JP2000195712A - Manufacture of permanent magnet powder and anisotropic bonded magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an anisotropic bonded magnet showing remarkably high magnetic characteristics by performing mechanical grinding or mechanical alloying in vacuum or inert gas while a magnetic field is applied. SOLUTION: Rare earth-transition metal based magnet alloy is worked in magnet powder by using mechanical grinding or mechanical alloying. This mechanical grinding or mechanical alloying is performed under a vacuum atmosphere or by sealing inert gas in a tightly closed vessel. Further, this mechanical grinding or mechanical alloying is performed in a magnetic field and/or the following thermal treatment and nitriding treatment are performed in a magnetic field. Magnet powder which has peculiar fined alloy organization and whose crystal grain is made unisotropic is obtained. As a result, rare earth-iron based magnetic powder of magnetic anisotropy is safely manufactured with small energy consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a bonded magnet having features such as excellent shape flexibility and dimensional accuracy. More specifically, the present invention relates to a method for producing a rare-earth-transition metal-based permanent magnet powder exhibiting magnetic anisotropy, which is useful for producing an anisotropic bonded magnet having excellent magnetic properties.

[0002]

2. Description of the Related Art Bonded magnets in which permanent magnet powders are bonded with a binder such as rubber or resin are free from chipping and cracking, have a large degree of freedom in shape, and have good dimensional accuracy. Since the bonded magnet contains a binder that is a non-magnetic material,
That is, some magnetic properties are reduced. However, various rare earth-transition metal based magnet materials exhibiting much better magnetic properties than ferrite and alnico have been developed, and it has become possible to manufacture high-performance bonded magnets using them. Bond magnets have been widely used as high performance magnets, and have greatly contributed to miniaturization and weight reduction of various products.

[0003] Rare earth-transition metal magnet materials are broadly classified into rare earth-cobalt (typically, Sm-Co) and rare earth-iron (typically, Nd-Fe-B). The Sm-Co system can easily produce an anisotropic bonded magnet having high magnetic properties.
Both Co and Co have high costs due to their low resources.

[0004] Nd-Fe-B-based materials developed later have the following properties:
Sintered magnets with uniaxial magnetic anisotropy whose axis is the easy axis of magnetization have a very large maximum energy product when used as an anisotropic sintered magnet. Shows the best magnetic properties among materials. In recent years, it has been reported that nitrogen-intercalated rare earth-iron materials obtained by heat-treating rare earth-iron alloys in an atmosphere of ammonia or nitrogen gas and exhibiting magnetic properties close to those of Nd-Fe-B materials have been reported. Actively studied. Since this material decomposes at 700 ° C. or higher and cannot be sintered, it is mainly used as a bonded magnet.

[0005] Nd-Fe-B based material, Nd ₂ Fe ₁₄ which is the main phase
A high coercive force is exhibited by surrounding the B crystal grains with an Nd-rich phase or a B-rich phase. Therefore, to increase the coercive force, it is effective to reduce the crystal grain size of the main phase. So, for example,
A pulverized powder of an alloy having a fine crystal grain size manufactured by a super quenching method is used as a magnet material. There are also powders whose structure has been refined by using hydrocracking called the HDR method, powders manufactured by a gas atomizing method, and powders obtained by simply pulverizing alloys using a ball mill or a jet mill.

Further, after obtaining an amorphous alloy by mechanical grinding or mechanical alloying,
Production of a magnet powder having a fine crystal grain size by heat treatment and crystallization is described in, for example, JP-A-4-39915. Japanese Patent Application Laid-Open No. 6-208913 discloses an example in which the nitrogen-infiltrated rare earth-iron-based magnet powder described above is manufactured by heat treatment and nitriding after mechanical alloying of Sm powder and Fe powder. Have been.

However, the Nd-Fe obtained by each of the above methods
-Bonded magnets manufactured from B-based magnet powder are basically isotropic, and magnetic properties are much lower than those of anisotropic sintered magnets having the same alloy composition. Lower than Co-based anisotropic bonded magnet. To obtain bonded magnets with higher magnetic properties, Nd for anisotropic bonded magnets
Some methods for producing -Fe-B based anisotropic magnet powders have also been developed. There are two typical methods.

[0008] One is to hot-press a powder having a fine structure obtained by a super-quenching method to form a compact, apply hot plastic deformation to the compact to make the structure anisotropic, and then form a powder. How to This method is not suitable for mass production due to the large number of steps, complicated process conditions and high cost. Another method is to obtain an anisotropic magnet powder by adding a small amount of additive element to the alloy in the HDR method and performing HDR processing under specific conditions, but heating in hydrogen is necessary. As a result, hydrogen gas and energy are consumed, resulting in high costs. Therefore, the production amount of Nd—Fe—B based magnet powder for anisotropic bonded magnets is naturally limited.

Japanese Patent Application Laid-Open No. 7-283019 discloses that after a raw material powder of a rare-earth / iron-based alloy is made into an amorphous fine powder by a mechanical grinding method and then heat-treated at 300 to 800 ° C., recrystallization occurs. It is described that magnetic anisotropy develops in the powder at the same time as it occurs. However, since the magnetic anisotropy imparted to the magnet powder by this method is small, even when an anisotropic bonded magnet is manufactured using this magnet powder, the improvement in magnetic properties as compared with the isotropic bonded magnet is not so large. not big.

[0010]

As described above, each of the conventional methods for producing Nd-Fe-B-based magnet powder for anisotropic bonded magnets has problems. An object of the present invention is to provide a method for producing a rare-earth-iron-based magnet powder for an anisotropic bonded magnet in which such a problem is solved.

More specifically, a magnetically anisotropic rare earth-iron magnet powder capable of producing an anisotropic bonded magnet exhibiting extremely high magnetic properties can be produced safely and without consuming as much energy as possible. It is an object of the present invention to provide a low-cost manufacturing method.

[0012]

Means for Solving the Problems The present inventors have proposed Nd-Fe-
As a result of various studies on means for anisotropicizing the microstructure of rare earth-transition metal based alloys such as B series, mechanical grinding or mechanical alloying performed in order to obtain an alloy with a fine structure is performed in a magnetic field. In comparison with the case without a magnetic field, the c-axis directions of the crystal grains were aligned in the microstructure of the obtained magnet powder, and it was found that the remanent magnetization and the maximum energy product of the magnet powder were remarkably improved by this anisotropy. . Therefore, an anisotropic bonded magnet having excellent magnetic properties can be manufactured from this magnet powder.

The above method can also be applied to a nitrogen intrusion type rare earth-iron material. For example, Sm ₂ F obtained by mechanical grinding or mechanical alloying in a magnetic field
The e ₁₇ alloy powder, the nitriding treatment after the heat treatment, it is possible to manufacture the Sm ₂ Fe ₁₇ N _x system magnet powder the anisotropy.

Further, in addition to mechanical grinding or mechanical alloying in a magnetic field, if a subsequent heat treatment is performed in a magnetic field, or in the case of a nitrogen intrusion type magnet powder, a nitriding treatment is performed in a magnetic field, anisotropically. Is more advanced.
Alternatively, instead of applying a magnetic field at the time of mechanical grinding or mechanical alloying, simply applying a magnetic field during the subsequent heat treatment and / or nitriding treatment,
It has also been found that the orientations of the c-axes of the crystal grains are aligned, and that a certain degree of anisotropy occurs.

The present invention has been completed based on the above findings, and includes the following various embodiments. In a method of manufacturing rare earth (R) -transition metal (TM) based permanent magnet powder by mechanical grinding or mechanical alloying, mechanical grinding or mechanical alloying is performed under a magnetic field in a vacuum or in an inert gas. A method for producing a permanent magnet powder for an anisotropic bonded magnet.

The permanent magnet powder according to the above, wherein after performing mechanical grinding or mechanical alloying under application of a magnetic field, the obtained magnet powder is heat-treated at a temperature of 400 to 1000 ° C. in a vacuum or an inert gas. Production method. The method for producing permanent magnet powder according to the above, wherein the heat treatment is performed under application of a magnetic field.

In a method for producing a rare earth (R) -transition metal (TM) permanent magnet powder by mechanical grinding or mechanical alloying, a powder obtained by mechanical grinding or mechanical alloying is applied to a magnetic field. Heat treatment in a vacuum or in an inert gas at a temperature of 400 to 1000 ° C. and / or nitriding at 350 to 700 ° C. in a nitrogen or ammonia containing gas atmosphere under application of a magnetic field. For producing permanent magnet powder for anisotropic bonded magnets. The method for producing a permanent magnet powder according to the above, wherein the permanent magnet powder mainly comprises an R ₂ TM ₁₄ B phase.

In a method for producing a permanent magnet powder mainly composed of R ₂ TM ₁₇ N _x phase by a mechanical grinding method or a mechanical alloying method, the mechanical grinding or the mechanical alloying is carried out in a vacuum, in an inert gas, or in a nitrogen atmosphere. And / or applying a magnetic field in an atmosphere containing ammonia to obtain a powder mainly composed of R ₂ TM ₁₇ phase, and then nitriding the powder at 350 to 700 ° C. in a nitrogen or ammonia containing gas atmosphere. A method for producing a permanent magnet powder for an anisotropic bonded magnet.

After mechanical grinding or mechanical alloying under the application of a magnetic field, before the obtained powder is nitrided, it is placed in a vacuum or in an inert gas.
The method for producing permanent magnet powder according to the above, wherein the heat treatment is performed at a temperature of 400 to 1000 ° C. The method for producing a permanent magnet powder according to the above, wherein the heat treatment and / or the nitriding treatment is performed under application of a magnetic field.

An anisotropic bonded magnet comprising a permanent magnet powder and a binder produced by the above-described method.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The type of rare earth (R) -transition metal (TM) magnet alloy which can be produced by the method of the present invention is not particularly limited, but the conventional method is used for producing anisotropic magnet powder having a fine structure. Rare earth / iron based magnet alloys, especially R-TM-B based (eg Nd-Fe-B based)
It is advantageous to produce a bonded magnet powder of the TM-N type (eg, Sm-Fe-N type) by the method of the present invention.

R-TM-B magnet powder is mainly composed of R ₂
An alloy composition composed of TM ₁₄ B phase is preferred. Throughout this specification, R is one or more rare earth metals including Y, and TM is one or more transition metals.

In the case of the R-TM-B magnet powder, R is Nd of 50.
It is preferable to contain at% or more. R may be Nd alone, but preferably contains Dy or Tb in addition to Nd.
Dy and Tb enhance the magnetic anisotropy of the crystal grains of the R ₂ TM ₁₄ B phase,
This is because the degree of orientation of the obtained magnet powder is increased. Preferred TMs are Fe, Co, or Fe + Co. To promote anisotropy, add a small amount of added element (e.g., Mg, Al, Si, T
i, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Hf, etc.)
Is also preferred. In order for the R-TM-B-based magnetic powder to exhibit its coercive force, an R-rich phase and a B-rich phase are required, so that the alloy composition is higher than that of the main phase, R ₂ TM ₁₄ B. Select so that B becomes rich. Specifically, it is known that an alloy composition near R ₁₅ TM ₇₇ B ₈ is desirable for improving magnetic properties, particularly coercive force.

The R-TM-N magnet powder is mainly composed of R ₂
An alloy composition comprising a TM ₁₇ N _x phase is preferred. Although the value of x is ideally 3, it is actually smaller than 3.
R preferably contains 50 at% or more of Sm, and may be Sm alone. Preferred TMs are Fe, Co, or Fe + Co.
Also in the case of the R-TM-N system, the presence of the R-rich phase is necessary, and the optimum alloy composition for obtaining excellent magnetic properties is R ₁₁ TM
It is in the vicinity of ₈₉ N _x.

In the present invention, a magnet powder is produced from a raw material powder by a mechanical grinding method or a mechanical alloying method. The production of rare earth-transition metal based magnet powders using mechanical grinding or mechanical alloying is known per se, and except for the application of a magnetic field, which is a feature of the present invention, is based on a conventionally known operation method. To produce magnetic powder.

Mechanical grinding is an operation in which a raw material powder that has already been alloyed is ground by a high energy ball mill or the like and mechanical stress is applied to obtain a powder having a fine structure. On the other hand, mechanical alloying involves grinding and mixing raw material powders composed of two or more kinds of metals and / or alloys with a high-energy ball mill or the like in the same manner as described above, and pressing, milling, interdiffusion, etc. This is an operation to obtain alloy powder having a fine structure by refining and alloying the alloy. In other words, mechanical grinding and mechanical alloying have different raw material powders, but the operation itself is substantially the same, and both are the same in obtaining an alloy powder having a fine structure. The difference is that the transformation occurs.

When the mechanical grinding method is employed, the raw material powder is, in principle, a powder of a master alloy having the same composition as the rare earth-transition metal alloy to be produced. However, in the case of producing a nitrogen intrusion type R-TM-N magnet powder, an alloy containing no nitrogen (that is, an R-TM alloy) is used as a master alloy. For example, the R-TM-B based master alloy is
Those containing at least 80 vol% of the R ₂ TM ₁₄ B phase are preferred.
The TM-based master alloy preferably contains at least 80 vol% of the R ₂ TM ₁₇ phase.

The ingot of the mother alloy is prepared by mixing two or more types of component metals or a raw material alloy having a different composition from a predetermined composition in such a ratio as to obtain a predetermined metal ratio, and melting by high frequency melting or arc melting. After that, it can be obtained by pouring into a mold and cooling. The pulverization of the mother alloy may be performed mechanically by a ball mill or the like, or pulverization may be performed by absorbing hydrogen into the alloy and utilizing hydrogen embrittlement. The mother alloy powder can also be obtained by a method other than the above, for example, an argon gas atomizing method.

The average particle size of the raw material powder (that is, the powder of the master alloy) is preferably in the range of 1 to 500 μm. If it is less than 1 μm, oxidation tends to occur during handling, and if it exceeds 500 μm, a polycrystalline structure is formed and anisotropic formation becomes insufficient. The average particle size of the raw material powder is more preferably 50 to 300 μm.

In the case of mechanical alloying, the raw material powder is a powder of each metal constituting the alloy to be produced, but a part of the metal may be alloyed in advance. For example, in the case of the R-TM-B system, R (eg, Nd), TM (eg,
It is common to use raw material powder of each metal of Fe or Fe and Co) and B, but two kinds of metals (eg, TM and B or TM
And R) may be alloyed before use. When producing nitrogen-intrusion type R-TM-N magnet powder, R and TM
Use only as raw material powder. The average particle size of the raw material powder may be the same as in the case of mechanical grinding.

The mechanical grinding or mechanical alloying is performed, for example, by enclosing a raw material powder, a spherical grinding medium (ball), and, if necessary, a liquid solvent in a closed container, and rotating the container at a high speed. It can be carried out according to the operation of As the ball mill, for example, a planetary ball mill having a higher pulverization efficiency than an ordinary one can be used. Instead of a ball mill, other grinding devices such as an attrition mill can be used.

Desirable processing time of mechanical grinding varies depending on, for example, the volume of a container used, the diameter of a grinding medium, the number of rotations, etc. in the case of a ball mill. If the time exceeds 500 hours, the oxidation of the raw material powder and the formation of fine particles are excessively advanced, which is not preferable. In the case of mechanical alloying, in order to achieve alloying, it is generally preferable to set the processing time to 10 hours or more.
Long processing times exceeding 500 hours are not preferred. The average particle size of the powder after the treatment is preferably in the range of 1 to 150 μm.

The processing temperature for mechanical grinding and mechanical alloying is usually room temperature, but lower or higher temperatures can be used. Also,
If necessary, the device may be cooled to maintain the temperature. The processing atmosphere is a vacuum or an inert gas atmosphere to prevent oxidation of the raw material powder. For example, the airtight container is evacuated and processed in a vacuum atmosphere, or an inert gas is sealed in the airtight container to perform the processing. When using a liquid solvent,
Processing in an inert gas atmosphere is preferred. As the inert gas, a rare gas such as argon or helium is suitable. In the case of the R-TM-N-based nitrogen intrusion type alloy, since the powder may be nitrided, the treatment can be performed in a nitrogen gas or an ammonia gas, or an inert gas containing nitrogen or ammonia. .

A feature of the present invention is that mechanical grinding or mechanical alloying is performed in a magnetic field to anisotropy the fine structure. As a method for applying a magnetic field, a method for applying a magnetic field from the outside of the closed container for performing the treatment is simple. The magnetic field can be generated by an electromagnet method or a permanent magnet method. The latter method is advantageous in that no electric power is required for generating the magnetic field. Regarding the location of the permanent magnet or electromagnet, the permanent magnet may be directly adhered to the outer wall of the sealed container to penetrate the magnetic field lines inside, or from the permanent magnet or electromagnet fixed separately from the rotating closed container. A magnetic field may be applied. In the latter case, the magnetic field rotates relative to the closed container, which is advantageous in that the stirring of the raw material powder is promoted. In addition, it is preferable that the permanent magnets are arranged so that the NS poles are alternately arranged because the stirring effect is still obtained.

The applied magnetic field strength is suitably in the range of 1 to 10 kOe. The magnetic field is preferably applied during mechanical grinding or mechanical alloying, but can also be applied during only part of it. In that case, it is particularly preferable to apply a magnetic field in the first half of the processing.

The structure of the alloy powder produced by mechanical grinding or mechanical alloying is refined by the treatment. However, as a result of mechanical strain during the treatment, many defects are formed in the crystal grains. As a result, the coercive force is reduced due to amorphization. Therefore, it is preferable that the strain is released by heat treatment to increase the crystallinity, thereby recovering the coercive force. However, when the degree of distortion or amorphization is small, for example, when mechanical grinding is performed for a relatively short time, a sufficient coercive force may be exhibited even without heat treatment.

The heat treatment is performed in a vacuum or in an inert gas (eg, a rare gas such as argon or helium) to prevent oxidation.
Perform at a temperature of 400-1000 ° C. If the heat treatment temperature is lower than 400 ° C., the recovery of the coercive force becomes insufficient, and if it exceeds 1000 ° C., the coercive force decreases due to crystal grain growth and oxidation. The preferred heat treatment temperature is between 600 and 850 ° C. The heat treatment time is preferably in the range of 10 minutes to 12 hours. If the time is less than 10 minutes, the recovery of the coercive force is often insufficient, and if the time exceeds 12 hours, the coercive force may decrease due to crystal grain growth and oxidation.

This heat treatment can also be performed in a magnetic field.
As described in JP-A-7-283019, when heat treatment is performed after mechanical grinding or mechanical alloying, recrystallization occurs during the heat treatment and magnetic anisotropy appears in the magnet powder at the same time. Is performed in a magnetic field, the appearing magnetic anisotropy becomes stronger.

As described above, the method of applying a magnetic field during heat treatment is simple in that an external magnetic field is applied, and either an electromagnet or a permanent magnet can be used. For example, a permanent magnet may be adhered directly to the outer wall of the heat treatment vessel, or a permanent magnet or electromagnet may be placed around the heat treatment vessel.
The applied magnetic field strength may be the same as above.

In the case of producing an R-TM-N magnet powder, the alloy powder produced by mechanical grinding or mechanical alloying is treated with or without the above-mentioned heat treatment. A treatment is performed to cause nitrogen to penetrate into the alloy to obtain a predetermined magnet alloy composition. The nitriding treatment is preferably performed after the heat treatment.
If the mechanical grinding or mechanical alloying treatment is performed in a nitriding atmosphere (eg, nitrogen gas or ammonia gas atmosphere), this treatment may already achieve the required nitridation. R that contains a sufficient amount of nitrogen without the need for a separate nitriding treatment
-TM-N-based magnet powder may be obtained.

The nitriding treatment is performed in a gas atmosphere containing nitrogen or ammonia, preferably in a nitrogen gas or ammonia gas at 350 to 700 ° C. If the temperature is lower than 350 ° C., a sufficient amount of nitrogen cannot be introduced. If the temperature exceeds 700 ° C., the alloy itself is thermally decomposed and the coercive force decreases as described above. The preferred nitriding temperature is 400-600 ° C. Usually, the time for the nitriding treatment is preferably in the range of 30 minutes to 4 hours. This nitriding treatment is also performed in the same manner as the above heat treatment.
It may be performed in a magnetic field.

When the above heat treatment and / or nitriding treatment is performed in a magnetic field, anisotropy is imparted to the microstructure of the alloy, so that mechanical grinding or mechanical alloying is not performed in a magnetic field. Even
A magnet powder having anisotropic crystal grains can be obtained. However, since the anisotropy due to this is not so large, it is preferable to perform mechanical grinding or mechanical alloying in a magnetic field even when a magnetic field is applied during heat treatment or nitriding treatment.

As explained above, the method of the present invention comprises:
In the production of magnet powder by mechanical grinding or mechanical alloying, the mechanical grinding or mechanical alloying is performed in a magnetic field, and / or the subsequent heat treatment or nitriding is performed in a magnetic field. . As a result, it is possible to obtain a magnet powder having a fine alloy structure specific to an alloy manufactured by mechanical grinding or mechanical alloying and having anisotropic crystal grains. Since the application of the magnetic field can be performed only by installing a permanent magnet or an electromagnet, it is only necessary to add relatively simple equipment. In the case of a permanent magnet, energy cost is unnecessary, and in the case of an electromagnet, the energy cost is not so high. Therefore, according to the present invention, it becomes possible to safely produce magnetically anisotropic rare earth-iron based magnet powder with low energy consumption.

From the rare earth-transition metal magnetic anisotropic permanent magnet powder produced by the method of the present invention, an anisotropic bonded magnet having excellent magnetic properties can be produced according to a conventional method. As the binder, metal and the like can be used in addition to resin and rubber. In the case of general plastic bonded magnets, anisotropic bonded magnets are prepared by mixing magnet powder with resin, molding in a magnetic field, and curing the resin by heat or applying a surface treatment to the magnet surface as necessary. Can be manufactured. The binder resin may be appropriately selected according to the molding method. For example, in the case of compression molding, a thermosetting resin such as an epoxy resin or a phenol resin is used, and in the case of injection molding, a thermoplastic resin such as nylon or polyolefin is generally used. Synthetic rubber such as nitrile butyl rubber can also be used.

[0045]

EXAMPLES Example 1 R-TM-B having the composition shown in Table 1
An ingot of the system mother alloy was prepared by a high-frequency melting method, and this was pulverized by an air stamp mill until the average particle size became 250 μm. The obtained pulverized powder of the mother alloy was put into a pot for a stainless steel ball mill having a diameter of 150 mm together with a ceramic spherical pulverization medium (diameter: 10 mm), and the inside was replaced with Ar gas and sealed. This pot was set on a base of a ball mill, and while applying a uniform magnetic field of 2 kOe by an electromagnet arranged around the pot, the pot was rotated at a rotation speed of 100 rpm for a time shown in Table 1 to perform a mechanical grinding process. went. The obtained alloy powder was then heat-treated in an Ar gas without applying a magnetic field under the conditions shown in Table 1, and then cooled in the same atmosphere to obtain a magnet powder.

These magnet powders have an R ₂ TM ₁₄ B phase as a main phase, a structure having an R-rich phase and a B-rich phase, and the ratio of the main phase is about 90 vol%. After the obtained magnet powder was oriented in a magnetic field, it was magnetized with a pulse magnetization of 65 kOe, and its magnetic properties were measured by VSM. The obtained magnetic properties,
Table 2 shows the average crystal grain size of the main phase of the magnet powder measured by SEM observation. The magnetic properties of the magnet powder thus obtained have a correlation with the magnetic properties when the magnet powder is used as an anisotropic bonded magnet. That is, the residual magnetic flux density of the anisotropic bonded magnet
Although [Br] and the maximum energy product [(BH) max] decrease by the amount of the binder, the Br and (BH) max of the magnet powder determined by the above method are reduced.
It has been empirically confirmed that the value is 50 to 80%.

Example 2 Mechanical grinding was performed without applying a magnetic field (in the absence of a magnetic field), and heat treatment was performed at 2 kO.
An R-TM-B-based magnet powder was produced in the same manner as in Example 1 except that the test was performed in the magnetic field of e, and its magnetic properties and average crystal grain size of the main phase were measured. Table 1 shows the alloy composition and processing conditions, and Table 2 shows the measurement results.

Example 3 In addition to mechanical grinding, heat treatment was also performed in a magnetic field of 2 kOe, except that
An R-TM-B-based magnet powder was produced in the same manner as in Example 1, and its magnetic properties and the average crystal grain size of the main phase were measured. Table 1 shows the alloy composition and processing conditions, and Table 2 shows the measurement results.

Comparative Example 1 An R-TM-B magnet powder was produced in the same manner as in Example 1 except that the mechanical grinding was performed without applying a magnetic field (in the absence of a magnetic field). The magnetic properties and the average crystal grain size of the main phase were measured.
Table 1 shows the alloy composition and processing conditions, and Table 2 shows the measurement results.

[0050]

[Table 1]

[0051]

[Table 2]

As can be seen from Table 1, the manufacturing conditions of Examples 1 to 3 and Comparative Example 1 were the same except for the presence or absence of the application of a magnetic field during mechanical grinding and / or heat treatment. The diameter (the degree of micronization of the structure) is the same. However, as can be seen from Table 2, in Examples 1 and 3 in which mechanical grinding was performed in a magnetic field according to the present invention, the obtained magnet powder had coercive force [iHc], residual magnetic flux density [Br], and maximum energy product. [(BH) max] is higher than that of the corresponding comparative example under the same conditions, and particularly, the remanence and the maximum energy product are remarkably improved, and the maximum energy product is more than doubled. Also, in Example 2 in which only heat treatment was performed in a magnetic field, the magnetic properties were significantly improved as compared with the corresponding comparative example. Therefore, according to the present invention, it is possible to manufacture a bonded magnet having excellent magnetic properties simply by adding equipment having a relatively simple mechanism.
-Production of magnetic anisotropic magnet powder of TM-B system becomes possible.

Example 4 Pure metals of Sm and Fe or Sm, Fe and Co (average particle diameter: 200 to 300 μm) were mixed at a ratio having a composition shown in Table 3, and this mixed powder was mixed. Then, a ceramic ball milling medium (diameter: 10 mm) was charged into a pot for a stainless steel ball mill having a diameter of 150 mm, the inside was replaced with Ar gas, and then sealed. This pot was set on the base of a ball mill, and 3 magnets were placed around the pot using electromagnets.
While applying a uniform magnetic field of kOe, the pot was rotated for a time shown in Table 1 at a rotation speed of 100 rpm to perform a mechanical alloying treatment. The obtained alloy powder was then heat-treated in Ar gas under the conditions shown in Table 1, then cooled in the same atmosphere, and further subjected to nitriding at 450 ° C. for 2 hours in nitrogen gas to obtain R-TM -N-based magnet powder was obtained. As shown in Table 3, the heat treatment and the nitriding treatment were performed without a magnetic field or in a magnetic field, or in only one of them in a magnetic field.
e).

This magnet powder has an R ₂ TM ₁₇ N _x phase as a main phase, a structure having an R-rich phase, and a ratio of the main phase of about 80%.
vol%. Table 4 shows the results of measuring the magnetic properties and the average crystal grain size of the main phase of the obtained magnet powder in the same manner as in Example 1. The alloy composition of this magnet powder contains nitrogen in addition to the composition shown in Table 3.

Comparative Example 2 An R-TM-N magnet powder was produced in the same manner as in Example 2 except that mechanical alloying was performed without applying a magnetic field (without a magnetic field). The magnetic properties and the average crystal grain size of the main phase were measured. Table 3 shows the alloy composition and processing conditions before nitriding, and Table 4 shows the measurement results.

[0056]

[Table 3]

[0057]

[Table 4]

From Tables 3 and 4, it can be seen that mechanical alloying is performed in a magnetic field even when the alloy composition is R-TM-N and the processing is different from mechanical alloying, as compared with Example 1. Example 1 by simply adding simple equipment
Similarly to the above, it can be seen that it is possible to produce a magnet powder for an anisotropic bonded magnet exhibiting extremely excellent magnetic properties. It can also be seen that, in addition to the mechanical alloying, when heat treatment and / or nitriding are also performed in a magnetic field, the magnetic properties are further improved.

[0059]

According to the present invention, in the production of rare earth-transition metal based magnet powder having a fine structure by a conventional mechanical grinding method or mechanical alloying method, this operation is performed in a magnetic field, and / or By simply changing the subsequent heat treatment or nitriding treatment in a magnetic field, it is possible to produce a magnetic powder having a fine structure exhibiting magnetic anisotropy. From this anisotropic magnet powder, an anisotropic magnet exhibiting excellent magnetic properties can be obtained. Can be manufactured.

Therefore, according to the present invention, it is possible to manufacture a high-performance anisotropic magnet powder for a bonded magnet with a safe and simple process and without consuming much energy by adding relatively simple equipment. R-TM-B system and R-TM-N
Production of anisotropic magnet powder for bonded magnets based on
It is expected that mass production of high-performance anisotropic bonded magnets, which are cheaper than Sm-Co magnets, will be realized.

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Claims (9)

[Claims] 1. A method for producing a rare earth (R) -transition metal (TM) permanent magnet powder by a mechanical grinding method or a mechanical alloying method, wherein the mechanical grinding or the mechanical alloying is carried out in a vacuum or in an inert gas. A method for producing a permanent magnet powder for an anisotropic bonded magnet, wherein the method is performed under application of a magnetic field. 2. The method according to claim 1, wherein after performing mechanical grinding or mechanical alloying under application of a magnetic field, the obtained magnet powder is heat-treated at a temperature of 400 to 1000 ° C. in a vacuum or an inert gas. Production method of permanent magnet powder. 3. The heat treatment is performed under application of a magnetic field.
A method for producing the permanent magnet powder according to the above. 4. A method for producing a rare earth (R) -transition metal (TM) permanent magnet powder by a mechanical grinding method or a mechanical alloying method, wherein the powder obtained by the mechanical grinding or the mechanical alloying is treated with a magnetic field. Heat treatment in a vacuum or inert gas at a temperature of 400 to 1000 ° C under the application of nitrogen and / or nitriding at 350 to 700 ° C in a nitrogen or ammonia containing gas atmosphere under the application of a magnetic field. A method for producing a permanent magnet powder for an anisotropic bonded magnet. 5. The method for producing a permanent magnet powder according to claim 1, wherein the permanent magnet powder mainly comprises an R ₂ TM ₁₄ B phase. 6. A method for producing a permanent magnet powder mainly composed of R ₂ TM ₁₇ N _x phase by mechanical grinding or mechanical alloying, wherein the mechanical grinding or mechanical alloying is performed in a vacuum, in an inert gas, Alternatively, the treatment is performed in a nitrogen and / or ammonia containing gas atmosphere under application of a magnetic field to obtain a powder mainly composed of R ₂ TM ₁₇ phase, and then the powder is nitrided at 350 to 700 ° C. in a nitrogen or ammonia containing gas atmosphere. A method for producing a permanent magnet powder for an anisotropic bonded magnet, comprising: 7. After performing mechanical grinding or mechanical alloying under application of a magnetic field, and before nitriding the obtained powder, in a vacuum or in an inert gas.
The method for producing a permanent magnet powder according to claim 6, wherein the heat treatment is performed at a temperature of 400 to 1000C. 8. The method for producing a permanent magnet powder according to claim 6, wherein the heat treatment and / or the nitriding treatment are performed under application of a magnetic field. 9. An anisotropic bonded magnet comprising a permanent magnet powder produced by the method according to claim 1 and a binder.