JPH0653019A - Rare earth magnet, rare earth magnet alloy powder and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a rare earth magnet excellent in magnetic characteristics, by turning Fe-Ni-B-R alloy melt or Fe-Ni-B-R-N alloy melt of specified composition into amorphous texture by a super-quenching method, and turning the texture into magnetic alloy powder by heat treatment under a specified condition. CONSTITUTION:A composition formula is expressed by Fe100-x-y-zNixByRz (R is one kind or two kinds out of Pr or Nd), or Fe100-x-y-zNixByRzMw (M is one more kinds out of Ag, Al, Si, Cu and Ga) where 0.01<=x<=2 atomic %, 16<=y<=22 atomic %, 3<=z<=5.5 atomic % and 0.1<=w<=3 atomic %. The title rare earth magnet is fine crystal aggregate whose average crystal grain diameter is 0.01-0.1mum which has ferromagnetic phase having Nd2Fe14B type crystal structure wherein the main phase is Fe3B type compound. Thereby an Fe3B type Nd-Fe-B based magnet having residual magnetic flux density of 5kG or higher wherein stable inductrial production is possible can be obtained at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth sintered magnet or a bonded magnet most suitable for a motor or an actuator, and has a specific composition of Fe-Ni containing a small amount of rare earth elements.
-BR (Nd, Pr) alloy melt or Fe-Ni-
The B-R (Nd, Pr) -M alloy melt was formed into an amorphous structure by the ultra-quenching method, and a fine crystal aggregate was obtained by a specific heat treatment to obtain a residual magnetic flux of 5 kG or more that could not be obtained with a hard ferrite magnet. The present invention relates to a manufacturing method for obtaining a rare earth magnet alloy powder most suitable for a bonded magnet having a density Br.

[0002]

2. Description of the Related Art Permanent magnets used in motors and actuators for electrical equipment have been mainly limited to hard ferrite magnets, but they have low mechanical strength due to low temperature demagnetization accompanying iHc reduction at low temperatures and ceramic materials. However, there were problems such as low hardness, easy cracking and chipping, and difficulty in obtaining a complicated shape.

Nowadays, automobiles are strongly required to reduce fuel consumption in order to save resources and to improve fuel efficiency, and electric components for automobiles are required to be further reduced in size and weight. Also,
Designs for maximizing the performance-to-weight ratio are also being considered for applications such as home electric motors other than automobile electrical components. In the current motor structure, magnet materials with Br of about 5 to 7 kG are optimal. It is said that. That is,
When the magnet material used has a Br of 8 kG or more, the current motor structure requires an increase in the cross-sectional area of the iron plate of the rotor or stator that becomes the magnetic path, which causes an increase in weight. If so, the performance-to-weight ratio can be maximized.

Therefore, a magnetic material for a small motor is required to have a residual magnetic flux density Br of 5 kG or more in terms of magnetic characteristics, but it cannot be obtained with a conventional hard ferrite magnet. For example, Nd-Fe-B based bonded magnets satisfy such magnetic characteristics, but Nd, etc., which require a large number of steps and a large-scale facility for separation and purification of metals and reduction reaction.
Since it is contained at ˜15 at%, it is remarkably expensive as compared with a hard ferrite magnet, and at present, a magnet material with a Br of about 5 to 7 kG that can be mass-produced and can be provided at low cost has not been found.

[0005]

On the other hand, Nd-Fe-B
In a magnet system, a magnet material having a Fe ₃ B type compound as a main phase in the vicinity of Nd ₄ Fe ₇₇ B ₁₉ (at%) has recently been proposed (R. Coehorn et al., J. de Phys., C).
8, 1988, pp. 669-670). This magnet material is made of Fe by heat treatment of the amorphous ribbon.
_Although it is a metastable structure having a crystal texture of ₃ B and Nd ₂ Fe ₁₄ B, iHc is not so high as about 2 to 3 kOe, and the heat treatment conditions for obtaining this iHc are narrowly limited, which is practical for industrial production. Not.

[0006] A study has been published in which an additive element is added to the magnetic material having the Fe ₃ B type compound as a main phase to make it a multi-component to improve the performance. One of them is to improve iHc by using Dy and Tb in addition to Nd as a rare earth element. However, in addition to the problem of adding an expensive element, the added rare earth element has a magnetic moment of Nd or Fe. There is a problem that the magnetization decreases due to coupling in antiparallel to the moment (R. Coehoorn, J. Magn, Magn, M
at. , 83 (1990) 228-230).

Other studies (Shen Bao-gen et al.,
J. Magn, Magn, Mat. , 89 (199
1) pages 335 to 340), a part of Fe is replaced with Co to raise the Curie temperature and improve the temperature coefficient of iHc, but there is a problem that Br is lowered with the addition of Co. .

In any case, Fe ₃ B type Nd-Fe-B
A system magnet can be made into a hard magnet material by heat treatment after being made amorphous by a super-quenching method, but iHc is low, and the heat treatment conditions are narrow, and if a high iHc is achieved by an additive element, the magnetic energy product decreases. As such, stable industrial production cannot be performed, and it cannot be provided at a low cost as an alternative to the hard ferrite magnet.

Further, in order to amorphize the Nd-Fe-B system alloy, it is necessary to remarkably increase the roll peripheral speed during the ultra-quenching, which causes a problem that the product recovery rate and the yield decrease. Since it is a base alloy, there is a problem that corrosion during storage tends to proceed, and the initial magnetic characteristics cannot be maintained and deteriorates after long-term storage.

The present invention focuses on an Fe ₃ B type Fe-BR magnet (R is a rare earth element), iHc and (BH) m
Fe ₃ B that can improve the ax and establish a manufacturing method that enables stable industrial production and has a residual magnetic flux density Br of 5 kG or more and can be provided at a low cost as an alternative to a hard ferrite magnet.
Aims to be a type Nd-Fe-B system magnet.

[0011]

The present invention has been variously studied for the purpose of improving the iHc and (BH) max of Fe ₃ B type Fe-B-R magnets and enabling a stable industrial production. As a result, the content of rare earth elements is low, and Ni or at least 1 of Ag, Al, Si, Ga and Cu is added.
It was not possible to obtain it with a hard ferrite magnet by making a molten alloy of iron-based specific composition with a small amount of seeds formed into an amorphous structure by the ultra-quenching method and obtaining a fine crystal aggregate by heat treatment at a specific heating rate. The inventors have found that an optimum rare earth magnet alloy powder can be obtained for a bonded magnet having a residual magnetic flux density Br of 5 kG or more, and completed the present invention.

This invention uses the composition formula Fe _100-xyz Ni _x.
B _y R _z (where R is one or two of Pr or Nd)
Or, in addition, the composition formula is Fe _100-xyz N
_{i x B y R z M w} ( where R is Pr or one or two Nd, M is Ag, Al, Si, one or more of Cu or Ga) represents the symbol limiting the composition range x,
y, z, w satisfy the following values, Fe ₃ B type compound as a main phase, a ferromagnetic phase having an Nd ₂ Fe ₁₄ B type crystal structure, and an average crystal grain size of 0.01 to 0. It is a rare earth magnet characterized by comprising a fine crystal aggregate of 1 μm. 0.01 ≦ x ≦ 2 at% 16 ≦ y ≦ 22 at% 3 ≦ z ≦ 5.5 at% 0.1 ≦ w ≦ 3 at%

Further, the present invention uses the composition formula Fe
_{100-xyz Ni x B y R} z ( where R is 1 Pr or Nd
Or two)), or in addition, the composition formula is Fe.
_{100-xyz Ni x B y R} z M w ( where R is Pr or N
1 or 2 kinds of d, M is 1 or 2 kinds or more of Ag, Al, Si, Cu or Ga), and the symbols x, y, z and w for limiting the composition range satisfy the above values, Fe ₃ B type compound as a main phase, a ferromagnetic phase having an Nd ₂ Fe ₁₄ B type crystal structure, and an average crystal grain size of 0.01 to 0.1 μm.
The average grain size is 3 to 500μ.
m, magnetic characteristics are iHc ≧ 2 kOe, Br ≧ 7 kG, (B
H) max ≧ 8 MGOe, which is a rare earth magnet alloy powder.

Further, according to the present invention, the composition formula (1) is represented by Fe
_{100-xyz Ni x B y R} z ( where R is 1 Pr or Nd
Or two)), or in addition, the composition formula is Fe.
_{100-xyz Ni x B y R} z M w ( where R is Pr or Nd
Alloy of which the symbols x, y, z and w for limiting the composition range satisfy the above-mentioned values, and M is one or more of Ag, Al, Si, Cu or Ga). Substantially 90% or more of the molten metal is formed into an amorphous structure by the ultra-quenching method, and (2) the temperature is raised from 500 ° C. at a rate of 1 to 15 ° C./min during heat treatment to 30 at 550 to 700 ° C.
A heat treatment is carried out for 2 seconds to 6 hours, and (3) a Fe ₃ B type compound as a main phase, a ferromagnetic phase having an Nd ₂ Fe ₁₄ B type crystal structure, and an average crystal grain size of 0.01 to 0. The method for producing a rare earth magnet alloy powder is characterized in that after obtaining a fine crystal aggregate of 1 μm, (4) this is pulverized to obtain a magnet alloy powder.

Reasons for limiting composition The rare earth element R has high magnetic characteristics only when one or two kinds of Pr or Nd are contained in a specified amount.
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. If R is less than 3 at%, iHc of 2 kOe or more cannot be obtained, and if it exceeds 5.5 at%, F is F.
e ₃ B phase is not generated and R ₂ F is a metastable phase that does not exhibit hard magnetism
The e ₂₃ B ₃ phase is unfavorably prominent because iHc is significantly reduced, so the range is 3 to 5.5 at%.

When B is less than 16 at% or more than 22 at%, iHc of 2 kOe or more cannot be obtained.
The range is -22 at%.

Ni is effective in improving the squareness of iHc and demagnetization curve, but if it is less than 0.05 at%, such an effect cannot be obtained, and if it exceeds 2 at%, iHc is remarkably reduced and 2 kOe or more. Since iHc of is not obtained, 0.0
The range is 5 to 2 at%.

Ag, Al, Si, Cu and Ga have the effects of expanding the heat treatment temperature range and improving the squareness of the demagnetization curve and increasing the magnetic properties Br and (BH) max. In order to obtain the effect, it is necessary to add at least 0.1 at% or more, but if it exceeds 3 at%, the squareness is rather deteriorated and (BH) max is also lowered.
The range is 1 to 3 at%.

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 amorphous by the ultra-quenching method, and it is 1 to 15 from 500 ° C. or higher.
After raising the temperature at a temperature rising rate of ℃ / min, 3 at 550 ~ 700 ℃
By performing a heat treatment for holding for 0 seconds to 6 hours, the Fe ₃ B type compound and Nd ₂ Fe ₁₄ B which are thermodynamically metastable phases are obtained.
It is most important to obtain a fine crystal aggregate having a ferromagnetic phase having a type crystal structure and an average crystal grain diameter of 0.01 to 0.1 μm. Although it is possible to adopt the ultra-quenching method using
It is necessary to make substantially 90% or more amorphous.
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 structure can be obtained. That is, when the peripheral speed is less than 10 m / sec, it does not become amorphous and the amount of α-Fe phase deposited increases, which is not preferable, and when the roll surface peripheral velocity exceeds 50 m / sec,
The rapidly cooled alloy does not form as a continuous ribbon, the alloy pieces scatter, and the recovery rate and recovery efficiency when recovering the alloy from the apparatus are reduced, which is not preferable. However, a small amount of α-Fe
The presence of phases in the quenched ribbon is acceptable as it does not significantly degrade the properties.

In the present invention, after the molten alloy having the above-mentioned specific composition is made substantially amorphous by 90% or more by the ultra-quenching method, the heat treatment at which the magnetic characteristics are maximized depends on the composition. If it is less than 550 ° C, iHc of 2 kOe or more cannot be obtained in the amorphous phase, and 700
When the temperature exceeds ℃, α-Fe phase and Fe ₂ B or Nd _1.1 Fe ₄ B ₄ phase, which are thermal equilibrium phases, are generated and iHc is not generated. Therefore, the heat treatment temperature is limited to 550 to 700 ° C. The heat treatment atmosphere is preferably an inert gas atmosphere such as Ar gas.

The heat treatment time may be short, but if it is less than 30 seconds, a sufficient microstructure is not formed, iHc and the squareness of the demagnetization curve are deteriorated, and if it exceeds 6 hours, it is 2 kO.
Since iHc above e cannot be obtained, the heat treatment holding time is set to 3
Limited to 0 seconds to 6 hours.

An important feature of the present invention is the rate of temperature increase from 500 ° C. or higher during heat treatment, which is 1 ° C. /
If the heating rate is less than a minute, the Nd ₂ Fe ₁₄ B phase and the F
Since the crystal grain size of the e ₃ B phase grows too large and iHc deteriorates, iHc of 2 kOe or more cannot be obtained. Also, 15 ℃
If the heating rate exceeds / min, the Nd ₂ Fe ₁₄ B phase generated after passing 500 ° C. is not sufficiently precipitated, and α-
The amount of precipitation of the Fe phase increases and Br falls to the second quadrant of the magnetization curve.
It becomes a demagnetization curve with a decrease in magnetization near the point, (BH) m
It is not preferable because ax is deteriorated. However, a small amount of α-
The presence of the Fe phase is acceptable. In addition, at the time of heat treatment, 50
The rate of temperature increase such as rapid heating up to 0 ° C. is arbitrary.

Crystal Structure The crystal phase of the rare earth magnet and the rare earth magnet alloy powder according to the present invention is Fe ₃ B type compound as a main phase and Nd ₂ Fe ₁₄ B.
It is characterized by having a ferromagnetic phase having a type crystal structure and comprising a fine crystal aggregate having an average crystal grain size of 0.01 to 0.1 μm.

In the present invention, when the average crystal grain size of the magnet alloy exceeds 0.1 μm, the squareness of the demagnetization curve is significantly deteriorated, and magnetic properties of Br ≧ 8 kG and (BH) max ≧ 7 MGOe are obtained. I can't. Further, the smaller the average crystal grain size is, the more preferable, but it is difficult to obtain the average crystal grain size of less than 0.01 μm in industrial production.
It is set to 01 μm.

Magnetization method A molten alloy having a specific composition is made amorphous by a super-quenching method, and the temperature rising rate from 500 ° C. or higher is raised at 1 to 15 ° C./minute, and then at 550 to 700 ° C. for 30 seconds to. By performing a heat treatment of holding for 6 hours, the average crystal grain size is 0.01 to
To magnetize using the rare earth magnet alloy powder according to the present invention obtained as a 0.1 μm fine crystal aggregate, 700 ° C.
Any of known sintering magnetizing methods and bond magnetizing methods that can be solidified and consolidated below can be adopted, and in particular,
After crushing the alloy into alloy powder having an average particle size of 3 to 500 μm and mixing it with a known binder to form a required bond magnet, a bond magnet having a residual magnetic flux density Br of 5 kG or more can be obtained. .

[0027]

According to the present invention, the Fe-Ni-BR (Nd, Pr) alloy melt or the Fe-Ni-BR (Nd, Pr) -M alloy melt having a specific composition containing a small amount of rare earth elements is used. When the amorphous structure is made to have substantially 90% or more by the quenching method, the recovery rate of the amorphous ribbon is remarkably improved because a specific amount of Ni is contained, and the obtained flakes and ribbons have a temperature of 500 ° C. or higher to 1 After the temperature is raised at a temperature rising rate of -15 ° C / min, a heat treatment is performed at 550 to 700 ° C for 30 seconds to 6 hours to obtain an average crystal grain size of 0.01 to 0.
It becomes a fine crystal aggregate of 1 μm, and in addition to the Fe ₃ B type compound phase of the main phase, the amount ratio of the ferromagnetic phase having the Nd ₂ Fe ₁₄ B type crystal structure phase increases, the α-Fe phase decreases, and A
By containing g, Al, Si, Cu, or Ga, iHc does not decrease even when Ni is contained, and further, the squareness of the demagnetization curve is improved, so that iHc ≧ 3 kOe,
Magnetic properties of Br ≧ 8 kG and (BH) max ≧ 8 MGOe are obtained, and further crushed to form a magnetic alloy powder, iHc ≧ 2 kOe, Br ≧ 7 kG, (B
H) magnetic properties of max ≧ 8 MGOe are obtained, and Fe is most suitable for a bond magnet having a residual magnetic flux density Br of 5 kG or more.
-Ni-B-R system or Fe-Ni-B-R-M system magnet alloy powder can be obtained, and by making it a sintered magnet, magnetic properties equivalent to or better than those of conventional Alnico system magnets can be obtained. it can.

[0028]

【Example】

Example 1 No. 1 in Table 1 Purity 99.5 so that the composition becomes 1 to 7.
% Or more of Fe, Ni, B, Nd, Pr, Ag, Al, S
Metals of i, Cu, and Ga 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 melted by high frequency heating in an Ar atmosphere with a pressure of 56 cmHg. , Melting temperature 1400
C., the molten metal surface is pressurized with Ar gas, and the molten metal is ejected from a height of 0.7 mm onto the outer peripheral surface of a Cu roll that rotates at a high speed at a roll peripheral speed of 20 m / sec at room temperature to give a width of 2
An ultra-quenched ribbon having a thickness of 3 mm and a thickness of 30 to 40 μm was produced. The obtained ultra-quenched ribbon was confirmed to be amorphous by the characteristic X-ray of CuKα.

After rapidly heating the ultra-quenched ribbon in Ar gas to 500 ° C., the temperature was raised to 500 ° C. or higher at the heating rate shown in Table 1 and kept at the heat treatment temperature shown in Table 1 for 10 minutes. Cool to room temperature, take out the ribbon, width 2-3 mm,
A sample having a thickness of 30 to 40 μm and a length of 3 to 5 mm is prepared,
The magnetic properties were measured using VSM. The measurement results are shown in Table 2. The measurement result of the sample is a multiphase structure in which the main phase is the Fe ₃ B phase in which the tetragonal crystal and the orthorhombic crystal are mixed and the Nd ₂ Fe ₁₄ B phase and the α-Fe phase are mixed, and the average crystal grain size is Was 0.1 μm or less. Although Ni replaces a part of Fe in each of these phases, Ag, Al, Si, Ga, C
With respect to u, the addition amount was small, and since it was an ultrafine crystal, analysis was impossible.

Comparative Example No. 1 in Table 1 Purity 99.5 so that the composition is 8 to 10
% Of Fe, B and Nd were used to fabricate an ultra-quenched ribbon under the same conditions as in Example 1. 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. 8 to 10), and the magnetic characteristics were measured using VSM. The measurement results are shown in Table 2. Comparative Example No. 8 ~
The structure of No. 10 was similar to that of Example 1, but the crystal grains were coarser than those of Example 1.

Example 2 Composition No. of Table 1 obtained in Example 1 After the heat treatment of Table 1, the ultra-thin quenched ribbon No. 2 was crushed to an average particle size of 100 μm or less, and a binder made of an epoxy resin was mixed at a ratio of 2 wt%, and then a bonded magnet having a size of 12 mm × 12 mm × 8 mm was prepared. . The magnetic properties of the obtained bonded magnet are as follows: density 5.7 g / cm ³ , iHc = 3.5 kOe, B
r = 7.3 kG, (BH) max = 6 MGOe.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

INDUSTRIAL APPLICABILITY The present invention has a specific composition of Fe-Ni-B.
-R (Nd, Pr) alloy melt or Fe-Ni-B-
The R (Nd, Pr) -M alloy melt is formed into an amorphous structure by the ultra-quenching method, and by subjecting this to a heat treatment under specific conditions, a fine crystal aggregate having an average crystal grain size of 0.01 to 0.1 μm is formed. , Fe ₃ B type compound phase of the main phase, Nd ₂
By increasing the amount ratio of the Fe ₁₄ B type crystal structure phase and decreasing the α-Fe phase, a permanent magnet ribbon is formed, which is further pulverized into a magnetic alloy powder to obtain iHc ≧ 2.
Magnetic properties of kOe, Br ≧ 7 kG, (BH) max ≧ 8 MGOe are obtained, and an Fe—Ni—B—R system or Fe—Ni—B—R— which is optimum for a bond magnet having a residual magnetic flux density Br of 5 kG or more. It is possible to obtain an M-based magnet alloy powder, and it is possible to obtain magnetic characteristics equivalent to or better than those of a conventional alnico-based magnet by forming a sintered magnet. In addition, the present invention has a low content of rare earth elements, a simple manufacturing method, and is suitable for mass production, and therefore has a residual magnetic flux density Br of 5 kG or more and magnetic performance exceeding that of a hard ferrite magnet. By adopting integral molding of the magnetic component and the magnet body, the process can be shortened, and it is possible to provide a bond magnet that can realize a performance-to-cost ratio exceeding that of sintered hard ferrite.

Claims (6)

[Claims] The method according to claim 1] composition formula _{Fe 100-xyz Ni x B y} R z
(However, R is one or two of Pr or Nd)
Symbols x, y, z that limit the composition range satisfy the following values,
Fe ₃ B type compound as a main phase, a ferromagnetic phase having an Nd ₂ Fe ₁₄ B type crystal structure, and an average crystal grain size of 0.01 to
A rare earth magnet comprising a 0.1 μm fine crystal aggregate. 0.01 ≦ x ≦ 2 at% 16 ≦ y ≦ 22 at% 3 ≦ z ≦ 5.5 at% 2. A method composition formula _{Fe 100-xyz Ni x B y} R z M
_w (wherein R is one or two of Pr or Nd, M is one or two or more of Ag, Al, Si, Cu or Ga), and the symbols x, y, z, w for limiting the composition range Satisfy the following values, Fe ₃ B type compound as the main phase, and Nd ₂ F
e ₁₄ A rare earth magnet having a ferromagnetic phase having a B-type crystal structure and comprising a fine crystal aggregate having an average crystal grain size of 0.01 to 0.1 μm. 0.01 ≦ x ≦ 2 at% 16 ≦ y ≦ 22 at% 3 ≦ z ≦ 5.5 at% 0.1 ≦ w ≦ 3 at% The 3. A composition formula _{Fe 100-xyz Ni x B y} R z
(However, R is one or two of Pr or Nd)
Symbols x, y, z that limit the composition range satisfy the following values,
Fe ₃ B type compound as a main phase, a ferromagnetic phase having an Nd ₂ Fe ₁₄ B type crystal structure, and an average crystal grain size of 0.01 to
It is composed of 0.1 μm fine crystal aggregates and has an average particle size of 3 to
500 μm, magnetic characteristics iHc ≧ 2 kOe, Br ≧ 7 k
G, (BH) max ≧ 8 MGOe, a rare earth magnet alloy powder. 0.01 ≦ x ≦ 2 at% 16 ≦ y ≦ 22 at% 3 ≦ z ≦ 5.5 at% The 4. A composition formula _{Fe 100-xyz Ni x B y} R z M
_w (wherein R is one or two of Pr or Nd, M is one or two or more of Ag, Al, Si, Cu or Ga), and the symbols x, y, z, w for limiting the composition range Satisfy the following values, Fe ₃ B type compound as the main phase, and Nd ₂ F
e ₁₄ has a ferromagnetic phase having a B-type crystal structure, and is composed of a fine crystal aggregate having an average crystal grain size of 0.01 to 0.1 μm,
Average particle size is 3 to 500 μm, magnetic property is iHc ≧ 3 kO
e, Br ≧ 8 kG, (BH) max ≧ 8 MGOe, a rare earth magnet alloy powder. 0.01 ≦ x ≦ 2 at% 16 ≦ y ≦ 22 at% 3 ≦ z ≦ 5.5 at% 0.1 ≦ w ≦ 3 at% 5. A composition formula _{Fe 100-xyz Ni x B y} R z
(However, R is one or two of Pr or Nd)
A molten alloy having the symbols x, y, and z that limit the composition range satisfying the following values is formed into an amorphous structure by substantially 90% or more by a superquenching method, and the rate of temperature rise from 500 ° C. is 1 to 1 during heat treatment. A heat treatment of heating at 15 ° C./min and holding at 550 to 700 ° C. for 30 seconds to 6 hours is performed to have a Fe ₃ B type compound as a main phase and a ferromagnetic phase having an Nd ₂ Fe ₁₄ B type crystal structure. Then, a fine crystal aggregate having an average crystal grain size of 0.01 to 0.1 μm is obtained and then pulverized to obtain a magnet alloy powder, which is a method for producing a rare earth magnet alloy powder. 0.01 ≦ x ≦ 2 at% 16 ≦ y ≦ 22 at% 3 ≦ z ≦ 5.5 at% 6. A composition formula _{Fe 100-xyz Ni x B y} R z M
_w (wherein R is one or two of Pr or Nd, M is one or two or more of Ag, Al, Si, Cu or Ga), and the symbols x, y, z, w for limiting the composition range Is 90% by the ultra-quenching method.
% Or more has an amorphous structure, and the temperature is raised from 500 ° C. at a heating rate of 1 to 15 ° C./min during heat treatment to 5
A heat treatment of holding at 50 to 700 ° C. for 30 seconds to 6 hours is performed to have a ferromagnetic phase having an Fe ₃ B type compound as a main phase and an Nd ₂ Fe ₁₄ B type crystal structure and an average crystal grain size of 0. 01
A method for producing a rare earth magnet alloy powder, which comprises obtaining a fine crystal aggregate of ˜0.1 μm and then pulverizing the fine crystal aggregate to obtain a magnet alloy powder. 0.01 ≦ x ≦ 2 at% 16 ≦ y ≦ 22 at% 3 ≦ z ≦ 5.5 at% 0.1 ≦ w ≦ 3 at%