JPH07263211A - Isotropic bond magnet and its production - Google Patents

Abstract

PURPOSE:To obtain a powder alloy of microcrystal aggregate having constitutional phases of an Fe3B type compound and alpha-iron and an Nd2Fe14B type crystal structure suitable for production of a bond magnet having a specified remanent magnetic flux density. CONSTITUTION:The powder alloy for permanent magnet has a composition represented by a formula Fe100-x-y-zBxRyMz (R represents one or two kinds of Pr and Nd, M represents one or more than one kind of Al, Si, S, Ni-, Cu, Zn, Ga, Ag, Pt, Au, or Pb) where, 10<=x<=30at%, 3<=y<=5at% and 0.1<=z<=3at%. An Fe3B type compound and alpha-iron coexist with a compound having Nd2Fe14B type crystal structure in one powder particle of a microcrystal aggregate. The average crystal particle size of each constitutional phase is in the range of 1-50nm and a powder having average particle size in the range of 3-500mum is bonded by resin to produce an isotropic bond magnet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an isotropic bonded magnet most suitable for various motors, speakers, meters, focus convergence rings and the like and a method for producing the same, and Fe-containing a specific composition containing a small amount of a rare earth element.
B-R-M (M = Al, Si, S, Ni, Cu, Zn,
Ga, Ag, Pt, Au, Pb) alloy melt is made into an amorphous structure or a structure in which fine crystals and amorphous are mixed by an ultra-quenching method using a rotating roll, a splat quenching method, a gas atomizing method or a combination thereof By heat treatment, Fe ₃ B type compound and α-iron and Nd ₂ Fe ₁₄
By obtaining an alloy powder composed of a fine crystal aggregate with a constituent phase of a B-type crystal structure and binding it with a resin, a residual magnetic flux density Br of 8 kG or more, which cannot be obtained with a hard ferrite magnet, is obtained, The present invention relates to an isotropic bonded magnet capable of obtaining an Fe-BR bonded magnet having excellent characteristics and a method for manufacturing the same.

[0002]

2. Description of the Related Art In fields requiring a high residual magnetic flux density Br and permanent magnets required to be used at high and low temperatures, Br is mainly 10 kG or more and an intrinsic coercive force iHc is 0.
An alnico magnet having a magnetic characteristic of 5 kOe to 2 kOe,
Or S with Br of 8 kG or more and iHc of 6 kOe or more
m-Co magnets are used.

These magnets are mainly made of Co, which is difficult to obtain stably because the supply amount from the country of origin is unstable. In the case of Alnico magnet, 20 to 30 wt%, Sm-C
It also contains 50 to 65 wt% of a magnet. Also, Sm
There is a problem that Sm contained in a Co magnet is extremely expensive because it is contained in a rare earth mineral in a small amount and is difficult to obtain stably. However, magnets used for motors and speedometers for automobile electrical components may be used in an environment of 80 ° C. or higher, so Alnico magnets and Sm-Co magnets are much cheaper for such applications. It occupies the mainstream over the available hard ferrites.

In particular, the Sm-Co magnet is an expensive magnet due to the demand for improving the fuel efficiency of today's automobiles, but has excellent magnetic characteristics, so that it is suitable for a magnetic circuit that requires a small size and high performance. It is used. So Co and S
A permanent magnet material that does not contain m and is excellent in magnetic characteristics and temperature characteristics is required, but at present, a bonded magnet having a Br of 8 kG or more, which can be mass-produced and can be provided at low cost, has not been found. .

[0005]

Recently, in an Nd-Fe-B system magnet containing no Co or Sm, Nd ₄ Fe _{77 was used.}
A magnetic material having a Fe ₃ B type compound as a main phase in the vicinity of B ₁₉ (at%) is proposed (R. Coehorn et al., J. de P.
hys. , C8, 1988, pp. 669-670). This magnet material is a metastable structure permanent magnet material having a crystal texture in which Fe ₃ B phase and Nd ₂ Fe ₁₄ B phase are mixed by heat-treating an amorphous ribbon.
Although it has Br of about 0 kG and iHc of 2 to 3 kOe,
The heat treatment conditions for becoming a hard magnetic material are narrowly limited, which is not practical in industrial production.

Further, a study has been published to improve iHc to 3 to 5 kOe by substituting a part of Nd of the Nd-Fe-B system magnet having the Fe ₃ B type compound as a main phase with Dy and Tb. However, in addition to the problem of adding an expensive element, there is a problem that the magnetic moment of the rare earth element added is coupled antiparallel to the magnetic moments of Nd and Fe, and the squareness of the magnetization and demagnetization curve is reduced (R Coehoorn, J .;
Magn, Magn, Mat. , 83 (1990) 22
8 to 230).

In any case, Fe ₃ B type Nd-Fe-B
The system magnet can be made into a hard magnetic material by heat treatment after being made amorphous by the ultra-quenching method, but iHc is low and the heat treatment conditions are narrow, and stable industrial production cannot be performed. As an alternative, it cannot be provided inexpensively.

The present invention focuses on an iron-based permanent magnet material in which a soft magnetic phase and a hard magnetic phase are mixed in the same structure and has a low rare earth concentration, and the iHc of this magnet is improved to enable stable industrial production. It is an object of the present invention to establish a manufacturing method, to provide an isotropic bonded magnet which has a residual magnetic flux density Br of 8 kG or more and has cost performance comparable to that of a hard ferrite magnet, and which can be provided at low cost, and a manufacturing method thereof.

[0009]

According to the present invention, a soft magnetic phase and a hard magnetic phase are mixed in the same structure, and the rare earth concentration is 4 at%.
As a result of various studies aimed at improving the iHc of the iron-based permanent magnet, which is as low as a degree, and enabling stable industrial production,
The content of rare earth elements is low, and Al, Si, S, Ni,
The alloy melt of the iron-based specific composition to which a small amount of at least one of Cu, Zn, Ga, Ag, Pt, Au, and Pb is added is made into an amorphous structure or a structure in which fine crystals and amorphous are mixed by the ultra-quenching method, etc. Heat treatment of Fe ₃ B
By obtaining an alloy powder consisting of a type compound and a fine crystal aggregate of α-iron and the constituent phases of the Nd ₂ Fe ₁₄ B type crystal structure, it is possible to obtain an alloy powder of 10k which is comparable to Alnico magnets and Sm-Co magnets.
It was found that an optimum permanent magnet alloy powder can be obtained for a bond magnet having a residual magnetic flux density Br of G or more, and further, by binding this alloy powder with a resin, Co or Sm can be obtained.
It was found that an isotropic bonded magnet having a residual magnetic flux density Br of not less than 8 kG and having excellent magnetic characteristics and temperature characteristics can be obtained without containing Al, and completed the present invention.

The present invention uses the composition formula Fe _100-xyz B _x
R _y M _z (where R is one or two of Pr or Nd,
M is Al, Si, S, Ni, Cu, Zn, Ga, Ag,
Pt, Au, Pb) or two or more), and the symbols x, y, z, w for limiting the composition range satisfy the following values,
Fe ₃ B type compound and α-iron, and a compound having an Nd ₂ Fe ₁₄ B type crystal structure coexist in the same powder particle, and the average crystal grain size of each constituent phase is a fine crystal in the range of 1 nm to 50 nm. An isotropic bonded magnet, which is an aggregate, in which powders having an average particle diameter of 3 μm to 500 μm are bonded with a resin. 10 ≦ x ≦ 30 at% 3 ≦ y ≦ 5 at% 0.1 ≦ z ≦ 3 at%

Further, according to the present invention, (1) the composition formula is represented by Fe
_100-xyz B _x R _y M _z (where R is one or two of Pr or Nd, M is Al, Si, S, Ni, Cu, Zn,
One or more of Ga, Ag, Pt, Au, Pb)
And the symbols x, y, and z that limit the composition range satisfy the above-mentioned values, and the alloy melt is quenched by a super-quenching method using a rotating roll, a splat quenching method, a gas atomizing method, or a combination of these methods. (2) Crystallization in which the temperature rising rate from around the temperature at which crystallization starts to the processing temperature of 600 ° C to 700 ° C is 10 ° C / min to 50 ° C / sec. After heat treatment, (3) the Fe ₃ B type compound and α-iron, and the compound having the Nd ₂ Fe ₁₄ B type crystal structure coexist in the same powder particle, and the average crystal grain size of each constituent phase is 1 nm.
After obtaining a microcrystalline aggregate in the range of ˜50 nm,
(4) A method for producing an isotropic bonded magnet, characterized in that the magnet alloy powder pulverized to have an average particle size of 3 μm to 500 μm is bonded with a resin.

Reasons for limiting the composition The rare earth element R has high magnetic characteristics only when one or two kinds of Pr or Nd are contained in a specific amount, and other rare earth elements R,
For example, in the case of Ce and La, the characteristic that iHc is 2 kOe or more cannot be obtained, and medium rare earth elements and heavy rare earth elements after Sm cause deterioration of magnetic characteristics and make the magnet expensive, which is not preferable. When R is less than 3 at%, iHc of 3 kOe or more cannot be obtained, and when it exceeds 5 at%, 8 kG.
Since the above Br cannot be obtained, the range is set to 3 to 5 at%.

If B is less than 10 at%, an amorphous structure cannot be obtained even if the ultra-quench method is used, and even if a heat treatment is applied, it becomes 3
Only iHc less than kOe can be obtained. Also, 30 at%
If it exceeds, the squareness of the demagnetization curve remarkably deteriorates and Br of 8 kG or more cannot be obtained, so the range is set to 10 to 30 at%. It is preferably 15 to 20 at%.

Al, Si, S, Ni, Cu, Zn, G
Although a, Ag, Pt, Au, and Pb have the effect of improving the squareness of the demagnetization curve and increasing Br and (BH) max, if less than 0.1 at%, such an effect cannot be obtained.
When it exceeds at%, since Br of 8 kG or more cannot be obtained,
The range is 0.1 to 3 at%. Preferably 0.5 to
1.5at% is good.

Fe occupies the remaining content of the above-mentioned elements.

Reasons for Limiting Manufacturing Conditions In the present invention, the molten alloy having the above-mentioned specific composition is made into an amorphous structure or a structure in which fine crystals and amorphous are mixed by the ultra-quenching method, and the temperature is about 6 from the temperature at which crystallization starts.
The temperature rising rate from the processing temperature of 00 ° C to 700 ° C is 10 ° C /
By performing the crystallization heat treatment at a temperature of min.
Fe ₃ B type compounds and α-iron, and a compound phase having an Nd ₂ Fe ₁₄ B type crystal structure coexist in the same powder, and the average crystal grain size of each constituent phase is in the range of 1 nm to 50 nm It is most important to obtain an aggregate, and a super-quenching method using a known rotating roll can be adopted for the super-quenching treatment of the molten alloy, but it is possible to obtain a structure in which amorphous or fine crystals are substantially mixed. For example, a splat quenching method, a gas atomizing method, or a quenching method combining these methods may be adopted in addition to the super quenching method using a rotating roll. For example, when a Cu roll is used, a roll surface peripheral velocity in the range of 10 to 50 m / sec is preferable because a suitable quenched structure can be obtained. That is, the roll peripheral speed is 1
When it is less than 0 m / sec, an amorphous structure is not formed, which is not preferable. On the other hand, if it exceeds 50 m / sec, it is not preferable because it does not form a fine crystal aggregate capable of obtaining good hard magnetic properties during crystallization. However, even if a small amount of α-Fe phase is present in the quenched structure, it does not significantly deteriorate the magnetic properties and is acceptable.

In the present invention, the heat treatment conditions for maximizing the magnetic properties after the alloy melt of the above-mentioned specific composition is made into an amorphous structure or a structure in which fine crystals and amorphous are mixed by the ultra-quenching method depend on the composition, Heat treatment temperature is 6
If the temperature is less than 00 ° C, the Nd ₂ Fe ₁₄ B phase does not precipitate, so iH
c is not expressed. Further, when the temperature exceeds 700 ° C., grain growth is remarkable, iHc, Br, and the squareness of the demagnetization curve are deteriorated, and the above-mentioned magnetic properties cannot be obtained.
Limit to 700 ° C. Since the heat treatment atmosphere prevents oxidation, it is preferably in an atmosphere of an inert gas such as Ar gas or N ₂ gas or in a vacuum of 10 ^-2 Torr or more. The magnetic characteristics do not depend on the heat treatment time, but if it exceeds 6 hours, Br tends to decrease with the passage of time, so that it is preferably less than 6 hours.

An important feature of the present invention is the rate of temperature increase from around the temperature at which crystallization starts during heat treatment. At a rate of temperature increase of less than 10 ° C./minute, grain growth occurs during temperature increase, which is good. It is not preferable because it does not form a fine crystal aggregate having excellent hard magnetic properties and iHc of 3 kOe or more cannot be obtained. Further, at a temperature rising rate exceeding 50 ° C./second, 60
The Nd ₂ Fe ₁₄ B phase generated after passing 0 ° C. is not sufficiently precipitated, and not only the iHc decreases, but also the demagnetization with a decrease in the magnetization in the second quadrant of the demagnetization curve near the Br point. It becomes a curve and (BH) max decreases, which is not preferable.
The temperature at which crystallization starts is the temperature at which Fe ₃ B and α-Fe crystallize in the amorphous alloy of the present magnet composition,
The exothermic reaction in the temperature rising process can be clearly measured using a technique such as DTA or DSC. In the heat treatment, the temperature rising rate up to the crystallization start temperature is arbitrary, and rapid heating or the like can be applied to increase the processing efficiency.

Crystal Structure The crystal phase of the permanent magnet alloy powder according to the present invention includes a soft magnetic phase composed of Fe ₃ B type compound having ferromagnetism and α-iron, and a hard magnetic phase having Nd ₂ Fe ₁₄ B type crystal structure. Coexist in the same powder, and the average crystal grain size of each constituent phase is 1 nm to
It is characterized by comprising a fine crystal aggregate in the range of 50 nm. In the present invention, when the average grain size of the magnet alloy exceeds 50 nm, the squareness of Br and the demagnetization curve deteriorates, and an isotropic bonded magnet having magnetic characteristics of Br ≧ 8 kG and (BH) max ≧ 8 MGOe is obtained. Can't get Further, the smaller the average crystal grain size is, the more preferable, but 1n
Since it is difficult to obtain an average crystal grain size of less than m in industrial production, the lower limit is set to 1 nm.

Magnetization Method A molten alloy having a specific composition is made into an amorphous structure or a structure in which fine crystals and amorphous are mixed by the above-mentioned ultra-quenching method, and 600 ° C. to 700 ° C. from around the temperature at which crystallization starts.
A permanent magnet having a fine crystal aggregate having an average crystal grain size in the range of 1 nm to 50 nm obtained by performing a crystallization heat treatment at a temperature rising rate up to a treatment temperature of 10 ° C. of 10 ° C./min to 50 ° C./sec. To magnetize using the alloy powder, any of the known bond magnetizing methods can be adopted, and if necessary,
It is possible to obtain an isotropic bonded magnet having a residual magnetic flux density Br of 8 kG or more by crushing the alloy to an average crystal grain size of 3 to 500 μm and then mixing it with a known binder to form a required bonded magnet. it can. The particle size of the powder must be sufficiently small in order to perform high-precision molding by taking advantage of the characteristics of a bonded magnet that can obtain a magnet with a complicated shape or a thin shape, but the particle size obtained by atomization is 10
Since the alloy powder exceeding 0 μm is not sufficiently cooled to the inside of the powder during the rapid cooling and most of it becomes the α-Fe phase, the Fe ₃ B and Nd ₂ Fe ₁₄ B phases do not precipitate even if the heat treatment is performed, and the hard magnetic material It cannot be. If the particle size is less than 3 μm, a large amount of resin needs to be used as the specific surface area increases, and the packing density decreases, which is not preferable.
To 500 μm.

The bonded magnet according to the present invention is an isotropic magnet, and is manufactured by the following compression molding, injection molding, extrusion molding,
Any known manufacturing method such as rolling molding or resin impregnation method may be used. In the case of compression molding, it is obtained by adding and kneading a thermosetting resin, a coupling agent, a lubricant and the like to the magnetic powder, and then compression molding and curing the heating resin. In the case of injection molding, extrusion molding, and roll molding, after kneading the magnetic powder with thermoplastic resin, coupling agent, lubricant, etc., and then molding by injection molding, extrusion molding, or roll molding. To be In the resin impregnation method, magnetic powder is compression-molded, heat-treated as necessary, impregnated with a thermosetting resin, and heated to cure the resin. Alternatively, the magnetic powder may be obtained by compression molding, heat treatment if necessary, and impregnation with a thermoplastic resin.

In the present invention, the weight ratio of the magnetic powder in the bonded magnet is 70 to 99.
5% by weight, and the remaining 0.5 to 30% by weight is resin or the like. In the case of compression molding, the weight ratio of magnetic powder is 95-9
9.5 wt%, in the case of injection molding, the filling rate of magnetic powder is 9
0 to 95 wt%, and in the case of the resin impregnation method, the weight ratio of the magnetic powder is preferably 96 to 99.5 wt%. As the synthetic resin in the present invention, those having any of thermosetting and thermoplastic properties can be used, but a thermally stable resin is preferable,
For example, polyamide, polyimide, phenol resin, fluorine resin, silicon resin, epoxy resin and the like can be appropriately selected.

[0023]

The present invention is characterized in that Fe-B-R-M (R is Pr or Nd, M is A) of a specific composition containing a small amount of rare earth elements.
l, Si, S, Ni, Cu, Zn, Ga, Ag, Pt,
The temperature at which crystallization of the obtained ribbons, flakes, or spherical powders is achieved by forming a molten alloy of one or more of Au and Pb) into an amorphous structure or a structure in which fine crystals and amorphous are mixed by the ultra-quenching method. 600 ~ from the neighborhood
Temperature rising rate up to temperature treatment at 700 ° C is 10 ° C / min to 5
By performing the crystallization heat treatment at 0 ° C./sec, the soft magnetic phase composed of the Fe ₃ B type compound having ferromagnetism and α-iron and the hard magnetic phase having the Nd ₂ Fe ₁₄ B type crystal structure are the same. Coexist in powder, average grain size of each constituent phase is 1 nm
Microcrystalline aggregates in the range of -50 nm are obtained. On this occasion,
M (= Al, Si, S, Ni, Cu, Zn, Ga, A
g, Pt, Au, Pb), the crystal grains become finer by about 1/2 to 1/3 as compared with the composition containing no M, and the fine crystallization can improve the Br and the squareness.
≧ 3 kOe, Br ≧ 10 kG, (BH) max ≧ 9 MG
It is possible to obtain a permanent magnet alloy powder having a magnetic property of Oe, which is made into a powder having a powder particle size of 3 μm to 500 μm and combined with a resin to obtain iHc ≧ 3 kOe, B
An isotropic bonded magnet having magnetic characteristics of r ≧ 8 kG and (BH) max ≧ 8 MGOe can be obtained.

[0024]

【Example】

Example 1 No. 1 in Table 1 Purity of 99.
5% or more of Fe, Al, Si, S, Ni, Cu, Zn,
Metals of Ga, Ag, Pt, Au, Pb, B, Nd, and Pr were weighed so that the total amount was 30 gr, put into a quartz crucible having an orifice with a diameter of 0.8 mm at the bottom, and the pressure was 56 cmHg. Melted by high frequency heating in Ar atmosphere, and the melting temperature was set to 1300 ° C.
The molten metal is jetted from a height of 0.7 mm onto the outer peripheral surface of a room temperature Cu roll that is pressurized with r gas and rotates at a roll peripheral speed of 20 m / sec, and has a width of 2 to 3 mm and a thickness of 20 to 40 μm.
An ultra-quenched ribbon of m was prepared. The obtained ultra-quenched ribbon is Cu
It was confirmed to be amorphous by the characteristic X-ray of Kα.

This ultra-quenched ribbon was heated in Ar gas at a temperature rising rate shown in Table 1 at a temperature of 580 ° C. to 600 ° C. at which crystallization begins, and was held at the heat treatment temperature shown in Table 1 for 7 minutes, and thereafter. After cooling to room temperature, the thin strip was taken out, and a sample having a width of 2 to 3 mm, a thickness of 20 to 40 μm, and a length of 3 to 5 mm was prepared.
The magnetic properties were measured using M. No. as the measurement result.
Demagnetization curve of sample 2 (sample shape; width 3 mm, thickness 30 μ
m, length 3 mm) is shown in FIG. As a result of investigating the constituent phases of the sample by the characteristic X-ray of CuKα, it was found that α-Fe phase, Fe
It had a multi-phase structure in which ₃ B phase and Nd ₂ Fe ₁₄ B phase were mixed.
In addition, Al, Si, S, Ni, Cu, Zn, Ga, A
g, Pt, Au and Pb replace part of Fe in each of these phases. The average crystal grain size was 30 nm or less in all cases.

The obtained ultra-quenched ribbon was heat-treated in Table 1 and then pulverized to an average powder particle size of 150 μm or less, and a binder made of an epoxy resin was mixed at a ratio of 3 wt%.
It was compression molded at a pressure of 6 ton / cm ² and cured at 150 ° C. to prepare a bonded magnet having dimensions of 12 mm × 12 mm × 8 mm. The density of each of the obtained bonded magnets was 6.
0 gr / cm ³ , magnetic properties and 25 ° C to 140
Table 2 shows the temperature coefficients of Br and iHc at ° C.

Comparative Example No. 1 in Table 1 Purity of 99.
An ultra-quenched ribbon was produced under the same conditions as in Example 1 using 5% or more of Fe, B, and R. The obtained ribbon was heat-treated under the same conditions as in Example 1, cooled, and then sampled under the same conditions as in Example 1 (Comparative Examples Nos. 14 to 16), and the magnetic characteristics were measured using VSM. No. as the measurement result. Demagnetization curve of 15 samples (sample shape; width 3 mm, thickness 30 μm, length 3 m
m) is shown in FIG. The constituent phase of the sample is a multi-phase structure of α-Fe phase and Nd ₂ Fe ₁₄ B phase having Fe ₃ B phase as a main phase, and the average crystal grain size is around 50 nm and No. 1-No.
It was coarser than the 13 samples. The obtained ribbon was subjected to a heat treatment under the same conditions as in Example 1, cooled and then pulverized under the same conditions as in Example 1 to obtain a powder having an average particle size of 60 μm, and then bonded under the same conditions as in Example 1. I made a magnet. Table 2 shows the magnetic properties of the obtained bonded magnet and the temperature coefficients of Br and iHc of the permanent magnet alloy powder at 25 ° C to 140 ° C.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

INDUSTRIAL APPLICABILITY The present invention has a specific composition of Fe-B-RM (where R is Pr or N) with a low content of rare earth elements.
d and M are Al, Si, S, Ni, Cu, Zn, Ga,
One or more alloy melts of Ag, Pt, Au and Pb) are made into an amorphous structure or a structure in which fine crystals and amorphous are mixed by the ultra-quenching method, and the ribbon, flakes and spherical powders obtained have specific conditions. Heat treatment of Fe ₃ B type compound and α-iron, Nd ₂ Fe ₁₄
A compound phase having a B-type crystal structure coexists in the same powder, and a fine crystal aggregate having an average crystal grain size of each constituent phase in the range of 1 nm to 50 nm is obtained. At this time, M (= Al, S
i, S, Ni, Cu, Zn, Ga, Ag, Pt, Au,
By adding Pb), compared with the composition in which the tissue does not contain M, 1
The squareness of Br and the demagnetization curve is improved by reducing the size to / 2 to 1/3, iHc ≧ 3 kOe, Br ≧ 10
It is possible to obtain a permanent magnet alloy powder having an excellent temperature characteristic having a magnetic characteristic of kG, (BH) max ≧ 9 MGOe,
By combining this with a resin, it does not contain Sm or Co, the manufacturing method is simple, and it is suitable for mass production.
c ≧ 3 kOe, Br ≧ 8 kG, (BH) max ≧ 8 MG
An inexpensive isotropic bonded magnet having Oe magnetic characteristics and excellent temperature characteristics can be stably provided.

[Brief description of drawings]

FIG. 1 is a graph showing a demagnetization curve.

Claims (2)

[Claims] 1. The composition formula is Fe _100-xyz B _x R _y M _z
(However, R is one or two of Pr or Nd, M is A
l, Si, S, Ni, Cu, Zn, Ga, Ag, Pt,
Au, Pb 1 type or 2 types or more), and the symbols x, y, z for limiting the composition range satisfy the following values, and Fe ₃ B type compounds and α-iron, and Nd ₂ Fe ₁₄ B type crystals A powder is a fine crystal aggregate in which the compound phase having a structure coexists in the same powder particle, and the average crystal grain size of each constituent phase is in the range of 1 nm to 50 nm, and the average grain size of the powder is 3 μm to 500 μm. An isotropic bonded magnet characterized by being bonded by. 10 ≦ x ≦ 30 at% 3 ≦ y ≦ 5 at% 0.1 ≦ z ≦ 3 at% 2. The composition formula is Fe _100-xyz B _x R _y M _z (wherein R is one or two of Pr or Nd, M is Al, S
i, S, Ni, Cu, Zn, Ga, Ag, Pt, Au,
One or more of Pb) and the symbols x, y, and z for limiting the composition range satisfying the following values, an alloy melt is subjected to an ultra-quenching method using a rotating roll, a splat quenching method, a gas atomizing method, or the like. Combined and rapidly cooled to form an amorphous structure or a structure in which fine crystals and amorphous coexist, and 600 ° C from around the temperature at which crystallization starts.
The temperature rising rate up to the processing temperature of ~ 700 ° C is 10 ° C / min ~ 5
The Fe ₃ B type compound and α-iron and the compound having the Nd ₂ Fe ₁₄ B type crystal structure coexist in the same powder particle after the crystallization heat treatment at 0 ° C./sec. A microcrystalline aggregate having a particle size in the range of 1 nm to 50 nm is obtained, and then magnet alloy powder crushed to have an average particle size of 3 μm to 500 μm is bonded with a resin to form an isotropic bonded magnet. Production method. 10 ≦ x ≦ 30 at% 3 ≦ y ≦ 5 at% 0.1 ≦ z ≦ 3 at%