JP2002217010A - Anisotropic magnetic powder improved in magnetization factor and anisotropic bonded magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide (Sm,La)-Fe-Mn-N-based anisotropic magnetic powder which is improved in magnetization factor and an anisotropic bonded magnet in which the powder is blended. SOLUTION: The anisotropic magnetic powder which is improved in magnetization factor is composed of an aggregate of crystal grains having a main component composition containing rare earths (Sm and La, with the content of the La being adjusted to 0.1-5 wt.%) in an amount of 20-30 wt.%, Mn in an amount of 1-10 wt.%, N in an amount of 4-7 wt.%, and the balance Fe, and has an oriented 2-17 type hard magnetic phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide variety of magnet-applied products, for example, various types of rotating machines, magnet rolls used in electrostatic developing type printers and copiers, voice coil motors and linear motors. (Sm, La) -Fe-Mn having a 2-17 type crystal structure phase as a main phase and having improved magnetism, which is useful for an actuator, an acoustic speaker, a buzzer, a sensor, a magnet for attracting or generating a magnetic field, and the like.
The present invention relates to -N-based anisotropic magnetic powder and an anisotropic bonded magnet using the same.

[0002]

2. Description of the Related Art Rare earth elements (R), Fe and nitrogen (N)
Production of an anisotropic R—Fe—N bonded magnet made of Anisotropic R-Fe-N bonded magnets have more shape freedom than anisotropic ferrite sintered magnets,
Due to its excellent workability and high magnetic properties, its application to various magnet applications is being studied in the future.

[0003] A conventional anisotropic R-Fe-N bonded magnet is disclosed in, for example, Japanese Patent No. 2703281.
The nitrided Sm-Fe-N-based alloy is pulverized into single domain fine particles having an average particle size of about 2 μm, and then the fine powder and the binder are blended at a predetermined ratio, kneaded, and the obtained compound is molded in a magnetic field. It is made. However, the Sm-Fe-
N-based magnetic powders are liable to be oxidized, and have poor filling properties into the compound and require high molding pressure to obtain a practically useful maximum energy product (BH) max. To solve this problem, Japanese Patent Application Laid-Open No. 8-55712 discloses a general formula R _{α
Fe 100-α-β-γ} Mn β N γ ( where, R is at least one rare earth element, alpha, is beta and gamma are each atom%, 3 ≦ α ≦ 20,0.5 ≦ β ≦ 25, And 17 ≦ γ
≦ 25), and the main phase is a phase having a rhombohedral or hexagonal crystal structure containing at least R, Fe, Mn and N as components, and having an average particle size of 10μ
m or more are proposed. This magnetic material powder is a nucleation type Sm ₂ Fe ₁₇ N ₃
Unlike compounds, they have a feature that they are pinned due to the effect of excessively containing nitrogen, and that a high coercive force can be obtained even in the state of coarse particles having a large particle size due to the effect of containing Mn. However, the magnetic powder and the binder are blended at a predetermined ratio, a compound is produced, and the anisotropic bonded magnet obtained by molding in a magnetic field has poor magnetic field orientation and magnetization,
Improvement was required. The orientation magnetic field strength in molding in a magnetic field varies depending on the molding method, the shape and size of the molded body, the number of magnetic poles, and the like. In general, the orientation magnetic field strength when imparting parallel anisotropy is 0.64 to 1.2 MA / m (8 to The orientation magnetic field strength in the case of imparting radial or multipolar anisotropy is about 0.24 to 0.64 MA / m (3 to 8 KOe). In industrial production, the lower the intensity of the orientation magnetic field, the lower the heat generated by the coil during molding, and the versatility of a magnetic field generating power supply and a molding die, so that the practicality is high. Therefore, it is desired to obtain a bonded magnet molded article which is molded in a magnetic field with a lower orientation magnetic field strength and imparts good anisotropy (higher (BH) max) in a desired direction. Magnetization at room temperature: 1.9MA /
It is evaluated by (BH) max when magnetized below m (25 kOe). The reason for limiting the magnetizing magnetic field strength to 1.9 MA / m (25 kOe) or less is that 1.9 MA / m (25 kOe) is required for industrial production, such as when magnetizing with an anisotropic bonded magnet incorporated in a predetermined magnetic circuit. This is because it is often difficult to magnetize with an excessively strong magnetic field strength.

[0004] Japanese Patent Application Laid-Open No. 2000-49006 discloses that
La content _{R α T 100- (α + β} + γ + δ) M β B γ N δ (R is Sm and La is 0.05 to 1%
T is Fe or Fe and Co, M is Al, Ti,
V, Cr, Mn, Cu, Ga, Zr, Nb, Mo, H
at least one selected from the group consisting of f, Ta, W and Zn
Α, β, γ and δ are respectively 6 ≦ α ≦ 15,
A rare earth element substantially composed of a 2-17 type hard magnetic phase having a composition represented by 0.5 ≦ β ≦ 10, 0 ≦ γ ≦ 4, and 4 ≦ δ ≦ 30) and having an average crystal grain size of 0.01 to 1 μm. A magnet powder and a bonded magnet are disclosed. However, they are all isotropic, and are different from the anisotropic magnetic powder of the present invention in that the magnet powder particles are not an aggregate of crystal grains oriented in a substantially constant direction.

[0005]

Accordingly, an object of the present invention is to improve the magnetization (Sm, Lm).
a) To provide an -Fe-Mn-N-based anisotropic magnetic powder and an anisotropic bonded magnet obtained by mixing the same.

[0006]

Means for Solving the Problems The anisotropic magnetic powder having improved magnetization according to the present invention, which has solved the above-mentioned problems, has a weight percentage of R
(R is composed of Sm and La, La content is 0.1-5%
Having a main component composition represented by 20 to 30%, Mn 1 to 10%, N4 to 7%, and the balance Fe, and consisting of an aggregate of crystal grains of an oriented 2-17 type hard magnetic phase. It is characterized by.

The anisotropic bonded magnet of the present invention has a weight percentage of R (R is composed of Sm and La, and has a La content of
0.1 to 5%) 20 to 30%, Mn 1 to 10%, N4 to 7
%, And the balance is substantially composed of an anisotropic magnetic powder having improved magnetizability, comprising an aggregate of crystal grains of a 2-17 type hard magnetic phase having a main component composition represented by Fe and a binder. It is characterized by becoming.

The average particle size of the anisotropic magnetic powder of the present invention is 10 to 300.
μm is preferred. Intrinsic coercivity when average particle size is less than 10μm
If the HcJ and (BH) max decrease, and if the average particle size exceeds 300 μm, it will be difficult to completely nitride the inside of the magnetic powder particles in industrial production, and furthermore, the surface properties will deteriorate and it will be used for applications where the gap of the magnetic circuit is small. It becomes difficult to apply. The average particle size of the anisotropic magnetic powder of the present invention is more preferably from 20 to 200 μm, particularly preferably from 25 to 125 μm.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the composition of the anisotropic magnetic powder of the present invention will be described below. Simply writing% means percent by weight. The R content is preferably 20-30%, and 22-28.
Is more preferred. When the R content is less than 20%, HcJ at room temperature is 3
It becomes less than 97.9 kA / m (5 kOe), and if it exceeds 30%, (BH) max is greatly reduced. R is composed of Sm, La and an unavoidable R component, and the La content is preferably set to 0.1 to 5%.
More preferably, it is set to ４4%. Y, Ce, Pr, N
d, Pm, Eu, Gd, Tb, Dy, Ho, Er, T
At least one selected from the group consisting of m, Yb and Lu corresponds to the unavoidable R component. When the La content is less than 0.1% or more than 5%, the decrease in (BH) max becomes remarkable. It is practical to use an inexpensive mixed rare earth alloy such as Sm misch metal or dymium as a raw material alloy for R. Room temperature HcJ ≧ 39
To obtain 7.9 kA / m (5 kOe), the ratio of Sm to R should be 5
It is preferably at least 0 atomic%, more preferably at least 95 atomic%.

The Mn content is preferably 1 to 10%, more preferably 2 to 6%. Mn content is 1
%, The effect of increasing the coercive force is virtually not obtained, and
Above that, the decrease in (BH) max becomes remarkable.

[0011] The nitrogen content is preferably 4 to 7%. If the nitrogen content is less than 4% or more than 7%, iHc and (BH) max are greatly reduced, and it is difficult to obtain useful magnetic properties.

It is preferable to replace a part of Fe with Co because Curie point, magnetization and oxidation resistance are improved.
The Co content is preferably 0.1-20%, and 1-10%
More preferably, If the Co content is less than 0.1%, a substantial addition effect cannot be obtained, and if it exceeds 20%, the decrease in magnetization is undesirably large. In addition, part of Fe is Ga,
1, Zn, Sn, Cr, Ni, Ti, Zr, Hf, V,
Substitution with at least one element selected from the group consisting of Nb, Ta, Mo, W, Pd, C, Si and Ge is preferable because magnetic properties and corrosion resistance can be improved. The total content of these elements is preferably 0.5 to 10%. If the content is less than 0.5%, the effect of addition is not substantially obtained, and if it exceeds 10%, the decrease in magnetization becomes remarkable.

In the anisotropic magnetic powder of the present invention, O, H, C, Al, Si, F, Na, Mg, C
It is permissible to contain at least one inevitable impurity element selected from the group of a and Li in a total of 5% or less.

The R—Fe—Mn base alloy to be subjected to nitriding is as follows:
For example, it can be produced by a reduction / diffusion method, a high-frequency melting method, an arc melting method, or a strip casting method.

Preferred manufacturing conditions for producing an R-Fe-Mn-based master alloy by the reduction / diffusion method will be described below. First, R oxide powder, Fe powder and Fe-Mn powder having an average particle size of about 100 μm were used, and blended into the main component composition of the R-Fe-Mn base alloy corresponding to the anisotropic magnetic powder of the present invention. And the R oxide in the composition is
An amount of the reducing agent (metal Ca) corresponding to 0.5 to 2 times the amount that is reduced by 100% (the stoichiometric requirement) is added to the formulation and mixed. Next, the mixture is placed in an inert gas atmosphere at 1000
Heat at 11300 ° C. × 1-20 hours to reduce the R oxide, and then allow the reduced R, Fe and Mn to sufficiently interdiffuse and then cool to room temperature. If the addition amount of the reducing agent is less than 0.5 times the stoichiometrically required amount, a reduction reaction useful for industrial production is not realized, and if it exceeds 2 times, the amount of Ca remaining in the finally obtained anisotropic magnetic powder increases. This leads to a decrease in magnetic properties. If the heating condition is less than 1000 ° C. × 1 hour, the reduction / diffusion reaction useful for industrial production does not proceed, and if it exceeds 1300 ° C. × 20 hours, the reduction / diffusion reaction furnace is significantly deteriorated. The obtained reaction product is put into a washing solution, and after removing reaction by-products such as CaO,
Dehydration and heat drying in a vacuum are performed to obtain an R-Fe-Mn-based mother alloy by a reduction / diffusion method. This R-Fe-M
Predetermined amounts of Ca, O, and C are inevitably mixed into the n-based master alloy. The Ca content is usually 0.4% by weight or less, and can be reduced to 0.2% by weight or less, particularly 0.1% by weight or less by appropriately selecting washing and drying conditions. The oxygen content is usually 0.8% by weight or less, and can be reduced to 0.4% by weight or less, particularly 0.2% by weight or less by appropriately selecting washing and drying conditions. The carbon content is usually 0.3% by weight or less, and can be reduced to 0.2% by weight or less, particularly 0.1% by weight or less by appropriately selecting washing and drying conditions.

The R-Fe-Mn base alloy prepared by the high frequency melting method, the arc melting method, or the strip casting method, is heated to 1010 to 1280 ° C. in an inert gas (excluding nitrogen) atmosphere.
A segregated phase such as αFe or SmFe ₃ can be reduced by performing a homogenizing heat treatment of heating for 1 to 40 hours and then cooling to room temperature. Homogenization heat treatment condition is 1010 ℃
If less than × 1 hour, the solid solution of the segregated phase such as αFe or SmFe ₃ does not progress, and if it exceeds 1280 ° C. × 40 hours, the effect of the homogenization heat treatment is saturated, and the composition shift due to evaporation of Sm or the like becomes remarkable.

The nitriding will be described. 1 to 95 volumes of hydrogen
% Mixed gas (hydrogen + nitrogen) with the balance being nitrogen
Or NH₃By volume is 10-90% and the balance is hydrogen
(NH ₃+ Hydrogen) at 300-650 ℃
It is preferable to adopt gas nitriding to heat for 0.1-30 hours
No. The heating conditions for gas nitriding are 400-550 ° C x 0.5-20 hours.
More preferred. Nitrogenation practically takes place below 300 ° C x 0.1 hours
If the temperature exceeds 650 ° C for 30 hours, the RN phase, αFe,
A morphous phase is formed and the magnetic properties are significantly reduced. Nitriding
Gas pressure is 2.0 × 10⁴~ 1.0 × 10⁶Pa (0.2-10atm)
Is preferred, and 5.0 × 10 ⁴~ 5.0 × 10⁵Pa (0.5-5atm)
Is more preferred. 2.0 × 10⁴Nitriding below Pa (0.2atm)
The reaction becomes very slow, 1.0 × 10⁶For Pa (10atm)
High-pressure gas equipment causes cost increase.

After nitriding, heat treatment at 300 to 600 ° C. for 0.5 to 50 hours in a vacuum atmosphere or an inert gas atmosphere (excluding nitrogen gas) increases residual magnetic flux density, HcJ, and (BH) max. Can be. In the anisotropic magnetic powder thus obtained, 10
A hydrogen content of ~ 1000 ppm (weight ratio) is acceptable.

The main phase of the anisotropic magnetic powder of the present invention is a hard magnetic phase having a 2-17 type crystal structure.
2 except for Fe and / or impurity phase (oxide, carbide, etc.)
It preferably comprises only a hard magnetic phase having a -17 type crystal structure. To obtain room temperature HcJ ≧ 397.9kA / m (5kOe),
The ratio of αFe present in the anisotropic magnetic powder of the present invention must be 5% or less in average area ratio, preferably 3% or less, particularly preferably 1% or less. The identification of the hard magnetic phase and the unavoidable αFe, etc., and the calculation of the area ratio of each phase are performed by photographing the cross-sectional structure of an anisotropic magnetic powder taken with an electron microscope or optical microscope, electron diffraction results, and X-rays. Determined in consideration of diffraction results and the like. For example,
The cross-sectional structure of the target anisotropic magnetic powder particles can be determined by matching a transmission electron micrograph of the cross-sectional structure with the identification result of the cross-sectional structure.

New Creation Type Sm ₂ Fe ₁₇
Unlike the N ₃ compound, the anisotropic magnetic powder of the present invention contains an excessive amount of nitrogen and has a pinning type coercive force mechanism.

In the anisotropic bonded magnet of the present invention, the blending weight ratio of anisotropic magnetic powder: binder is from 80:20 to 98.5: 1.
5 is preferable, and 95: 5 to 98: 2 is more preferable. Below the compounding weight ratio, the anisotropic ferrite sintered magnet or more (B
H) It is difficult to obtain max, and if it exceeds the above compounding weight ratio,
(BH) max and density decrease.

As the binder, a known thermosetting resin,
Use of a thermoplastic resin or a rubber material is highly practical. A thermosetting resin is preferable when using a compression molding method in a magnetic field, and a thermoplastic resin is preferable when using an extrusion molding method in a magnetic field or an injection molding method in a magnetic field. Further, for example, when a sheet-like molded body having a thickness of 0.1 to 5 mm having anisotropy in the thickness direction is formed by calender roll, a thermosetting resin, a thermoplastic resin, or a rubber material is preferable. When molding the bonded magnet of the present invention by compression molding in a magnetic field, it is necessary to select a binder resin having low viscosity in the range of 0.24 to 0.80 MA / m (3 to 10 kO
e), more preferably 0.24 to 0.48 MA / m (3 to 6 kOe), particularly preferably 0.24 to 0.40 MA / m (3 to 5 kOe). Is important for imparting a good degree of orientation to the magnetically bonded magnet.
The same applies to extrusion in a magnetic field or injection molding in a magnetic field. In particular, the binder resin is diluted with an organic solvent to obtain a low-viscosity state, a predetermined amount of anisotropic magnetic powder is dispersed therein to form a slurry, and the slurry is subjected to compression molding in a magnetic field at room temperature, extrusion molding in a magnetic field, or a magnetic field. By performing medium injection molding, an anisotropic bonded magnet with good anisotropy can be obtained. Alternatively, by molding in a magnetic field at a temperature of usually 100 to 350 ° C. in an inert gas atmosphere using pellets of a normal compound,
An anisotropic bonded magnet with good anisotropy is obtained.
In this case, the pellets of the compound in which the anisotropic magnetic powder is dispersed are heated to a predetermined temperature, whereby the coercive force of the anisotropic magnetic powder and the viscosity of the binder resin are reduced, and good anisotropy can be imparted to the molded article.

In order to enhance the formability, strength, or oxidation resistance of the anisotropic bonded magnet of the present invention, a known surface modifier (such as a silane coupling agent), a lubricant, a filler, and an antioxidant are used. May be added in a total of 2% by weight or less based on the total weight of the compound of the present invention. Further, in order to increase the corrosion resistance of the anisotropic bonded magnet or to prevent the magnetic powder from peeling off, the surface of the anisotropic bonded magnet of the present invention is coated with a corrosion resistant coating (e.g., epoxy resin film) having an average thickness of 0.5 to 30 μm. Is preferred. When the average thickness of the corrosion-resistant coating is less than 0.5 μm, the coating effect is practically not obtained, and when the average thickness exceeds 30 μm, the coating effect is saturated.

[0024]

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

(Example 1) A molten Sm-La-Fe-Mn base alloy corresponding to the magnetic nitride powder shown in Table 1 was produced by high-frequency melting, and was cast in a mold. Obtained Sm-La-Fe-M
n-type mother alloy ingot in argon gas atmosphere at 1100 ℃
For 10 hours, and then a homogenizing heat treatment of cooling to room temperature was performed. Next, the ingot was pulverized in a nitrogen gas atmosphere and classified to a size under 75 μm. Next, the mixture was heated in a mixed gas stream of 35% by volume of ammonia and 65% by volume of hydrogen at 490 ° C. × 5 hours, then cooled to room temperature, and average particle size was 38 μm (Sympatec
(Measured by HEROS / RODOS, manufactured by the Company).
This anisotropic magnetic powder is composed of a hard magnetic phase having a Th ₂ Zn ₁₇ type crystal structure and minute αFe, and the average area ratio of αFe is 0.1%.
%Met. A copper container for VSM was filled with a predetermined amount of anisotropic magnetic powder and paraffin wax and sealed. Next, the copper container was heated to 80 ° C while a parallel magnetic field of 1.9 MA / m (25 kOe) was applied.
To melt the paraffin wax, orient the anisotropic magnetic powder, and cool to room temperature to fix the magnetic powder. Next, the magnetic properties at room temperature were measured using a VSM having a maximum applied magnetic field of 1.6 MA / m (20 kOe). Table 1 shows the results obtained by converting the obtained measured values into only 100% magnetic powder. Note that (BH) max was determined by setting the theoretical density of the anisotropic magnetic powder to 7.65 Mg / m ³ .

Comparative Example 1 The anisotropic magnetic powder prepared in Example 1 was finely pulverized by a jet mill using nitrogen gas as a pulverizing medium to an average particle size of 4 μm (according to HEROS / RODOS), and then wet-processed using hexane. Average particle size 2μm by ball mill
(According to HEROS / RODOS). Thereafter, the magnetic properties of the fine powder were evaluated in the same manner as in Example 1 using the obtained fine powder. Table 1 shows the results.

(Examples 2 to 5) Sm-La-Fe-Mn based mother alloy ingots corresponding to the respective magnetic nitride powder compositions shown in Table 1 were produced. Using these ingots, anisotropic magnetic powder having an average particle diameter of 10 to 300 μm was prepared in the same manner as in Example 1 and the magnetic properties were measured. Each of these anisotropic magnetic powders was composed of a hard magnetic phase having a Th ₂ Zn ₁₇ type crystal structure and minute αFe, and the average area ratio of αFe was 0.2% or less. Table 1 shows the evaluation results.

(Comparative Examples 2 to 5) In Comparative Example 2, the anisotropic magnetic powder of Example 2 was used. In Comparative Example 3, the anisotropic magnetic powder of Example 3 was used.
In Comparative Example 4, the anisotropic magnetic powder of Example 4 was used, and in Comparative Example 5, the anisotropic magnetic powder of Example 5 was used, respectively, by a jet mill using nitrogen gas as a pulverizing medium.
OS)) and then a wet ball mill using hexane with an average particle size of 2 μm (according to HEROS / RODOS).
And finely ground. The magnetic properties of the obtained fine powder were evaluated in the same manner as in Example 1 thereafter. Table 1 shows the results.

Comparative Examples 6 and 7 In the same manner as in Example 1 except that the composition of the molten master alloy was changed, an Sm—Fe—Mn based mother alloy ingot having a main component composition corresponding to the magnetic nitride powder in Table 1 (comparative example) Example 6) and Sm-La-Fe-M with La excess composition
An n-type mother alloy ingot (Comparative Example 7) was produced. The magnetic properties of the magnetic powder were evaluated in the same manner as in Example 1 except that each of these ingots was used. Table 1 shows the results.

[0030]

[Table 1]

In Table 6, Examples 1 to 5 and Comparative Examples 1 to
From the comparison with No. 5, it can be seen that when the La content is 1 to 5% and the average particle size is 10 to 300 µm, (BH) max and HcJ higher than the average particle size of 2 µm can be obtained. In addition, from the comparison between Examples 1 to 5 and Comparative Examples 6 and 7, when the La content is 1 to 5%, the (BH) max is high when the average particle diameter is the same.
And HcJ can be obtained.

(Example 6) Average particle size produced in Example 2
38 μm anisotropic magnetic powder: 92.2 parts by weight, liquid epoxy resin: 2.6 parts by weight, and curing agent (DDS: diaminoaminophenylsulfone):
2.6 parts by weight, and organic solvent methyl ethyl ketone (boiling point 79.5 ° C):
2.6 parts by weight were blended and charged into a mixer. Then 50r.p.
The mixture was stirred at m. for 20 minutes to form a slurry. A parallel magnetic field having an orientation magnetic field strength of 0.64 MA / m (8 kOe) was applied to the slurry at room temperature, and a cube having a length of 10 mm, a width of 10 mm and a length of 10 mm was formed at a molding pressure of 5.9 × 10 ⁸ Pa (6 ton / cm ² ). The shaped body was compression molded. 85 ° C. in an argon stream
For 1 hour to remove the solvent. Next, 170 ° C in an argon stream
For 2 hours to obtain an anisotropic bonded magnet of the present invention. As a result of measuring the magnetic properties of the anisotropic bonded magnet obtained at room temperature and a magnetizing magnetic field strength of 1.9 MA / m (25 kOe), (BH) max in the direction of providing anisotropy = 95.5 kJ / m ³ (12MGOe )
(BH) max = 8.0kJ / m in the direction perpendicular to the direction of providing anisotropy
³ (1.0 MGOe).

From Example 6, it can be seen that the anisotropic magnetic powder of the present invention can provide a high-performance anisotropic bonded magnet having good magnetic field orientation and magnetization even with a coarse powder having an average particle size of 38 μm. I understand. From this result, it can be determined at the same time that the individual magnetic powder particles are substantially oriented in one direction.

[0034]

As described above, according to the present invention, anisotropic magnetic powder having good magnetizability even when the average particle size is large, 10 μm or more, and high performance obtained by blending the same. Can be provided.

Claims (4)

[Claims] 1. In a weight percentage, R is 20 to 30% (R is composed of Sm and La and the La content is 0.1 to 5%), M
Improves magnetism, characterized by being composed of an aggregate of crystal grains of an oriented 2-17 type hard magnetic phase having a main component composition represented by n1 to 10%, N4 to 7%, and balance Fe. Anisotropic magnetic powder. 2. The method according to claim 1, wherein the average particle size is 10 to 300 μm.
The anisotropic magnetic powder described in the above. 3. In weight percentage, R (R is Sm and La, content of La is 0.1-5%) 20-30%, M
An anisotropic material having a main component composition represented by n1 to 10%, N4 to 7%, and the balance Fe, comprising an aggregate of crystal grains of an oriented 2-17 type hard magnetic phase, and having improved magnetization. An anisotropic bonded magnet, comprising substantially magnetic powder and a binder. 4. An anisotropic magnetic powder having an average particle size of 10 to 300 μm.
The anisotropic bonded magnet according to claim 3, wherein m is m.