lower or exceeds 600 ° C., magnetostriction increases, 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 total amount of the alloy to be heat-treated and the stability of the characteristics, it can be held for 3 hours or less.

  As a temperature profile of the heat treatment, for example, a temperature increase rate of 3 to 5 ° C./min is compared from room temperature to a temperature close to the temperature at which nanocrystallization starts (typically 20 ° C. lower than the crystallization start temperature). The temperature is rapidly increased, and thereafter, from the vicinity of the above-mentioned nanocrystallization start temperature to the high start temperature of 60 ° C (or up to the highest temperature), the average is 0.2 to 1.0 ° C / min. Stable nanocrystallization can be performed by increasing the temperature at a moderate temperature increase rate. In addition, it is preferable to cool at the cooling rate of 2-5 degree-C / min from the highest attained temperature to 200 degreeC. Usually, the alloy can be taken out into the atmosphere at 100 ° C. or lower.

  When used as a magnetic component, a nano-crystallizable Fe-based amorphous alloy ribbon is wound to produce an annular body, and then a heat treatment step of heating and cooling to a crystallization temperature region may be performed. By applying the magnetic field at this time in the height direction of the annular body (core), a predetermined 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. This Fe-based amorphous alloy ribbon was slit (cut) to a width of 15 mm, and then wound around an outer diameter of 31 mm and an inner diameter of 21 mm to produce a toroidal core (height 15 mm). As shown in FIG. 5, the crystallization start temperature of this alloy was 500 ° C. as measured by a differential scanning calorimeter (DSC).

  The manufactured 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 is performed for 30 minutes in a temperature range of 530 to 550 ° C. (a temperature range from a high crystallization start temperature of 30 ° C. to a crystallization start temperature of 50 ° C.). The magnetic field application direction was the width direction of the alloy ribbon, that is, the height direction of the core. The magnetic field strength was 280 kA / m. The maximum temperature reached in the heat treatment is 580 ° C.

  The impedance relative permeability μrz at 10 kHz, 100 kHz, and 1 MHz of the core after the heat treatment was measured. The results are shown in Table 1.

  The impedance relative permeability μrz was measured 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 core and connected to an input / output terminal for measurement.

  In Example 1, the impedance relative permeability μrz was 98,000 at 10 kHz, 42,000 at 100 kHz, and 8,600 at 1 MHz.

(Example 2)
Using the Fe-based amorphous alloy described in Example 1, a toroidal core was similarly produced. The prepared 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 magnetic field application and the magnetic field strength are different from those 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 performed for 15 minutes in a temperature range of 540 to 550 ° C. (temperature range from 40 ° C. as the crystallization start temperature to 50 ° C. as the crystallization start temperature). The magnetic field strength was 160 kA / m. Table 1 shows the measurement results of impedance relative permeability μrz at 10 kHz, 100 kHz, and 1 MHz of the core after the heat treatment.

  In Example 2, the impedance relative permeability μrz was 109,000 at 10 kHz, 47,000 at 100 kHz, and 9,500 at 1 MHz. That is, a higher impedance relative permeability μrz could be obtained at each frequency of 10 kHz, 100 kHz, and 1 MHz compared to Example 1.

(Example 3)
A single-roll method using a molten alloy (as in Example 1) consisting of atomic percent, Cu: 1%, Nb: 3%, Si: 15.5%, B: 6.5%, balance Fe and inevitable impurities. To obtain an Fe-based amorphous alloy ribbon having a width of 50 mm and a thickness of 10 μm. A toroidal core was similarly produced using this Fe-based amorphous alloy ribbon having a thickness of 10 μm (13 μm in Example 1). In the same manner as in Example 2, the prepared core was subjected to heat treatment and magnetic field application with the temperature and magnetic field application profiles shown in FIG. Table 1 shows the measurement results of impedance relative permeability μrz at 10 kHz, 100 kHz, and 1 MHz of the core after the heat treatment.

  In Example 3, the impedance relative permeability μrz was 91,000 at 10 kHz, 46,000 at 100 kHz, and 9,300 at 1 MHz.

Example 4
Using the Fe-based amorphous alloy ribbon having a thickness of 13 μm described in Example 1, a toroidal core was similarly produced. A magnetic field was applied to the prepared core at an intensity of 160 kA / m for 15 minutes in a heat treatment temperature range of 530 ° C to 540 ° C. Table 1 shows the measurement results of impedance relative permeability μrz at 10 kHz, 100 kHz, and 1 MHz of the core after the heat treatment.

  In Example 4, the impedance permeability μrz was 90,000 at 10 kHz, 46,000 at 100 kHz, and 10,000 at 1 MHz.

(Comparative Example 1)
Using the Fe-based amorphous alloy described in Example 1, a toroidal core was similarly produced. The manufactured core was heat-treated with the temperature and magnetic field application profile shown in FIG. 3 without applying a magnetic field (no magnetic field). As can be seen from FIG. 3, the temperature profile in Comparative Example 1 is the same as in Example 1.

  Table 1 shows the measurement results of impedance relative permeability μrz at 10 kHz, 100 kHz, and 1 MHz of the core after the heat treatment.

  Comparing Comparative Example 1 in which no magnetic field is applied with Examples 1 and 2, the value of impedance relative permeability μrz of Comparative Example 1 is less than that of Examples 1 and 2 at each frequency.

(Comparative Example 2)
Using the Fe-based amorphous alloy described in Example 1, a toroidal core was similarly produced. The prepared core was subjected to heat treatment and magnetic field application with the temperature and magnetic field application profiles shown in FIG. As can be seen from FIG. 4, the temperature profile in Comparative Example 2 is the same as in Example 1.

  In Comparative Example 2, the magnetic field strength in the magnetic field application is the same as in Example 1 (FIG. 1), but the temperature range of the magnetic field application reaches the cooling after reaching the highest equivalent temperature of 580 ° C. from the start of the heat treatment. is there. The temperature range of this magnetic field application is outside the scope of the present invention.

  Table 1 shows the measurement results of impedance relative permeability μrz at 10 kHz, 100 kHz, and 1 MHz of the core after the heat treatment.

  Comparing Comparative Example 2 with Examples 1 and 2, the value of impedance relative permeability μrz of Comparative Example 2 is less than that of Examples 1 and 2 at each frequency.

(Reference example)
As a reference example, with respect to the toroidal core having the same composition and shape as in Example 2, the impedance relative permeability when a magnetic field is applied for a longer time in a lower temperature range in the temperature rising period of the heat treatment step. explain.

  In this reference example, the application of the magnetic field was continuously performed for about 60 minutes over a temperature range of 480 to 520 ° C. (a temperature range of 20 ° C. lower than the crystallization start temperature to 20 ° C. higher than the crystallization start temperature). The magnetic field application direction was the width direction of the alloy ribbon, that is, the core height direction, and the magnetic field strength was 120 kA / m.

  Table 1 shows the measurement results of impedance relative permeability μrz at 10 kHz, 100 kHz, and 1 MHz of the core after the heat treatment.

  FIG. 6 shows frequency characteristics of impedance relative permeability μrz in the core (core E1) according to the embodiment of the present invention (similar to Example 2) and the core (core R1) according to the above reference example. FIG. 6 also shows the core (core C1) when no magnetic field is applied corresponding to Comparative Example 1, and the core (core C2) when the magnetic field corresponding to Comparative Example 2 is continuously applied. Yes.

  As can be seen from FIG. 6, when a magnetic field is applied for about 60 minutes in the temperature range near the crystallization start temperature lower than the 25 ° C. crystallization start temperature, as in the core R1, no magnetic field is applied (core Compared to C1), the impedance relative permeability μrz in the low frequency region may be lowered. However, in a high frequency region higher than 100 kHz, the impedance relative permeability tends to be higher in the core R1 than in the core C1.

  On the other hand, when the magnetic field is applied for a relatively short time at the crystallization start temperature of 25 ° C. or higher and 60 ° C. or lower (typically, the magnetic field is not applied when the maximum temperature is reached) as in the embodiment of the present invention (core E1). It was confirmed that the impedance relative permeability μrz was improved not only in the high frequency range but also in the low frequency range. As described above, in the embodiment of the present invention, a unique effect of improving the impedance relative permeability μrz in the low frequency region is obtained even in the form in which the magnetic field is applied in the specific period before the maximum temperature.

  According to the embodiment of the present invention, a core exhibiting a high impedance relative permeability μrz corresponding to a wide frequency band is provided, and is suitably used in a common mode choke coil, a high frequency transformer, and the like.

Claims (8)

A core wound with a Fe-based nanocrystalline alloy ribbon,
The impedance relative permeability μrz of the core is
More than 90,000 at a frequency of 10 kHz
40,000 or more at a frequency of 100 kHz, and
More than 8,500 at 1MHz frequency
A Fe-based nanocrystalline alloy core. The impedance relative permeability μrz of the core is
105,000 or more at a frequency of 10 kHz,
45,000 or more at a frequency of 100 kHz, and
More than 9,000 at 1MHz frequency
The Fe-based nanocrystalline alloy core according to claim 1, wherein   The Fe-based nanocrystalline alloy core according to claim 1 or 2, wherein the Fe-based nanocrystalline alloy ribbon has a thickness of 9 µm or more and 20 µm or less. A method of manufacturing a core wound with an Fe-based nanocrystalline alloy ribbon, comprising a heat treatment step of winding and cooling a nano-crystallizable Fe-based amorphous alloy ribbon to a crystallization temperature region and then cooling. ,
The heat treatment step includes
It is limited to a temperature range during a temperature rising period corresponding to from a high crystallization start temperature of 25 ° C. to a high crystallization start temperature of 60 ° C. in the differential scanning calorimeter. Having a magnetic field application step of applying a magnetic field in the height direction,
A method for producing an Fe-based nanocrystalline alloy core. The heat treatment step includes
In the differential scanning calorimeter, the core is formed within a temperature range of 15 minutes to 40 minutes, limited to a temperature range during the temperature increase period corresponding to a temperature from 30 ° C. as the crystallization start temperature to 50 ° C. as the crystallization start temperature. The manufacturing method of the Fe group nanocrystal alloy core of Claim 4 which has a magnetic field application process which applies a magnetic field to the height direction of this.   The method for producing an Fe-based nanocrystalline alloy core according to claim 4 or 5, 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 height direction of the core.   The manufacturing method of the Fe group nanocrystal alloy core in any one of Claim 4 to 6 whose thickness of the said Fe group nanocrystal alloy ribbon is 9 micrometers or more and 20 micrometers or less. The impedance relative permeability μrz of the manufactured core is
More than 90,000 at a frequency of 10 kHz
40,000 or more at a frequency of 100 kHz, and
More than 8,500 at 1MHz frequency
The manufacturing method of the Fe group nanocrystal alloy core in any one of Claim 4 to 7 which is these.

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