Soft magnetic powder

Abstract

To provide a soft magnetic powder allowed to be nano-crystallized with stability.SOLUTION: A soft magnetic powder has a glass transition temperature Tg, a first crystallization-onset temperature Tx1 and a second crystallization-onset temperature Tx2. The first crystallization-onset temperature Tx1 is 400°C or higher and 475°C or lower. The first crystallization-onset temperature Tx1 and the glass transition temperature Tg has a difference, ΔTx=Tx1-Tg, of 50°C or lower. The second crystallization-onset temperature Tx2 and the first crystallization-onset temperature Tx1 has a difference, ΔT=Tx2-Tx1, of 65°C or higher and 135°C or lower.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to soft magnetic powder, and more particularly to soft magnetic powder used for magnetic components.

Background Art

[0002] For the magnetic core constituting the magnetic component, excellent magnetic properties (high saturation magnetic flux density and low core loss) are required. As a magnetic material capable of realizing such magnetic properties, nanocrystalline materials are known. The nanocrystalline material can be obtained by heat-treating soft magnetic powder in a nanocrystallization process. The soft magnetic powder used for producing the nanocrystalline material is disclosed, for example, in Patent Document 1 and Patent Document 2.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The heat treatment in the nanocrystallization process causes self-heating of the soft magnetic powder. Therefore, it is difficult to control the temperature of the soft magnetic powder during the nanocrystallization process. As a result, the nanocrystalline material obtained by the nanocrystallization process has a problem that its characteristics are likely to vary. In other words, there is a problem that it is difficult to stably perform nanocrystallization of the soft magnetic powder.

[0005] Therefore, an object of the present invention is to provide a soft magnetic powder capable of stably performing nanocrystallization.

Means for Solving the Problems

[0006] The present invention provides, as a first soft magnetic powder, a soft magnetic powder, The soft magnetic powder has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2, The first crystallization start temperature Tx1 is 400°C or higher and 475°C or lower, The difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50°C or lower, The difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is 65°C or higher and 135°C or lower A soft magnetic powder is provided.

[0007] Further, the present invention provides a second soft magnetic powder which is the first soft magnetic powder, The first crystallization start temperature Tx1 is 420°C or higher and 460°C or lower A soft magnetic powder is provided.

[0008] Further, the present invention provides a third soft magnetic powder which is the first or second soft magnetic powder, The difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 20°C or higher and 50°C or lower A soft magnetic powder is provided.

[0009] Further, the present invention provides a fourth soft magnetic powder which is any one of the first to third soft magnetic powders, The difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is 75°C or higher A soft magnetic powder is provided.

[0010] Further, the present invention provides a fifth soft magnetic powder which is any one of the first to fourth soft magnetic powders, The soft magnetic powder is represented by the composition formula FeaSibPcBdCuxCryNbz, 75.4 at% ≤ a ≤ 80.4 at% 0 at% ≤ b ≤ 9 at% 4.5 at% ≤ c ≤ 12 at% 4 at% ≤ d ≤ 12 at% 0.3 at% ≤ x ≤ 0.9 at% 0 at% ≤ y + z ≤ 5 at% is to provide a soft magnetic powder.

[0011] Further, the present invention provides, as a sixth soft magnetic powder, the fifth soft magnetic powder, 77 at% ≤ a ≤ 79 at% is to provide a soft magnetic powder.

[0012] Further, the present invention provides, as a seventh soft magnetic powder, the sixth soft magnetic powder, wherein a part of the Fe, which is 3 at% or less of the whole composition, is substituted with one or more elements selected from Co, Ni, Zn, Zr, Hf, Mo, Ta, W, Ag, Au, Pd, K, Ca, Mg, Sn, Ti, V, Mn, Al, S, C, O, N, Bi, and rare earth elements to provide a soft magnetic powder.

[0013] Further, the present invention provides, as an eighth soft magnetic powder, any one of the first to seventh soft magnetic powders, having an average particle diameter of 1 μm or more and 20 μm or less to provide a soft magnetic powder.

[0014] Furthermore, the present invention provides, as a ninth soft magnetic powder, any one of the first to eighth soft magnetic powders, having a crystallinity of 10% or less after rapid cooling to provide a soft magnetic powder.

Advantages of the Invention

[0015] Since the soft magnetic powder of the present invention has a glass transition temperature Tg, an endotherm associated with glass transition occurs in the nanocrystallization process, suppressing self-heating during nanocrystallization. In addition, the soft magnetic powder of the present invention has a first crystallization start temperature Tx1 and a second crystallization start temperature Tx2 that satisfy predetermined temperature conditions. Therefore, the soft magnetic powder of the present invention can perform nanocrystallization stably and can sufficiently precipitate fine nanocrystals.

Brief Description of the Drawings

[0016]

Figure 1

Modes for Carrying Out the Invention

[0017] The soft magnetic powder according to an embodiment of the present invention is an Fe-based soft magnetic alloy powder having Fe as a main element and an amorphous phase as a main phase. Its composition will be described later. The soft magnetic powder of the present embodiment is used, for example, in the production of magnetic cores of magnetic components. In the process of producing the magnetic core, the soft magnetic powder is heat-treated to perform nanocrystallization.

[0018] The soft magnetic powder according to the present embodiment can be produced by various production methods. For example, the soft magnetic powder may be produced by an atomization method such as a water atomization method or a gas atomization method. In the powder production process by the atomization method, first, raw materials are prepared. Next, the raw materials are weighed so as to have a predetermined composition (described in Table 1-8) and melted to produce an alloy melt. Next, the alloy melt is discharged from a nozzle and divided into alloy droplets using high-pressure gas or water, thereby producing fine soft magnetic powder.

[0019] In the above powder production process, the gas used for division may be an inert gas such as argon or nitrogen. Further, in order to improve the cooling rate, the alloy droplets immediately after division may be brought into contact with a cooling liquid or solid and rapidly cooled, or the alloy droplets may be re-divided to be further refined. When using a liquid for cooling, for example, water or oil may be used. When using a solid for cooling, for example, a rotating copper roll or a rotating aluminum plate may be used. However, the cooling liquid or solid is not limited to this, and various materials can be used.

[0020] Also, in the above powder production process, by changing the production conditions, the powder shape and particle size of the soft magnetic powder can be adjusted.

[0021] The soft magnetic powder according to this embodiment has characteristics as shown in FIG. 1. Specifically, the soft magnetic powder according to this embodiment has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2. Here, the first crystallization start temperature Tx1 is a temperature depending on the bcc-Fe(-Si) precipitation reaction (first crystallization reaction), and the second crystallization temperature Tx2 is a temperature depending on the compound precipitation reaction (second crystallization reaction).

[0022] In this embodiment, the first crystallization start temperature Tx1 is within a predetermined range. Also, in this embodiment, the first crystallization start temperature Tx1 and the glass transition temperature Tg have a predetermined relationship. Further, in this embodiment, the first crystallization start temperature Tx1 and the second crystallization temperature Tx2 have a predetermined relationship. By satisfying these requirements, when the soft magnetic powder of this embodiment is subjected to heat treatment for nanocrystallization, self-heating is suppressed by the endotherm associated with glass transition, and fine nanocrystals can be sufficiently precipitated. Hereinafter, the soft magnetic powder of this embodiment will be described in detail.

[0023] In this embodiment, the first crystallization start temperature Tx1 is 400°C or higher and 475°C or lower. This is because the soft magnetic powder produced by the atomization method, if Tx1 < 400°C, has poor amorphousness after rapid cooling and good magnetic properties cannot be obtained. Also, for the soft magnetic powder with Tx1 > 475°C, since the heat generated during nanocrystallization (heat treatment) easily raises the temperature of the surrounding atmosphere, grain coarsening is likely to occur, leading to a deterioration of the soft magnetic properties.

[0024] In this embodiment, the first crystallization start temperature Tx1 is preferably 420°C or higher and 460°C or lower. The soft magnetic powder having the first crystallization start temperature Tx1 within this range has good amorphousness after rapid cooling, and since the temperature rise of the surrounding atmosphere due to the heat generated during heat treatment is suppressed, the soft magnetic properties after heat treatment become good.

[0025] In addition, in the present embodiment, the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50°C or less. This is because a supercooled liquid region is required to utilize the endothermic reaction associated with the glass transition during crystallization. Further, if ΔTx is too large, it becomes difficult for the endothermic reaction and the nanocrystallization (exothermic) reaction to occur simultaneously, leading to coarsening of the crystals and deterioration of the magnetic properties.

[0026] The difference ΔTx is preferably 20°C or more. If ΔTx is 20°C or more, the endothermic amount due to the glass transition is sufficiently large, so that the temperature rise due to the nanocrystallization (exothermic) reaction can be effectively suppressed, and good soft magnetic properties are obtained.

[0027] Furthermore, in the present embodiment, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is 65°C or more and 135°C or less. If ΔT is less than 65°C, the second crystallization (compound precipitation) reaction is promoted by the temperature rise due to the first crystallization reaction. Also, soft magnetic powder with ΔT exceeding 135°C has poor amorphousness and good soft magnetic properties cannot be obtained.

[0028] In the present embodiment, the difference ΔT is preferably 75°C or more and 120°C or less. For soft magnetic powder having a difference ΔT within this range, heat treatment is possible without causing the second crystallization (compound precipitation) reaction, the amorphousness is good, and the soft magnetic properties are good.

[0029] The soft magnetic powder according to the present embodiment has a composition represented by the formula Fe a Si b P c B d Cu x Cr y Nb z where a, b, c, d, x, y, and z are numerical values satisfying the conditions of 75.4 at% ≤ a ≤ 80.4 at%, 0 at% ≤ b ≤ 9 at%, 4.5 at% ≤ c ≤ 12 at%, 4 at% ≤ d ≤ 12 at%, 0.3 at% ≤ x ≤ 0.9 at%, and 0 at% ≤ y + z ≤ 5 at%.

[0030] In the soft magnetic powder according to this embodiment, the Fe element is the main element and an essential element responsible for magnetism. The higher the proportion of Fe, the more the magnetic flux density Bs can be improved and the raw material cost can be reduced. Also, when the proportion of Fe is less than 75.4 at%, Tx1 becomes high and ΔT becomes small. Therefore, heat treatment of the soft magnetic powder becomes difficult and the magnetic properties after heat treatment deteriorate. Further, when the proportion of Fe exceeds 80.4 at%, the amorphousness decreases and the soft magnetic properties deteriorate.

[0031] In this embodiment, the proportion of the Fe element is preferably 77 at% ≤ a ≤ 79 at%. This is because the soft magnetic powder with the proportion of the Fe element in this range has good amorphousness (crystallinity less than 3%), a wide ΔT (75 °C or more), and good soft magnetic properties after heat treatment.

[0032] In the soft magnetic powder according to this embodiment, the Si element is an element responsible for amorphous phase formation. When the soft magnetic powder contains the Si element, ΔT becomes large and heat treatment can be performed stably. However, when the proportion of Si exceeds 9 at%, the amorphous formation ability decreases and a soft magnetic powder with an amorphous main phase cannot be obtained.

[0033] In the soft magnetic powder according to this embodiment, the P element is an essential element responsible for amorphous phase formation. The P element makes it easier to form a fine and uniform nanocrystalline structure after heat treatment so as to obtain good magnetic properties. When the proportion of P is less than 4.5 at%, the amorphous formation ability decreases. In addition, since it becomes difficult to form a fine and uniform nanocrystalline structure after heat treatment, the soft magnetic properties deteriorate. On the other hand, when the proportion of P increases, Tx1 becomes low. Also, when the proportion of P exceeds 12 at%, the balance with other metalloid elements deteriorates and the amorphous formation ability decreases. Also, when the proportion of P exceeds 12 at%, the saturation magnetic flux density Bs decreases significantly.

[0034] In the soft magnetic powder according to this embodiment, the B element is an essential element responsible for the formation of the amorphous phase. When the proportion of B is less than 4 at%, it becomes difficult to form the amorphous phase by rapid cooling, and good magnetic properties cannot be obtained. Also, when the proportion of B increases, Tx1 increases. When the proportion of B exceeds 12 at%, the melting point becomes high, which is not preferable for manufacturing, and the amorphous forming ability also decreases.

[0035] In the soft magnetic powder according to this embodiment, the Cu element is an essential element contributing to the formation of the nanocrystalline phase. When the proportion of Cu is less than 0.3 at%, there is little cluster precipitation during heat treatment and uniform nanocrystallization is difficult. Also, when the proportion of Cu exceeds 0.9 at%, the amorphous forming ability decreases, and it becomes difficult to obtain a soft magnetic powder with high amorphousness. In the soft magnetic powder according to this embodiment, the proportion of the Cu element is preferably less than 0.7 at%. This is because the soft magnetic powder in this range has good amorphousness, enables uniform nanocrystallization, and has good soft magnetic properties after heat treatment.

[0036] In the soft magnetic powder according to this embodiment, Cr and Nb are not essential. However, by adding the Cr element, an oxide film is formed on the powder surface, improving the corrosion resistance. Also, by adding the Nb element, there is an effect of suppressing the growth of bcc crystal grains during nanocrystallization, making it easier to form a fine nanocrystalline structure. However, when Cr and Nb are added, the proportion of Fe relatively decreases, and the saturation magnetic flux density Bs decreases. Also, the amorphous forming ability decreases. Therefore, the total addition of Cr and Nb is preferably 5 at% or less.

[0037] In the soft magnetic powder according to this embodiment, a part of Fe may be substituted with one or more elements selected from Co, Ni, Zn, Zr, Hf, Mo, Ta, W, Ag, Au, Pd, K, Ca, Mg, Sn, Ti, V, Mn, Al, S, C, O, N, Bi, and rare earth elements. The inclusion of such elements facilitates uniform nanocrystallization after heat treatment. However, in order to keep the adverse effects of these elements on magnetic properties, etc. within an acceptable range, the proportion of these elements is preferably 3 at% or less of Fe.

[0038] In the soft magnetic powder according to this embodiment, its average particle size is preferably 1 μm or more and 20 μm or less. Further, the crystallinity of the soft magnetic powder according to this embodiment after rapid cooling is preferably 10% or less. These values are for obtaining good magnetic properties after heat treatment.

[0039] Here, the rapid cooling rate by the atomization method is 10 3 K / s or more. Preferably, it is 10 4 K / s or more. When the rapid cooling rate is less than 10 3 K / s, the amount of the initially precipitated crystals (mainly bcc-Fe) increases and the amorphous phase decreases. Also, the composition of the amorphous phase in the soft magnetic powder deviates from the desired composition, and the glass transition temperature Tg does not appear. Furthermore, the first crystallization start temperature Tx1 shifts to the high temperature side, or the temperature peak due to the first crystallization decreases.

[0040] Soft magnetic powders (hereinafter referred to as samples) were prepared as several examples and comparative examples, and the results of evaluating their properties are shown in Tables 1 - 8. The evaluation was performed as follows.

[0041] Thermal analysis was performed on each sample using a differential scanning calorimetry (DSC) apparatus. Specifically, the thermal analysis of the sample was performed at a heating rate of 10 °C / min from 40 °C to 730 °C. From this thermal analysis, the glass transition temperature (Tg), the first crystallization start temperature (Tx1: precipitation of bcc-Fe(-Si)), and the second crystallization start temperature (Tx2: precipitation of compound phases such as Fe-B and Fe-P) of each sample were determined.

[0042] Each sample was introduced into an electric furnace and heat-treated in an inert atmosphere. The heat treatment was performed by heating each sample to a predetermined temperature (described in Table 1-8) and holding it for 30 minutes. For each sample, the precipitated phase was evaluated by X-ray diffraction (XRD) before and after the heat treatment, and the ratio of the crystalline phase (crystallinity) was calculated by the Whole-powder-pattern decomposition method (WPPD). Furthermore, using a Vibrating Sample Magnetometer (VSM), the saturation magnetization of each sample was measured, and the saturation magnetic flux density Bs of each sample was calculated from the measured saturation magnetization and the density of each sample. The density of each sample was determined using the Archimedes method. Additionally, the particle size of the soft magnetic powder was evaluated using a laser particle size distribution analyzer, and the average particle size was calculated from the evaluated particle size.

[0043] Furthermore, powder cores were fabricated using each sample. The fabrication of the powder cores was carried out by hot press molding or cold press molding, which will be described later. For each fabricated powder core, as a magnetic property evaluation, the core loss Pcv was measured using a B-H analyzer. The measurement conditions were determined based on the particle size of each sample and the fabrication method of the powder core (described in Table 1-8). Based on the measured core loss Pcv, the samples were distinguished into examples and comparative examples. Specifically, in each of Table 1-6, when Pcv is 1250 kW / m 3 The following samples were taken as examples. Also, in each of Table 7-8, when Pcv is 300 kW / m 3 The following samples were taken as examples.

[0044] The cold press forming was carried out as follows. First, a binder was added to the soft magnetic powder as a sample in a weight ratio of 3% and stirred and mixed to obtain granulated powder. Here, a phenolic resin was used as the binder. Next, the particle size of the granulated powder was adjusted using a mesh with an opening of 500 μm to obtain particle size-adjusted granulated powder. Next, a green compact was produced using the particle size-adjusted granulated powder. Specifically, 2.0 g of the particle size-adjusted granulated powder was weighed, placed in a mold, and formed at a pressure of 490 MPa using a hydraulic automatic press. The shape of the green compact was a cylindrical shape with an outer diameter of 13 mm and an inner diameter of 8 mm. Next, the green compact was heated in an inert atmosphere using an infrared heating device. The heating was carried out at a heating rate of 300 °C per minute to a predetermined heat treatment temperature (described in Tables 1-5, 7-8), and the heat treatment temperature was maintained for 20 minutes. By this heat treatment, the curing of the binder and the nanocrystallization of the soft magnetic powder were carried out, and the green compact changed into a powder core. Thereafter, the powder core was air-cooled and taken out of the mold.

[0045] The hot press forming was carried out as follows. First, an insulating coating was formed on the surface of the soft magnetic powder as a sample to obtain insulating coated powder. The formation of the insulating coating was carried out by immersing the soft magnetic powder in a solution obtained by diluting a silicone resin with methanol and then volatilizing the methanol. The coating amount (solid content) of the silicone resin was 1% by weight based on the soft magnetic powder. Next, a binder was added to the insulating coated powder in a weight ratio of 1% and stirred and mixed to obtain granulated powder. Next, pre-forming was carried out on the granulated powder to obtain a pre-form. Specifically, 2.0 g of the granulated powder was weighed, placed in a mold, and pre-formed at a pressure of 150 MPa using a hydraulic automatic press. Next, final forming was carried out on the pre-form. Specifically, a cylindrical mold with an outer diameter of 13 mm and an inner diameter of 8 mm that had been pre-heated to a predetermined heat treatment temperature (described in Table 6) using an electric heater was used. With a lower punch inserted into the mold, the pre-form was filled into the mold, and then an upper punch was inserted into the mold and a pressure of 1 GPa was applied. The pressurized state was maintained for 30 seconds to change the pre-form into a powder core. Thereafter, the powder core was taken out of the mold.

[0046] In addition, as binders used in cold press forming and hot press forming, in addition to phenolic resins and silicone resins, various organic and inorganic binders such as epoxy resins, polyamide resins, polyimide resins, melamine resins, polyurethane resins, and water glass can be used. Also, the amount of the binder may be appropriately determined in consideration of the powder particle size, application frequency, use, etc.

[0047] (Examples 1-6 and Comparative Examples 1 and 2) As raw materials for the soft magnetic powders of Examples 1-6 and Comparative Examples 1 and 2 described in Table 1 below, commercially pure iron, ferrosilicon, ferrophosphorus, ferroboron, ferrochrome, and electrolytic copper were prepared. The raw materials were weighed so as to have the alloy compositions of Examples 1-6 and Comparative Examples 1 and 2 described in Table 1, and melted by high-frequency melting in an argon atmosphere to produce an alloy melt. Next, the produced alloy melt was rapidly cooled by the water atomization method to produce soft magnetic powders with an average particle size of 8 to 14 μm. For the produced soft magnetic powders, thermal analysis by DSC and evaluation of the crystal phase by XRD were performed. Also, powder cores were produced by cold press forming using the produced soft magnetic powders, and magnetic property evaluations were carried out. Furthermore, the produced soft magnetic powders were heat-treated in an electric furnace at the heat treatment temperatures shown in Table 1 in an argon atmosphere, and saturation magnetic flux density Bs measurements by VSM were performed on the heat-treated soft magnetic powders. The results of the measurement and evaluation of the produced soft magnetic powders are shown in Table 1.

[0048]

Table 1

[0049] Referring to Table 1, each of Examples 1-6 has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2. In each of Examples 1-6, the first crystallization start temperature Tx1 is in the range of 400°C or higher and 475°C or lower. Also, in each of Examples 1-6, the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50°C or lower. Also, in each of Examples 1-6, ΔTx is 20°C or higher. Further, in each of Examples 1-6, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is in the range of 65°C or higher and 135°C or lower. In addition, in each of Examples 1-6, the crystallinity after rapid cooling (as Q.) is 10% or lower. Also, in each of Examples 1-6, the average particle size is 8 to 14 μm, and the average particle size is in the range of 1 μm or higher and 20 μm or lower. Further, in each of Examples 1-6, the crystal phase is the bcc-Fe phase.

[0050] As shown in Table 1, each of Examples 1-6 satisfies the requirements of the composition of the present invention. On the other hand, Comparative Example 1 has an Fe ratio of 81.4 at% and does not satisfy the requirements of the composition of the present invention. Also, Comparative Example 2 has an Fe ratio of 74.9 at% and does not satisfy the requirements of the composition of the present invention.

[0051] As shown in Table 1, the saturation magnetic flux density Bs of each of Examples 1-6 is 1.30 T or higher, and the core loss Pcv is 1250 kW / m 3 or lower. In other words, each of Examples 1-6 has good magnetic properties.

[0052] In particular, the core loss Pcv of each of Examples 2-5 is 1000 kW / m as shown in Table 1 3 or lower. In these Examples 2-5, the first crystallization start temperature Tx1 is in the range of 420°C or higher and 460°C or lower. Therefore, it is preferable that the first crystallization start temperature Tx1 in the soft magnetic powder of the present invention is in the range of 420°C or higher and 460°C or lower.

[0053] Furthermore, each core loss Pcv of Examples 3 - 4 is 750 kW / m as shown in Table 1. 3 as follows. In addition, the crystallinities of Examples 3 - 4 are 1.3% and 0.5% respectively, and Examples 3 - 4 are excellent in amorphousness. In these Examples 3 - 4, the proportion of Fe is in the range of 77 at% to 79 at%. Therefore, the proportion of Fe in the soft magnetic powder of the present invention is preferably 77 at% or more and 79 at% or less.

[0054] On the other hand, Comparative Example 1 does not have a glass transition temperature Tg as shown in Table 1. Also, in Comparative Example 1, the crystallinity is 23.0%, greatly exceeding 10%. Further, in Comparative Example 2, the first crystallization start temperature Tx1 is 480 °C, exceeding 475 °C. Also, in Comparative Example 2, the difference ΔTx between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 53 °C, exceeding 50 °C. Furthermore, in Comparative Example 2, the crystal phase includes not only the bcc - Fe phase but also a compound phase (Com.).

[0055] As shown in Table 1, in Comparative Example 1, although the saturation magnetic flux density Bs is 1.30 T or more, the core loss Pcv is much higher than 1880 kW / m 3 and 1250 kW / m 3 In Comparative Example 2, although the saturation magnetic flux density Bs is 1.30 T or more, the core loss Pcv is higher than 1350 kW / m 3 and 1250 kW / m 3 exceeding them.

[0056] (Examples 7 - 12 and Comparative Example 3) As raw materials for the soft magnetic powders of Examples 7-12 and Comparative Example 3 described in Table 2 below, commercially pure iron, ferrosilicon, ferrophosphorus, ferroboron, ferrochrome, and electrolytic copper were prepared. The raw materials were weighed so as to have the alloy compositions of Examples 7-12 and Comparative Example 3 described in Table 2, and melted by high-frequency melting in an argon atmosphere to produce an alloy melt. Next, the produced alloy melt was rapidly cooled by the water atomization method to produce soft magnetic powders with an average particle size of 8 to 14 μm. For the produced soft magnetic powders, thermal analysis by DSC and evaluation of the crystal phase by XRD were performed. Further, a powder core was produced by cold press molding using the produced soft magnetic powders, and magnetic property evaluation was conducted. Furthermore, the produced soft magnetic powders were heat-treated in an argon atmosphere in an electric furnace at the heat treatment temperatures shown in Table 2, and for the heat-treated soft magnetic powders, measurement of the saturation magnetic flux density Bs by VSM was carried out. The results of the measurement and evaluation of the produced soft magnetic powders are shown in Table 2.

[0057]

Table 2

[0058] Referring to Table 2, each of Examples 7-12 has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2. In each of Examples 7-12, the first crystallization start temperature Tx1 is in the range of 400°C or higher and 475°C or lower. Also, in each of Examples 7-12, the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50°C or lower. Further, in each of Examples 7-12, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is in the range of 65°C or higher and 135°C or lower. In addition, in each of Examples 7-12, the crystallinity after rapid cooling (as Q.) is 10% or lower. Also, in each of Examples 7-12, the average particle size is 8 to 14 μm, within the range of 1 μm or higher and 20 μm or lower. Further, in each of Examples 7-12, the crystal phase is the bcc-Fe phase.

[0059] As shown in Table 2, each of Examples 7 - 12 satisfies the requirements of the composition of the present invention. On the other hand, Comparative Example 3 has a Si ratio of 9.5 at%, which does not satisfy the requirements of the composition of the present invention (0 at% ≤ b ≤ 9 at%).

[0060] As shown in Table 2, the saturation magnetic flux density Bs of each of Examples 7 - 12 is 1.30 T or more, and the core loss Pcv is 1250 kW / m 3 as follows. In other words, each of Examples 7 - 12 has good magnetic properties.

[0061] In particular, the core loss Pcv of Examples 8 - 11 is 1000 kW / m 3 or less as shown in Table 2. In these Examples 8 - 11, ΔT is 75°C or more and 120°C or less. Therefore, it is preferable that ΔT in the soft magnetic powder of the present invention is 75°C or more and 120°C or less.

[0062] On the other hand, Comparative Example 3 does not have a glass transition temperature Tg as shown in Table 2. Also, in Comparative Example 3, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is 140°C, which exceeds 135°C. Further, in Comparative Example 3, the crystallinity is 15.6%, which exceeds 15%.

[0063] As shown in Table 2, in Comparative Example 3, although the saturation magnetic flux density Bs is 1.30 T or more, the core loss Pcv is 1500 kW / m 3 and much higher than 1250 kW / m 3 .

[0064] (Examples 13 - 17 and Comparative Examples 4, 5) As raw materials for the soft magnetic powders of Examples 13 - 17 and Comparative Examples 4 and 5 described in Table 3 below, commercially pure iron, ferrosilicon, ferrophosphorus, ferroboron, ferrochrome, and electrolytic copper were prepared. The raw materials were weighed so as to have the alloy compositions of Examples 13 - 17 and Comparative Examples 4 and 5 described in Table 3, and melted by high-frequency melting in an argon atmosphere to produce an alloy melt. Next, the produced alloy melt was gas atomized and then rapidly cooled with cooling water to produce soft magnetic powders having an average particle size of 8 - 14 μm. For the produced soft magnetic powders, thermal analysis by DSC and evaluation of the crystal phase by XRD were performed. Also, powder cores were produced by cold press molding using the produced soft magnetic powders, and magnetic property evaluations were carried out. Furthermore, the produced soft magnetic powders were heat-treated in an argon atmosphere in an electric furnace at the heat treatment temperatures shown in Table 3, and saturation magnetic flux density Bs measurements by VSM were performed on the heat-treated soft magnetic powders. The results of the measurements and evaluations of the produced soft magnetic powders are shown in Table 3.

[0065]

Table 3

[0066] Referring to Table 3, each of Examples 13 - 17 has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2. In each of Examples 13 - 17, the first crystallization start temperature Tx1 is in the range of 400°C or higher and 475°C or lower. Also, in each of Examples 13 - 17, the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50°C or lower. Furthermore, in each of Examples 13 - 17, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is in the range of 65°C or higher and 135°C or lower. In addition, in each of Examples 13 - 17, the crystallinity after rapid cooling (as Q.) is 10% or lower. Also, in each of Examples 13 - 17, the average particle size is 8 - 14 μm, which is in the range of 1 μm or higher and 20 μm or lower. Furthermore, in each of Examples 13 - 17, the crystal phase is a bcc-Fe phase.

[0067] As shown in Table 3, each of Examples 13 - 17 satisfies the requirements of the composition of the present invention. On the other hand, Comparative Example 4 has a P ratio of 4 at%, which does not satisfy the requirements of the composition of the present invention (4.5 at% ≤ c ≤ 12 at%). Further, Comparative Example 5 has a P ratio of 12.5 at%, which does not satisfy the requirements of the composition of the present invention (4.5 at% ≤ c ≤ 12 at%).

[0068] As shown in Table 3, the saturation magnetic flux density Bs of each of Examples 13 - 17 is 1.30 T or more, and the core loss Pcv is 1250 kW / m 3 or less. In other words, each of Examples 13 - 17 has good magnetic properties.

[0069] On the other hand, Comparative Example 4 does not have a glass transition temperature Tg as shown in Table 3. Further, in Comparative Example 5, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is 60°C, which is lower than 65°C. Also, in Comparative Example 5, the crystallinity after rapid cooling (as Q.) is 12.1%, which exceeds 10%. Furthermore, in Comparative Example 5, the crystal phase includes not only the bcc-Fe phase but also a compound phase (Com.).

[0070] As shown in Table 3, in Comparative Example 4, although the saturation magnetic flux density Bs is 1.30 T or more, the core loss Pcv is 1430 kW / m 3 which is higher than 1250 kW / m 3 Also, in Comparative Example 5, although the saturation magnetic flux density Bs is 1.30 T or more, the core loss Pcv is 1550 kW / m 3 which is much higher than 1250 kW / m 3 and exceeds it by a large margin.

[0071] (Examples 3, 18 - 21 and Comparative Examples 6, 7) As raw materials for the soft magnetic powders of Example 3, Examples 18 - 21, and Comparative Examples 6 and 7 described in Table 4 below, commercially pure iron, ferrosilicon, ferrophosphorus, ferroboron, ferrochrome, and electrolytic copper were prepared. The raw materials were weighed so as to have the alloy compositions of Example 3, Examples 18 - 21, and Comparative Examples 6 and 7 described in Table 4, and melted by high-frequency melting in an argon atmosphere to produce an alloy melt. Next, the produced alloy melt was rapidly cooled by the water atomization method to produce soft magnetic powders with an average particle size of 8 - 14 μm. For the produced soft magnetic powders, thermal analysis by DSC and evaluation of the crystal phase by XRD were performed. Also, powder cores were produced by cold press molding using the produced soft magnetic powders, and magnetic property evaluations were conducted. Furthermore, the produced soft magnetic powders were heat-treated in an argon atmosphere in an electric furnace at the heat treatment temperatures shown in Table 4, and saturation magnetic flux density Bs measurements by VSM were performed on the heat-treated soft magnetic powders. The results of the measurement and evaluation of the produced soft magnetic powders are shown in Table 4.

[0072]

Table 4

[0073] Referring to Table 4, each of Example 3 and Examples 18 - 21 has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2. In each of Example 3 and Examples 18 - 21, the first crystallization start temperature Tx1 is in the range of 400°C or more and 475°C or less. Also, in each of Example 3 and Examples 18 - 21, the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50°C or less. Furthermore, in each of Example 3 and Examples 18 - 21, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is in the range of 65°C or more and 135°C or less. In addition, in each of Example 3 and Examples 18 - 21, the crystallinity after rapid cooling (as Q.) is 10% or less. Also, in each of Example 3 and Examples 18 - 21, the average particle size is 8 - 14 μm, within the range of 1 μm or more and 20 μm or less. Furthermore, in each of Example 3 and Examples 18 - 21, the crystal phase is the bcc-Fe phase.

[0074] As shown in Table 4, in addition to Example 3, each of Examples 18 - 21 satisfies the requirements of the composition of the present invention. On the other hand, in Comparative Example 6, the proportion of B is 3.5 at%, which does not satisfy the requirements of the composition of the present invention (4 at% ≤ d ≤ 12 at%). Further, in Comparative Example 7, the proportion of B is 12.5 at%, which does not satisfy the requirements of the composition of the present invention (4 at% ≤ d ≤ 12 at%).

[0075] As shown in Table 4, the saturation magnetic flux density Bs of each of Example 3 and Examples 18 - 21 is 1.30 T or more, and the core loss Pcv is 1250 kW / m 3 is as follows. In other words, each of Example 3 and Examples 18 - 21 has good magnetic properties.

[0076] On the other hand, as shown in Table 4, both Comparative Example 6 and Comparative Example 7 do not have a glass transition temperature Tg. Also, in Comparative Example 6 and Comparative Example 7, the crystallinities are 11.5% and 13.8% respectively, which exceed 10%.

[0077] As shown in Table 4, in Comparative Example 6, although the saturation magnetic flux density Bs is 1.30 T or more, the core loss Pcv is 1260 kW / m 3 and exceeds 1250 kW / m 3 Similarly, in Comparative Example 7, although the saturation magnetic flux density Bs is 1.30 T or more, the core loss Pcv is 1390 kW / m 3 and exceeds 1250 kW / m 3 and exceeds 1250 kW / m

[0078] (Examples 19, 22 - 27 and Comparative Examples 8, 9) As raw materials for the soft magnetic powders of Example 19, Examples 22 - 27, and Comparative Examples 8 and 9 described in Table 5 below, commercially pure iron, ferrosilicon, ferrophosphorus, ferroboron, ferrochrome, and electrolytic copper were prepared. The raw materials were weighed so as to have the alloy compositions of Example 19, Examples 22 - 27, and Comparative Examples 8 and 9 described in Table 5, and melted by high-frequency melting in an argon atmosphere to produce an alloy melt. Next, the produced alloy melt was rapidly cooled by the water atomization method to produce soft magnetic powders with an average particle size of 8 - 14 μm. For the produced soft magnetic powders, thermal analysis by DSC and evaluation of the crystal phase by XRD were performed. Also, powder cores were produced by cold press molding using the produced soft magnetic powders, and magnetic property evaluation was conducted. Furthermore, the produced soft magnetic powders were heat-treated in an argon atmosphere in an electric furnace at the heat treatment temperatures shown in Table 5, and saturation magnetic flux density Bs measurement by VSM was performed on the heat-treated soft magnetic powders. The results of the measurement and evaluation of the produced soft magnetic powders are shown in Table 5.

[0079]

Table 5

[0080] Referring to Table 5, each of Example 19 and Examples 22 - 27 has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2. In each of Example 19 and Examples 22 - 27, the first crystallization start temperature Tx1 is in the range of 400°C or more and 475°C or less. Also, in each of Example 19 and Examples 22 - 27, the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50°C or less. Furthermore, in each of Example 19 and Examples 22 - 27, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is in the range of 65°C or more and 135°C or less. In addition, in each of Example 19 and Examples 22 - 27, the crystallinity after rapid cooling (as Q.) is 10% or less. Also, in each of Example 19 and Examples 22 - 27, the average particle size is 8 - 14 μm, within the range of 1 μm or more and 20 μm or less. Furthermore, in each of Example 19 and Examples 22 - 27, the crystal phase is the bcc-Fe phase.

[0081] As shown in Table 5, in addition to Example 19, each of Examples 22 - 27 satisfies the requirements of the composition of the present invention. On the other hand, in Comparative Example 8, the proportion of Cu is 1.0 at%, which does not satisfy the requirements of the composition of the present invention (0.3 at% ≤ x ≤ 0.9 at%). Further, in Comparative Example 9, the proportion of Cu is 0.2 at%, which does not satisfy the requirements of the composition of the present invention (0.3 at% ≤ x ≤ 0.9 at%).

[0082] As shown in Table 5, the saturation magnetic flux density Bs of each of Example 19 and Examples 22 - 27 is 1.30 T or more, and the core loss Pcv is 1250 kW / m 3 is as follows. In other words, each of Example 19 and Examples 22 - 27 has good magnetic properties.

[0083] In particular, the core loss Pcv of Examples 19, 24 - 27 is 1000 kW / m 3 or less as shown in Table 5. In these Examples 19, 24 - 27, the proportion of Cu is less than 0.7 at%. Therefore, it is preferable that the proportion of Cu in the soft magnetic powder of the present invention is 0.3 at% or more and less than 0.7 at%.

[0084] On the other hand, as shown in Table 5, Comparative Example 8 does not have a glass transition temperature Tg. Further, in Comparative Example 8, the crystallinity is 13.5%, which exceeds 10%. Also, in Comparative Example 9, the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 62 °C, which is lower than 65 °C. Furthermore, in Comparative Example 9, the crystal phase contains not only the bcc - Fe phase but also a compound phase (Com.).

[0085] As shown in Table 5, in Comparative Example 8, although the saturation magnetic flux density Bs is 1.30 T or more, the core loss Pcv is 1470 kW / m 3 and exceeds 1250 kW / m 3 Similarly, in Comparative Example 9, although the saturation magnetic flux density Bs is 1.30 T or more, the core loss Pcv is 1520 kW / m 3 and 1250 kW / m3 exceeds

[0086] (Examples 19, 28 - 31 and Comparative Example 10) As raw materials for the soft magnetic powders of Examples 28 - 31 and Comparative Example 10 described in Table 6 below, commercially pure iron, ferrosilicon, ferrophosphorus, ferroboron, ferrochrome, niobium, and electrolytic copper were prepared. The raw materials were weighed so as to have the alloy compositions of Examples 28 - 31 and Comparative Example 10 described in Table 6, and melted by high-frequency melting in an argon atmosphere to produce an alloy melt. Next, the produced alloy melt was rapidly cooled by the high-pressure water atomization method to produce soft magnetic powders with an average particle size of 3 - 8 μm. For the produced soft magnetic powders, thermal analysis by DSC and evaluation of the crystal phase by XRD were performed. Further, a powder compact core was produced by hot press molding using the produced soft magnetic powders, and magnetic property evaluation was carried out. Furthermore, the produced soft magnetic powders were heat-treated in an electric furnace at the heat treatment temperatures shown in Table 6 in an argon atmosphere, and saturation magnetic flux density Bs measurement by VSM was performed on the heat-treated soft magnetic powders. The results of the measurement and evaluation of the produced soft magnetic powders are shown in Table 6.

[0087]

Table 6

[0088] Referring to Table 6, each of Example 19 and Examples 28 - 31 has a glass transition temperature Tg, a first crystallization onset temperature Tx1, and a second crystallization temperature Tx2. In each of Example 19 and Examples 28 - 31, the first crystallization onset temperature Tx1 is in the range of 400°C or higher and 475°C or lower. Also, in each of Example 19 and Examples 28 - 31, the difference ΔTx = Tx1 - Tg between the first crystallization onset temperature Tx1 and the glass transition temperature Tg is 50°C or lower. Further, in each of Example 19 and Examples 28 - 31, the difference ΔT = Tx2 - Tx1 between the second crystallization onset temperature Tx2 and the first crystallization onset temperature Tx1 is in the range of 65°C or higher and 135°C or lower. In addition, in each of Example 19 and Examples 28 - 31, the crystallinity after rapid cooling (as Q.) is 10% or lower. Also, in each of Example 19 and Examples 28 - 31, the average particle size is 3 - 8 μm, within the range of 1 μm or higher and 20 μm or lower. Further, in each of Example 19 and Examples 28 - 31, the crystal phase is the bcc - Fe phase.

[0089] As shown in Table 6, in addition to Example 19, each of Examples 28 - 31 satisfies the requirements of the composition of the present invention. On the other hand, Comparative Example 10 does not satisfy the requirements of the composition of the present invention (0 at% ≦ y + z ≦ 5 at%) as the total ratio of Cr and Nb is 5.5 at%.

[0090] As shown in Table 6, the saturation magnetic flux density Bs of each of Example 19 and Examples 28 - 31 is 1.30 T or higher, and the core loss Pcv is 1250 kW / m 3 or less. In other words, each of Example 19 and Examples 28 - 31 has good magnetic properties.

[0091] On the other hand, as shown in Table 6, Comparative Example 10 has a saturation magnetic flux density Bs that is lower than 1.25 T and 1.30 T, and the core loss Pcv is higher than 1300 kW / m 3 and 1250 kW / m 3 or more.

[0092] (Examples 32 - 42) As raw materials for the soft magnetic powders of Examples 32 - 42 described in Table 7 below, commercially pure iron, ferrosilicon, ferrophosphorus, ferroboron, ferrochrome, electrolytic copper, ferrocarbon, Co, zinc, Sn, Ni, Mn, Al, and Ti were prepared. The raw materials were weighed to have the alloy compositions of Examples 32 - 42 described in Table 7, and melted by high-frequency melting in an argon atmosphere to produce an alloy melt. Next, the produced alloy melt was gas atomized and then rapidly cooled with cooling water to produce soft magnetic powders with an average particle size of 14 - 20 μm. For the produced soft magnetic powders, thermal analysis by DSC and evaluation of the crystal phase by XRD were performed. Also, a powder core was produced by cold press molding using the produced soft magnetic powders, and magnetic property evaluation was carried out. Furthermore, the produced soft magnetic powders were heat-treated in an electric furnace in an argon atmosphere at the heat treatment temperatures shown in Table 7, and for the heat-treated soft magnetic powders, measurement of the saturation magnetic flux density Bs by VSM was performed. The results of the measurement and evaluation of the produced soft magnetic powders are shown in Table 7.

[0093]

Table 7

[0094] Referring to Table 7, each of Examples 32 - 42 has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2. In each of Examples 32 - 42, the first crystallization start temperature Tx1 is in the range of 400°C or more and 475°C or less. Also, in each of Examples 32 - 42, the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50°C or less. Furthermore, in each of Examples 32 - 42, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is in the range of 65°C or more and 135°C or less. In addition, in each of Examples 32 - 42, the crystallinity after rapid cooling (as Q.) is 10% or less. Also, in each of Examples 32 - 42, the average particle size is 14 - 20 μm, within the range of 1 μm or more and 20 μm or less. Furthermore, in each of Examples 32 - 42, the crystal phase is the bcc-Fe phase.

[0095] As shown in Table 7, in each of Examples 32 - 42, a part (3 at% or less) of Fe is replaced by a predetermined element. Specifically, each of Example 32 and Example 33 contains C. Example 34 contains Co. Example 35 contains Zn. Each of Example 36 and Example 37 contains Sn. Example 38 contains Ni. Example 39 contains Mn. Example 40 contains Al. Example 41 contains Ti. Example 42 contains O.

[0096] As shown in Table 7, in each of Examples 32 - 42, the saturation magnetic flux density Bs is 1.30 T or more, and the core loss Pcv is 300 kW / m 3 or less. In other words, each of Examples 32 - 42 has good magnetic properties. Note that the measurement conditions of the core loss Pcv in Table 7 are different from those of the core loss Pcv in Tables 1 - 6.

[0097] (Example 43) As raw materials for the soft magnetic powder of Example 43 described in Table 8 below, commercially pure iron, ferrosilicon, ferrophosphorus, ferroboron, ferrochrome, and electrolytic copper were prepared. The raw materials were weighed to have the alloy composition of Example 43 described in Table 8, and melted by high-frequency melting in an argon atmosphere to produce an alloy melt. Next, the produced alloy melt was rapidly cooled by gas atomization to produce soft magnetic powder with an average particle size of 14 - 20 μm. For the produced soft magnetic powder, thermal analysis by DSC and evaluation of the crystal phase by XRD were performed. Also, a powder core was produced by cold press molding using the produced soft magnetic powder, and magnetic property evaluation was carried out. Furthermore, the produced soft magnetic powder was heat-treated in an electric furnace at the heat treatment temperature shown in Table 8 in an argon atmosphere, and for the heat-treated soft magnetic powder, measurement of the saturation magnetic flux density Bs by VSM was performed. The results of the measurement and evaluation of the produced soft magnetic powder are shown in Table 8.

[0098]

Table 8

[0099] Referring to Table 8, Example 43 has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2. In Example 43, the first crystallization start temperature Tx1 is in the range of 400°C or more and 475°C or less. Also, in Example 43, the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50°C or less. Further, in Example 43, the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is in the range of 65°C or more and 135°C or less. In addition, in Example 43, the crystallinity after quenching (as Q.) is 10% or less. Also, in Example 43, the average particle size is 14 - 20 μm, within the range of 1 μm or more and 20 μm or less.

[0100] As shown in Table 8, the first crystallization start temperature Tx1 of Example 43 is 442°C. For this Example 43, heat treatment was performed at various temperatures from 400°C to 500°C. At any treatment temperature, a saturation magnetic flux density Bs of 1.30T or more and 300 kW / m 3 The following core loss Pcv was obtained. From this, it can be seen that the soft magnetic powder of the present invention can obtain good magnetic properties even when heat treatment is performed at a temperature lower than or higher than the first crystallization start temperature Tx1. However, referring to Table 7 in addition to Table 8, when the heat treatment temperature is close to the first crystallization start temperature Tx1, the core loss Pcv is 200 kW / m 3 or less. Therefore, it is preferable that the heat treatment temperature is closer to the first crystallization start temperature Tx1.

[0101] As described above, the compacted cores of Examples 1 - 43 have excellent magnetic properties. From this, it can be said that the soft magnetic powders of Examples 1 - 43 can stably perform nanocrystallization and can sufficiently precipitate fine nanocrystals.

[0102] As described above, the present invention has been described with several embodiments, but the present invention is not limited to the above embodiments, and various modifications and changes are possible without departing from the gist of the present invention.

[0103] For example, the soft magnetic powder of the present invention may be one in which initial crystals are precipitated. In this case, low-grade and inexpensive materials can be used as raw materials. Also, the amount of heat generated during heating can be suppressed. Furthermore, a high saturation magnetic flux density Bs can be expected.

[0104] Also, in the above embodiment, the atomization method is used for manufacturing the soft magnetic powder, but other methods may be used. For example, a thin strip may be produced from a molten alloy and the thin strip may be pulverized to obtain the soft magnetic powder. In this case, a high saturation magnetic flux density Bs and a high magnetic permeability μ can be expected.

[0105] Furthermore, the surface of the soft magnetic powder of the present invention may be coated with glass or the like. Thereby, an improvement in electrical resistance and an improvement in fluidity during magnetic core production can be expected.

Claims

1. A soft magnetic powder, wherein the soft magnetic powder has a glass transition temperature Tg, a first crystallization start temperature Tx1, and a second crystallization temperature Tx2, wherein the first crystallization start temperature Tx1 is 400 °C or higher and 475 °C or lower, wherein the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 50 °C or lower, and wherein the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is 65 °C or higher and 135 °C or lower soft magnetic powder.

2. The soft magnetic powder according to Claim 1, wherein the first crystallization start temperature Tx1 is 420 °C or higher and 460 °C or lower soft magnetic powder.

3. The soft magnetic powder according to Claim 1 or Claim 2, wherein the difference ΔTx = Tx1 - Tg between the first crystallization start temperature Tx1 and the glass transition temperature Tg is 20 °C or higher and 50 °C or lower soft magnetic powder.

4. The soft magnetic powder according to any one of Claims 1 to 3, wherein the difference ΔT = Tx2 - Tx1 between the second crystallization start temperature Tx2 and the first crystallization start temperature Tx1 is 75 °C or higher soft magnetic powder.

5. The soft magnetic powder according to any one of Claims 1 to 4, The soft magnetic powder has a composition formula of Fe ａ Si ｂ P ｃ B ｄ Cu ｘ Cr ｙ Nb ｚ represented by where 75.4 at% ≤ a ≤ 80.4 at% 0 at% ≤ b ≤ 9 at% 4.5 at% ≤ c ≤ 12 at% 4 at% ≤ d ≤ 12 at% 0.3 at% ≤ x ≤ 0.9 at% 0 at% ≤ y + z ≤ 5 at% and soft magnetic powder.

6. The soft magnetic powder according to Claim 5, where 77 at% ≤ a ≤ 79 at% and soft magnetic powder.

7. The soft magnetic powder according to Claim 6, where a portion of the Fe that is 3 at% or less of the entire composition is replaced with one or more elements selected from Co, Ni, Zn, Zr, Hf, Mo, Ta, W, Ag, Au, Pd, K, Ca, Mg, Sn, Ti, V, Mn, Al, S, C, O, N, Bi, and rare earth elements soft magnetic powder.

8. The soft magnetic powder according to any one of Claims 1 to 7, having an average particle size of 1 μm or more and 20 μm or less soft magnetic powder.

9. The soft magnetic powder according to any one of Claims 1 to 8, having a crystallinity of 10% or less after rapid cooling soft magnetic powder.

Images