JP3415208B2 - Method for producing R-Fe-B permanent magnet material - Google Patents

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 permanent magnet material containing R (where R is at least one of rare earth elements including Y), Fe and B as main components. A cast alloy having a homogeneous structure in which the R-rich phase of a specific plate thickness is finely separated is obtained by strip casting method such as single roll method or twin roll method using molten alloy mainly composed of Fe and B.
The H ₂ occlusion property of the R-containing Fe alloy is used to spontaneously collapse the slab, and further de-H ₂ treatment is performed to stabilize it, enabling efficient pulverization and applying a pulse magnetic field to the fine powder for orientation. Then, by molding and sintering, one of the magnet characteristics is the maximum energy product value (BH) max (MGOe); A and the coercive force iHc (kO
e) Characteristic value; High-performance RF showing a total value of A + B of 59 or more
The present invention relates to a manufacturing method for obtaining an eB-based permanent magnet.

[0002]

2. Description of the Related Art Today, R- is a typical high-performance permanent magnet.
The Fe-B system permanent magnet (Japanese Patent Laid-Open No. 59-46008) has high magnet characteristics due to the structure having the main phase of the ternary tetragonal compound and the R-rich phase. R-Fe-B based permanent magnets of various compositions have been proposed to be used in a wide range of fields from computer peripherals to exhibit various magnet characteristics according to the application. However, there is a strong demand for smaller and lighter electrical and electronic devices and higher functionality, and R-Fe
-It is required to further improve the performance and reduce the cost of B type permanent magnets.

In order to increase the residual magnetic flux density (Br) of the R-Fe-B system sintered magnet, 1) increase the abundance of the R ₂ Fe ₁₄ B phase, which is a ferromagnetic phase, as the main phase, 2) It is required to increase the density of the sintered body to the theoretical density of the main phase, and 3) to further increase the degree of orientation of the main phase crystal grains in the easy magnetization axis direction. That is, in order to achieve the above item 1), it is important to bring the composition of the magnet close to the stoichiometric composition of the R ₂ Fe ₁₄ B, but the alloy having the above composition was melted and cast in a mold. When an R-Fe-B based sintered magnet is produced using an alloy lump as a starting material, α-Fe crystallized in the alloy lump and the R-rich phase are locally ubiquitous. In particular, there is a problem that pulverization becomes difficult during fine pulverization and compositional deviation occurs.

More specifically, in the case where the alloy ingot is subjected to H ₂ occlusion and H ₂ removal treatment and mechanical pulverization is performed (Japanese Patent Laid-Open No. 60-63304).
, JP-A-63-33505), α-Fe crystallized in the alloy lump remains as it is at the time of crushing, and because of its spreadability, it hinders crushing, and the locally ubiquitous R-rich phase some H ₂ occlusion processing, to generate a hydride, to become a fine powder, or is accelerated oxidation during mechanical milling, also the composition shift by scattering in eugenics manner in grinding using a jet mill Occurs.

Further, if an attempt is made to produce a sintered body by using an alloy powder having a stoichiometric composition of R ₂ Fe ₁₄ B in order to achieve the above item 1), it is inevitable in the production process of the sintered body. Due to the oxidation, the Nd-rich phase for causing liquid-phase sintering is consumed because it forms an oxide and cannot be sintered, or the amount of the R ₂ Fe ₁₄ B phase is increased, which inevitably leads to Nd-rich phase. rich
Since the abundance of the B-rich phase and the B-rich phase is reduced, it has become more difficult to manufacture a sintered body. Further, as for the above item 3), in the method of manufacturing an R-Fe-B system permanent magnet, a method of press molding in a magnetic field is adopted in order to align the easy-axis directions of the main phase crystal grains. At that time, the residual magnetic flux density depends on the direction in which the magnetic field is applied and the direction in which the press is applied.
It is known that the (Br) value changes and is also affected by the strength of the applied magnetic field.

[0006]

Recently, coarsening of crystal grains, which is a defect of R-Fe-B alloy powder by the ingot crushing method, α-Fe
In order to prevent the residual and segregation of the R-Fe-B alloy melt by the twin roll method, it is made into a slab of a specific plate, and the slab is stamped according to the usual powder metallurgy method. Proposal of a manufacturing method in which after coarsely pulverizing with, etc., further finely pulverizing into powder with an average particle diameter of 3 to 5 μm by a mechanical pulverizing method such as a disc mill, a ball mill, an attritor, a jet mill, pressing in a magnetic field, and sintering aging treatment (JP-A-63-31
No. 7643).

However, in the above-mentioned method, it is not possible to expect a drastic improvement in the pulverization efficiency in the fine pulverization, as compared with the case of the conventional ingot pulverization method in which it is cast in a mold, and in addition to the grain boundary pulverization in the fine pulverization. However, since intra-particle pulverization also occurred, it was not possible to achieve a significant improvement in magnetic properties. In addition, the R-rich phase is stable against oxidation.
Since it is not RH ₂ , it is further inferior in oxidation resistance due to the fine and large surface area of the R-rich phase, and oxidation progresses during the process, and high magnet characteristics cannot be obtained. Further, there is a strong demand for cost reduction of R-Fe-B based permanent magnet materials, and it is extremely important to efficiently manufacture high-performance permanent magnets. Therefore, it is necessary to improve the manufacturing conditions to bring out the characteristics that are close to the limit.

The present invention solves the above-mentioned problems in the method for producing an R-Fe-B system permanent magnet material, enables efficient fine pulverization, is excellent in oxidation resistance, and has a fine crystal grain of the magnet. By expressing a high iHc, further increasing the degree of orientation of each crystal grain in the easy magnetization direction, (BH) max value (MGOe); A and i
High-performance R-Fe-B showing Hc value (kOe); B total value, A + B ≧ 59 value
An object of the present invention is to provide a method for manufacturing a permanent magnet material.

[0009]

[Means for Solving the Problems] First, the inventors
Based on the results of various studies on the pulverization method with the aim of improving the fine pulverization efficiency using a base alloy as a starting material, and having excellent oxidation resistance, and improving the magnetic properties of the magnet alloy, especially iHc, a fine and uniform R-Fe structure was obtained. -When hydrogen-absorbing the B-based alloy and then pulverizing the stabilized alloy powder by de-H ₂ treatment, the pulverizing ability is improved to about twice that of the conventional one, and the pulsed magnetic field is applied to the fine powder. (B)
It was found that the sum of (H) max value and iHc value has a value of 59 or more, and the iHc of the sintered magnet is improved.

That is, when H _{2 is} occluded in an R-Fe-B alloy having a specific composition having a structure in which the strip-cast R-rich phase of a specific plate thickness is finely separated, the finely dispersed R-rich phase is formed. By generating a hydride and expanding in volume, the alloy can be naturally disintegrated, and as a result, by fine pulverization, it becomes possible to subdivide the crystal grains of the main phase constituting the alloy block, A powder having a uniform particle size distribution can be produced.

In this case, it is particularly important that the R-rich phase is finely dispersed and the R ₂ Fe ₁₄ B phase is fine.
Moreover, in the method of melting an alloy lump using a normal mold,
When the alloy composition is brought close to the stoichiometric composition of R ₂ Fe ₁₄ B, F
e Crystallization of primary crystals is unavoidable, and this becomes a factor that greatly reduces the fine pulverization ability in the next step. Therefore, heat treatment is applied for the purpose of homogenizing the alloy ingot to eliminate α-Fe, but coarsening of the main phase crystal grains and segregation of the R-rich phase also proceed, so that the iHc of the sintered magnet is increased. It will be difficult to improve. Also, the easy-axis directions of the main phase crystal grains are aligned,
That is, increasing the degree of orientation is also an essential condition for achieving high Br. Therefore, permanent magnet materials manufactured by powder metallurgical methods, such as hard ferrite magnets,
Sm-Co magnets and R-Fe-B magnets employ a method of pressing the powder in a magnetic field.

However, a coil and a power source arranged in a usual press device (hydraulic press, mechanical press) for generating a magnetic field can generate only a magnetic field of 10 kOe to 20 kOe at most, and a higher magnetic field is generated. In order to generate it, it is necessary to increase the number of turns of the coil, and it is necessary to increase the size of the device that requires a high power supply.

The present inventors analyzed the relationship between the magnetic field strength during pressing and Br of the sintered body. The higher the magnetic field strength, the higher the Br value and the instantaneous generation of a strong magnetic field. It was found that even higher Br can be achieved by using a pulsed magnetic field capable of achieving this. Furthermore, in the method using a pulsed magnetic field, it is important to momentarily orientate once with the pulsed magnetic field, and it is possible to shape the powder by a hydrostatic press, and the combination of the pulsed magnetic field and the static magnetic field by an electromagnet can be combined. It was found that it is also possible to perform press molding in a magnetic field.

According to the present invention, R (where R is at least one of rare earth elements including Y) is 10 at% to 30 at.
%, The plate at B2at% ~28at%, remainder Fe (except be substituted one <br/> portion of Fe Co, at one or or two of Ni) and a molten alloy consisting of unavoidable impurities strip casting Mainly a thin plate with a thickness of 0.03 mm to 10 mm
The dimension of the R ₂ Fe ₁₄ B phase in the minor axis direction is 0.1 μm to 5
0 μm, the dimension in the long axis direction is 5 μm to 200 μm,
And the R-rich phase is 5μ so as to surround the main phase crystal grains.
After casting the cast piece having m was finely distributed in the following tissues, for example, the slab is accommodated in the intake and exhaust can container, after replacing the air in said vessel at a H ₂ gas, said vessel To 200T
or ^{2 to} 50 kg / mm ² of H ₂ gas to absorb hydrogen to obtain a collapsed alloy powder, for example, 100 ° C. to 75 ° C.
A fine powder having an average particle size of 1 to 10 μm obtained by pulverizing in an inert gas stream after heating to 0 ° C. to remove H ₂ and filling density in the mold is 1.4 to 3.0 g / cm 3. Fill ³
R is characterized in that after instantaneously applying a pulse magnetic field of 10 kOe or more for orientation, forming, sintering, and aging treatment
It is a manufacturing method of a -Fe-B system permanent magnet material.

The magnetic characteristics of the R-Fe-B system permanent magnet according to the present invention have iHc of 10 kOe or more when BH (max) is 50 MGOe or more, and iHc when BH (max) is 45 MGOe or more. Is 15 kOe
As described above, desired magnetic characteristics can be obtained by appropriately selecting the composition, manufacturing conditions, and the like.

The slab of the magnetic material having the structure in which the R-rich phase of the specific composition is finely separated according to the present invention is produced by the alloy casting of the specific composition by the single-roll method or the strip-casting method by the twin-roll method. . The obtained slab is a thin plate material having a plate thickness of 0.03 mm to 10 mm, and depending on the desired slab plate thickness, the single roll method and the twin roll method are used separately, but if the plate thickness is thick, the twin roll method is used. When the plate thickness is thin, it is preferable to adopt the single roll method.

The reason for limiting the plate thickness of the cast slab to 0.03 mm to 10 mm is that if the thickness is less than 0.03 mm, the quenching effect becomes large and the crystal grain size becomes 3
It becomes smaller than μm and is easily oxidized when pulverized, which causes deterioration of magnetic characteristics, which is not preferable.
If it exceeds 10 mm, the cooling rate becomes slow, α-Fe is easily crystallized, the crystal grain size becomes large, and the Nd-rich phase is unevenly distributed, which deteriorates the magnetic properties, which is not preferable.

The cross-sectional structure of the R-Fe-B alloy having a specific composition obtained by the strip casting method of the present invention is the ingot obtained by casting the main phase R ₂ Fe ₁₄ B crystal in a conventional mold. Compared to the ones, it is about 1/10 or more finer, for example, the dimension in the minor axis direction is 0.1 μm to 50 μm, and the major axis direction is 5 μm to 200 μm.
The R-rich phase is finely dispersed so as to surround the main-phase crystal grains, and the size is 20 μm or less even in a locally ubiquitous region.

By finely separating the R-rich phase to 5 μm or less, volume expansion when the R-rich phase produces a hydride during the H ₂ occlusion treatment is uniformly generated and finely divided, so that the R-rich phase is finely pulverized. As a result, the crystal grains of the main phase are subdivided to obtain a fine powder having a uniform particle size distribution. The slab may be subjected to H ₂ occlusion treatment as it is, but it is preferable to break it to a required size and expose the metal surface for H ₂ occlusion treatment.

For the H ₂ occlusion treatment, for example, a slab of 0.03 mm to 10 mm thickness broken to a predetermined size is inserted into the raw material case, and the raw material case is placed in a container that can be closed by closing the lid. After sealing with a vacuum, evacuate the inside of the container sufficiently,
H ₂ gas having a pressure of 200 Torr to 50 kg / cm ² is supplied to cause the slab to occlude H ₂ .

Since this H ₂ storage reaction is an exothermic reaction,
While cooling pipes for supplying cooling water are provided around the outer periphery of the container to prevent temperature rise in the container, by supplying H ₂ gas at a predetermined pressure for a certain period of time, the H ₂ gas is absorbed and the casting is performed. The pieces spontaneously disintegrate and powder. Further, after cooling the powdered alloy, H ₂ gas treatment is performed in vacuum. Since the alloy powder of the process inherent fine cracks in the grains, ball Lumpur mill, milled in a short time in a jet mill or the like, it is possible to obtain an alloy powder of the required particle size of 1Myuemu～80myuemu.

In the present invention, the inside of the processing container may be replaced with air beforehand by an inert gas, and then the inert gas may be replaced by a H ₂ gas. Further, the fracture size of the ingot, the smaller the H ₂ crushing pressure can be made smaller, and the H ₂ gas pressure is such that the fractured ingot is H ₂ absorbed and powdered even under reduced pressure,
The higher the pressure is higher than the atmospheric pressure, the easier the powder is to be pulverized.
However, if it is less than 200 Torr, the powdering property becomes poor and 50 kg / cm ²
Although preferred in view of powdering by weight, the H ₂ absorption and not preferable from the safety of equipment and work, H ₂ gas pressure
200 Torr to 50 kg / cm ² 2 kg / cm ² to 10 for mass production
kg / cm ² is preferred. In the present invention, the processing time for pulverization by H ₂ occlusion varies depending on the size of the closed container, the size of the crushed lump, and the H ₂ gas pressure, but 5 minutes or more is required.

After cooling the alloy powder pulverized by H ₂ occlusion,
The primary de-H ₂ gas treatment is performed in vacuum. Moreover, in a vacuum or in argon gas, heating the powdered alloy to 100 ° C. to 750 ° C., when 2 Tsugida' H ₂ gas treatment over 0.5 hours, with H ₂ gas in the pulverized alloy can be completely removed It is possible to prevent the powder or the press-molded body from being oxidized due to long-term storage and prevent the magnetic properties of the obtained permanent magnet from being deteriorated.

Since the dehydrogenation treatment by heating to 100 ° C. or higher according to the present invention has an excellent dehydrogenation effect, the above-mentioned primary dehydrogenation treatment in vacuum is omitted and the disintegrated powder is directly treated with 100
The dehydrogenation treatment may be performed in a vacuum at a temperature of not less than 0 ° C or in an argon gas atmosphere. That can be done with H ₂ After absorption and degradation reactions, dehydrogenation treatment which subsequently resulting collapse powder is heated to above 100 ° C. in an atmosphere of the container in the container for H ₂ occlusion reaction described above . Alternatively, after dehydrogenation treatment in vacuum, after taking out from the treatment container and finely crushing the disintegrated powder,
The dehydrogenation treatment of the present invention in which the treatment container is heated to 100 ° C. or higher may be performed again.

The heating temperature in the above dehydrogenation treatment is 10
If the temperature is lower than 0 ° C, it takes a long time to remove the H ₂ remaining in the disintegrated alloy powder, which is not mass production. Further, at a temperature exceeding 750 ° C., a liquid phase appears and the powder is solidified, which makes it difficult to finely pulverize or deteriorates the formability at the time of pressing, which is preferable in the case of producing a sintered magnet. Absent. Further, considering the sinterability of the sintered magnet, the preferable dehydrogenation treatment temperature is 200 ° C to 600 ° C. Further, the treatment time varies depending on the treatment amount, but 0.5 hours or more is required.

Next, for fine pulverization, an inert gas (for example,
Fine pulverization with a jet mill using N ₂ , Ar). Of course, it is also possible to use a ball mill using an organic solvent (for example, benzene, toluene, etc.) or attritor grinding. The average particle size of the finely pulverized powder is preferably 1 μm to 10 μm. If it is less than 1 μm, the pulverized powder becomes extremely active and is prone to be easily oxidized, which may cause ignition. Further, if it exceeds 10 μm, coarse particles that are not crushed remain,
The coercive force will decrease, or the progress of sintering will be slow and the density will decrease. More preferably, it is a fine powder having an average particle size of 2 to 4 μm.

The following method is proposed for pressing using a magnetic field. The finely pulverized powder is filled in a mold in an inert gas atmosphere. The mold may be made of non-magnetic metal or oxide, or may be an organic compound such as plastic or rubber. The packing density of the powder is preferably in the range of the bulk density of the powder in a static state (packing density 1.4 g / cm ³ ) to the solidified bulk density after tapping (packing density 3.0 g / cm ³ ). Therefore, the packing density is limited to 1.4 to 3.0 g / cm ³ .

The powder is oriented by applying a pulsed magnetic field from an air-core coil or a condenser power source. During orientation,
A pulse magnetic field may be repeatedly applied while performing compression using the upper and lower punches. The higher the strength of the pulse magnetic field, the better, and at least 10 kOe or more is required. The time of the pulsed magnetic field is preferably 1 μmsec to 10 sec, further 5 μmsec to 100 as shown in the graph of time and magnetic field strength in FIG.
mmsec is preferred, and the pulsed magnetic field is applied 1 to 10 times, more preferably 1 to 5 times.

The oriented powder can be solidified by isostatic pressing. At this time, when a plastic mold is used, the isostatic pressing can be performed as it is. In order to continuously perform the orientation and the pressing by the pulsed magnetic field, a coil for generating the pulsed magnetic field is embedded in the die, the orientation is performed by using the pulsed magnetic field, and then the ordinary magnetic field pressing method is used for molding. Is also possible.

The reasons for limiting the composition of the ingot for rare earth / boron / iron-based permanent magnet alloy in the present invention will be described below. The rare earth element R contained in the ingot for permanent magnet alloy of the present invention is a rare earth element including yttrium (Y) and including light rare earth and heavy rare earth. As R, a light rare earth element is sufficient, and Nd and Pr are particularly preferable. Also usually out of R
It is sufficient to have one kind, but in practice, a mixture of two or more kinds (Missille metal, didymium, etc.) can be used for reasons such as convenience in obtaining, Sm, Y, La, Ce, Gd etc. are other R, especially Nd, Pr
Etc. can be used as a mixture. In addition, this R
Does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within a range that is industrially available.

R is an essential element of the alloy ingot for producing the R-Fe-B system permanent magnet, and if less than 10 atomic%, it has high magnetic properties,
In particular, a high coercive force cannot be obtained, and if it exceeds 30 atomic%, the residual magnetic flux density (Br) decreases, and a permanent magnet with excellent characteristics cannot be obtained. Therefore, R is in the range of 10 atom% to 30 atom%, and a particularly preferable range of R is 12 to 15 at%.

B is an essential element of the alloy ingot for producing the R-Fe-B system permanent magnet, and a coercive force (iH
c) cannot be obtained, and if the content exceeds 28%, the residual magnetic flux density (Br) decreases, so an excellent permanent magnet cannot be obtained. Therefore, B is in the range of 2 atom% to 28 atom% and a particularly preferred range is 4
It is ~ 8at%.

If the Fe content is less than 42 atomic%, the residual magnetic flux density (Br) is lowered, and if it exceeds 88 atom, a high coercive force cannot be obtained. Therefore, the Fe content is preferably 77 to 84 at%. More preferably Fe77
It is from atomic% to 84 atomic%. The reason for substituting a part of Fe with one or two of Co and Ni is that the effect of improving the temperature characteristics of the permanent magnet and the effect of improving corrosion resistance can be obtained. When 50% or more of Fe is contained in the seeds or the two, a high coercive force cannot be obtained, and an excellent permanent magnet cannot be obtained.
Therefore, Co has an upper limit of 50% of Fe.

In order to obtain an excellent permanent magnet having both a high residual magnetic flux density and a high coercive force in the alloy ingot of the present invention, R12 atom% to 15 atom%, B4 atom% to 8 atom%, Fe
77 atom% to 84 atom% is preferable. Further, the alloy ingot according to the present invention, R, B, other than Fe, it is possible to allow the presence of impurities unavoidable in industrial production, but part of B is 4.0 atomic% or less C, 3.
By substituting at least one of P of 5 atomic% or less, S of 2.5 atomic% or less, and Cu of 3.5 atomic% or less with a total amount of 4.0 atomic% or less, it is possible to improve the manufacturability of the magnet alloy and reduce the cost. It is possible.

Further, in the above R, B, Fe alloy or R-Fe-B alloy containing Co, 9.5 atomic% or less Al, 4.5 atomic% or less Ti, 9.5 atomic% or less V, 8.5 atomic% or less Cr, 8.0 atom%
Mn below, Bi below 5 atomic%, Nb below 12.5 atomic%, 10.5
Atomic% or less Ta, 9.5 atomic% or less Mo, 9.5 atomic% or less W,
2.5 atomic% or less Sb, 7 atomic% or less Ge, 35 atomic% or less Sb
By adding at least one of n, 5.5 at% or less of Zr and 5.5 at% or less of Hf, a high coercive force of the permanent magnet alloy becomes possible. In the RB-Fe based permanent magnet of the present invention, it is essential that the main phase of the crystal phase is a tetragonal crystal, and in particular, a fine and uniform alloy powder is obtained to obtain a sintered permanent magnet having excellent magnetic properties. Effective to create.

If the average particle size of the finely pulverized powder of the alloy according to the present invention exceeds 80 μm, excellent magnetic properties, especially high coercive force, cannot be obtained at the time of producing a permanent magnet, and if the average particle size is less than 1 μm, The average particle size is set to 1 to 80 μm because oxidation in the manufacturing process of the sintered magnet, that is, press molding, sintering, and aging treatment is significant and excellent magnetic properties cannot be obtained. Furthermore, alloy powder having an average particle size of 2 to 10 μm is most desirable for obtaining excellent magnetic properties.

[0037]

The present invention is characterized in that strip-cast R-Fe-B based alloy having a specific composition with a specific plate thickness is allowed to occlude H ₂ so that the finely dispersed R-rich phase forms a hydride to generate a volume. The alloy is allowed to expand to spontaneously disintegrate, and then it is possible to finely pulverize the crystal grains of the main phase constituting the alloy ingot, and to produce a powder with a uniform particle size distribution. When the R-rich phase is finely dispersed and the R ₂ Fe ₁₄ B phase is also finely pulverized, and the alloy powder stabilized by de-H ₂ treatment is pulverized, the pulverization ability is about
Since it is doubled, manufacturing efficiency is greatly improved, and Br, BH (max) and iHc are significantly improved by instantaneously orienting using a pulsed magnetic field, followed by press molding and sintering. The obtained R-Fe-B system permanent magnet is obtained.

[0038]

[Example] Example 1 Nd13.4-B6.0-Fe80.6 obtained by melting in a high frequency melting furnace
Using a twin roll type strip caster provided with two copper rolls having a diameter of 200 mm, the molten alloy having the composition was used to obtain a thin plate cast piece having a plate thickness of about 1 mm. The crystal grain size in the slab is 0.5 μm to 15 μm in the minor axis direction, 5 μm to 80 μm in the major axis direction, and the R-rich phase is present in a finely separated state of about 3 μm so as to surround the main phase. .

After the slab was broken into 50 mm square or less, 1000 g of the broken piece was housed in a closed container capable of sucking and exhausting, and N ₂ gas was flowed into the container for 30 minutes to replace with air, H ₂ gas of 3 kg / cm ² was supplied into the container for 2 hours to spontaneously disintegrate the slab by the H ₂ sucker, and after that, it was held at 500 ° C. in vacuum for 5 hours to remove H ₂ and then, The mixture was cooled to room temperature and further pulverized to 100 mesh.

Next, 800 g of the coarsely pulverized sample was pulverized by a jet mill to obtain an alloy powder having an average particle size of 3.5 μm.
Using the obtained alloy powder, a raw material powder was filled in a rubber mold, and a pulsed magnetic field of 60 kOe was momentarily added and oriented, and then at a pressure of 2.5 T / cm ^{2 in} a hydrostatic pressing device. It was hydrostatically pressed. The molded body taken out from the mold is 1090
Sintering was performed for 3 hours at ℃, and aging treatment was performed at 600 ℃ for 1 hour to obtain a permanent magnet. Table 1 shows the magnetic properties of the obtained permanent magnets.

Example 2 The powder obtained in Example 1 was punched up and down as shown in FIG.
The static magnetic field coils 3 and 4 are arranged on the outer peripheral portions of 1 and 2, the pulse magnetic field coil 6 is arranged inside the die 5, and the raw material powder 7 is operated by using both the pulse magnetic field and the normal static magnetic field in combination. Using a press machine capable of performing the above, firstly, it was oriented in a pulsed magnetic field of about 30 kOe and then press-molded in a magnetic field of about 12 kOe. Thereafter, the molded body was sintered and aged under the same conditions as in Example 1. Table 1 shows the magnetic properties of the obtained permanent magnets.

Example 3 An alloy of Nd13.0-Dy0.5-B6.5-Co1.0-Fe7 was strip cast in the same manner as in Example 1 to obtain a thin plate-shaped cast piece. After breaking this to 50 mm square or less, 1000 g was allowed to spontaneously disintegrate by H ₂ occlusion in the same manner as in Example 1, and then subjected to H ₂ removal treatment in vacuum for 6 hours. After coarsely crushing this, crush it with a jet mill to obtain an average particle size.
A 3.5 μm powder was obtained. The obtained powder is subjected to pulse magnetic field orientation and isostatic pressing in the same manner as in Example 1, to prepare a molded body,
Similarly, the sintering heat treatment was performed. Table 1 shows the magnetic properties of the obtained permanent magnets.

COMPARATIVE EXAMPLE 1 The powder obtained in Example 1 was used in a conventional magnetic field press to obtain about 1
Press molding was performed in a magnetic field of 2 kOe, and thereafter, sintering and aging treatment were performed under the same conditions as in Example 1. Table 1 shows the magnetic properties of the obtained permanent magnets.

Comparative Example 2 Nd13.4-B6.0-Fe80.6 obtained by melting in a high frequency melting furnace
A molten alloy having the composition was cast in an iron mold. As a result of observing the structure of the obtained alloy ingot, crystallization of primary crystal Fe was observed, so heat treatment was performed at 1050 ° C. for 10 hours to perform homogenization treatment. The crystal grain size of the ingot is 30 to 150 μm in the short axis direction, 100 to 100 in the long axis direction.
It became several mm, and the R-rich phase was locally segregated with a size of about 150 μm.

[0045] The alloy ingot crude after grinding, H ₂ adsorption treatment in the same manner as in Example 1, and removing H ₂ treatment to obtain a crude powder. Furthermore, a jet mill was pulverized under the same conditions as in Example 1, the powder obtained with an alloy having an average particle size of about 3.7 μm was press-molded in a magnetic field of about 12 kOe, and sintered under the same conditions as in Example 1, Heat treatment was performed. The properties of the obtained permanent magnet are shown in Table 1.

Comparative Example 3 A strip-cast casting slab having the same composition and the same plate thickness as in Example 1 was roughly crushed to 50 mm or less, and then 1000 g of the roughly crushed powder was stamp-milled without H ₂ occlusion treatment and de-H ₂ treatment. At 1
After pulverizing for a time to obtain a coarsely pulverized powder of 100 mesh, it was pulverized by a jet mill to obtain an alloy powder having an average particle diameter of about 3.8 μm.
The alloy powder was pressed in a magnetic field in a magnetic field of about 12 kOe, sintered, and aged to obtain a permanent magnet. Table 1 shows the magnetic properties of the obtained permanent magnets.

Comparative Example 4 An alloy having a composition of Nd13.0-Dy0.5-B6.5-Co1.0-Fe79 was used as Comparative Example 2.
It was cast by the same method as. Since the obtained alloy ingot had Fe primary crystals crystallized, it was heat-treated at 1050 ° C. × 6 Hr.
After roughly crushing this alloy lump, H ₂ occluding treatment was performed at the same time as in Example 1, and H ₂ removal treatment was performed in vacuum. This was roughly pulverized and then jet mill pulverized to obtain a powder having an average particle size of about 3.7 μm. Further, after pressing in a magnetic field in a magnetic field of about 12 kOe, Example 1
Sintering and heat treatment were performed under the same conditions as above. Table 1 shows the magnetic properties of the obtained permanent magnets.

[0048]

[Table 1]

[0049]

EFFECTS OF THE INVENTION According to the production method of the present invention, an R-Fe-B alloy melt having a specific composition is formed into a slab with a specific plate thickness by strip casting, and this slab is allowed to occlude H ₂ and spontaneously disintegrate. by, then, it becomes possible to subdivide the crystal grains of the main phase constituting an alloy ingot alloy powder was stabilized by removing H ₂ treated with finely ground, particle size distribution uniform powder , R-rich phase and R ₂ Fe ₁₄ B phase are also miniaturized at the time of crushing, and can be made with about twice the efficiency of conventional ones, and by pressing with a pulse magnetic field, it becomes oxidation resistant when magnetized. Excellent magnetic properties of magnet alloys, especially maximum energy product value (BH) max (MGOe); A and coercive force iHc (kOe) characteristic value; B
A high-performance R-Fe-B system permanent magnet having a total value A + B of 59 or more is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a press device that can act by using a pulse magnetic field and a normal static magnetic field together.

FIG. 2 is a graph showing a relationship between time of a pulsed magnetic field and magnetic field strength.

[Explanation of symbols]

1,2 punch 3,4 Static magnetic field coil 5 dice 6 Pulse magnetic field coil 7 Raw powder

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-222304 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 33/02 C22C 38/00 303

Claims (2)

(57) [Claims] 1. R (provided that R is at least one of rare earth elements including Y) 10 at% to 30 at%, B2a
t% ~28at%, a part of the remainder Fe (except Fe Co,
The molten alloy consisting of substituted possible) and unavoidable impurities in one kind or two kinds of Ni by the strip casting method of a thin plate having a thickness 0.03Mm～10mm, the main phase R ₂ F
e ₁₄ B phase dimension in the minor axis direction is 0.1 μm to 50 μm, long
The axial dimension is 5 μm to 200 μm, and its main
After casting the cast piece having a phase crystal grains so as to surround the R-rich phase is finely distributed in the 5μm or less tissue, the cast pieces were accommodated in a container supplying a H ₂ gas of 200Torr~50kg / mm ² To obtain a disintegrated alloy powder, which is subjected to H ₂ removal treatment and then finely pulverized in an inert gas stream to obtain an average particle size of 1
Packing density of fine powder of -10 μm in mold is 1.4-
A method for producing an R-Fe-B based permanent magnet material, which comprises filling to 3.0 g / cm ³ and orienting by applying a pulse magnetic field of 10 kOe or more, followed by shaping, sintering and aging treatment. 2. The R—Fe—B based permanent magnet material according to claim 1, wherein the decay alloy powder obtained by hydrogen storage is heated to 100 ° C. to 750 ° C. for de-H ₂ treatment. Production method.