JPH05345947A - Anisotropic rare earth alloy powder for permanent magnet and its production - Google Patents

Abstract

PURPOSE:To obtain an alloy powder improved in magnetic anisotropy, increased in residual magnetic flux density at the time of being formed into magnet, and having superior magnetic properties by specifying the composition of a rare earth alloy for permanent magnet and replacing a part of B by C. CONSTITUTION:An alloy powder having a composition containing, by atom, 10-20% R (where R means rare earth elements and containing >=50% Pr and/or Nd), 67-85% T (where T means Fe or a part of Fe is replaced by <=50% Co), and B by the amount in the range where C content satisfies (B+C=4 to 10%) and C/(B+C) becomes 0.01-0.8 is prepared. This raw material powder is heated and held at 500-900 deg.C for 15min-8hr in an H2 gas of 10-1000KPa. The powder is further held at 500-900 deg.C for 15min-8hr at <=10Pa partial pressure of H, to undergo dehydrogenation, followed by cooling. By this method, the alloy powder where >=70vol.% of alloy powder has tetragonal Nd2Fe14B type crystalline structure and >= at least 50vol.% of crystals have 0.05-1mum grain size and which has 10-1000mum average grain size and 0.9-1.6T residual magnetic flux density in a direction of easy magnetization can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to R (rare earth element) -T (iron group element) -M (additive element) -which has a high coercive force and can be used in various motors and actuators.
B-C system for bonded magnets and relates to a permanent magnet alloy powder and its manufacturing method for a sintered magnet, in particular the present system coarsely pulverized powder H ₂
An RT-T having a high magnetic anisotropy and a high coercive force, which is obtained by performing heat treatment in a gas and H ₂ treatment for heating and holding in a predetermined atmosphere to obtain ultrafine crystal grains of 1 μm or less.
-MBC system alloy powder for permanent magnets and a method for producing the same.

[0002]

2. Description of the Related Art A method for producing a rare earth alloy powder for permanent magnets by a hydrogen treatment method is disclosed, for example, in Japanese Patent Application Laid-Open No. 1-132106. The hydrogen treatment method is RT-
The MB raw material alloy ingot or powder is kept at a temperature of 500 ° C. to 1000 ° C. in a H ₂ gas atmosphere or a mixed atmosphere of H ₂ gas and an inert gas to cause H ₂ to be occluded in the alloy ingot or powder. And then H ₂ gas pressure 13 Pa
(1 × 10 ^-1 Torr) until the following vacuum atmosphere or H ₂ gas partial pressure 13 Pa (1 × 10 ^-1 Torr) or less inert gas atmosphere, de-H at a temperature 500 ° C. to 1000 ° C.
₂ treatment, followed by cooling, RT-
This is a method for producing an M-B alloy powder.

[0003]

The R-T-M-B type alloy powder produced by the above method has large coercive force and magnetic anisotropy. This treatment results in a structure having a very fine recrystallized grain size, substantially having an average recrystallized grain size of 0.1 to 1 μm, and magnetically tetragonal Nd ₂ Fe ₁₄ B.
This is because the crystal grain size is close to the single domain critical grain size of the system compound, and these ultrafine crystals are recrystallized with their crystal orientations aligned to some extent.

However, the RT- manufactured by the above method
The magnetic properties of the alloy powder for MB-based magnets are particularly insufficient with respect to magnetic anisotropy, and the magnetic anisotropy inherent in the raw material alloy itself has not been reached, and the magnetic properties remain. There is a drawback that the magnetic flux density Br is small.

According to the present invention, the residual magnetic flux density B when magnetizing the R-T-M-B type alloy powder by improving the magnetic anisotropy
An object of the present invention is to provide an R-T-M-B based alloy powder capable of providing an R-T-M-B based permanent magnet having a high r and excellent magnetic characteristics, and a method for producing the same.

[0006]

In order to increase the residual magnetic flux density Br in the present invention, the raw material composition was examined, and as a result, a substitution element and an addition element capable of obtaining a large magnetic anisotropy were found. Is. That is, it was found that a large magnetic anisotropy can be stably obtained by substituting a part of B with C. Furthermore, Al, N
i, Ga, Zr, In, Sn. Hf, Ti, V, Nb,
It was found that adding one or more of Mo, Ta and W improves and improves the magnetic properties. Furthermore, by limiting the composition range of such a component system, setting the hydrogen pressure in the hydrogen treatment method to 10 kPa or higher and the hydrogen pressure in the dehydrogenation step to 10 Pa or lower, a powder having stable magnetic anisotropy can be produced. It was found that this anisotropic powder can be used as a raw material for a bonded magnet in which a binder is combined, and the present invention has been completed.

That is, the present invention provides R: 10 to 20 atomic% (R; at least 1 of rare earth elements).
And one or two of Pr or Nd is 5 out of R
0 atom% or more), T: 67 to 85 atom% (T: Fe or 1 part of Fe is 5
Substituted by Co of 0 atomic% or less), and the amount of B and C is B + C
= 4 to 10 atomic% C / (B + C) = 0.01 to 0.8
Which is a compound having a tetragonal Nd ₂ Fe ₁₄ B type crystal structure, and 70% by volume or more of the alloy powder is a crystal grain of at least 50% by volume of the compound. A permanent magnet alloy having a diameter of 0.05 to 1 μm, an average particle diameter of 10 to 1000 μm, and an alloy powder having a residual magnetic flux density in the easy magnetization direction of 0.9 to 1.6 T. It is a rare earth alloy powder.

The present invention also provides R: 10 to 20 atomic% (R: at least 1 of rare earth element).
And one or two of Pr or Nd is 5 out of R
0 atom% or more), T: 67 to 85 atom% (T: Fe or 1 part of Fe is 5
Substituted with 0 atomic% or less of Co), M; 10 atomic% or less (M; Al, Ti, V, Cr, N)
i, Ga, Zr, Nb, Mo, In, Sn, Hf, T
a, W, one or more, and the amounts of B and C are B
+ C = 4 to 10 atom% C / (B + C) = 0.01 to
Consisting of alloy powder having a composition satisfying 0.8,
70% by volume or more of the alloy powder is a compound having a tetragonal Nd ₂ Fe ₁₄ B type crystal structure, and at least 50% by volume of the compound has a crystal grain size of 0.05 to 1 μm.
And an anisotropic rare earth alloy powder for permanent magnets, wherein the average particle diameter is 10 to 1000 μm and the residual magnetic flux density in the easy magnetization direction is 0.9 to 1.6 T. ..

The present invention also provides: 1) R: 10 to 20 atomic% (R: at least one rare earth element and one or two Pr or Nd contained in 50 or more atomic% of R), T : 67 to 85 atomic% (T: Fe or 1 part of Fe is 5
Substituted by Co of 0 atomic% or less), and the amount of B and C is B + C
= 4 to 10 atomic% C / (B + C) = 0.01 to 0.8
After roughly crushing an alloy ingot having a composition having a value satisfying 2), 2) using the roughly crushed powder as a raw material powder, 10 kPa to 1
15 at 500 to 900 ° C. in H ₂ gas of 000 kPa
Hold by heating for min to 8 hours, and 3) 500 to 900 at H ₂ partial pressure of 10 Pa or less.
After dehydrogenating H ₂ for 15 minutes to 8 hours, cooling is performed, and 4) 70% by volume or more of the alloy powder is tetragonal Nd ₂ Fe.
₁₄ A compound having a B-type crystal structure, and the crystal grain size of at least 50% by volume of the compound is 0.05 to
An anisotropic rare earth alloy powder for permanent magnets, characterized in that it has an average particle size of 10 to 1000 μm and a residual magnetic flux density in the easy magnetization direction of 0.9 to 1.6 T. It is a manufacturing method.

The present invention also provides: 1) R: 10 to 20 atomic% (R; at least one rare earth element and one or two Pr or Nd contained in 50 or more atomic% of R), T : 67-85 atom%
(T: Fe or a part of Fe is replaced by 50 atomic% or less of Co), M; 10 atomic% or less (M; Al, Ti, V,
Cr, Ni, Ga, Zr, Nb, Mo, In, Sn, H
f, Ta, W, one or more, and the amount of B and C is B + C = 4 to 10 atom% C / (B + C) = 0.0
After roughly crushing an alloy ingot having a composition having a value satisfying 1 to 0.8, 2) 10 kPa to 1 using the coarsely crushed powder as a raw material powder
15 at 500 to 900 ° C. in H ₂ gas of 000 kPa
Hold by heating for min to 8 hours, and 3) 500 to 900 at H ₂ partial pressure of 10 Pa or less.
After dehydrogenating H ₂ for 15 minutes to 8 hours, cooling is performed, and 4) 70% by volume or more of the alloy powder is tetragonal Nd ₂ Fe.
₁₄ A compound having a B-type crystal structure, and the crystal grain size of at least 50% by volume of the compound is 0.05 to
An anisotropic rare earth alloy powder for permanent magnets, characterized in that it has an average particle size of 10 to 1000 μm and a residual magnetic flux density in the easy magnetization direction of 0.9 to 1.6 T. It is a manufacturing method.

Reasons for limiting the composition R used in the raw material alloy used in the present invention, that is, the rare earth elements are Y, La, Ce, Pr, Nd, Sm, Gd,
Tb, Dy, Ho, Er, Tm, Lu are included, and at least one of them is contained and at least one or two of Pr and Nd are contained in 50 at% or more of R.
Further, all of R may be one or two of Pr and Nd. The reason why 50 atomic% or more of R is at least one of Pr and Nd is that sufficient magnetization cannot be obtained if the atomic ratio is less than 50 atomic%.

When R is less than 10 atomic%, the coercive force is lowered due to precipitation of αFe phase, and when it exceeds 20 atomic%, in addition to the intended tetragonal Nd ₂ Fe ₁₄ B type compound, R-rich second A large amount of phases precipitate, and an excessive amount of this second phase lowers the magnetization of the alloy. Therefore, the range of R is 10 to 20 atomic%.

T is an iron group element, and Fe or a part of Fe can be replaced by 50% or less of Co. When T is less than 67 atomic%, the second coercive force and low magnetization precipitates and the magnetic properties are deteriorated. When it exceeds 85 atomic%, coercive force and squareness are deteriorated due to the precipitation of αFe phase. , 67 to 85 atom%. Further, addition of 50% or less of Co is effective in improving the Curie temperature, but when Fe is less than 50% in the atomic ratio of Fe and Co, the amount of decrease in the saturation magnetization of the Nd ₂ Fe ₁₄ B type compound itself is large. Because it will be T
Of these, the atomic ratio of Fe was 50% or more.

Of M, Al, Ni, Ga, Zr, I
n, Sn, and Hf have a recrystallized grain content of 0.05 when de-H ₂ treatment is applied.
It is an element effective for imparting magnetic anisotropy to the powder by growing it to a size of up to 1 μm, and is necessary for obtaining stable magnetic anisotropy even when C is added. Ti, V, Nb,
Mo, Ta, and W have a recrystallized grain size of 1 μm during de-H ₂ treatment.
As described above, it has an effect of preventing the coarsening, and as a result, suppressing a decrease in the coercive force. Therefore, although it may not be added as M at all, it is a good idea to use the above elements in combination according to the purpose. Addition amount is 10 atom%
If M exceeds, the second phase that is not ferromagnetic precipitates and the magnetization decreases, so M is preferably 10 atomic% or less.

B is essential for stable precipitation of a tetragonal Nd ₂ Fe ₁₄ B type crystal structure, but part of it can be replaced with C described later. The addition amount is
When the sum of B and C is 4 atomic% or less, the R ₂ T ₁₇ phase precipitates to lower the coercive force, and the squareness of the demagnetization curve is significantly impaired. Further, when added in excess of 10 atomic%, the second phase having small magnetization precipitates and reduces the magnetization of the powder, so the sum of B and C was set to 4 to 10 atomic%. Also, C /
The reason for limiting (B + C) = 0.01 to 0.8 is 0.
If it is less than 01, there is no effect of improving the magnetic anisotropy of the alloy powder after hydrogen treatment, and if it exceeds 0.8, R carbides are easily generated, and the Th ₂ Zn ₁₇ type structure is stabilized in the high temperature region. There is a risk that the amount of αFe precipitation will increase, the tetragonal ratio in the ingot will decrease, and not only the residual magnetic flux density will decrease, but the coercive force of the alloy powder after hydrogen treatment will also decrease significantly, which is not desirable. , C / (B + C) is preferably 0.
It is 1 to 0.5.

Reason for Limitation of Alloy Powder Structure In the present invention, if the abundance ratio of the tetragonal Nd ₂ Fe ₁₄ B type compound is less than 70 vol%, the magnetic properties, especially the residual magnetic flux density are lowered. More specifically, the coercive force is reduced when the mixed second phase is the αFe phase, and the magnetization is reduced when the mixed second phase is the R-rich phase or the B-rich phase. Therefore, the abundance ratio of the tetragonal Nd ₂ Fe ₁₄ B type compound is set to 70 vol% or more. In order to obtain a coarsely pulverized powder having a tetragonal Nd ₂ Fe ₁₄ B type compound in a volume ratio of 70% or more, it is preferable to anneal at a temperature of 800 ° C. to 1200 ° C. for 1 hour or more at the stage of alloy ingot, or Means such as controlling the cooling rate of the mold in the ingot making process may be appropriately selected. The abundance ratio of tetragonal crystals in this ingot is maintained almost as it is after the hydrogen treatment.

In the present invention, tetragonal Nd ₂ Fe ₁₄ B
High coercive force can be obtained with a crystal grain size of 1 μm or less, but even if there are crystal compounds with a crystal grain size of 1 μm or more, if the crystal grains of 1 μm or less are present in a volume ratio of 50% or more, as a whole, High coercive force can be maintained. Also, 0.0
Crystals having a size of 5 μm or less are practically difficult to manufacture, and even if they are obtained, there are no particularly excellent magnetic properties. Therefore, the crystal grain size of the Nd ₂ Fe ₁₄ B-type compound, which is the main phase, is 0.05 to 1 μm when the volume ratio is 50% or more.
It is preferable that the crystals are occupied. More preferably, crystals of 0.1 to 0.5 μm occupy 80% or more by volume.

Reason for Limitation of Residual Magnetic Flux Density The alloy powder for permanent magnets according to the present invention is characterized by having a magnetically high anisotropy. The saturation magnetization of the Nd ₂ Fe ₁₄ B type compound, which is the main phase of this alloy powder, is 1.6 T, and the residual magnetic flux density of the alloy powder cannot exceed 1.6 T. On the other hand, if the residual magnetic flux density is less than 0.9T, theoretically, there is no superior magnetic property to the rare earth alloy powder for isotropic permanent magnets that can obtain a residual magnetic flux density of 0.8T. It has no practical meaning. Therefore, the value of the residual magnetic flux density is set to 0.9 to 1.6T.

Reasons for Limiting Manufacturing Conditions The hydrogen treatment method is characterized in that a coarsely pulverized powder having a required particle size does not change its size in appearance and an aggregate having an ultrafine crystal structure can be obtained. That is, tetragonal Nd ₂ Fe ₁₄
When a B-type compound is reacted with H ₂ gas at a high temperature, R
After phase separation into H _{2 ■ 3} , αFe, Fe ₂ B, etc., and further removing H ₂ gas by de-H ₂ treatment, tetragonal Nd ₂ Fe
_{14 A} recrystallized structure of the B-type compound is obtained.

As the coarse pulverization method of the starting material, a so-called hydrogen pulverization method by H ₂ occlusion may be used in addition to the conventional mechanical pulverization method or gas atomization method. To simplify the process, the coarse pulverization method by the hydrogen pulverization is used. The crushing step and the hydrogen treatment method for obtaining ultrafine crystals may be continuously performed in the same apparatus. The average particle size of the obtained coarsely pulverized powder is 50 to 1000 μm.
Is preferred.

[0021] In this invention, when heating with H ₂ gas, H in ₂ gas pressure is less than 10 kPa, it does not proceed sufficiently that the above decomposition reaction, also processing facility becomes too large and exceeds 1000 kPa, industrial Since it is not preferable in terms of cost and safety, the pressure range is 10 kPa to 10 kPa.
It was set to 00 kPa. More preferably 50 kPa to 15
It is 0 kPa.

The heat treatment temperature in H ₂ gas is 500 ° C.
If the temperature is less than 1, the decomposition reaction into RH _{2 ■ 3} , αFe, Fe ₂ B, etc. does not occur, and if the temperature exceeds 900 ° C., the RH _{2 ■ 3} becomes unstable, and the product grows grains to form tetragonal Nd ₂ Fe _14. B
Since it becomes difficult to obtain an ultrafine crystal structure of the type compound, the temperature range is set to 500 ° C to 900 ° C. Regarding the heat treatment holding time, it is necessary to hold the heating treatment for 15 minutes to 8 hours in order to sufficiently carry out the above decomposition reaction.

The H ₂ partial pressure during de H ₂ treatment of the present invention, 10
If it exceeds Pa, the decomposition condition of the RH _{2 3} phase will not be reached in the following temperature range, that is, 900 ° C or lower, or a practical de-H ₂ rate will be obtained even if the decomposition condition is reached in equilibrium theory. Therefore, the partial pressure of H ₂ at the time of removing H ₂ was set to 10 Pa or less.

In the present invention, the temperature for the H ₂ removal treatment is 5
If the temperature is lower than 00 ° C., H ₂ is not released from the RH _{2 3} phase, so that the tetragonal Nd ₂ Fe ₁₄ B type compound is not recrystallized. Further, when the temperature exceeds 900 ° C., tetragonal Nd ₂ Fe ₁₄ B
Although a type compound is produced, recrystallized grains grow coarsely and a high coercive force cannot be obtained. Therefore, the temperature range of the H ₂ removal treatment is 500 ° C. to 900 ° C. The heat treatment holding time is required to be 15 minutes to 8 hours in order to sufficiently carry out the recrystallization reaction.

The recrystallized grain size of the de H ₂ treatment tetragonal Nd ₂ Fe ₁₄ B type compound after is substantially difficult to obtain an average recrystallized grain size of less 0.05 .mu.m, also obtained if Even if it does, there is no advantage in magnetic characteristics. On the other hand, if the average recrystallized grain size exceeds 1 μm, the coercive force of the powder decreases, which is not preferable. Therefore, the average recrystallized grain size is 0.05 to
1 μm.

[0026]

In the present invention, by substituting C for a part of B in the RTB permanent magnet powder, a large magnetic anisotropy can be stably obtained and the residual magnetic flux density Br can be increased. And further, Al, Ni, Ga, Zr, I
n, Sn. Hf, Ti, V, Nb, Mo, Ta, W 1
It is possible to improve and improve the magnetic characteristics by adding one kind or two or more kinds. Furthermore, R in a specific composition range
By using the -T-M-B-C based alloy coarsely pulverized powder, the hydrogen pressure in the hydrogen treatment method is set to 10 kPa or more and the hydrogen pressure in the dehydrogenation step is set to 10 Pa or less, so that the average crystal grain size is 0.05. Magnetic particles having a large magnetic anisotropy and high coercive force, which are composed of recrystallized grains of ˜1 μm, can be stably obtained.

[0027]

【Example】

Example 1 No. 1 shown in Table 1 obtained by melting by a high frequency induction melting method. The ingots having the compositions of 1 to 17 were annealed at 1100 ° C. for 24 hours in a vacuum of 10 Pa or less so that the volume ratio of the tetragonal Nd ₂ Fe ₁₄ B type compound in the ingot was 90% or more.
This ingot was placed in an Ar gas atmosphere (O ₂ amount of 0.5% or less).
After roughly pulverizing with a stamp mill to an average particle size of 100 μm, this coarsely pulverized powder was put into a tubular furnace and evacuated to 1 Pa or less. Then, the purity of 99.9999% or more 10
While introducing 0 kPa of H ₂ gas, the raw material temperature was kept at 800 ° C. for 2 hours. Subsequently, while keeping the raw material at 800 ° C., the supply of H ₂ gas was stopped, the inside of the furnace was evacuated by a rotary pump and an oil diffusion pump, and it was kept for 1 hour.
The pressure inside the raw material processing chamber at this time is finally 0.05 Pa.
Fell to. After that, Ar gas having a purity of 99.999% or more was introduced into the furnace, and the raw material was cooled to a raw material temperature of 5
The raw material was taken out when the temperature became 0 ° C or lower. The obtained powder for magnets according to the present invention has a crystal grain size of 0.05 to
The volume ratio of 1 μm is 80% to 95%,
The average particle size is in the range of 0.3 μm to 0.5 μm, and the coercive force HcJ, the magnetization I, and the residual magnetic flux density Br in the easy magnetization direction are measured and shown in Table 1. The value of magnetization is the value when the external magnetic field is 0.8 MA / m, and the orientation was measured in the magnetic field.

Comparative Example No. 1 shown in Table 1 The coarsely pulverized powders having the six compositions of 18 to 23 were treated in the same manner as in the example to obtain alloy powder for permanent magnet by hydrogen treatment. The coercive force HcJ, magnetization I, and residual magnetic flux density Br of the obtained magnet powder according to the comparative example were measured and shown in Table 1.

Example 2 A basic composition was Nd _12.5 Fe _70.0 Co _11.0 Ga _0.5 B _6.0, and an ingot (Nd _12.5 F) in which a part of B was replaced with various C amounts was used.
to produce _{e 70.0 Co 11.0 Ga 0.5 B 6.0} -x C x), then subjected to the same treatment as in Example 1 to obtain an alloy powder for permanent magnets according to hydrotreating. The magnetic characteristics of this powder are expressed as C substitution amount x
Is shown in FIG.

[0030]

[Table 1]

[0031]

According to the composition of the present invention, R-T-M-B-
C-based permanent magnet powder has a specific composition range of R-T-M-B.
-C-based coarsely pulverized powder is heat-treated at a hydrogen pressure of 10 kPa or more in a high-purity H ₂ gas released from, for example, a hydrogen storage alloy, and de-H ₂ treatment is performed by heating and holding the hydrogen pressure at a predetermined atmosphere of 10 Pa or less. By performing the above, it is possible to obtain a magnetic alloy powder having a large magnetic anisotropy and a high coercive force, which is composed of recrystallized grains having an average crystal grain size of 0.05 to 1 μm. Can be manufactured.

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[Procedure amendment]

[Submission date] February 25, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief explanation of the drawing

[Correction method] Added

[Correction content]

[Brief description of drawings]

FIG. 1 is a graph showing the relationship among C substitution amount, coercive force, magnetization I, and residual density.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C22C 38/00 303 D H01F 1/053 1/06

Claims (4)

[Claims] 1. R: 10 to 20 atomic% (R; at least one rare earth element and one or two Pr or Nd).
Seed content of R is 50 atomic% or more), T: 67 to 85 atomic% (T: Fe or a part of Fe is 50 atomic% or less of C).
the amount of B and C is B + C = 4 to 10 atom%.
C / (B + C) = consisting of an alloy powder having a composition satisfying a value of 0.01 to 0.8, 70 vol% of the alloy powder
The above is a compound having a tetragonal Nd ₂ Fe ₁₄ B type crystal structure, and at least 50% or more by volume of the compound has a crystal grain size of 0.05 to 1 μm and an average grain size of 10 to 1.
An anisotropic rare earth alloy powder for permanent magnets, which is made of an alloy powder having a residual magnetic flux density of 000 μm and a residual magnetic flux density in the easy magnetization direction of 0.9 to 1.6 T. 2. R: 10 to 20 atomic% (R: at least one rare earth element and one or two Pr or Nd).
Seed content of R is 50 atomic% or more), T: 67 to 85 atomic% (T: Fe or a part of Fe is 50 atomic% or less of C).
Substituted with o), M; 10 atomic% or less (M; Al, Ti,
V, Cr, Ni, Ga, Zr, Nb, Mo, In, S
one or more of n, Hf, Ta, W), B,
The amount of C is B + C = 4 to 10 atomic% C / (B + C) =
It is composed of an alloy powder having a composition satisfying a value of 0.01 to 0.8, and 70 vol% or more of the alloy powder is tetragonal Nd.
₂ Fe ₁₄ B-type crystal structure compound, and the crystal grain size of at least 50% by volume of the compound is 0.
It has an average particle size of 10 to 1000 μm and a residual magnetic flux density in the easy magnetization direction of 0.9 to 1.6.
An anisotropic rare earth alloy powder for permanent magnets, which is composed of an alloy powder having T. 3. R: 10 to 20 atomic% (R; at least one rare earth element and one or two Pr or Nd).
Seed content of R is 50 atomic% or more), T: 67 to 85 atomic% (T: Fe or a part of Fe is 50 atomic% or less of C).
the amount of B and C is B + C = 4 to 10 atom%.
After roughly crushing an alloy ingot having a composition having a value satisfying C / (B + C) = 0.01 to 0.8, the coarsely crushed powder is used as a raw material powder in H ₂ gas of 10 kPa to 1000 kPa at 500 ° C. After heating and holding at 900 ° C. for 15 minutes to 8 hours, and further performing de-H ₂ treatment of maintaining H ₂ partial pressure of 10 Pa or less at 500 ° C. to 900 ° C. for 15 minutes to 8 hours, and cooling, 70 vol of alloy powder is added. % Or more is a compound having a tetragonal Nd ₂ Fe ₁₄ B type crystal structure, and at least 50% or more by volume of the compound has a crystal grain size of 0.05 to 1 μm.
To obtain an alloy powder having an average particle size of 10 to 1000 μm and a residual magnetic flux density in the easy magnetization direction of 0.9 to 1.6 T, and manufacturing an anisotropic rare earth alloy powder for permanent magnets. Method. 4. R: 10 to 20 atomic% (R; at least one rare earth element and one or two Pr or Nd).
Seed content of R is 50 atomic% or more), T: 67 to 85 atomic% (T: Fe or a part of Fe is 50 atomic% or less of C).
Substituted with o), M; 10 atomic% or less (M; Al, Ti,
V, Cr, Ni, Ga, Zr, Nb, Mo, In, S
one or more of n, Hf, Ta, W), B,
The amount of C is B + C = 4 to 10 atomic% C / (B + C) =
After roughly crushing an alloy ingot having a composition having a value satisfying 0.01 to 0.8, the coarsely crushed powder is used as a raw material powder for 10 k
500 ° C. to 900 in H ₂ gas of Pa to 1000 kPa
Heat and hold at 15 ℃ for 8 minutes, then H ₂ partial pressure 10Pa
The following treatment is carried out at 500 ° C. to 900 ° C. for 15 minutes to 8 hours to remove H ₂ and then cooled to 70 vo of the alloy powder.
1% or more is a compound having a tetragonal Nd ₂ Fe ₁₄ B type crystal structure, and at least 50% by volume of the compound
The above crystal grain size is 0.05 to 1 μm, and the average grain size is 10
A method for producing anisotropic rare earth alloy powders for permanent magnets, characterized in that an alloy powder having a residual magnetic flux density in the easy magnetization direction of 0.9 to 1.6 T is obtained.