JPH0776754A - Production of anisotropy rare earth alloy powder for peamanent magnet - Google Patents

Abstract

PURPOSE:To provide a producing method capable of obtaining R-T-(M)-B series anisotropy rare earth alloy powder for a permanent magnet in which magnetic anisotropy characteristic of the raw material alloy is completely attained, constituted of extrafine crystals and showing high coercive force with high mass- productivity regardless of the amt. to be treated. CONSTITUTION:The temp. of the coarsely crushed powder of an R-T-(M)-B alloy is raised to the 9 range of >=750 deg.C at 10 to 200 deg.C/min temp. rising rate in an atmosphere of gaseous hydrogen, and furthermore, heat treatment is executed at 750 to 900 deg.C in hydrogen, by which an R2T14B phase as the nucleus deciding the crystal orientation at the thime of recrystallization can be left by a suitable amt. Successively, it is subjected to dehydrogenation heat treatment at 700 to 900 deg.C in an evacuated air flow under 100Pa to 50kPa absolute pressure by gaseous Ar or He and is cooled, by which the R-T-(M)-B series rare earth alloy powder for a permanent magnet simultaneously having high coercive force and high magnetic anisotropy can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an R (rare earth element) -T (iron group element)-(M) -B type bond magnet having a high coercive force which can be used in various motors, actuators and the like. According to the method for producing anisotropic permanent magnet powder for a sintered magnet, the coarsely pulverized powder of this system is heated at a specific heating rate to generate H ₂
Heat treatment is performed in gas to form a four-phase mixed structure, and H ₂ treatment for heating and holding in a predetermined atmosphere is performed to make crystal grains 1
R-T- which has a high coercive force as an ultrafine crystal of μm or less
(M) -B relates to a method for producing an anisotropic rare earth alloy powder for a permanent magnet.

[0002]

2. Description of the Related Art A method for producing rare earth-based permanent magnet powder by a hydrogen treatment method is disclosed, for example, in JP-A-1-132106. That is, such a hydrogen treatment method means that an RT- (M) -B-based raw material alloy ingot or powder is heated to 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. after H ₂ occluded in ingot or powder of the alloy is held, the H ₂ gas pressure 13Pa (1 × 10 ^-1 Torr) or less of vacuum atmosphere or H ₂ gas partial pressure 13Pa (1 × 10 ^-1 Torr) or less Temperature of 500 ℃ to 100
By removing H ₂ treatment at 0 ° C. and then cooling, RT
-(M) -B is a method for producing a B-based alloy magnet powder.

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

Further, Japanese Patent Application Laid-Open No. 2-4901 discloses various heat patterns by a hydrogen treatment method, and it is also proposed to add an ingot homogenizing treatment. For example, the ingot is heated at 600 ° C. to 1200 ° C. And homogenize the alloy powder in H ₂ or in a mixed atmosphere of H ₂ and H ₂ and an inert gas at 500 ° C. to 1000 ° C. to occlude H ₂ and then degas it under vacuum at 500 ° C. to 1000 ° C. , A method of cooling is shown. Furthermore, JP-A-3-1466
As a method for reducing the characteristic fluctuation due to the temperature change during the hydrogen treatment, Japanese Patent Publication No. 08-008 proposes a method of performing the hydrogen treatment together with the heat storage material. That is, in the hydrotreating method,
A chemical reaction involving a large amount of heat of reaction occurs in the treatment process, and variations in magnetic characteristics occur due to temperature changes due to the heat of reaction. Therefore, it is intended to minimize the temperature change due to the reaction heat by using a heat storage material having a large heat capacity.

[0005]

However, the magnetic properties of the R-T- (M) -B magnet alloy powder produced by the above method are insufficient in terms of magnetic anisotropy in particular. The alloy itself does not reach the magnetic anisotropy inherently possessed, and the magnetic properties have a drawback that the residual magnetic flux density Br is small. This is because the easy magnetization direction of many crystal grains present in powder particles is not aligned in one specific direction,
As a result, the average residual magnetic flux density of the powder particles becomes small. In addition, there is a very important problem that magnetic properties, especially coercive force, change depending on the amount of raw material processed, which is not suitable for mass production. In the method of reducing the temperature change using the heat storage material described above, there is a new problem that, in practice, a large facility is required for the amount of raw material to be processed and a large amount of heat capacity requires a lot of time and energy for heating and cooling. Occurs.
Moreover, the cause of the fluctuations in the magnetic properties, especially the coercive force, due to the hydrogen treatment method is not simply the temperature rise due to the exothermic reaction during hydrogenation or the temperature decrease due to the endothermic reaction during dehydrogenation, so even if a heat storage material is used, the coercive force The problems of variation and deterioration cannot be solved.

These problems are caused by, for example, Japanese Patent Laid-Open No. 2-49.
First, in JP-A No. 01-101, although it is pointed out that the magnetic powder obtained by the hydrogen treatment method has a recrystallized texture, a prestructure that has a decisive influence on the recrystallized texture, that is, intermediate formation by heat treatment in hydrogen. This is because the metallographic structure of the product is not optimized, and secondly, the hydrogenation conditions for producing the optimum structure of the intermediate product are not limited.

As a result, according to the disclosed method, the intermediate product after hydrogen storage has a three-phase structure of RH, TB and T phases, which is dehydrogenated by evacuation. , The structure is substantially isotropic, and high magnetization cannot be obtained. In addition, the H ₂ pressure during the temperature rise of the H ₂ treatment is set to 1 atm,
The temperature is raised to 30 ° C. and H _{2 of 5} Torr to 850 Torr
After maintaining under pressure at 830 ° C. for 5 hours, 1 × 10 ⁻⁵ To
It is disclosed that a sample that is evacuated to rr and rapidly cooled in Ar is magnetically anisotropic. However, Br of the manufactured bonded magnet is 5.1 kG to 7.2 kG in a magnetic field molded product. , 6.3 kG to 9.0 when converted to 100% magnetic powder
It is kG (0.63T-0.90T). This value is the value when anisotropy is complete (about 1.2T to 1.5T)
Compared with, the anisotropy is not sufficiently high and the anisotropy cannot be said to be perfect.

The present invention completely achieves the magnetic anisotropy inherent in the raw material alloy itself in the method for producing the R-T- (M) -B system rare earth alloy powder for permanent magnets by the hydrogen treatment method. , R- that exhibits high coercive force with ultrafine crystals
An object of the present invention is to provide a manufacturing method capable of obtaining anisotropic rare earth alloy powders for T- (M) -B type permanent magnets with good mass productivity.

[0009]

In order to increase the residual magnetic flux density Br in the present invention, a metallographic examination of the raw material composition and the processing conditions was conducted, and as a result, a large anisotropy was obtained by devising the hydrogenation conditions. It has been found that sex can be obtained. That is, the inventors of the present invention have adopted the RT method by the hydrogen treatment
As a result of various metallographic examinations of raw material composition and processing conditions for the purpose of completely anisotroping the magnetic powder when obtaining the (M) -B rare earth alloy powder for permanent magnets, hydrogenation The resulting intermediate product contains the R ₂ T ₁₄ B phase,
The presence of R—H, T—B compound and T phase in addition to the above is an essential condition for obtaining high residual magnetization, and the condition for producing the intermediate product is specified at the time of hydrogenation. The present invention has been completed by finding that it is necessary to pass through the temperature range of 1. sufficiently quickly. Further, the hydrogen partial pressure during the dehydrogenation treatment can be gradually raised near the equilibrium hydrogen dissociation pressure without lowering the equilibrium hydrogen dissociation pressure of R hydride, for example, NdH ₂ at 850 ° C. less than 1 kPa. It was found that a high coercive force can be obtained regardless of the amount of raw material processed by optimizing the amount of nucleation and the growth rate of nuclei, and completed the present invention.

That is, according to the present invention, R: 10 to 20a
t% (R: at least one of rare earth elements including Y, and one or two of Pr or Nd of 50 at R
% Or more), T: 67 to 85 at% (T: Fe or a part of Fe is replaced with 50 at% or less of Co), B: 4 to
The alloy ingot of 10 at% is roughly crushed to have an average particle size of 5
At least 80 vol% of 0 to 5000 μm is made into a coarsely pulverized powder composed of a tetragonal crystal structure Nd ₂ Fe ₁₄ B type compound, and then 10 to 10
In H ₂ gas of 00 kPa, the temperature range of 600 ° C. to 750 ° C. or lower is raised at a heating rate of 10 ° C./min to 200 ° C./min, and further heated and held at 750 ° C. to 900 ° C. for 15 minutes to 8 hours. , Tissue R hydride, TB compound, T phase, R
After forming a mixed structure of at least four phases of ₂ T ₁₄ B compound,
Further, the absolute pressure of 100 Pa or more by Ar gas or He gas
A de-H ₂ treatment of maintaining at 700 ° C. to 900 ° C. for 5 minutes to 8 hours in a reduced pressure air flow of 50 kPa is performed, and then cooling is performed to obtain magnetic anisotropy with an average crystal grain size of 0.05 μm to 1 μm. A method for producing a rare earth alloy powder for a permanent magnet, characterized in that the obtained alloy powder is obtained.

The present invention is also characterized in that R: 10 to 20 at%.
(R: at least one rare earth element including Y, and P
One or two of r or Nd is contained in R at 50 at% or more), T: 67 to 85 at% (T: Fe or Fe
Is replaced with 50 at% or less of Co), M: 10 at
% Or less (M: Al, Ti, V, Cr, Ni, Ga, Z
1 of r, Nb, Mo, In, Sn, Hf, Ta, W
Or 2 or more), B: 4 to 10 at% of an alloy ingot is coarsely crushed, and at least 80 vol% or more having an average particle size of 50 μm to 5000 μm has a tetragonal structure Nd ₂ Fe ₁₄ B.
After forming a coarsely pulverized powder of a type compound, the coarsely pulverized powder is used as a raw material powder in a H ₂ gas of 10 to 1000 kPa and a temperature range of 600 ° C. to 750 ° C.
℃ / min ~ 200 ℃ / min or more to raise the temperature, 7
After heating and holding at 50 ° C. to 900 ° C. for 15 minutes to 8 hours to make the structure a mixed structure of at least four phases of R hydride, TB compound, T phase, and R ₂ T ₁₄ B compound, Ar gas or He gas which resulted in the removal of H ₂ by keeping 5 minutes to 8 hours 700 ° C. to 900 ° C. under vacuum in a stream of absolute pressure 100Pa~50kPa by, then the average crystal grain size cooled to 0.
A method for producing a rare earth alloy powder for a permanent magnet, characterized in that an alloy powder having a magnetic anisotropy of 05 μm to 1 μm is obtained.

Reason for limiting the composition R used in the raw material alloy used in the present invention, that is, the rare earth element, is Y, La, Ce, Pr, Nd, Sm, Gd, T.
b, Dy, Ho, Er, Tm, and Lu are included, at least one of which contains at least one or two of Pr and Nd in an amount of 50 at% or more of R, and all of R is Pr. , Nd may be one or two. The reason why 50 at% or more of R is at least one of Pr and Nd is that sufficient magnetization cannot be obtained at less than 50 at%. R is less than 10 at% α
When the coercive force decreases due to precipitation of the Fe phase, and when it exceeds 20 at%, a large amount of R-rich second phase is precipitated in addition to the target tetragonal Nd ₂ Fe ₁₄ B type compound, and this second phase is often contained. If too much, the magnetization of the alloy is reduced. Therefore, the range of R is 1
It is set to 0 to 20 at%.

T is an iron group element and includes Fe and Co. When T is less than 67 at%, it has a low coercive force and low magnetization.
The phase is precipitated to deteriorate the magnetic properties, and when it exceeds 85 at%, the coercive force and the squareness are deteriorated due to the precipitation of the αFe phase, so T is set to 67 to 85 at%. Further, even if only Fe is used, the necessary magnetic properties can be obtained, but addition of an appropriate amount of Co is useful for improving the Curie temperature, and Co can be added if necessary. Fe is 5 in atomic ratio of Fe and Co
When it is 0% or less, the amount of decrease in the saturation magnetization itself of the Nd ₂ Fe ₁₄ B type compound becomes large, so that Fe in the atomic ratio of T is set to 50% or more.

The effect of the additional element M is that the decomposition reaction of the mother phase is not completely completed during hydrogenation, and the mother phase, that is, R ₂ T ₁₄ B
An element effective in stabilizing the phase and intentionally remaining is desired. Ni, Ga, and
There are Zr and Hf. Also, of M, Al, Ni, G
a, Zr, In, Sn, and Hf are elements useful for growing recrystallized grains at the time of H ₂ removal treatment to a size of 0.1 μm to 1 μm and imparting magnetic anisotropy to the powder. Ti,
V, Cr, Nb, Mo, Ta, and W have the effect of preventing the recrystallized grains during the H ₂ removal treatment from coarsening to 1 μm or more, and consequently suppressing the decrease in coercive force. Therefore, it is advisable to use, as M, a combination of the above elements according to the purpose. The addition amount may not be added at all, but if it exceeds 10 at%, the second phase that is not ferromagnetic precipitates to lower the magnetization.
Was 10 at% or less.

B is essential for stable precipitation of a tetragonal Nd ₂ Fe ₁₄ B type crystal structure. If the addition amount is 4 at% 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 it is added in excess of 10 at%, the second phase having a small magnetization precipitates to reduce the magnetization of the powder. Therefore,
B was set to 4 to 10 at%.

In the present invention, 80 vol of coarsely crushed powder
% Or more is the tetragonal Nd ₂ Fe ₁₄ B type compound, the magnetic properties are deteriorated when the compound is less than 80 vol%. 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, so that the tetragonal Nd ₂ Fe ₁₄ B-type compound The abundance ratio was 80 vol% or more. In order to obtain a coarse pulverization having a tetragonal Nd ₂ Fe ₁₄ B type compound in a volume ratio of 80% or more, the alloy ingot is annealed at a temperature of 900 ° C. to 1200 ° C. for 1 hour or more, or in an ingot making process. It may be appropriately selected, for example, by controlling the cooling rate of the mold.

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 extremely fine crystal structure can be obtained. That is, tetragonal Nd ₂ Fe
₁₄ B-type compound, high temperature, practically 600 ℃ ~ 900
When reacted with H ₂ gas in the temperature range of ℃, RH _{2 ■ 3} , α
When phase separation into Fe, Fe ₂ B, etc. is carried out, and H ₂ gas is removed by de-H ₂ treatment in the same temperature range, tetragonal Nd ₂ Fe is again obtained.
_{14 A} recrystallized structure of the B-type compound is obtained. However,
In reality, the crystal grain size of the decomposition product and the degree of reaction differ depending on the hydrotreatment conditions, and the metallographic structure in the hydrogenated state is
The hydrogenation temperature is clearly different between less than 750 ° C and above 750 ° C. This difference in metal structure has a great influence on the magnetic properties of the magnetic powder after the dehydrogenation treatment. Further, the dehydrogenation treatment conditions greatly influence the recrystallized state of the tetragonal Nd ₂ Fe ₁₄ B type compound, and greatly affect the magnetic properties of the magnetic powder produced by the hydrogen treatment method, especially the coercive force.

The starting material may be coarsely pulverized by a conventional mechanical pulverization method or a gas atomization method, or a so-called hydrogen pulverization method by H ₂ occlusion may be used. The crushing step and the hydrogen treatment method for obtaining ultrafine crystals may be continuously performed in the same apparatus.

In the present invention, the average particle size of the coarsely crushed powder is limited to 50 μm to 5000 μm. If the average particle size is less than 50 μm, there is a risk of magnetic deterioration due to oxidation of the powder.
This is because if it exceeds 00 μm, it becomes difficult to give a large magnetic anisotropy by hydrogen treatment.

[0020] In this invention, when heating with H ₂ gas, H ₂ gas pressure not above the decomposition reaction proceed sufficiently at lower than 10 kPa, also exceeding 1000kPa and processing equipment too large, industrially The pressure range is 10 to 1000 kP because it is not preferable in terms of cost and safety.
a. More preferable pressure range is 50 to 150 kP
a.

The heat treatment temperature in H ₂ gas is 600 ° C.
If it is less than the above, the decomposition reaction into RH _{2 3} , αFe, Fe ₂ B, etc. does not occur. Further, in the temperature range of 600 ° C. to 750 ° C., the decomposition reaction proceeds almost completely, and an appropriate amount of R ₂ T ₁₄ B phase does not remain in the decomposition product. Sufficient anisotropy cannot be obtained. On the other hand, if the temperature exceeds 900 ° C., RH _{2 3} becomes unstable _, and the product grains grow to make it difficult to obtain a tetragonal Nd ₂ Fe ₁₄ B type compound ultrafine crystal structure. Hydrogenation temperature range is 7
In the range of 50 ° C. to 900 ° C., the R ₂ T ₁₄ B phase, which is the nucleus of the recrystallization reaction during dehydrogenation, disperses and remains in an appropriate amount, so the crystal orientation of the R ₂ T ₁₄ B phase after dehydrogenation Remains R ₂ T ₁₄ B
The crystal orientation of the recrystallized structure is determined by the phase, and as a result, the crystal orientation of the recrystallized structure coincides with the crystal orientation of the raw material ingot, and exhibits a large anisotropy at least within the range of the crystal grain size of the raw material ingot. Therefore, the temperature range of the hydrotreatment is 750 ° C to
It is set to 900 ° C. Regarding the holding time during the heat treatment, 15 minutes or more is required to sufficiently carry out the above decomposition reaction, and when it exceeds 8 hours, the residual R ₂ T ₁₄ B remains.
Since the phase is reduced, the anisotropy after dehydrogenation is lowered, which is not preferable. Therefore, the heating is kept for 15 minutes to 8 hours.

Maintaining the temperature rising rate in the H ₂ gas within a predetermined range is the most important step in the present invention. That is, the heating rate is 10 ° C./min. When the temperature is less than the above value, the decomposition reaction passes through the temperature range of 600 ° C. to 750 ° C. in the temperature rising process, so that the mother phase, that is, the R ₂ T ₁₄ B phase is not completely decomposed and dehydrogenated. Most of the magnetic and crystallographic anisotropy after the treatment is lost. In addition, when a large amount of treatment is performed, the reaction heat may be locally exceeded the optimum treatment temperature range, and thus a practical coercive force may not be obtained. Temperature rising rate is 10 ° C /
When it is set to min or more, the reaction does not proceed sufficiently in the range of 600 ° C to 750 ° C and the mother phase remains 750 ° C to 90 ° C.
Since the hydrogenation temperature range of 0 ° C. is reached, it is possible to obtain a powder having a large anisotropy in magnetic and crystal orientation after the dehydrogenation treatment. Further, the temperature rise due to the reaction heat during the decomposition reaction in the temperature range of 750 ° C. to 900 ° C. is small, and it is easy to obtain a practical coercive force even in the case of a large amount of treatment. Therefore, the rate of temperature increase needs to be 10 ° C./min or higher in the temperature range of 750 ° C. or lower. Further, a heating rate exceeding 200 ° C./min is not practically feasible even if an infrared heating furnace or the like is used, and even if it is possible, the equipment cost becomes excessive, which is not preferable. 10 ℃ / min ~ 2
00 ° C./min.

The H ₂ removal treatment of the present invention is performed by using Ar gas or H 2
It is carried out in a reduced pressure gas flow of e gas, and by this, the substantial H ₂ partial pressure around the raw material is changed to the equilibrium hydrogen dissociation pressure of R hydride,
For example, NdH ₂ has a temperature of about 1 kPa at 850 ° C., and the H ₂ removal reaction gradually proceeds. The atmosphere is Ar gas or He
Gas is limited to Ar gas because of its cost,
This is also because He gas can be used from the viewpoint of H ₂ gas substitution property and temperature control. Further, N ₂ gas, which is generally used as an inert gas, is unsuitable because it reacts with a rare earth compound to form a nitride, and other rare gases have no merit in performance and are disadvantageous in cost. . Removal of H _{2 of} this invention
If the absolute pressure of the atmosphere during the treatment is less than 10 Pa, the de-H ₂ reaction abruptly occurs, the temperature due to the chemical reaction greatly decreases, and the de-H ₂ reaction is too rapid, so that the structure of the magnetic powder after cooling is coarse. It is not preferable because the coercive force is greatly reduced due to the inclusion of crystal grains, and when the pressure exceeds 50 kPa, de-H
_{2 The} reaction takes too much time and becomes a problem in practice, so the absolute pressure is set within the range of 10 Pa to 50 kPa. Also, de-H ₂
The treatment is performed in a reduced pressure air flow in order to prevent the pressure inside the furnace from rising due to the H ₂ gas released from the raw material due to the H ₂ removal reaction. Practically, while introducing the inert gas from one side, the other side is evacuated by the vacuum pump, and the pressure control may be performed by using the flow rate adjusting valve attached to each of the supply port and the exhaust port.

In the present invention, the temperature for the H ₂ removal treatment is 7
If the temperature is lower than 00 ° C., H ₂ is not released from the RH _{2 3} phase or recrystallization of the tetragonal Nd ₂ Fe ₁₄ B type compound does not proceed sufficiently. Further, when the temperature exceeds 900 ° C., tetragonal Nd ₂ F
Although the e ₁₄ B 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 700 ° C. to 900 ° C.

Although the heat treatment holding time depends on the evacuation capacity of the treatment equipment, it is also important to sufficiently carry out the above recrystallization reaction, and it is necessary to hold the heat treatment for at least 5 minutes. If the crystal is coarsened by a general recrystallization reaction, the coercive force is lowered, so that the time is preferably as short as possible. Therefore, heating and holding for 5 minutes to 8 hours is sufficient. De H ₂ treatment, from the viewpoint of preventing oxidation of the raw materials, also in terms of thermal efficiency of the process equipment, but may be carried out following the hydrogenation process, after hydrogenation treatment, then once cooling the material, again again de A heat treatment for H ₂ may be performed.

The recrystallized grain size of the tetragonal Nd ₂ Fe ₁₄ B type compound after the de-H ₂ treatment is practically difficult to obtain, even if it is obtained. However, 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 from 0.05 μm to
It was 1 μm.

[0027]

According to the present invention, in the method for producing the R-T- (M) -B system rare earth alloy powder for permanent magnets by the hydrotreating method, the R-T- (M) -B-based rare earth alloy powder is passed through a specific temperature region sufficiently quickly during hydrogenation. By having a mixed structure of at least four phases of hydride, T-B compound, T phase, and R ₂ T ₁₄ B compound, the magnetic anisotropy inherent in the raw material alloy itself is completely achieved, and further Ar gas is used. Or absolute pressure 100 with He gas
RT- which shows high coercive force with ultrafine crystals by performing H ₂ removal treatment by heating and holding in a reduced pressure air flow of Pa to 50 kPa.
An anisotropic rare earth alloy powder for a (M) -B system permanent magnet can be obtained with good mass productivity regardless of the treatment amount.

[0028]

【Example】

Example 1 No. 1 shown in Table 1 obtained by melting by the high frequency induction melting method. The ingots having the compositions of 1 to 12 were annealed in an Ar atmosphere at 1100 ° C. for 24 hours to obtain tetragonal Nd ₂ F in the ingot.
The volume ratio of the e ₁₄ B type compound was 90% or more. This ingot was coarsely crushed in an Ar gas atmosphere (O ₂ amount of 0.5% or less) by a stamp mill to an average particle size of 500 μm, and the coarsely pulverized powder was put into a tubular furnace and vacuum exhausted to 1 Pa or less. . A rotary pump and an oil diffusion pump were used for evacuation. After that, H _{2 with} a purity of 99.9999% or more
While introducing gas, hydrotreating was performed under the hydrotreating conditions shown in Table 2. The hydrogenated raw material thus obtained was subsequently subjected to dehydrogenation treatment under the dehydrogenation treatment conditions shown in Table 2.
The cooling was performed by blowing the atmospheric gas used in the dehydrogenation treatment. After cooling, the raw material was taken out when the raw material temperature became 50 ° C. or lower. Magnetic powder (N
o. The magnetic properties of 1 to 20) are shown in Table 2. In Table 2, the value of Is shows the magnetization when Hex = 0.8 MA / m. Also,

Example 2 No. used in Example 1 was used. Using 12 raw material powders, the dependence of the magnetic properties on the throughput was investigated. Raw material particle size is 500 μm
In the hydrogenation process, the hydrogen pressure is 100 kPa and the heating rate is 15 ° C.
/ Min for 2 hours at 850 ° C., the dehydrogenation treatment is maintained at 840 ° C. for 2 hours in a reduced pressure gas stream of 10 kPa with Ar gas,
The cooling condition is fixed to Ar gas spray cooling, and the treatment amount is changed from 2 g to 2 kg. At that time, the residual magnetization Br of the magnetic powder, the coercive force Hc, and the magnetization Is in the easy magnetization direction and the difficult direction are set as the treatment amount. In contrast, it is graphed and shown in FIG.
The processing amount of 2 kg is due to the limitation of the experimental apparatus and does not indicate the upper limit of application of the present invention. The magnetization is a value at an external magnetic field of 0.8 MA / m, and the larger the difference between the values in the easy magnetization direction and the hard direction, the greater the magnetic anisotropy.

Comparative Example Regarding 12 kinds of coarsely pulverized powders having the same composition as the example shown in Table 1, the coarsely pulverized powders were put in a tubular furnace and 1
It was evacuated to Pa or less. Then, the purity is 99.99
While introducing 99% or more of H ₂ gas, hydrogenation treatment and dehydrogenation treatment were performed under the treatment conditions shown in Table 3. The hydrogen partial pressure or the treatment temperature during the dehydrogenation treatment shown here is outside the scope of the present invention. Magnetic powder at this time (No. 21 to 3)
Table 3 shows the magnetic characteristics of 7).

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

The method for producing anisotropic rare earth alloy powder for RT- (M) -B permanent magnets according to the present invention is RT-.
The coarsely pulverized powder of the (M) -B alloy is heated in a hydrogen gas atmosphere at a heating rate of 10 ° C./min to 200 ° C./min to 7
The temperature is raised to a temperature range of 50 ° C or higher, and further 750 ° C to 90 ° C.
By performing a heat treatment in hydrogen at 0 ° C., an appropriate amount of R ₂ T ₁₄ B phase as a nucleus that determines the crystal orientation during recrystallization can be left, and then the absolute pressure of Ar gas or He gas of 100 Pa to 50 kPa. 700 ℃ in depressurized air flow
By performing a dehydrogenation heat treatment at ˜900 ° C. and cooling, the RT- which is optimal as a raw material for bonded magnets and annealed magnets, having high coercive force and large magnetic anisotropy at the same time.
An anisotropic rare earth alloy powder for a (M) -B system permanent magnet can be stably obtained.

[Brief description of drawings]

FIG. 1 is a graph showing changes in coercive force of a magnetic powder and magnetization in an easy magnetization direction and a hard magnetization direction with respect to a processing amount.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minor Uehara Minoru Uehara 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Pref. Chome 15-17 Sumitomo Special Metals Co., Ltd. Yamazaki Works (72) Inventor Toshiro Tomita 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Sumitomo Metal Industries Co., Ltd.

Claims (2)

[Claims] 1. R: 10 to 20 at% (R: at least one kind of rare earth element including Y, and Pr or Nd of 1
Or 2 kinds of R in 50 at% or more), T: 6
7 to 85 at% (T: Fe or a part of Fe is 50 at
% Or less Co), B: 4 to 10 at% of the alloy ingot is roughly crushed, and at least 80 vol% or more having an average particle size of 50 to 5000 μm has a tetragonal structure Nd ₂ Fe ₁₄ B.
After forming a coarsely pulverized powder of a type compound, the coarsely pulverized powder is used as a raw material powder in a H ₂ gas of 10 to 1000 kPa and a temperature range of 600 ° C. to 750 ° C.
C./min to 200.degree. C./min to raise the temperature to 750
After heating and holding at 15 ° C to 900 ° C for 15 minutes to 8 hours to make the structure a mixed structure of at least four phases of R hydride, TB compound, T phase, and R ₂ T ₁₄ B compound, Ar gas or H
E-gas dehydrogenation by maintaining at 700 ° C to 900 ° C for 5 minutes to 8 hours in a reduced pressure air flow of absolute pressure 100 Pa to 50 kPa
₂ treatments followed by cooling to an average crystal grain size of 0.05
A method for producing a rare earth alloy powder for a permanent magnet, characterized in that an alloy powder having a magnetic anisotropy of 1 μm to 1 μm is obtained. 2. R: 10 to 20 at% (R: at least one of rare earth elements including Y, and Pr or Nd of 1
Or 2 kinds of R in 50 at% or more), T: 6
7 to 85 at% (T: Fe or a part of Fe is 50 at
% Or less Co replaced), M: 10 at% or less (M: A
l, Ti, V, Cr, Ni, Ga, Zr, Nb, Mo,
One or more of In, Sn, Hf, Ta, W), and B: 4 to 10 at% of the alloy ingot is coarsely crushed to have an average particle size of at least 80 v of 50 μm to 5000 μm.
ol% or more is made into a coarsely pulverized powder composed of a tetragonal structure Nd ₂ Fe ₁₄ B type compound, and the coarsely pulverized powder is used as a raw material powder in H ₂ gas of 10 to 1000 kPa at 600 ° C.
Up to 750 ° C or lower temperature rising rate 10 ° C / min to 2
Temperature is raised at 00 ° C / min or more, and further 750 ° C to 900
The tissue is heated and kept at 15 ° C. for 15 minutes to 8 hours to make the tissue R hydride, T
-B compounds in T-phase, R ₂ T ₁₄ B was a mixed structure of at least 4 phases compound, further pressure reduction in a stream of absolute pressure 100Pa~50kPa with Ar gas or He gas 70
0 ° C. to 900 ° C. to perform de H ₂ by keeping 5 minutes to 8 hours, and then an average grain size cooled to the 0.05μm~1μ
A method for producing a rare earth alloy powder for a permanent magnet, characterized in that an alloy powder having a magnetic anisotropy of m is obtained.