Soft magnetic alloy powder, magnetic core, magnetic component, and electronic device

Abstract

To provide a soft-magnetic alloy powder allowing for obtaining a magnetic core improved in magnetic permeability without greatly changing the particle size.SOLUTION: A soft-magnetic alloy powder has a main component consisting of a composition formula (Co(1-(α+β))X1αX2β)(1-(a+b+c+d+e+f))MaBbPcSidCreSf (atomic ratio), in which X1 is one or more selected from a group consisting of Fe and Ni, X2 is one or more selected from a group consisting of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Bi, N, O, C and rare earth elements, M is one or more selected from a group consisting of Nb, Hf, Zr, Ta, Mo, W, Ti and V, and a-f, α and β are within a particular range. The soft-magnetic alloy powder has a grass transfer point Tg and a melting point Tm, in which 900°C≤Tm≤1200°C is given.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to soft magnetic alloy powders, magnetic cores, magnetic components, and electronic devices.

Background Art

[0002] In recent years, there has been a demand for lower power consumption and higher efficiency in electronic, information, and communication devices, particularly in electronic devices. Furthermore, with the trend towards a low-carbon society, such requirements have become even stronger. Therefore, there is also a demand for reducing energy loss and improving power efficiency in the power supply circuits of electronic, information, and communication devices, particularly in electronic devices.

[0003] Here, in order to reduce energy loss and improve power efficiency, it is required to obtain soft magnetic alloy powders that have excellent soft magnetic properties and can achieve an improved filling rate when used in magnetic cores.

[0004] Patent Document 1 describes soft magnetic metal powders with improved Wardell sphericity. It also describes that excellent power inductors can be manufactured by improving the sphericity.

[0005] Patent Document 2 describes Co-based amorphous alloy ribbons. It also describes that the permeability and rectangularity ratio are improved by setting the S content to 30 ppm or less and the Al content to 40 ppm or less.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a soft magnetic alloy powder capable of obtaining a magnetic core with improved magnetic permeability without significantly changing the particle size.

Means for Solving the Problems

[0008] To achieve the above object, the soft magnetic alloy powder of the present invention is Composition formula (Co (1-(α+β)) X1 α X2 β ) (1-(a+b+c+d+e+f)) M a B b P c Si d Cr e S f (atomic ratio), which is a soft magnetic alloy powder having a main component, X1 is one or more selected from the group consisting of Fe and Ni, X2 is one or more selected from the group consisting of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Bi, N, O, C, and rare earth elements, M is one or more selected from the group consisting of Nb, Hf, Zr, Ta, Mo, W, Ti, and V, 0 < a ≦ 0.140 0.160 < b ≦ 0.250 0 ≦ c ≦ 0.200 0 ≦ d ≦ 0.250 0 ≦ e ≦ 0.030 0 ≦ f ≦ 0.010 0.160 < b + c + d + e + f ≦ 0.430 0.500 < 1 - (a + b + c + d + e + f) < 0.840 α ≧ 0 β ≧ 0 0 ≦ α + β < 0.50 and the soft magnetic alloy powder has a glass transition temperature Tg and a melting point Tm, 900°C ≦ Tm ≦ 1200°C.

[0009] The soft magnetic alloy powder according to the present invention has the above composition and has the above glass transition point and melting point, thereby optimizing the magnetic permeability of the soft magnetic alloy powder itself. Furthermore, the sphericity of the powder particles is increased and the proportion of irregular particles is decreased. As a result, the magnetic permeability of the magnetic core using the soft magnetic alloy powder can be improved without changing the particle size of the soft magnetic alloy powder.

[0010] The average circularity of the powder particles contained in the soft magnetic alloy powder according to the present invention may be 0.93 or more, and the cumulative number ratio from the lower circularity of the powder particles to 0.50 may be 2.0% or less.

[0011] The average circularity of the powder particles contained in the soft magnetic alloy powder according to the present invention may be 0.95 or more, and the cumulative number ratio from the lower circularity of the powder particles to 0.50 may be 1.5% or less.

[0012] For the soft magnetic alloy powder according to the present invention, the value obtained by dividing the Co content ratio by the B content ratio may be greater than 2.000 and less than 5.000.

[0013] The soft magnetic alloy powder according to the present invention may have an amorphous structure.

[0014] The soft magnetic alloy powder according to the present invention may have a nanocrystalline structure.

[0015] The magnetic core according to the present invention contains the above soft magnetic alloy powder.

[0016] The magnetic component according to the present invention contains the above soft magnetic alloy powder.

[0017] The electronic device according to the present invention contains the above soft magnetic alloy powder.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8A

Figure 8B

Mode for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described.

[0020] The soft magnetic alloy powder of the present embodiment has a main component consisting of a composition formula (Co (1-(α+β)) X1 α X2 β )(atomic ratio), and is a soft magnetic alloy powder, (1-(a+b+c+d+e+f)) M a B b P c Si d Cr e S f where X1 is one or more selected from the group consisting of Fe and Ni, X2 is one or more selected from the group consisting of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Bi, N, O, C, and rare earth elements, M is one or more selected from the group consisting of Nb, Hf, Zr, Ta, Mo, W, Ti, and V, 0 < a ≤ 0.140 0.160 < b ≤ 0.250 0 ≤ c ≤ 0.200 0 ≤ d ≤ 0.250 0 ≤ e ≤ 0.030 0 ≦ f ≦ 0.010 0.160 < b + c + d + e + f ≦ 0.430 0.500 < 1 - (a + b + c + d + e + f) < 0.840 α ≧ 0 β ≧ 0 0 ≦ α + β < 0.50 and the soft magnetic alloy powder has a glass transition point Tg and a melting point Tm, characterized in that 900°C ≦ Tm ≦ 1200°C.

[0021] Generally, soft magnetic alloy powders having a composition containing a large amount of Co have a higher relative permeability compared to soft magnetic alloy powders having a composition containing a large amount of Fe. Also, soft magnetic alloy powders having a composition containing a large amount of Co tend to have high corrosion resistance and electrical resistance, and tend to have low dielectric loss. Furthermore, soft magnetic alloy powders having a composition containing a large amount of Co have a lower melting point than soft magnetic alloy powders having a composition containing a large amount of Fe. As a result, when producing soft magnetic alloy powders by an atomization method such as gas atomization described later, it is easy to lower the atomization temperature. Note that the melting point of the molten metal made of the soft magnetic alloy before atomization and the melting point of the soft magnetic alloy powder obtained by atomization are usually the same.

[0022] The soft magnetic alloy powder according to this embodiment has the above composition and has the glass transition point and the above melting point, whereby the particle shape of the powder particles can be improved. Specifically, by having the above composition and having the glass transition point and the above melting point, a soft magnetic alloy powder composed of powder particles with a high average sphericity can be obtained. Furthermore, a soft magnetic alloy powder with few powder particles having a particle shape with a low circularity, that is, a soft magnetic alloy powder with a small proportion of irregular particles, can be obtained.

[0023] And, since the soft magnetic alloy powder according to this embodiment is composed of powder particles having the above particle shape, the filling rate of a magnetic core or the like using the soft magnetic alloy powder can be improved, and various properties such as the relative permeability of the magnetic core or the like can be improved. Hereinafter, the powder particles may sometimes be simply referred to as particles.

[0024] Also, when heat-treating the soft magnetic alloy powder of the present embodiment, nanocrystals with a crystal grain size of 50 nm or less are likely to precipitate. In other words, the soft magnetic alloy powder of the present embodiment is likely to be a starting material for a soft magnetic alloy powder in which nanocrystals are precipitated. Whether or not it contains nanocrystals and whether or not it contains amorphous can be confirmed by XRD.

[0025] Note that when the soft magnetic alloy powder of the present embodiment contains nanocrystals, each particle contains a large number of nanocrystals. That is, the particle diameter of the soft magnetic alloy powder described later is different from the crystal grain size of the nanocrystals.

[0026] Hereinafter, each component of the soft magnetic alloy powder according to the present embodiment will be described in detail.

[0027] M is one or more selected from the group consisting of Nb, Hf, Zr, Ta, Mo, W, Ti, and V.

[0028] The content (a) of M satisfies 0 < a ≤ 0.140. It may satisfy 0.001 ≤ a ≤ 0.140. Further, it may satisfy 0.003 ≤ a ≤ 0.140, or may satisfy 0.040 ≤ a ≤ 0.100. When M is not included, it becomes difficult for the soft magnetic alloy powder to have a glass transition point Tg. As a result, the roundness of the particles tends to decrease, and the relative permeability decreases. When a is too large, the melting point Tm of the soft magnetic alloy powder tends to decrease. As a result, the roundness of the particles tends to decrease, the ratio of irregularly shaped particles in the soft magnetic alloy powder increases, and the relative permeability decreases. Further, the saturation magnetic flux density tends to decrease. Note that from the viewpoint of easily reducing the coercive force, it is preferably 0.010 ≤ a ≤ 0.140.

[0029] The content of B (b) satisfies 0.160 < b ≤ 0.250. It may also satisfy 0.180 ≤ b ≤ 0.250. If b is too small, the melting point Tm of the soft magnetic alloy becomes too high and the molten metal cannot be sprayed, and it may be impossible to produce soft magnetic alloy powder. If b is too large, the melting point Tm becomes too low, the proportion of irregular particles in the soft magnetic alloy powder increases, the coercive force increases, and the relative permeability decreases.

[0030] The content of P (c) satisfies 0 ≤ c ≤ 0.200. That is, it may not contain P. More preferably, it satisfies 0 ≤ c ≤ 0.150, and even more preferably, it satisfies 0.010 ≤ c ≤ 0.050. If c is too large, the melting point Tm of the soft magnetic alloy powder becomes too low, the proportion of irregular particles in the soft magnetic alloy powder increases, the coercive force increases, and the relative permeability decreases.

[0031] The content of Si (d) satisfies 0 ≤ d ≤ 0.250. That is, it may not contain Si. More preferably, it satisfies 0 ≤ d ≤ 0.200. If d is too large, the melting point Tm of the soft magnetic alloy powder becomes too low, the roundness decreases, the proportion of irregular particles in the soft magnetic alloy powder increases, the coercive force increases, and the relative permeability decreases.

[0032] The content of Cr (e) satisfies 0 ≤ e ≤ 0.030. That is, it may not contain Cr. More preferably, it satisfies 0.001 ≤ e ≤ 0.010. By containing Cr, the corrosion resistance of the soft magnetic alloy powder tends to increase. If e is too large, the proportion of irregular particles in the soft magnetic alloy powder increases, the coercive force increases, and the relative permeability decreases.

[0033] The content of S (f) satisfies 0 ≤ f ≤ 0.010. That is, it may not contain S. The larger f is, the smaller the proportion of irregular particles in the soft magnetic alloy powder becomes. However, if f is too large, the coercive force increases and the relative permeability decreases.

[0034] In addition, the soft magnetic alloy powder according to this embodiment satisfies 0.160 < b + c + d + e + f ≤ 0.430. It may also satisfy 0.190 ≤ b + c + d + e + f ≤ 0.430. If b + c + d + e + f is too large, soft magnetic alloy powder with a high relative permeability cannot be obtained.

[0035] Furthermore, the soft magnetic alloy powder according to this embodiment satisfies 0.500 < 1 - (a + b + c + d + e + f) < 0.840. It may also satisfy 0.550 ≤ 1 - (a + b + c + d + e + f) ≤ 0.800. If 1 - (a + b + c + d + e + f) is too small or too large, soft magnetic alloy powder with a high relative permeability cannot be obtained.

[0036] In addition, in the soft magnetic alloy powder of this embodiment, part of Co may be replaced with X1 and / or X2.

[0037] X1 is one or more selected from the group consisting of Fe and Ni. Regarding the content of X1, α = 0 may be the case. That is, X1 may not be contained. Also, the atomic number of X1 is preferably 40 at% or less with the total atomic number of the composition being 100 at%. That is, it is preferable to satisfy 0 ≤ α{1 - (a + b + c + d + e + f)} ≤ 0.400. Further, it is more preferable to satisfy 0 ≤ α{1 - (a + b + c + d + e + f)} ≤ 0.100. Also, when a small amount of Fe is contained rather than when no Fe is contained at all, the coercive force is more likely to decrease and the relative permeability is more likely to increase. In particular, when the atomic ratio of Co / Fe is 5 or more and 20 or less, the coercive force is more likely to decrease and the relative permeability is more likely to increase.

[0038] X2 is one or more selected from the group consisting of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Bi, N, O, C, and rare earth elements. Regarding the content of X2, β = 0 may be the case. That is, X2 may not be contained. Also, the atomic number of X2 is preferably 5.0 at% or less with the total atomic number of the composition being 100 at%. That is, it is preferable to satisfy 0 ≤ β{1 - (a + b + c + d + e + f + g)} ≤ 0.050.

[0039] The substitution amount of Co for X1 and / or X2 is less than half of Co on an atomic number basis. That is, 0 ≦ α + β < 0.50. It may be 0 ≦ α + β ≦ 0.40. If α + β is too large, especially when α + β ≧ 0.50, the melting point of the soft magnetic alloy becomes too high and the molten metal cannot be sprayed, and soft magnetic alloy powder may not be produced.

[0040] Even when the melting point of the soft magnetic alloy is high, it is possible to spray the molten metal by raising the atomization temperature. However, when the atomization temperature is high, the circularity of the soft magnetic alloy powder tends to decrease, the ratio of irregular particles in the soft magnetic alloy powder tends to increase, the coercive force tends to increase, and the relative permeability tends to decrease.

[0041] Also, the value obtained by dividing the content ratio of Co by the content ratio of B (hereinafter may be referred to as Co / B) may be greater than 2.000 and less than 5.250, may be greater than 2.000 and less than 5.000, or may be 2.340 or more and 4.000 or less. When Co / B is within the above range, the melting point Tm of the soft magnetic alloy powder described later tends to be low, and the atomization temperature tends to be reduced.

[0042] The soft magnetic alloy powder of the present embodiment may contain elements other than the elements contained in the above main components as inevitable impurities within a range that does not significantly affect characteristics such as relative permeability. For example, it may contain 0.1 mass% or less based on 100 mass% of the soft magnetic alloy powder.

[0043] Hereinafter, a method for evaluating the particle shape and particle diameter of the soft magnetic alloy powder of the present embodiment will be described.

[0044] The sphericity of the soft magnetic alloy powder may be evaluated by evaluating the circularity of the figure obtained by projecting the particle shape of the soft magnetic alloy powder.

[0045] In this embodiment, the particle shape is evaluated using Morphologi G3 (Malvern Panalytical). Morphologi G3 is a device that can disperse powder by air, project individual particle shapes, and evaluate them. It is possible to evaluate particle shapes with a particle diameter in the range of approximately 0.5 μm to several millimeters using an optical microscope or a laser microscope. Specifically, as can be seen from the particle shape measurement results 1 and 2 shown in FIGS. 1 and 2, a large number of particle shapes can be projected and evaluated at once. However, in reality, a much larger number of particle shapes than those described in the particle shape measurement results 1 and 2 shown in FIGS. 1 and 2 can be projected and evaluated at once. Note that FIG. 1 shows the projection result of powder particles with a good particle shape and a high sphericity, and FIG. 2 shows the projection result of powder particles with a poor particle shape and a low sphericity.

[0046] Since Morphologi G3 can create and evaluate projection diagrams of a large number of particles at once, it is possible to evaluate the shapes of a large number of particles in a shorter time compared to the conventional evaluation methods such as SEM observation. For example, in the examples described later, projection diagrams are created for 20,000 particles, the circularity of each individual particle is automatically calculated, and the average circularity is calculated based on the number of particles. On the other hand, in the conventional SEM observation, since the circularity is calculated for each individual particle using SEM images, it is difficult to evaluate the shapes of a large number of particles in a short time.

[0047] The circularity of a particle is expressed as 2(πS) / L, where S is the area in the projection diagram and L is the length of the perimeter in the projection diagram. The circularity of a circle is 1, and the closer the circularity of a particle is to 1, the higher the sphericity of the particle. 1 / 2 / L. The circularity of a circle is 1, and the closer the circularity of a particle is to 1, the higher the sphericity of the particle.

[0048] The soft magnetic alloy powder according to this embodiment can have a high average circularity by having the above composition, specifically, it can be 0.93 or more. The average circularity is preferably 0.95 or more.

[0049] The ratio of irregularly shaped particles is evaluated by the following method.

[0050] For 20,000 particles whose circularity has been measured, calculate the cumulative number ratio (cumulative frequency) from the lower circularity. Then, the smaller the cumulative number ratio from the lower circularity to 0.50, the smaller the ratio of irregularly shaped particles.

[0051] Due to having the above composition, the soft magnetic alloy powder according to this embodiment can have a melting point Tm in the range of 900°C ≤ Tm ≤ 1200°C, and can reduce the ratio of irregularly shaped particles. And the cumulative number ratio from the lower circularity to 0.50 can specifically be 2.5% or less. The cumulative number ratio from the lower circularity to 0.50 is preferably 1.5% or less. Note that there is no particular lower limit for the cumulative number ratio from the lower circularity to 0.50. For example, it may be 0.05% or more.

[0052] Examples of graphs with circularity on the horizontal axis and cumulative number ratio on the vertical axis are shown in FIGS. 3 and 4. In the case of the solid line, the cumulative number ratio from the lower circularity to 0.50 is 1.5% or less. In contrast, in the case of the dotted line, the cumulative number ratio from the lower circularity to 0.50 exceeds 1.5% and is 2.0% or less. That is, in the case of the solid line, it can be evaluated that the ratio of irregularly shaped particles is smaller than in the case of the dotted line.

[0053] The method for evaluating the particle size is shown below.

[0054] In this embodiment and the examples described later, the particle size is evaluated based on volume. There is no particular limitation on the method for measuring the average particle size (D50) based on volume. For example, the average particle size (D50) based on volume can be obtained using a laser diffraction particle size distribution measuring device.

[0055] In this embodiment, there is no particular limitation on the average particle size of the soft magnetic metal powder. For example, it may be 5 μm or more and 50 μm or less.

[0056] Hereinafter, the glass transition point Tg, melting point Tm, etc. will be described with reference to the drawings.

[0057] In Fig. 5, the solid line is an example of the results of thermophysical property measurement by a differential scanning calorimeter (DSC) for the soft magnetic alloy powder of the present embodiment (hereinafter, also simply referred to as the DSC measurement results), and the dotted line is an example of the DSC measurement results for the Fe-based soft magnetic alloy powder made of amorphous. The heating rate is constant. Generally, when the temperature at which the soft magnetic alloy starts to melt (Tm1 in Fig. 5) is taken as the melting point, and when the temperature at which melting is completed (Tm2 in Fig. 5) is taken as the melting point. In the present application, the temperature at which melting is completed (Tm2 in Fig. 5) is taken as the melting point Tm. This is because the temperature at which melting is completed has a greater influence on the atomization temperature and the temperature of the molten metal when performing atomization methods such as gas atomization described later, and has a greater influence on the properties of the soft magnetic alloy powder obtained by the atomization method.

[0058] Also, when the temperature of the soft magnetic alloy powder of the present embodiment containing amorphous is raised, a glass transition reaction (endothermic reaction) occurs at a specific temperature. This temperature is the glass transition point Tg. When the temperature becomes higher, a crystallization reaction (exothermic reaction) occurs at a certain temperature. This temperature is the crystallization start point Tx. In this case, the supercooled liquid region ΔT is represented by Tx - Tg.

[0059] The supercooled liquid region is related to the stabilization of amorphous. The wider the supercooled liquid region and the larger ΔT, the higher the amorphous forming ability. On the contrary, when the supercooled liquid region is narrow, the amorphous forming ability is low. It is preferable that ΔT is 20°C or more.

[0060] In Figs. 6 and 7, the solid line is an example of the results of thermophysical property measurement by DSC for the soft magnetic alloy powder of the present embodiment, and the dotted line is an example of the DSC measurement results for the Fe-based soft magnetic alloy powder made of amorphous. The heating rate is constant. The soft magnetic alloy powder of the present embodiment has a glass transition point Tg and a crystallization start point Tx. In contrast, the Fe-based soft magnetic alloy powder made of amorphous does not have a glass transition point Tg. Note that the crystallization start point of the Fe-based soft magnetic alloy powder made of amorphous is not shown.

[0061] The soft magnetic alloy powder of this embodiment has a lower Tm and has a Tg compared with the Fe-based soft magnetic alloy powder made of amorphous. Thereby, the atomization temperature can be lowered. And, the coercive force of the soft magnetic alloy powder can be reduced, the relative permeability of the soft magnetic alloy powder itself can be improved, the average circularity of the soft magnetic alloy powder can be increased, and the proportion of irregular particles in the soft magnetic alloy powder can be lowered. And, the filling factor of the magnetic core using the soft magnetic alloy powder can be improved, and the relative permeability can be improved.

[0062] Hereinafter, the manufacturing method of the soft magnetic alloy powder of this embodiment will be described.

[0063] Examples of the manufacturing method of the soft magnetic alloy powder of this embodiment include the gas atomization method.

[0064] Hereinafter, the manufacturing method of the soft magnetic alloy powder by the gas atomization method will be described.

[0065] The inventors have found that when using the atomization device shown in FIGS. 8A and 8B as the atomization device, it is easy to obtain a soft magnetic metal powder with a good particle shape.

[0066] As shown in FIG. 8A, the atomization device 10 has a molten metal supply unit 20 and a cooling unit 30 disposed vertically below the molten metal supply unit 20. In the drawing, the vertical direction is the direction along the Z axis.

[0067] The molten metal supply unit 20 has a heat-resistant container 22 that houses the molten metal 21. In the heat-resistant container 22, the raw materials of each metal element weighed so as to have the composition of the finally obtained soft magnetic alloy powder are melted by the heating coil 24 to become the molten metal 21. The temperature at the time of melting, that is, the temperature of the molten metal 21, may be determined in consideration of the melting points of the raw materials of each metal element and the melting point of the molten metal 21 (the above-mentioned Tm), but for example, it can be set to 1200 to 1600°C.

[0068] The molten metal 21 is discharged as the dripping molten metal 21a from the discharge port 23 toward the cooling section 30. High-pressure gas is jetted from the gas injection nozzle 26 toward the discharged dripping molten metal 21a, and the dripping molten metal 21a becomes a number of droplets and is carried along the gas flow toward the inner surface of the cylindrical body 32.

[0069] As the gas jetted from the gas injection nozzle 26, an inert gas or a reducing gas is preferable. As the inert gas, for example, nitrogen gas, argon gas, helium gas, etc. can be used. As the reducing gas, for example, ammonia cracked gas, etc. can be used. However, when the molten metal 21 is a metal that is difficult to oxidize, the gas jetted from the gas injection nozzle 26 may be air.

[0070] The dripping molten metal 21a carried toward the inner surface of the cylindrical body 32 collides with the coolant flow 50 formed in an inverted conical shape inside the cylindrical body 32, and is further divided and refined and cooled and solidified to become solid alloy powder. The axis O of the cylindrical body 32 is inclined at a predetermined angle θ1 with respect to the vertical line Z. The predetermined angle θ1 is not particularly limited, but is preferably 0 to 45 degrees. By setting such an angle range, it becomes easy to discharge the dripping molten metal 21a from the discharge port 23 toward the coolant flow 50 formed in an inverted conical shape inside the cylindrical body 32.

[0071] A discharge section 34 is provided downward along the axis O of the cylindrical body 32, and the alloy powder contained in the coolant flow 50 can be discharged to the outside together with the coolant. The alloy powder discharged together with the coolant is separated from the coolant and taken out in an external storage tank or the like. Note that, although not particularly limited, cooling water is used as the coolant.

[0072] Here, by adjusting the water pressure of the cooling water, the average circularity of the finally obtained soft magnetic alloy powder can be adjusted. The lower the water pressure, the higher the average circularity of the finally obtained soft magnetic alloy powder. However, if the water pressure is too low, a reverse conical cooling water flow 50 cannot be obtained. However, the ratio of irregularly shaped particles does not change much even when the water pressure is changed. Note that there are no particular restrictions on the method for adjusting the water pressure. It may be appropriately determined according to the method for supplying the cooling water. For example, when the cooling water is supplied by a pump, the water pressure of the cooling water can be adjusted by adjusting the pump pressure.

[0073] In this embodiment, since the dropped molten metal 21a collides with the reverse conical cooling liquid flow 50, the flight time of the droplets of the dropped molten metal 21a is shortened compared to the case where the cooling liquid flow follows the inner surface 33 of the cylindrical body 32. When the flight time is shortened, the rapid cooling effect is promoted, and the amorphization rate X of the obtained soft magnetic alloy powder increases. Furthermore, the average circularity is likely to increase. Also, when the flight time is shortened, the droplets of the dropped molten metal 21a are less likely to be oxidized, so the refinement of the obtained soft magnetic alloy powder is promoted and the quality of the soft magnetic alloy powder is improved.

[0074] In this embodiment, inside the cylindrical body 32, in order to form the cooling liquid flow in a reverse conical shape, the flow of the cooling liquid in the cooling liquid introduction part (cooling liquid discharge part) 36 for introducing the cooling liquid into the cylindrical body 32 is controlled. FIG. 8B shows the configuration of the cooling liquid introduction part 36.

[0075] As shown in FIG. 8B, the frame body 38 defines an outer part (outer space part) 44 located outside the cylindrical body 32 in the radial direction and an inner part (inner space part) 46 located inside the cylindrical body 32 in the radial direction. The outer part 44 and the inner part 46 are partitioned by a partition part 40, and the outer part 44 and the inner part 46 communicate with each other through a passage part 42 formed at the upper part of the partition part 40 in the axial direction of the axis O, and the cooling liquid can flow through.

[0076] A single or a plurality of nozzles 37 are connected to the outer portion 44, and the coolant enters the outer portion 44 from the nozzles 37. Further, a coolant discharge portion 52 is formed below the inner portion 46 in the direction of the axis O, and the coolant inside the inner portion 46 is discharged (led out) into the inside of the cylindrical body 32 from there.

[0077] The outer peripheral surface of the frame body 38 serves as the inner peripheral surface 38b of the flow path that guides the flow of the coolant inside the inner portion 46. At the lower end 38a of the frame body 38, an outward convex portion 38a1 that is continuous from the inner peripheral surface 38b of the flow path of the frame body 38 and protrudes outward in the radial direction is formed. Therefore, the ring-shaped gap between the tip of the outward convex portion 38a1 and the inner surface 33 of the cylindrical body 32 becomes the coolant discharge portion 52. A flow path deflection surface 62 is formed on the upper surface of the outward convex portion 38a1 on the flow path side.

[0078] As shown in FIG. 8B, due to the outward convex portion 38a1, the radial width D1 of the coolant discharge portion 52 is narrower than the radial width D2 in the main portion of the inner portion 46. Since D1 is narrower than D2, the coolant flowing downward along the inner peripheral surface 38b of the flow path inside the inner portion 46 and below the axis O then flows along the flow path deflection surface 62 of the frame body 38 and collides with and reflects off the inner surface 33 of the cylindrical body 32. As a result, as shown in FIG. 8A, the coolant is discharged in an inverted conical shape from the coolant discharge portion 52 into the inside of the cylindrical body 32, forming a coolant flow 50. When D1 = D2, the coolant discharged from the coolant discharge portion 52 forms a coolant flow along the inner surface 33 of the cylindrical body 32.

[0079] D1 / D2 is preferably 2 / 3 or less, more preferably 1 / 2 or less, and most preferably 1 / 10 or more.

[0080] The coolant flow 50 flowing out from the coolant discharge portion 52 is an inverted conical flow that travels straight from the coolant discharge portion 52 toward the axis O, but it may also be a swirling inverted conical flow.

[0081] Also, the gas injection temperature, gas injection pressure, etc. may be appropriately set according to the particle diameter of the target soft magnetic alloy powder. The gas injection temperature may be, for example, room temperature or higher and 200°C or lower. The gas injection pressure may be, for example, 0.5 MPa or higher and 19 MPa or lower.

[0082] By the above method, the soft magnetic alloy powder according to this embodiment can be obtained. In order to preferably control the particle shape and particle diameter, it is preferable that the soft magnetic alloy powder is amorphous and does not contain crystals (nanocrystals).

[0083] It is preferable to perform heat treatment on the amorphous soft magnetic alloy powder obtained by the above gas atomization method. For example, by performing heat treatment at 350 to 575°C for 0.1 to 2 hours, while preventing the powders from sintering and coarsening, the diffusion of elements can be promoted, the thermodynamic equilibrium state can be reached in a short time, and strain and stress can be removed. At this time, nanocrystals may precipitate.

[0084] There is no particular limitation on the use of the soft magnetic alloy powder according to this embodiment, and it is preferably used for applications that require high relative permeability. For example, a magnetic core can be mentioned. In particular, it can be preferably used as a magnetic core for a power inductor. Also, it can be preferably used for magnetic components using the soft magnetic alloy powder, such as thin film inductors and magnetic heads. Furthermore, the magnetic core and magnetic components using the soft magnetic alloy powder can be preferably used for electronic devices.

[0085] Note that the smaller the average particle diameter of the soft magnetic alloy powder, the more the loss at high frequencies can be reduced. Therefore, the soft magnetic alloy powder with a small average particle diameter is particularly preferably used for high-frequency components. Also, the larger the average particle diameter of the soft magnetic alloy powder, the easier it is to improve the magnetic permeability of the magnetic core. Therefore, the soft magnetic alloy powder with a large average particle diameter is preferably used for components that require high magnetic permeability.

Examples

[0086] Hereinafter, the present invention will be specifically described based on examples.

[0087] (Experimental Example 1) Ingots of various materials were prepared and weighed so as to obtain a master alloy having the composition shown in Table 1. Then, they were placed in a crucible disposed in a gas atomization apparatus.

[0088] Next, the master alloy was placed in a heat-resistant container 22 disposed in the atomization apparatus 10. Subsequently, after evacuating the inside of the cylindrical body 32, the heat-resistant container 22 was heated by high-frequency induction using a heating coil 24 provided outside the heat-resistant container 22 to melt and mix the raw material metals in the heat-resistant container 22 to obtain a molten metal (molten bath).

[0089] The obtained molten bath was injected into the casing 32 of the cooling unit 30 at the atomization temperature described in Table 1, and argon gas was injected at an injection gas pressure of 7 MPa to form a large number of droplets. The droplets collided with an inverted conical cooling water flow formed by cooling water supplied at a pump pressure of 10 MPa to become fine powder, and then were recovered. However, for Sample Nos. 3 and 4 in Table 1, the atomization temperature was too low to inject the molten bath.

[0090] In addition, in the atomization apparatus 10 shown in FIGS. 8A and 8B, the inner diameter of the inner surface of the cylindrical body 32 was 300 mm, D1 / D2 was 1 / 2, and the angle θ1 was 20 degrees.

[0091] Furthermore, in Experimental Example 1, heat treatment was performed at 475°C for 60 minutes. Also, it was confirmed by ICP analysis that the composition of the master alloy and the composition of the soft magnetic alloy powder were generally in agreement.

[0092] It was confirmed whether each of the obtained soft magnetic alloy powders contained an amorphous phase or a nanocrystal. The presence or absence of peaks due to nanocrystals was confirmed using XRD. When it contained an amorphous phase, it was described as amorphous in the fine structure column, and when it contained both an amorphous phase and nanocrystals, it was described as amorphous + nanocrystals. The results are shown in Table 1.

[0093] The shape of the powder particles in each of the obtained soft magnetic alloy powders was evaluated. Specifically, the circularity of 20,000 particles was measured, and the average circularity on a number basis and the cumulative number ratio up to 0.50 from the lower circularity were calculated. The results are shown in Table 1. Further, for each example and comparative example, it was assumed that there were few irregularly shaped particles when the cumulative number ratio was 2.0% or less, and there were particularly few irregularly shaped particles when the cumulative number ratio was 1.5% or less. Also, for each example and comparative example, it was confirmed using a laser diffraction particle size distribution measuring device (HELOS&RODOS (Sympatec)) that the average particle diameter (D50) on a volume basis was about 25 μm.

[0094] DSC measurement was performed on each of the obtained soft magnetic alloy powders using (STA449F3 (NETZSCH)), and the presence or absence of Tg was confirmed. Further, Tm and ΔT were measured. The results are shown in Table 1.

[0095] The coercive force Hc of each of the obtained soft magnetic alloy powders was measured using (K-HC1000 type (Tohoku Special Steel)). The results are shown in Table 1. There are no particular restrictions on Hc. Hc may be 0.50 Oe or less. It is preferable that Hc is 0.20 Oe or less.

[0096] Next, toroidal cores were fabricated from each of the soft magnetic alloy powders. Specifically, each soft magnetic alloy powder was mixed so that the amount of phenolic resin as an insulating binder was 3% by mass of the whole, and granulated using a general planetary mixer as a stirrer to obtain granulated powder of about 500 μm. Next, the obtained granulated powder was molded at a surface pressure of 4 ton / cm 2 (392 MPa) to produce a molded body having a toroidal shape with an outer diameter of 13 mmφ, an inner diameter of 8 mmφ, and a height of 6 mm. The obtained molded body was cured at 150 °C to produce a toroidal core.

[0097] Then, UEW wire was wound around the toroidal core, and μ (relative permeability) was measured at 100 kHz using a 4284A PRECISION LCR METER (Hewlett Packard). The results are shown in Table 1. Note that a case where the relative permeability μ is 30 or more was regarded as good.

[0098]

Table 1

[0099] From Table 1, for Samples No. 1 to 4 and 1a which are Fe-based soft magnetic alloys made of amorphous, since the Tm was high, the atomizing temperature required for spraying was as high as 1500 °C or more. That is, the range of atomizing temperature at which soft magnetic alloy powder could be produced was narrow. Furthermore, the obtained soft magnetic alloy powder did not have a Tg. Therefore, the coercive force of the soft magnetic alloy powder became high, the circularity became low, and there were many irregularly shaped particles. Furthermore, the relative permeability μ of the toroidal core made using the soft magnetic alloy powder became low.

[0100] On the other hand, for Samples No. 5 to 8 and 5a which have a composition containing a large amount of Co, since the Tm was low, the atomizing temperature required for spraying was low, and spraying could be performed at an atomizing temperature of 1300 °C. That is, the range of atomizing temperature at which soft magnetic alloy powder could be produced was wide. Furthermore, the obtained soft magnetic alloy powder had a Tg. Therefore, the coercive force of the soft magnetic alloy powder became low, the circularity became high, and there were few irregularly shaped particles. Furthermore, the relative permeability μ of the toroidal core made using the soft magnetic alloy powder became high.

[0101] (Experimental Example 2) In Experimental Example 2, soft magnetic alloy powder and toroidal cores of Samples No. 9 and 10 were produced under the conditions described in Experimental Example 1 except that the pump pressure for supplying cooling water was changed from Sample No. 1. The results are shown in Table 2.

[0102]

Table 2

[0103] From Table 2, the average circularity of the particles of the soft magnetic alloy powder was improved by reducing the pump pressure. However, the change in the cumulative number ratio was small, and the change in the ratio of irregularly shaped particles was also small. Since Samples No. 9 and 10 are Fe-based soft magnetic alloys composed of amorphous, their Tm was high. Furthermore, the obtained soft magnetic alloy powder did not have a Tg. Therefore, the coercive force of the soft magnetic alloy powder was high, and there were many irregularly shaped particles. Furthermore, the relative permeability μ of the toroidal core produced using the soft magnetic alloy powder was low.

[0104] (Experimental Example 3) In Experimental Example 3, soft magnetic alloy powders and toroidal cores of Samples No. 9 to 16 were produced under the conditions described in Experimental Example 1, except that a part of Co was replaced with Fe in Sample No. 8. The results are shown in Table 3.

[0105] Furthermore, soft magnetic alloy powders and toroidal cores of Sample Nos. 8a to 8e were produced under the same conditions as Sample No. 8, except for the change in composition. The results are shown in Table 3A.

[0106] [Table 3]

[0107] [Table 3A]

[0108] From Table 3, Samples No. 11 to 14 having a composition within a predetermined range had good particle shapes, and the relative permeability μ of the toroidal core was good. From Samples No. 11 to 14, as the Fe content increased, the Tm increased, the coercive force increased, and the relative permeability μ tended to decrease. And Sample No. 16 with α + β > 0.500 and too small Co content had too high melting point of the soft magnetic alloy, and the molten metal could not be sprayed at the atomizing temperature of 1300°C. However, Sample No. 11 with an atomic ratio of Co / Fe of 5 or more and 20 or less had a lower coercive force and a higher relative permeability μ compared with Samples No. 8 and 12 outside the above range.

[0109] From Table 3A, each sample having a composition within a predetermined range, having a Tg, and having a Tm within a predetermined range had a low atomization temperature required for injection and could be injected at an atomization temperature of 1300°C. That is, the range of atomization temperatures at which soft magnetic alloy powder could be produced was wide. Furthermore, the obtained soft magnetic alloy powder had a Tg. Therefore, the coercive force of the soft magnetic alloy powder was low, the roundness was high, and there were few irregularly shaped particles. Furthermore, the relative permeability μ of the toroidal core produced using the soft magnetic alloy powder was high. Also, when Co / B was higher than Sample No. 8, as Co / B increased, Tm increased, the average roundness decreased, the coercive force increased, and the relative permeability μ tended to decrease.

[0110] (Experimental Example 4) In Experimental Example 4, soft magnetic alloy powder and toroidal cores were produced under the same conditions as in Experimental Example 3, Sample No. 11, except that the content of each element contained in the main component was changed. The results are shown in Tables 4 to 7.

[0111] [Table 4]

[0112] [Table 5]

[0113] [Table 6]

[0114] [Table 7]

[0115] Table 4 shows experimental examples in which the contents of Co, Fe, and M(Nb) were changed. Samples Nos. 18 to 22 having compositions within a predetermined range had Tg and had Tm within a predetermined range. And, the average circularity of the soft magnetic alloy powder was high, the number of irregularly shaped particles was small, and the coercive force was low. Furthermore, the relative permeability of the toroidal core became high.

[0116] On the other hand, Sample No. 17 not containing M(Nb) did not have Tg. As a result, the average circularity of the soft magnetic alloy powder was low, the number of irregularly shaped particles was large, and the coercive force was high. Furthermore, the relative permeability of the toroidal core became high. Also, in Sample No. 23 where the content of M was too high, Tm became too low. As a result, the average circularity of the soft magnetic alloy powder was low, the number of irregularly shaped particles was large, and the coercive force was high. Furthermore, the relative permeability of the toroidal core became high.

[0117] Table 5, Samples Nos. 24 to 27 are experimental examples in which the contents (b) of Co, Fe, and B were changed from Sample No. 11. Samples Nos. 25 and 26 having compositions within a predetermined range had Tg and had Tm within a predetermined range. And, the average circularity of the soft magnetic alloy powder was high, the number of irregularly shaped particles was small, and the coercive force was low. Furthermore, the relative permeability of the toroidal core became high. On the other hand, in Sample No. 24 where the content of B was too low, the melting point of the soft magnetic alloy became too high, and the molten metal could not be sprayed at an atomizing temperature of 1300°C. In Sample No. 27 where the content of B was too high, Tm became too low. As a result, the number of irregularly shaped particles of the soft magnetic alloy powder was large, and the coercive force was high. Furthermore, the relative permeability of the toroidal core became low.

[0118] Table 5. Samples Nos. 28 to 34 are experimental examples in which the contents (c) of Co, Fe, and P were changed from Sample No. 11. Samples Nos. 28 to 33 having compositions within a predetermined range had Tg and had Tm within a predetermined range. And the average circularity of the soft magnetic alloy powder was high, the irregularly shaped particles were few, and the coercive force was low. Furthermore, the relative permeability of the toroidal core became high. On the other hand, in Sample No. 34 where the content of P was too high, Tm became too low. As a result, the average circularity of the soft magnetic alloy powder was low, the irregularly shaped particles were many, and the coercive force was high. Furthermore, the relative permeability of the toroidal core became low.

[0119] Table 5. Samples Nos. 35 to 41 are experimental examples in which the contents (d) of Co, Fe, and Si were changed from Sample No. 11. Samples Nos. 35 to 40 having compositions within a predetermined range had Tg and had Tm within a predetermined range. And the average circularity of the soft magnetic alloy powder was high, the irregularly shaped particles were few, and the coercive force was low. Furthermore, the relative permeability of the toroidal core became high. On the other hand, in Sample No. 41 where the content of Si was too high, Tm became too low. As a result, the average circularity of the soft magnetic alloy powder was low, the irregularly shaped particles were many, and the coercive force was high. Furthermore, the relative permeability of the toroidal core became low.

[0120] Table 6. Samples Nos. 42 to 46 are experimental examples in which the contents (e) of Co, Fe, and Cr were mainly changed from Sample No. 11. Samples Nos. 42 to 45 having compositions within a predetermined range had Tg and had Tm within a predetermined range. And the average circularity of the soft magnetic alloy powder was high, the irregularly shaped particles were few, and the coercive force was low. Furthermore, the relative permeability of the toroidal core became high. On the other hand, in Sample No. 46 where the content of Cr was too high, the irregularly shaped particles of the soft magnetic alloy powder were many, and the coercive force was high. Furthermore, the relative permeability of the toroidal core became low.

[0121] Table 7. Samples Nos. 47 to 49 are experimental examples in which the contents (f) of Co, Fe, and S were mainly changed from Sample No. 11. Samples Nos. 47 and 48 having compositions within a predetermined range had Tg and had Tm within a predetermined range. Further, the average circularity of the soft magnetic alloy powder was high, the number of irregularly shaped particles was small, the coercive force was low, and the relative permeability of the toroidal core was high. Further, since Samples Nos. 47 and 48 contained S, the proportion of the presence of irregularly shaped particles decreased as compared with Sample No. 11. On the other hand, in Sample No. 49 in which the content of S was too high, the coercive force of the soft magnetic alloy powder increased. Further, the relative permeability of the toroidal core decreased.

[0122] (Experimental Example 5) In Experimental Example 5, soft magnetic alloy powder and a toroidal core were produced under the conditions described in Experimental Example 1, except that a part of Co in Sample No. 8 was replaced with X1 and / or X2. The results are shown in Tables 8 and 9.

[0123] [Table 8]

[0124] [Table 9]

[0125] Even when a part of Co was replaced with X1 and / or X2, each sample having a composition within a predetermined range had Tg and had Tm within a predetermined range. Further, the average circularity of the soft magnetic alloy powder was high, the number of irregularly shaped particles was small, the coercive force was low, and the relative permeability of the toroidal core was high.

[0126] (Experimental Example 6) In Experimental Example 6, soft magnetic alloy powder and a toroidal core were produced under the conditions described in Experimental Example 1, except that the type of M was changed for Sample No. 8. The results are shown in Table 10.

[0127] [Table 10]

[0128] Even when the type of M was changed, each sample having a composition within a predetermined range had a Tg and had a Tm within a predetermined range. And, the average circularity of the soft magnetic alloy powder was high, the number of irregularly shaped particles was small, and the coercive force was low. Furthermore, the relative permeability of the toroidal core became high.

[0129] (Experimental Example 7) In Experimental Example 7, for Sample No. 8, soft magnetic alloy powder and a toroidal core were produced under the conditions described in Experimental Example 1 except that the heat treatment conditions were changed. Specifically, no heat treatment was performed for Sample No. 109. For Sample No. 110, the heat treatment temperature was raised to 575°C. The results are shown in Table 11. Although not described in Table 11, each sample had a Tg and had a Tm within a predetermined range. And, the average circularity of the soft magnetic alloy powder was high, the number of irregularly shaped particles was small, and the coercive force was low.

[0130]

Table 11

[0131] The soft magnetic alloy powder of Sample No. 109 can be said to be the soft magnetic alloy powder before heat treatment during the manufacturing process of the soft magnetic alloy powder of Sample No. 8. When comparing before and after the heat treatment at 475°C, it is considered that no crystal was formed during the heat treatment and the relative permeability μ increased because strain and stress could be removed.

[0132] Since the soft magnetic alloy powder of Sample No. 110 was heat-treated at 575°C, nanocrystals were formed and it has a nanoheterostructure in which the nanocrystals are contained in the amorphous phase.

[0133] (Experimental Example 8) In Experimental Example 8, soft magnetic alloy powders and toroidal cores of Sample Nos. 111 and 112 were produced under the conditions described in Experimental Example 3, except that the average particle diameter based on volume was changed from Sample No. 11. Further, soft magnetic alloy powders and toroidal cores of Sample Nos. 113 to 115 were produced under the same conditions as Sample Nos. 11, 111, and 112, except that the content (b) of B was decreased and the atomization temperature was set to 1600°C. The results are shown in Table 12.

[0134]

Table 12

[0135] From Table 12, it can be seen that the higher the average particle diameter, the higher the relative permeability of the toroidal core. Also, each of Sample Nos. 11, 111, and 112 having a composition within a predetermined range had a Tg and a Tm within a predetermined range. And, the soft magnetic alloy powder had a high average circularity, few irregularly shaped particles, a low coercive force, and further, the relative permeability of the toroidal core was high.

[0136] On the other hand, each of Sample Nos. 113 to 115 with too small a content (b) of B did not have a Tg and had an overly high Tm. As a result, the soft magnetic alloy powder had a low average circularity, many irregularly shaped particles, a high coercive force, and further, the relative permeability of the toroidal core was low.

Explanation of Symbols

[0137] 1, 2… Particle shape measurement results 10… Atomizer 20… Molten metal supply section 21… Molten metal 21a… Dropped molten metal 30… Cooling section 36… Coolant introduction section 38a1… Outer convex portion 50… Coolant flow

Claims

1. Composition formula (Co (1-( α + β )) X1αX2β) (1-(a+b+c+d+e+f)) M a B b P c Si d Cr e S f (atomic ratio), which is a soft magnetic alloy powder having a main component X1 is one or more selected from the group consisting of Fe and Ni, X2 is one or more selected from the group consisting of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Bi, N, O, C and rare earth elements, M is one or more selected from the group consisting of Nb, Hf, Zr, Ta, Mo, W, Ti and V, 0 < a ≤ 0.140 0.160 < b ≤ 0.250 0.010 ≤ c ≤ 0.050 0 ≤ d ≤ 0.250 0 ≤ e ≤ 0.030 0 ≤ f ≤ 0.010 0.160 < b + c + d + e + f ≤ 0.430 0.500 < 1 - (a + b + c + d + e + f) < 0.840 α≧０ β≧０ ０≦α＋β≦０．４０ and the average circularity of the powder particles contained in the soft magnetic alloy powder is 0.93 or more, and the cumulative number ratio from the lower circularity of the powder particles to 0.50 is 2.0% or less, the soft magnetic alloy powder has a glass transition point Tg and a melting point Tm, a soft magnetic alloy powder with 900°C ≤ Tm ≤ 1200°C.

2. The soft magnetic alloy powder according to Claim 1, wherein the average circularity of the powder particles contained in the soft magnetic alloy powder is 0.95 or more, and the cumulative number ratio from the lower circularity of the powder particles to 0.50 is 1.5% or less.

3. The soft magnetic alloy powder according to Claim 1 or 2, wherein the value obtained by dividing the content ratio of Co by the content ratio of B is greater than 2.000 and less than 5.

000.

4. The soft magnetic alloy powder according to any one of Claims 1 to 3, which has an amorphous structure.

5. The soft magnetic alloy powder according to any one of Claims 1 to 3, which has a nanocrystalline structure.

6. A magnetic core containing the soft magnetic alloy powder according to any one of Claims 1 to 5.

7. A magnetic component containing the soft magnetic alloy powder according to any one of Claims 1 to 5.

8. An electronic device containing the soft magnetic alloy powder according to any one of Claims 1 to 5.

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