JP2003031432A - Rare-earth sintered magnet and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a rare-earth sintered magnet by obtaining a mold by isostatic pressing after orientation in a pulse magnetic field, wherein a high-performance magnet is obtained by improving the orientation rate even when a rare-earth magnet alloy having a high coercive force is used. SOLUTION: A rare-earth magnet alloy whose coercive force is made low by occluding hydrogen is pulverized, and the powder is oriented by a pulse magnetic field. Then, a mold is obtained by isostatic pressing. This mold is dehydrogenated, sintered, and subjected to aging to manufacture a rear-earth sintered magnet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rare earth sintered magnet by powder metallurgy for producing a sintered magnet having a high orientation ratio by using a magnet alloy powder having a high coercive force, and a large coercive force. It relates to a rare earth sintered magnet having an orientation ratio.

[0002]

2. Description of the Related Art R-T-B system (where R is a rare earth element containing Y and T is a transition metal element) magnets, which are mainly composed of rare earth elements, are used for hard disk voice coil motors. In the current situation, the demands for motors from VCM) and medical magnetic resonance imaging (MRI) applications are further increasing, and the demand for high coercive force type magnets is further increasing.

The steps of manufacturing a sintered magnet include the steps of forming an alloy, crushing an alloy, forming a powder by magnetic field orientation, forming a sintered body into a sintered body, and further processing and It can be divided into the steps of surface treatment.

Generally, the magnetic field orientation of the rare earth magnet alloy powder is carried out at the time of molding or before molding. The purpose of magnetic field orientation is to align the easy axis of magnetization of each powder particle made of a ferromagnetic material with the direction of the magnetic field by applying a strong magnetic field to the alloy powder. By this step, the easy axis of magnetization of the crystal grains of the powder particles constituting the magnet are aligned in the desired direction,
It is possible to concentrate the magnetic energy product in a specific direction. In order to manufacture a high-performance sintered magnet, it is important to orient the powder particles in the magnetic field orientation step and perform compression molding without disturbing the orientation.

[0005] Generally, the powder molding method can be roughly classified into mold molding by a uniaxial press using a mold and molding by a hydrostatic press (including a pseudo-hydrostatic press). Of which
Conventionally, die molding, which is excellent in productivity, has been used more often in the production of sintered magnets.

Molding can be classified into two types, a parallel magnetic field press and a vertical magnetic field press, depending on the relationship between the pressing direction and the direction of magnetic field orientation. In the parallel magnetic field press, the pressing direction and the magnetic field orientation direction coincide with each other, and the orientation ratio of the magnet tends to be lowered by disturbing the orientation of the powder aligned in the magnetic field orientation during pressing. On the other hand, when a magnet that is thin and oriented in the thickness direction is manufactured, it can be manufactured with a near net shape and is excellent in productivity. On the other hand, in the vertical magnetic field press, since the pressing is performed perpendicularly to the magnetic field orientation direction, the powder arrangement during molding is less likely to be disturbed, and the magnet orientation ratio is higher than in the parallel magnetic field press. However, in order to make a thin shape oriented in the thickness direction, it is necessary to cut the block into a thin plate shape perpendicular to the orientation direction, and the loss of the cutting margin is large, resulting in poor yield and high processing cost.

On the other hand, isostatic pressing is a method in which isotropic pressing is performed to suppress the disorder of the orientation caused by the pressing. As a specific method of isostatic pressing, a cold isostatic pressing (hereinafter, CIP) in which a powder is filled in a flexible mold and isotropically compressed as a whole, or a special rubber mold in which the powder is filled is used. By compressing the mold from above and below in the mold, the same press pressure is applied from the horizontal direction, and a pseudo-hydrostatic press is performed (hereinafter, RI method).
P) and the like. Among them, especially RIP is CI
Since it was possible to solve the problem of productivity, which was a drawback of P, and to obtain a high orientation ratio similar to that of CIP, it has rapidly spread as a method for producing a high-performance magnet.

In the conventional molding method using a uniaxial press using a die, pressure is applied in one direction during molding and the orientation of the powder is disturbed. It was necessary to keep applying the magnetic field. However, a large magnetic field is required to obtain a high orientation rate, and a magnetic field generator for that purpose is extremely large.

On the other hand, in CIP or RIP, since the pressure during molding is almost isotropic, the disorder of orientation during press molding is small. Therefore, if the powder particles are oriented in a magnetic field before molding, it is not usually necessary to apply a static magnetic field during press molding. Furthermore, a pulsed magnetic field can be used for the magnetic field orientation before the shaping. The pulsed magnetic field can easily generate a large magnetic field that cannot be generated by a static magnetic field with a simple device, and thus has an advantage that the orientation rate can be easily increased.

Further, a hydrostatic press (CIP or RI
In P), a very large-scale device is required to apply a magnetic field during pressure molding. Therefore, from the viewpoint of productivity and cost, it is preferable to use a means of performing magnetic field orientation of the powder particles with a pulsed magnetic field and performing press molding without applying a static magnetic field when molding by a hydrostatic press.

The magnetic field orientation is brought about by the direction of the easy axis of magnetization of the ferromagnetic particles being parallel to the direction of the external magnetic field, and is an element that impedes the rotation of the particles, such as the shape of the particles and the friction between the particles. In addition, it depends on the magnetism of the particles. The ferromagnet is magnetized by an external magnetic field, and the larger the magnetization, and the larger the anisotropic magnetic field, which is the force that directs the magnetic moment in the easy axis direction, rotate in the direction of the external magnetic field. Power increases. In particular, it is well known that the anisotropic magnetic field greatly contributes to the orientation. Further, the particles of the alloy powder are magnetized to some extent during the magnetic field orientation process. When the compact has a large magnetization, the interaction between the magnetic poles of each particle causes a force to disturb the orientation and lower the magnetostatic energy.

As described above, the static magnetic field is used for the orientation in the general die molding, and the static magnetic field is continuously applied during the molding.
In the method of molding in a static magnetic field, even if a large amount of magnetization remains, the magnetic field is applied until it becomes a high-density molded body by pressurization, so each particle can no longer move even if the external magnetic field disappears. .

On the other hand, in CIP and RIP, since a pulsed magnetic field is used for orientation, it is possible to improve the orientation rate by a strong magnetic field. However, when a pulsed magnetic field is used for orientation, the particles are oriented instantaneously by the strong pulsed magnetic field, but the magnetic field works only for a short time. In the case of CIP or RIP molding, after magnetic field orientation, press molding is performed under the condition without a magnetic field. Therefore, the orientation may be disturbed by the relatively large magnetization remaining in the particles.

Conventionally, hydrostatic presses such as CIP and RIP have been mainly performed on highly magnetized materials. CIP, R
In IP, the packing density during magnetic field orientation is relatively high, about 25% or more of the true density of the material, and the frictional force between particles that hinders rotation and rearrangement of particles is large. The deterioration of the orientation was small, and the disorder of the orientation was conventionally overlooked.

However, in recent years, as demand for motors has increased, not only high magnetized materials but also high coercive force materials are being molded by isostatic pressing. However, it has been found that when a hydrostatic press is used for a magnet alloy powder having a high coercive force to make a magnet, the orientation ratio becomes lower than that in die molding. It is considered that this is because the particles of the rare earth magnet alloy powder of the high coercive force material are rotated and rearranged to lower the orientation rate.

[0016]

In recent years, in rare earth-based high coercive force magnets, especially in R-T-B based magnets, the coercive force is increased by increasing the anisotropic magnetic field of the ferromagnetic phase. For example, a part of Nd, which is the most common rare earth element, is used as Dy or T
Substitution with a heavy rare earth element such as b, R2T1 in the ferromagnetic phase
The anisotropic magnetic field of the 4B magnet alloy increases, and the coercive force of the magnet can be increased. In addition, additive elements such as Cu, Al, and Ga are also effective, and these contribute to the change of the fine structure of the grain boundary, but their coercive force increasing effect is limited. Therefore, the high coercive force R-T-B magnet used in practice is Dy.
Or a certain amount of heavy rare earth such as Tb (several mass%)
The R2T14B compound contained therein has an increased anisotropic magnetic field.

When the anisotropic magnetic field of the R2T14B magnet alloy increases, not only the magnet but also the coercive force of the powder of the raw material alloy increases. The coercive force of the powder is extremely small, about 300 kA / m at the maximum, as compared with the magnet. But CI
When oriented in a pulsed magnetic field before hydrostatic pressing such as P and RIP, about 300 kA of this raw alloy powder is used.
A coercive force of about / m is a big problem. That is, as the coercive force of the powder itself increases, the remanent magnetization of the powder increases, causing rotation and rearrangement of the particles and lowering the orientation rate. Therefore, it has been difficult to manufacture a high coercive force material by the method for manufacturing a rare earth sintered magnet which is subjected to pulse magnetic field orientation and is molded by a hydrostatic press.

The present invention is a method for producing a rare earth sintered magnet in which a compact is obtained by hydrostatic pressing after orienting with a pulsed magnetic field. Even when a rare earth magnet alloy with high coercive force is used, the orientation ratio is improved and The purpose is to obtain a high performance magnet.

[0019]

Means for Solving the Problems That is, according to the present invention, (1) a rare earth magnet alloy having hydrogen absorbed therein to have a low coercive force is powdered, and the powder is oriented by a pulsed magnetic field and then molded by a hydrostatic press. A method for producing a rare earth sintered magnet, which comprises forming a body, further dehydrogenating the formed body, and then sintering and aging the formed body. (2) In the rare earth magnet alloy, the alloy main phase is composed of the R2T14B phase (provided that R is a rare earth element containing Y and T is a transition metal element), and R'in the R component (R 'is D
Represents at least one or more of y and Tb. The method for producing a rare earth sintered magnet according to (1) above, which comprises a rare earth magnet alloy having a mass ratio R ′ / R of 5) of 5% or more. (3) The method for producing a rare earth sintered magnet according to the above (2), wherein the mass ratio R ′ / R of R ′ in the R component of the alloy main phase is 10% or more. (4) The hydrogen storage amount of the rare earth magnet alloy is controlled by causing the rare earth magnet alloy to store hydrogen up to a saturated amount and then setting the heating temperature in the subsequent dehydrogenation step to 250 ° C. or less. The method for producing a rare earth sintered magnet according to 1) to 3). (5) The rare earth sintered magnet according to any one of (1) to (4) above, wherein the coercive force of the powder of the rare earth magnet alloy that absorbs hydrogen to reduce the coercive force is 160 kA / m or less. Production method. (6) Rare earth sintering according to the above (1) to (5), wherein the isostatic pressing is performed by a pseudo isostatic pressing (RIP) in which powder is filled in a rubber mold and pressed in a mold. Magnet manufacturing method. (7) As a dehydrogenation treatment of the compact, the compact is subjected to 1 at a temperature of 700 to 900 ° C. in vacuum or in an inert gas flow.
The method for producing a rare earth sintered magnet according to any one of (1) to (6) above, characterized in that the heat treatment for holding for a time or more is performed before sintering. Is.

The present invention also provides (8) a rare earth sintered magnet obtained by the manufacturing method according to any one of (1) to (7) above. (9) The rare earth sintered magnet according to the above (8), which has an orientation rate of 90% or more. (10) The rare earth sintered magnet according to (8) or (9), which has a coercive force of 950 kA / m or more. Is.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have investigated in detail the relationship between the characteristics of raw material powders of rare earth magnet alloys and the orientation ratio of magnets,
It has been found that the coercive force of the raw material alloy powder of the magnet has a great influence on the decrease in the orientation ratio of the sintered magnet. As a result of diligent research, since the coercive force of the raw material alloy powder was conventionally high,
A magnet using a high coercive force R-T-B type alloy that could not obtain a high orientation ratio in a hydrostatic press such as P or RIP, pulse magnetic field orientation and press molding without changing the alloy composition and structure at all. Only during the period, a method of reducing the coercive force of the raw material powder was found.

The present invention relates to a method for producing a rare earth sintered magnet having a high orientation rate using an isostatic press, which is RTB.
It was obtained by lowering the coercive force of the raw material powder of the system alloy by absorbing hydrogen in the alloy, performing the pulse magnetic field orientation using the powder, and further forming the compact by the hydrostatic pressing. This brings about an improvement in the orientation ratio of the magnet.

Then, by sintering the molded body formed by the hydrostatic pressing, a rare earth sintered magnet having a high coercive force and a high orientation rate is manufactured.

The constitution of the present invention will be described in detail below. (1) Coercive force of powder The alloy powder for rare earth magnets used for hydrostatic pressing such as CIP or RIP in the present invention absorbs hydrogen to reduce the coercive force to preferably 160 kA / m or less. Further, after being formed by pulsed magnetic field orientation and hydrostatic pressing, it is subjected to dehydrogenation treatment and then sintered to make the coercive force of the sintered magnet 950 kA / m or more.

As described above, in the case of a hydrostatic press such as CIP or RIP, when the raw material powder has a large coercive force when oriented by a pulsed magnetic field, the orientation ratio of the magnet decreases. It is considered that this is because of the rotation and rearrangement of the particles due to the increase in the residual magnetization of the powder. Generally, the larger the coercive force of the magnet, the larger the coercive force of the powder, but the coercive force of the magnet is 950 kA / m or more, and the coercive force of the powder is 16
When it is as high as 0 kA / m or more, the decrease in the orientation rate is remarkable. Therefore, in the present invention, the coercive force of the raw material powder is preferably 160
The magnetic field is oriented to a magnetic field by a pulsed magnetic field and the formed body is processed by a hydrostatic press while reducing the pressure to kA / m or less.

(2) Alloy main phase and Dy, Tb concentration in the main phase In the rare earth magnet alloy used in the present invention, the alloy main phase is R2T1.
4B phase (where R is a rare earth element containing Y and T is a transition metal element), and R ′ in the R component (R ′ is Dy,
It represents at least one or more of Tb. ) Mass ratio R '/ R is 5% or more. Ferromagnetic R
By using the 2T14B phase as the main phase, magnetic field orientation becomes possible and a magnet with a high orientation rate can be produced. At this time, in particular, if the mass ratio R ′ / R of R ′ (at least one of Dy and Tb) is 5% or more, the coercive force of the alloy powder also increases with an increase in the coercive force of the magnet. The effect of the present invention becomes clear. Further, when R '/ R is 10% or more, the present invention is extremely effective.

(3) Method of controlling hydrogen storage amount in rare earth magnet alloy The present invention controls the hydrogen storage amount of a rare earth magnet alloy by allowing the rare earth magnet alloy to store hydrogen to a saturated amount and then performing a dehydrogenation step. The heating temperature is set to 250 ° C. or lower. The control of the hydrogen storage amount can be performed, for example, in combination with the hydrogen crushing treatment of the rare earth magnet alloy and the subsequent dehydrogenation treatment. The hydrogen crushing process is used as a part of the crushing process of the RTB-based alloy. The hydrogen disintegration process will be described below.

In the hydrogen crushing treatment of the rare earth magnet alloy, first, the raw material alloy is appropriately crushed and then inserted into a furnace which can be evacuated and pressurized with gas to be hermetically sealed. After the alloy is set, the furnace is evacuated, and then hydrogen gas is introduced into the furnace. At this time, generally, in consideration of safety reasons and efficiency, the internal pressure is increased to atmospheric pressure or higher (for example, about 0.14 MPa). The treatment temperature is preferably 150 ° C. or lower. Above 150 ° C, part of the R-rich phase becomes 3
Since hydrogen is not occluded until it becomes a hydride, cracking tends to be delayed with the expansion of the alloy. Considering the work efficiency, it is preferable to carry out at room temperature of about 10 to 35 ° C.

The alloy occludes hydrogen gas and expands, cracking itself and crushing. At this time, the pressure inside the furnace is lowered because the hydrogen gas is decreasing, so the pressure is replenished appropriately. It is judged that the crushing phenomenon accompanying the storage of hydrogen in the alloy ended when the decrease in the furnace pressure was no longer observed.
In this state, it is considered that the rare earth magnet alloy was able to store hydrogen up to the saturated amount.

After absorbing hydrogen to a saturated amount, the alloy is heated to dehydrogenate. Here, the heating temperature in the conventional method is 300 ° C. or higher. The thermal dehydrogenation releases hydrogen from the main phase. Further, the residual hydrogen in the main phase lowers the anisotropic magnetic field of the main phase. Therefore, in the conventional magnetic field orientation method using a static magnetic field, 300 ° C. is used at the stage of this dehydrogenation treatment.
By heating above, hydrogen was released from the main phase to eliminate residual hydrogen.

However, in the present invention, dehydrogenation is performed by heating to a temperature at which the coercive force of the raw material powder is not recovered. Therefore, the dehydrogenation temperature is preferably 250 ° C or lower.
The heating time depends on the characteristics of the processing equipment,
Considering the reaction time of releasing hydrogen atoms for the R-rich phase to be in a more stable state, it is desirable to set the elapsed time from the time when the entire sample is heated to 30 minutes or more. In terms of work efficiency, it is desirable not to exceed 2 hours.

(4) Magnetic Field Orientation In the present invention, rare earth magnet alloy powder having a coercive force of 160 kA / m or less is oriented using a pulse magnetic field. As described above, the rare earth magnet alloy powder having a low coercive force of 160 kA / m or less can be used to produce a magnet having a high orientation rate by using a pulsed magnetic field in the orientation step.

(5) Molding Method The present invention is characterized in that the molding method of the molded body is isostatic pressing (CIP or RIP). With a hydrostatic press such as CIP or RIP or a pseudo hydrostatic press, it is possible to suppress the disorder of the orientation due to the press pressure during molding. Especially RIP
Solves the productivity problem that was a drawback of CIP,
This is a preferable molding method because a high orientation ratio similar to P can be obtained.

(6) Dehydrogenation treatment method After forming the molded body, dehydrogenation treatment is carried out before sintering treatment.
This dehydrogenation treatment is usually completed by heating at around 800 ° C. for a long time, for example, for about 30 minutes, but when the same treatment is performed on the molded body made from the raw material powder of the present invention, dehydrogenation is performed. The molded body is heated to a temperature close to the sintering temperature in an insufficient state, whereby abnormal grain growth of crystal grains is likely to occur and magnet characteristics are deteriorated. this is,
This is because the molded body made from the raw material powder of the present invention contains a certain amount or more of hydrogen in the main phase, which is different from the conventional case. Therefore, in the present invention, as the dehydrogenation treatment of the molded body, a heat treatment is carried out by holding the molded body in a vacuum or an inert gas flow at a temperature of 700 to 900 ° C. for 1 hour or more, more preferably 3 hours or more.

After the above dehydrogenation treatment, sintering and aging treatment are performed as in the conventional case, and if necessary, processing and surface treatment are performed to obtain a sintered magnet product.

[0036]

According to the present invention, in the powder for high coercive force material, a high orientation ratio could not be obtained by the conventional method of performing hydrostatic pressing such as CIP and RIP or pseudo hydrostatic pressing after orienting with a pulsed magnetic field. Also, a high orientation rate can be obtained.

[0037]

EXAMPLES Example 1 The alloy composition is Nd = 23.0 mass%, Dy = 7.0 mass%, B = 0.98 mass%, Al =
Nd metal, Dy metal, pure iron as a raw material so that 0.3% by mass, Cu = 0.03% by mass, and the balance = Fe.
Ferroboron, Al, and Cu were mixed and made into a molten metal in a vacuum atmosphere or an inert gas atmosphere. Then, it was made into a quenched alloy by the strip casting method.

The obtained alloy was crushed with a hydrogen crusher. As conditions for hydrogen storage, the operating temperature was 30 ° C. and the initial hydrogen pressure was 0.14 MPa. Then, dehydrogenation was performed by heating the inside of the apparatus to about 170 ° C. for 2 hours while vacuuming.

The above-mentioned alloy which had been subjected to hydrogen disintegration treatment was coarsely pulverized by a brown mill and then finely pulverized by a jet mill in a nitrogen atmosphere to obtain a powder. The particle size of the powder was 3.1 μm on a Fisher subsieve sizer. The coercive force of the powder was measured by VSM (vibration magnetometer), and it was 104 kA / m. Add 0.03% by mass of zinc stearate after pulverizing with a brown mill,
Mixed.

A compact was produced from the above powder by the RIP method. 2.8 × 10 ³ k powder into rubber mold
After filling to a density of g / m ³ , it was oriented with a pulsed magnetic field of 3T, and a compact was obtained at a pressure of about 100 MPa.

The above molded body was set in a sintering furnace,
Sintering was performed at 1037 ° C. for 3 hours in a vacuum atmosphere. Before reaching the sintering temperature, heating was performed at 790 ° C. for 5 hours to remove hydrogen contained in the powder. For the obtained sintered body, it was further maintained at 790 ° C. for 1 hour and then 570 ° C.
Aged for 1 hour.

The sintered body obtained by the above treatment was cut, polished, processed into a cube of about 7 mm square, and magnetic measurement was performed. As a result, the obtained magnetic characteristics are as follows: residual magnetic flux density (hereinafter, abbreviated as Br) = 1.23T, coercive force (hereinafter, iH).
abbreviated as c) = 1.83 × 10 ³ kA / m, magnetic energy product (hereinafter abbreviated as BHmax) = 294 kJ / m ³ ,
The orientation rate was 95.3%.

(Comparative Example 1) The alloy obtained under the same composition and casting conditions as in Example 1 was subjected to hydrogen crushing with a hydrogen crusher. The conditions for hydrogen storage were the same as in Example 1. After that, dehydrogenation was performed by heating to about 500 ° C. for 2 hours while evacuating the inside of the apparatus.

The alloy obtained above was pulverized in the same manner as in Example 1. As a result, the particle size of the obtained powder was about 3.0 μm with a Fisher subsieve sizer.
Met. In addition, the coercive force of the powder is VSM (vibration type magnetometer).
The result was 255 kA / m.

With respect to the above powder, R as in Example 1
A molded body was produced by the IP method to obtain a sintered body. as a result,
The obtained magnetic properties are Br = 0.72T, iHc = 1.
It was 85 × 10 ³ kA / m, BHmax = 96 kJ / m ³ , and the orientation rate = 58.9%.

The magnetic characteristics obtained in Example 1 and Comparative Example 1 are shown in FIG. The vertical axis represents magnetization and the horizontal axis represents coercive force.
Comparing the two, it was found that in Comparative Example 1, the square shape of the curve was not good and was not preferable as a magnet, whereas in Example 1, the square shape of the curve was better and was preferable as a magnet.

(Comparative Example 2) The powder obtained in Comparative Example 1 was filled in a mold and a static magnetic field of 1.2T was generated in the direction perpendicular to the pressing direction from the time when the upper punch was inserted into the mold. While doing so, press at a pressure of about 78 MPa,
A molded body was produced. Then, the same heat treatment as in Example 1 was performed to obtain a sintered body. This sintered body was processed into the same shape as in Example 1 and magnetic measurements were performed. As a result, the obtained magnetic characteristics were Br = 1.17T and iHc = 1.7.
7 × 10 ³ kA / m, BHmax = 280 kJ / m ³ , and orientation rate = 93.5%.

[0048]

According to the present invention, a high coercive force material cannot be obtained by pulse magnetic field orientation and hydrostatic pressing, whereas a high coercive force material is obtained by pulse magnetic field orientation and hydrostatic pressing according to the present invention. A molded body having a high rate can be obtained. The sintered magnet thus produced has a higher orientation rate than the magnet obtained by the die press, and it has become possible to manufacture a highly-oriented high coercive force thin magnet which has not been obtained in the past.

[Brief description of drawings]

FIG. 1 is a diagram showing magnetic characteristics of sintered magnets obtained in Example 1 and Comparative Example 1.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // C22C 38/00 303 C22C 38/00 303D (72) Inventor Shiro Sasaki Chichibu City Saitama 1505 Shimokagemori Address Showa Denko Co., Ltd., Chichibu Production and Technology Management Department (72) Inventor Masato Sagawa 1 F-22, Intermetallics Co., Ltd., at 22, Matsumuro Ouegami-cho, Nishikyo-ku, Kyoto (reference) 4K018 AA27 AB10 CA04 FA08 KA45 5E040 AA04 AA19 BD01 CA01 HB03 HB07 NN01 NN12 NN18 5E062 CD05 CF04 CG02 CG03 CG05

Claims (10)

[Claims] 1. A powder of a rare earth magnet alloy having a low coercive force which is occluded with hydrogen, powdered, orientated by a pulsed magnetic field and formed into a compact by isostatic pressing, and the compact is dehydrogenated. Then, the method for producing a rare earth sintered magnet, in which the compact is then sintered and the aging treatment is performed. 2. A rare earth magnet alloy having an alloy main phase of R2T14.
It is composed of a B phase (where R represents a rare earth element including Y and T represents a transition metal element), and is R ′ in the R component (R ′ represents at least one of Dy and Tb). The method for producing a rare earth sintered magnet according to claim 1, wherein the rare earth sintered magnet has a mass ratio R '/ R of 5% or more. 3. A mass ratio R'of R'in the R component of the alloy main phase.
/ R is 10% or more, The manufacturing method of the rare earth sintered magnet of Claim 2 characterized by the above-mentioned. 4. The control of the hydrogen storage amount of the rare earth magnet alloy is performed by causing the rare earth magnet alloy to store hydrogen up to a saturated amount and then setting the heating temperature in the subsequent dehydrogenation step to 250 ° C. or lower. The method for manufacturing the rare earth sintered magnet according to claim 1. 5. The production of a rare earth sintered magnet according to claim 1, wherein the coercive force of the powder of the rare earth magnet alloy that has absorbed hydrogen to have a low coercive force is 160 kA / m or less. Method. 6. A hydrostatic press (RIP) in which powder is filled in a rubber mold and pressed in a mold.
The method for producing a rare earth sintered magnet according to any one of claims 1 to 5, wherein 7. As a dehydrogenation treatment of a compact, a heat treatment for holding the compact in a vacuum or an inert gas flow at a temperature of 700 to 900 ° C. for 1 hour or more is performed before sintering. The method for producing a rare earth sintered magnet according to claim 1. 8. A rare earth sintered magnet obtained by the manufacturing method according to claim 1. 9. The rare earth sintered magnet according to claim 8, wherein the orientation ratio is 90% or more. 10. The rare earth sintered magnet according to claim 8, which has a coercive force of 950 kA / m or more.