JP2012234971A - Method for manufacturing r-t-b-based sintered magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnet in which heavy rare earth elements RH are efficiently diffused in the inner part of an R-T-B-based sintered magnet, and which obtains predetermined magnetic characteristics.SOLUTION: The method for manufacturing the R-T-B-based sintered magnet includes the steps of: preparing an R-T-B-based sintered magnet material; preparing a powdery diffusion material formed of an RH-Fe alloy made from a heavy rare earth element RH (RH contains at least one of Dy and Tb) and Fe of 40 mass% or more but 95 mass% or less, and RL metal containing a light rare earth element RL (which contains at least one of Nd, Pr, Ce, and La), and in which a total amount of contained rare earth is 65 mass% or more, the light rare earth element RL is contained 20 mass% or more but 70 mass% or less, and the heavy rare earth element RH is contained 50 mass% or less; and subjecting the R-T-B-based sintered magnet material to RH diffusion treatment at a temperature of 800°C or higher but 1,000°C or lower in a vacuum or an inert gas in a state that the diffusion material exists on the surface of the R-T-B-based sintered magnet material.

Description

The present invention relates to a method for producing an R-T-B-based sintered magnet (R is a rare earth element and T is Fe or Fe and Co) having an R ₂ T ₁₄ B type compound as a main phase.

R-T-B based sintered magnets with R ₂ T ₁₄ B-type compounds as the main phase are known as the most powerful magnets among permanent magnets, and are used in various motors for hybrid vehicles and home appliances. ing.

The _RTB -based sintered magnet has irreversible thermal demagnetization because its intrinsic coercive force H _cJ (hereinafter simply referred to as “H _cJ ”) decreases at high temperatures. In order to avoid irreversible thermal demagnetization, when used for a motor or the like, it is required to maintain a high coercive force even at a high temperature.

When a part of R in the R ₂ T ₁₄ B type compound phase is replaced with a heavy rare earth element RH (including at least one of Dy or Tb), the coercive force of the RTB-based sintered magnet is improved. It has been known. In order to obtain a high coercive force at a high temperature, it is effective to add a large amount of heavy rare earth element RH to the RTB-based sintered magnet. However, in the R-T-B based sintered magnet, replacing the light rare earth element RL (including at least one of Nd and Pr) as R with the heavy rare earth element RH improves the coercive force, whereas the residual magnetic flux density B _r. (Hereinafter simply referred to as “B _r ”) is reduced. Moreover, since the heavy rare earth element RH is a rare resource, it is required to reduce the amount of use thereof.

In recent years, so as not to reduce the B _r, to improve the coercive force of the R-T-B based sintered magnets have been studied with less heavy rare-earth element RH.

  Patent Document 1 discloses a first step in which a heavy rare earth compound containing Dy or Tb as a heavy rare earth element is attached to an RTB based sintered magnet, and an RTB based sintering in which the heavy rare earth compound is attached. And a second step of heat-treating the magnet material, wherein the heavy rare earth compound is a Dy iron compound or a Tb iron compound.

  In Patent Document 1, an iron compound of a specific heavy rare earth element is attached to an RTB-based sintered magnet and subjected to heat treatment, whereby the heavy rare earth compound from the surface to the inside of the RTB-based sintered magnet is obtained. In this case, it is considered that the heavy rare earth compound mainly diffuses along the boundary of the main phase particles constituting the RTB-based sintered magnet.

  In Patent Document 1, Dy or Tb iron compounds are particularly excellent in the effect of improving the coercive force because they easily aggregate and can increase the amount of adhesion as compared with fluorides.

  In addition, it is stated that the iron compound containing Dy or Tb has a lower melting point in the vicinity of the eutectic point, so that the heat treatment temperature of the RH diffusion treatment can be lowered, and is less susceptible to temperature variations during the heat treatment. ing.

  Moreover, in patent document 1, it is preferable that the average particle diameter of the heavy rare earth compound adhering to a R-T-B type | system | group sintered magnet is 100 nm-50 micrometers, and, thereby, can diffuse the heavy rare earth compound by heat processing more. It is said that it can be generated well.

  In Patent Document 2, there is a method in which a heat treatment is performed in a state where an alloy powder in which a rare earth element and an M element such as Al or Si or Fe and Co are further added is present on the surface of an RTB-based sintered magnet. Have been described. In Patent Document 2, the alloy powder is heat-treated in the state of being present on the surface of the R-T-B system sintered magnet, whereby the rare earth element and the M element in the alloy powder are R-T-B system sintered. It diffuses inside the magnet and concentrates them near the interface of the main phase grains.

In patent document 2, it is excellent in productivity by apply | coating the alloy powder which mainly has the intermetallic compound phase containing the rare earth which is easy to grind | pulverize on the surface of a RTB system sintered magnet, and performing a diffusion process. by concentrating constituent elements of the diffusion alloy near the interface of major phase grains of the sintered body portion is characterized by capable of increasing the H _cJ while suppressing a decrease in B _r.

  In Patent Document 2, the alloy powder is dispersed in an organic solvent or water and applied to the surface of an RTB-based sintered magnet material. The smaller the average particle size of the powder, the higher the diffusion efficiency.

JP 2009-289994 A JP 2008-250179 A

  In the method of Patent Document 1, Dy or Tb-containing heavy rare earth element and iron compound is formed into a slurry and applied to the surface of the RTB-based sintered magnet material, followed by heat treatment. Alternatively, an object was to introduce an iron compound containing Tb as it is into the R-T-B system sintered magnet material. In order to improve the diffusion, the average particle size of the heavy rare earth compound needs to be 100 nm or more and 50 μm.

  Further, in Patent Document 2, an alloy obtained by adding rare earth element and M element such as Al or Si or further Fe and Co or the like is used as a powder, and the powder is present on the surface of the RTB-based sintered magnet material. By performing the heat treatment, an alloy in which rare earth elements and M elements or Fe and Co are further added is introduced as it is inside the magnet, and there is the same problem as in Patent Document 1.

  In both Patent Documents 1 and 2, the RH diffusion process becomes unstable due to oxidation of the RH-Fe alloy or the alloy of the rare earth element and the M element, and stable magnetic characteristics cannot be obtained. Alternatively, there is a problem that magnetic properties cannot be obtained without efficient diffusion. Moreover, the problem of the grinding | pulverization cost for producing the fine powder of the alloy of RH-Fe alloy and a rare earth element and M element generate | occur | produced.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to perform RH diffusion treatment with a powdery diffusion material in which RL metal is mixed with an RH-Fe alloy containing a large amount of Fe. The heavy rare earth element RH is stably diffused inside the TB sintered magnet so as to obtain stable predetermined magnetic characteristics.

  Another object of the present invention is to reduce the pulverization cost, and the particle size of the powdery diffusing material in which the RH-Fe alloy, which is an RH diffusion source, and RL metal are mixed is 63 μm or more. The heavy rare earth element RH is efficiently diffused by an RH-Fe alloy of 500 μm or less.

The manufacturing method of the RTB-based sintered magnet of the present invention is as follows:
Preparing a R-T-B sintered magnet material (R is a rare earth element, T is Fe or Fe and Co);
An RH-Fe alloy comprising heavy rare earth element RH (RH includes at least one of Dy and Tb) and 40 mass% or more and 95 mass% or less of Fe;
An RL metal containing a light rare earth element RL (including at least one of Nd, Pr, Ce, La), and
The total rare earth amount is 65% by mass or more,
Light rare earth element RL is 20 mass% or more and 70 mass% or less,
Heavy rare earth element RH is 50 mass% or less,
A step of preparing a powdery diffusion material,
With respect to the R-T-B system sintered magnet material, the diffusion material is present on the surface of the R-T-B system sintered magnet material, and vacuum or non-reactance is performed at a temperature of 800 ° C. or higher and 1000 ° C. or lower. And an RH diffusion process in the active gas.

  In a preferred embodiment, the diffusing material has a particle size of 63 μm or more and 500 μm or less. In the present invention, the “R-T-B system sintered magnet material” before the RH diffusion treatment is referred to as “R-T-B system sintered magnet” after the RH diffusion treatment.

  According to the present invention, even if the particle size of a heavy rare earth element RH alloy such as an RH-Fe alloy is rough, the heavy rare earth element RH is stabilized in the RTB-based sintered magnet by the RH diffusion treatment, and the efficiency is high. RH diffusion treatment can be performed. In addition, the pulverization cost is reduced because it is not necessary to make an alloy that diffuses the heavy rare earth element RH such as the RH-Fe alloy into a fine powder.

It is a figure which shows the result of having measured the DTA curve of the diffusion material of this invention.

Hereinafter, embodiments of the production method of the present invention will be described.
Preparing a R-T-B sintered magnet material (R is a rare earth element, T is Fe or Fe and Co);
An RH-Fe alloy comprising heavy rare earth element RH (RH includes at least one of Dy and Tb) and 40 mass% or more and 95 mass% or less of Fe;
An RL metal containing a light rare earth element RL (including at least one of Nd, Pr, Ce, La), and
The total rare earth amount is 65% by mass or more,
Light rare earth element RL is 20 mass% or more and 70 mass% or less,
Heavy rare earth element RH is 50 mass% or less,
A step of preparing a powdery diffusion material,
With respect to the R-T-B system sintered magnet material, the diffusion material is present on the surface of the R-T-B system sintered magnet material, and vacuum or non-reactance is performed at a temperature of 800 ° C. or higher and 1000 ° C. or lower. And an RH diffusion process in the active gas.

  According to the present invention, in the RH diffusion treatment, the RL metal in the diffusion material present on the surface of the RTB-based sintered magnet material is brought into contact with the RH-Fe alloy to generate a liquid phase. A liquid phase is formed on the surface of the B-based sintered magnet material. Through the liquid phase, the heavy rare earth element RH is efficiently introduced into the RTB-based sintered magnet material.

Also, since no high concentration of the heavy rare-earth element RH in the diffusion material, excessively heavy rare-earth element RH is not introduced into the R-T-B based sintered magnet material, improving the H _cJ no decrease in B _r Can be made. This will be described in more detail below.

[R-T-B sintered magnet material]
First, in the present invention, an RTB-based sintered magnet material that is a target for diffusing the heavy rare earth element RH is prepared. As this RTB-based sintered magnet material, a known material can be used, and for example, it has the following composition.
Rare earth element R: 12 atomic% or more and 17 atomic% or less B (a part of B may be substituted with C): 5 atomic% or more and 8 atomic% or less Additive element M (Al, Ti, V, Cr, Mn Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb, and Bi. At least one selected from the group consisting of: 0 atomic% and 2 atomic% T (transition metal mainly containing Fe and may contain Co) and unavoidable impurities: remainder Here, the rare earth element R is at least one selected from light rare earth elements RL (Nd, Pr) However, it may contain a heavy rare earth element. In addition, when a heavy rare earth element is contained, it is preferable that at least one of Dy and Tb is included.

  The RTB-based sintered magnet material having the above composition is manufactured by a known manufacturing method.

[Diffusion material]
The diffusion material of the present invention is a powder comprising an RH-Fe alloy and an RL metal,
The total rare earth amount is 65% by mass or more,
Light rare earth element RL is 20 mass% or more and 70 mass% or less,
Heavy rare earth element RH is 50 mass% or less,
Consists of.

Here, the total rare earth amount (TRE) contained in the diffusion material is set to 65% by mass or more.
When the total rare earth amount is less than 65% by mass, in the RH diffusion step, a liquid phase formed by contacting the RL metal and the RH-Fe alloy with a high temperature stable compound composed of the heavy rare earth elements RH and Fe is formed. I can't. Therefore, the heavy rare earth element RH is not diffused into the sintered magnet material, but most or part of the heavy rare earth element RH remains on the surface of the RTB-based sintered magnet material. If it remains on the surface, the amount of diffusion is insufficient and stable magnetic properties cannot be obtained.

  Preferably, the total rare earth amount (TRE) contained in the diffusing material is 65% by mass or more and 80% by mass or less.

  Further, the light rare earth element RL in the diffusing material is contained in an amount of 20% by mass to 70% by mass.

When the content of the light rare earth element RL in the diffusion material is less than 20% by mass, the liquid phase generated in the RH diffusion process is small, and the heavy rare earth element RH is efficiently diffused inside the R-T-B system sintered magnet material. It becomes difficult to make it. When the content of the light rare earth element RL in the diffusing material exceeds 70% by mass, the RH concentration of the liquid phase generated during the diffusion treatment is small, so that the effect of improving _HcJ is reduced. Preferably, it is 25 mass% or more and 55 mass% or less.

Further, the content of the heavy rare earth element RH in the diffusing material is preferably 50% by mass or less. Maximum order, the reduction of the B _r of this range hardly occurs diffusion into the crystal grain inside the R-T-B based sintered magnet material due to the heavy rare-earth element RH when in, the RH diffusion remain grain shell portion A suppressed magnet is obtained. Preferably, the content of heavy rare earth element RH is 15% by mass or more and 45% by mass or less.

When the content of the heavy rare earth element RH in the diffusing material is more than 50% by mass, the diffusion of the RTB-based sintered magnet material into the crystal grains can be achieved even in the RH diffusion treatment of 800 ° C. or more and 1000 ° C. or less not be obtained proceeds desired tissue, cause a decrease in B _r while H _cJ is improved, the waste of the heavy rare-earth element RH.

As an embodiment of the diffusing material of the present invention, the diffusing material is composed of an RH-Fe alloy and an RL metal.
The RH-Fe alloy contains a heavy rare earth element RH composed of at least one of Dy and Tb, and contains 40% by mass or more and 95% by mass or less of Fe.

Here, when the Fe content of the RH-Fe alloy is less than 40% by mass, the Dy phase and the Tb phase are easily generated, and the surface of the sintered magnet material is excessively supplied with the heavy rare earth element RH. diffusion into the crystal grain inside the T-B based sintered magnet material proceeds, which may cause a decrease in B _r.
Conversely, when the Fe content in the RH-Fe alloy exceeds 95% by mass, the content of heavy rare earth element RH decreases because the content of heavy rare earth element RH is small. Even if it is possible, a desired _HcJ improvement effect cannot be obtained.

  Next, the RL metal includes a light rare earth element RL including at least one of Nd, Pr, Ce, and La. Here, the light rare earth element RL may contain Fe of less than 25% by mass.

As a method for producing the RH-Fe alloy and the RL metal, the RH-Fe alloy is produced by, for example, putting a raw material alloy into a melting furnace so as to have a predetermined composition, melting it, and then cooling it. For example, after melting in a high-frequency melting furnace using a Dy ₈₁ Fe ₁₉ (mass%) alloy and electrolytic Fe, the molten metal is applied to a copper water-cooled roll rotating at a roll surface speed in the range of 1 m / sec to 30 m / sec. To form a rapidly solidified alloy.

  Preferably, the RH-Fe alloy is further pulverized by a stamp mill, hydrogen pulverization or the like, and the particle size is adjusted by a sieve.

  Similarly to the RH-Fe alloy, the RL metal can also be produced by putting the raw material alloy into a melting furnace so as to have a predetermined composition and then cooling it. When the RL metal is a pure metal, since the RL metal is not easily pulverized, an RL-Fe alloy substituted with less than 25% by mass of Fe may be used for the purpose of improving the pulverizability. In this case, the composition of the diffusion material in which the RH-Fe alloy and the RL-Fe alloy are mixed is set within a predetermined range.

  The RL metal can also be produced in a powder form by, for example, dropping and spraying Nd metal, Pr metal, Ce metal, and La metal melted in an inert gas atmosphere from a heat-resistant container.

  In addition, the RH-Fe alloy and the RL metal may be made into powder by cutting with a cutting powder cut with a cutting tool such as super steel or with a grindstone such as diamond.

  After producing the RH-Fe alloy and the RL metal, a diffusion material composed of these two kinds of mixed powders is produced.

  As a method for producing a mixed powder composed of the RH-Fe alloy and the RL metal, the produced RH-Fe alloy and RL metal are mixed and pulverized until a predetermined particle size is obtained, and RH- A method of mixing two kinds of metals, that is, an Fe alloy and an RL metal, after individually individually pulverizing them into a predetermined particle diameter can be applied.

  When mixing individually prepared RH-Fe alloy powder and RL metal powder, the mixing method is not particularly limited, but the rotation does not generate heat in an inert atmosphere by a rocking mixer, double cone type mixer, etc. It is preferable to stir at a speed. By doing so, the RH-Fe alloy and the RL metal are uniformly stirred.

  The particle sizes of the RH-Fe alloy and the RL metal are preferably 63 μm or more and 500 μm or less on the sieve. In order to make the diffusion material formed by mixing the RH-Fe alloy and the RL metal to have a sieve size of 63 μm or more and 500 μm or less, the alloy is preferably pulverized only by hydrogen pulverization or by a stamp mill only. Further, when the mixing ratio of the RL metal is small, it is desirable that the powder particle diameter of the RH-Fe alloy is further small within this range.

When the particle size of the diffusing material exceeds 500 μm, the specific surface area of the powder becomes small, so that the reaction between the RH—Fe alloy and the RL metal becomes uneven and insufficient, and the heavy rare earth element RH in the RH—Fe alloy becomes R or remaining in -T-B based sintered magnet surface, uniformly it is difficult to diffuse into the interior R-T-B based sintered magnet material, which may H _CJ improving effect becomes small. On the other hand, if the particle size of the diffusing material is less than 63 μm, it takes time to grind to obtain a powder of less than 63 μm. More preferably, the particle size of the diffusing material is not less than 63 μm and not more than 250 μm by sieve.

Any method may be used as a method for causing the diffusion material to exist on the surface of the RTB-based sintered magnet material.
As an arbitrary method, for example, a structure in which powder that is fed in a fixed amount from a dusting roller disposed in the bottom opening of a powder supply tank and a doctor blade adjacent thereto is scattered and dropped with a brush or the like is similar. There is a simple spraying method using a jig.

  Preferably, a binder is applied to the magnet material before spreading the diffusing material. By applying a binder, a predetermined amount of heavy rare earth element RH can be reliably introduced to the surface of the magnet using RH diffusion.

  As this binder, for example, a water-soluble rust preventive agent (for example, a trade name made by Fuso Chemical Industry, whose main component is a special carboxylic acid) is used in an aqueous solution such as a thickener such as methylcellulose, hydroxypropylcellulose, and hydroxyethylmethylcellulose. What added the elephant SY-12) can be used.

  In addition, even if it does not spray directly on the R-T-B system sintered magnet material, after spraying the powder on the base plate on which the R-T-B system sintered magnet material is arranged, the R is brought into contact with the powder. -A T-B type sintered magnet material may be disposed, or a combination thereof may be laminated to be brought into contact with a plurality of R-T-B type sintered magnet materials. Further, after the powder is sprayed on the RTB-based sintered magnet material or the base plate, the spraying amount may be uniformly adjusted with a ground plate or the like.

[RH diffusion processing]
An RH diffusion process is performed on the processing vessel in which the RTB-based sintered magnet material is disposed. The RH diffusion process is performed under the following conditions.

[atmosphere]
The atmosphere during the RH diffusion step is preferably an inert gas atmosphere. The “inert atmosphere” in this specification includes a vacuum or an inert gas. The “inert gas” is, for example, a rare gas such as argon (Ar), but if it is a gas that does not chemically react with the RTB-based sintered magnet material or the diffusion material, It can be included in “inert gas”. It is preferable that the pressure of an inert gas is below atmospheric pressure. The pressure of the atmospheric gas during the RH diffusion step (atmospheric pressure in the processing container) can be set, for example, within a range of 1 Pa to atmospheric pressure.

[Heat treatment temperature]
The heat treatment temperature during the RH diffusion step is 800 ° C. or higher and 1000 ° C. or lower. This temperature range is a preferable temperature range in which the heavy rare earth element RH in the diffusion material diffuses inward through the grain boundary phase of the RTB-based sintered magnet material.

If the heat treatment temperature is less than 800 ° C., the generated liquid phase is small, so that RH in the diffusing material is difficult to diffuse into the magnet, and a desired H _cJ improvement effect cannot be obtained, or a desired H _cJ improvement effect. It takes a long time for the RH diffusion step for obtaining the above, which is not preferable. Moreover, when it exceeds 1000 degreeC, it will become easy to produce the problem that a RTB system sintered magnet raw material and a diffusion material will weld.

  In the diffusion material composed of RH-Fe alloy and RL metal, the RH-Fe alloy is composed of heavy rare earth element RH composed of at least one of Dy or Tb and Fe of 40 mass% or more and 95 mass% or less. When the RH diffusion treatment is performed below, the liquid phase generated is sufficiently generated, and the heavy rare earth element RH in the diffusion material is efficiently supplied into the magnet.

  The heat treatment time is the ratio of the amount of the R-T-B system sintered magnet material, the diffusion material (RH-Fe alloy and RL metal) input when performing the RH diffusion treatment process, the R-T-B system sintered magnet. Depending on the shape of the material, the shape of the diffusion material (RH-Fe alloy and RL metal), and the RH diffusion treatment temperature, the amount of heavy rare earth element RH (diffusion amount) to be diffused into the RTB-based sintered magnet material For example, it is 10 minutes to 72 hours. Preferably it is 1 to 12 hours.

[Temper processing]
Further, tempering (heat treatment at 400 ° C. or higher and 700 ° C. or lower) is further performed as necessary. The RH diffusion process and the temper process may be performed in the same processing chamber. The tempering time is, for example, 10 minutes to 72 hours. Preferably it is 1 to 12 hours.

  Here, the atmosphere of the heat treatment furnace for performing the tempering treatment is preferably a vacuum or an inert gas atmosphere, and the atmospheric gas pressure is preferably atmospheric pressure or lower.

[processing]
In the RTB-based sintered magnet of the present invention, the liquid phase generated on the surface of the RTB-based sintered magnet remains in the form of a film after the RH diffusion step. Since the film does not contribute to the development of magnetic properties, the surface is processed from several tens to several hundreds of micrometers from the surface of the RTB-based sintered magnet by shot blasting or a grindstone.
Furthermore, in order to obtain a predetermined shape and size, general machining such as cutting and grinding can be performed.

[surface treatment]
The RTB-based sintered magnet of the present invention is preferably subjected to a surface coating treatment for rust prevention. For example, Ni plating, Sn plating, Zn plating, Al vapor deposition film, Al alloy vapor deposition film, resin coating, etc. can be performed.

  Hereinafter, specific contents of the present invention will be described with reference to examples, but the present invention is not limited thereto.

Example 1
R-T-B system sintering whose composition is Nd _28.2 Pr _0.7 Dy _0.2 B _0.95 Co _0.9 Al _0.1 Cu _0.1 Ga _0.1 balance Fe (mass%) A raw material alloy was prepared so that a magnet material could be obtained.
The raw material alloy is a slab produced by a strip cast method, which is coarsely pulverized into an amorphous powder of a size by hydrogen pulverization, then subjected to jet mill pulverization with high-pressure N ₂ gas, and the average particle diameter of the powder is 4 at D50. A fine powder of 9 μm was prepared.

  The fine powder thus produced was molded by a press apparatus to produce a powder compact. Specifically, compression molding was performed in a state where the powder particles were magnetically oriented in an applied magnetic field. Thereafter, the compact was extracted from the press device and sintered in a vacuum furnace at 1040 ° C. for 4 hours to obtain an RTB-based sintered magnet material having the above composition. The sintered magnet material was ground to prepare 3.3 × 33 × 21 (unit: mm) RTB-based sintered magnet material.

Next, although it is a RH-Fe diffusion material, after melting in a high-frequency melting furnace using a Dy ₈₁ Fe ₁₉ (mass%) alloy and electrolytic Fe, a copper water-cooled roll rotating at a roll surface speed of 20 m / sec. A rapidly solidified alloy was prepared by contacting the molten metal. Next, this was pulverized by a stamp mill, and RH-Fe alloy powders having a Dy content of 59% by mass and 80% by mass with the balance being Fe were prepared. The particle diameters of these alloy powders were 63 μm or more and 125 μm or less on a sieve screen.

  A powder that becomes RL metal was produced by dropping and spraying Nd metal, Pr metal, La metal, or Ce metal melted in an inert gas atmosphere from a heat-resistant container. The particle diameters of these powders were 63 μm or more and 125 μm or less in all sieves.

  After applying an aqueous solution containing 2% hydroxypropylcellulose and 1% water-soluble rust preventive (trade name rust) to the RTB-based sintered magnet material, RH-Fe made of Dy-Fe alloy powder A diffusion material prepared by mixing an alloy and RL metal composed of Nd, Pr, La, or Ce powder with a rocking mixer was sprayed and air-dried for 3 hours. The total amount of diffusion material used was as shown in Table 1. The spraying amount in Table 1 represents the amount of RHFe alloy and RL metal introduced into the RTB-based sintered magnet material after the RH diffusion treatment.

Next, the RTB-based sintered magnet material was subjected to a diffusion treatment at 900 ° C. for 4 hours in an Ar atmosphere and a temper heat treatment at 480 ° C. for 2 hours. Magnets of Example 7, Comparative Example 4, and Comparative Example 5 were obtained. Further, the composition containing the same amount of Dy as in Example 4 (Nd _28.2 Pr _0.7 Dy _0.5 B _0.95 Co _0.9 Al _0.1 Cu _0.1 Ga _0.1 balance Fe An RTB-based sintered magnet material made of (mass%) was subjected only to heat treatment (Br: 1.44, HcJ: 972) was set as Comparative Example 1. Furthermore, Dy-, which is an RH-Fe alloy. The same heat treatment without mixing the Fe alloy was made Comparative Example 2, and the one not mixed with the RL metal composed of Nd or Pr was made Comparative Example 3. The RTB-based sintering prepared in advance this time. The magnet material was subjected to only heat treatment without spraying the diffusion material as a mixed powder as a reference example.

Table 1 shows the total amount of rare earths (TRE), the total amount of light rare earths (TRL) that is an amount including Nd, Pr, La, and Ce, and the amount of total heavy rare earths that is an amount that includes Dy and Tb. (TRH) and magnetic properties (B _r , H _cJ ) measured by a BH tracer after processing the sintered magnet surface from 100 μm to several hundred μm to 3 mm × 10 mm × 10 mm after RH diffusion. As a reference example, the R-T-B system sintered magnet material before RH diffusion is processed into 3 mm × 10 mm × 10 mm, and then the magnetic property values measured by the BH tracer are described. Here, "ΔB _r" represents what has changed much from the value of B _r of the reference example. “ΔH _cJ ” represents how much the value has changed from the value of H _{cJ in} the reference example.

Magnet of Example 7 from Example 1 according to the present invention are all reduced without H _cJ of B _r magnet having improved obtained for reference example.
In Example 1, the total amount of the diffusing material was the same as that in Comparative Example 3, or ΔHcJ was three times higher, regardless of the application amount of Dy-Fe alloy, which is an RH-Fe alloy, of 75%.
In Examples 2 and 3 which are the same as Example 1 except that RL is La and Ce, the total amount of the diffusing material is the same as in Comparative Example 3, or the dispersion of Dy-Fe alloy which is an RH-Fe alloy Regardless of the amount of 75%, ΔH _cJ was 1.7 times higher in Example 2 and about 3 times higher in Example 3.
In Examples 4 to 6, compared with Examples 1 to 3, the total amount of the diffusing material was small and the amount of RH-Fe applied was about 50%, but the value of ΔH _cJ was almost the same. . When the TRE is 75.4% or more and 80.2% or less, the TRL is 40% or more and 51.7% or less, and the TRH is 28.5% or more and 35.4% or more, the R-T-B system firing is performed from the diffusion material. The heavy rare earth element RH introduced into the magnet material improved _HcJ efficiently.
Further, in Example 4, ΔH _cJ was about 300 kA / m higher than Comparative Example 1 in which the same amount of Dy introduced in Example 4 was added to the Reference Example. The introduced heavy rare earth element RH was diffused so as to improve _HcJ efficiently.
Comparative Example 2 is a diffusion material consisting RL metal alone had allowed to improve the [Delta] H _CJ only slightly.
In Example 7, the amount of RH-Fe alloy is the same as that of Comparative Example 4, but the amount of RL alloy is different. In Example 7, which had 20% TRL, ΔH _cJ was twice as high as Comparative Example 4 in which TRL was 10.5%.
Further, Dy content is high Comparative Example 6 in Dy-Fe alloy, with respect to Comparative Example 1 was subjected only heat treatment, .DELTA.B _r was reduced 0.05 T. Compared with Example 1, [Delta] H _CJ Although it is similar values, .DELTA.B _r was reduced 0.05 T.

Thermal analysis TG-DTA (manufactured by Rigaku) is a DTA curve of the diffusion material of the present invention in which an RH-Fe alloy composed of DyFe ₂ , DyFe ₃ , Dy ₆ Fe ₂₃ and RL metal composed of Nd are mixed at a weight ratio of 3: 1. When measured with TG8110D), it was as shown in FIG. From FIG. 1, in the diffusing material of the present invention, even when the RH-Fe alloy was any of DyFe ₂ , DyFe ₃ , and Dy ₆ Fe ₂₃ , there was endotherm and heat generation near 750 ° C. because Nd was mixed. On the other hand, heat absorption and heat generation could not be confirmed at around 750 ° C. with only DyFe ₂ .
As can be seen from FIG. 1, in the diffusing material of the present invention, the RL metal and RH-Fe react to generate a liquid phase at around 750 ° C.

(Example 2)
The same RTB-based sintered magnet material as in Example 1 was prepared.
After melting in a high-frequency melting furnace using a Dy ₈₁ Fe ₁₉ (mass%) alloy and electrolytic Fe, hot water was poured onto a water-cooled roll to create a super-quenched ribbon. Next, this was pulverized by a stamp mill to obtain RH-Fe alloys composed of various Dy-Fe alloys having different Dy concentrations.

A dispersion material in which Nd powder, which is RL metal, and the various Dy-Fe powders, which are RH-Fe alloys, is dispersed on the surface of the sintered magnet material, and then subjected to diffusion treatment at 900 ° C. for 4 hours. These were designated as Examples 8 to 14. On the other hand, Comparative Example 6 to Comparative Example 10 were subjected to the same treatment without mixing the RL metal Nd powder.
Here, the sieves of the RH-Fe alloys made of the Dy-Fe alloy powders used in Examples 8, 10, 11, 13, 14 and Comparative Examples 6 to 10 were 63 µm or more and 125 µm or less.
The RH-Fe alloy composed of the Dy-Fe alloy powder used in Examples 9 and 12 had a sieve mesh of 63 µm or more and 710 µm or less.
Further, the RL metal composed of the Nd powder used in Examples 8 to 11, 13, 14 and Comparative Examples 6 to 10 had a sieve size of 63 μm or more and 125 μm or less. The RL metal composed of Nd powder used in Example 12 had a sieve mesh of 63 μm or more and 500 μm or less.

Table 2 shows the total rare earth amount (TRE amount), the total light rare earth amount (TRL), the total heavy rare earth amount (TRH), the magnetic properties measured by the BH tracer, B _r , and H _cJ , which are the composition of the mixed powder. Indicated.

Examples 8, 10, 11, 13, and 14 according to the present invention use RH-Fe having the same composition and the same application amount, but comparative examples 6 to 10 using a diffusion material that does not contain RL metal. In comparison, it can be seen that ΔB _r is not decreased and ΔH _cJ is improved.
In Examples 9 and 12 in which the particle size of the diffusing material was large, the diffusing material remained on the surface of the sintered magnet material, and the effect of improving the H _cJ value was reduced accordingly, but ΔH _cJ was Comparative Example 6, respectively. 3 times higher than 8.

(Example 3)
R-T-B system sintering whose composition consists of Nd _25.6 Pr _2.8 Dy _2.0 B _0.97 Co _0.9 Al _0.2 Cu _0.1 Ga _0.1 balance Fe (mass%) A raw material alloy was prepared so that a magnet was obtained. The raw material alloy is a slab produced by a strip cast method, which is roughly pulverized into an amorphous powder by hydrogen pulverization, and then subjected to jet mill pulverization with high-pressure N ₂ gas, and the average particle diameter of the powder is D50 of 4.9 μm. A fine powder was prepared.

  The fine powder thus produced was molded by a press apparatus to produce a powder compact. Specifically, compression molding was performed in a state where the powder particles were magnetically oriented in an applied magnetic field. Thereafter, the compact was extracted from the press machine and sintered in a vacuum furnace at 1050 ° C. for 4 hours to obtain a sintered magnet material of an RTB-based sintered magnet having the above composition. The sintered magnet material was ground to prepare a 2.3 × 33 × 21 (mm) sintered magnet material.

After melting in a high-frequency melting furnace using Tb metal, Dy metal, and electrolytic Fe, hot water was discharged on a water-cooled roll to form a super-quenched ribbon. Next, this was pulverized by a stamp mill to prepare an RH-Fe alloy powder composed of Tb ₅₀ Fe ₅₀ (mass%) and Tb ₂₅ Dy ₂₅ Fe ₅₀ (mass%). In this powder, Tb ₅₀ Fe ₅₀ had a sieve mesh of 63 μm or more and 125 μm or less, and Tb ₂₅ Dy ₂₅ Fe ₅₀ was 63 μm or more and 180 μm or less.

Pure Nd powder and Nd ₇₅ Pr ₂₅ (mass%) RL metal powder were produced in the same manner as in Example 1 using Nd metal and Pr metal melted in an inert gas atmosphere. The particle diameters of these powders were 63 μm or more and 125 μm or less in all sieves.

  After mixing the Tb-Fe alloy powder and the Nd powder with a mixer, the mixture dispersed on the R-T-B system sintered magnet material is Example 15 and the R-T-B system sintering without mixing the Nd powder. What was spread on the magnet material was set as Comparative Example 11. Similarly, the Tb—Dy—Fe alloy powder and the Nd—Pr alloy powder were mixed with a mixer and then applied to a sintered magnet material as Example 16.

  Next, the RTB-based sintered magnet material of Example 15 and Example 16 was subjected to RH diffusion treatment and temper treatment at 850 ° C. for 6 hours in an Ar atmosphere. Further, Comparative Example 12 was obtained by applying only the same heat treatment as the RH diffusion treatment to the sintered magnet material prepared in advance without spraying the mixed powder.

Table 3 shows the total amount of rare earths (TRE amount), total light rare earth amount (TRL), total heavy rare earth amount (TRH), and 2 mm × 7 mm × 7 mm. After processing, two samples prepared under the same conditions were overlapped, and the magnetic properties, B _r and H _cJ measured with a BH tracer were shown.

Examples 15 and 16 according to the present invention, as compared to the magnet of Comparative Example 11 and Comparative Example 12, .DELTA.B _r magnets decrease the [Delta] H _cJ not greatly improved over 500 kA / m was obtained. The magnet of Comparative Example 11 had a higher H _cJ than the magnet (Comparative Example 12) that was only heat-treated without diffusing heavy rare earth elements, but the effect was small and a large amount of Tb—Fe diffuser remained on the magnet surface. Was.

Example 4
RL metal instead of pure Nd, Nd ₈₀ Fe ₂₀ (mass%), RL metal consisting of 125 μm or less by sieve (TRE = 67.4 mass%, TRL = 32.0 mass%, TRH = 35.4 mass) %) Was used to produce the magnet of Example 16 by the same manufacturing method as that of the magnet of Example 2 of the present invention. When the magnetic properties of this magnet were measured, it was B _r = 1.44 (T) and H _CJ = 1265 (kA / m). From this result, Example 17 as compared to the magnet of Comparative Example 5 Comparative Example 1, the difference in B _r is very small, and the improvement of H _CJ was obtained.
Thus, it was found that even if a part of the RL metal is replaced with Fe within the scope of the present invention, the effect is maintained.

Claims (2)

Preparing a R-T-B sintered magnet material (R is a rare earth element, T is Fe or Fe and Co);
An RH-Fe alloy comprising heavy rare earth element RH (RH includes at least one of Dy and Tb) and 40 mass% or more and 95 mass% or less of Fe;
An RL metal containing a light rare earth element RL (including at least one of Nd, Pr, Ce, La), and
The total rare earth amount is 65% by mass or more,
Light rare earth element RL is 20 mass% or more and 70 mass% or less,
Heavy rare earth element RH is 50 mass% or less,
A step of preparing a powdery diffusion material,
With respect to the R-T-B system sintered magnet material, the diffusion material is present on the surface of the R-T-B system sintered magnet material, and vacuum or non-reactance is performed at a temperature of 800 ° C. or higher and 1000 ° C. or lower. A step of RH diffusion treatment in an active gas;
The manufacturing method of the RTB type | system | group sintered magnet which has this.   2. The method for producing an RTB-based sintered magnet according to claim 1, wherein the diffusion material has a particle size of 63 μm or more and 500 μm or less.

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