JP2018060997A - Method for manufacturing r-t-b based sintered magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an R-T-B based sintered magnet having a high coercive force H.SOLUTION: A method for manufacturing an R-T-B based sintered magnet including 28.5-33.5 mass% of a rare earth element including at least one kind of Nd and Pr, 0.84-0.92 mass% of B, 0.3-0.7 mass% of Ga, 0.05-0.35 mass% of Cu, 0.02-0.50 mass% of Al, and 61.0 mass% or more of Fe+Co, and satisfying an expression given by 14[B]/10.8<[Fe+Co]/55.85 comprises the steps of: heating at least one or more kinds of R-Ga alloys in a hydrogen atmosphere at a temperature of 200-450°C to obtain a hydrogen-occluding R-Ga alloy; mixing the hydrogen-occluding R-Ga alloy with one or more kinds of primary alloys to obtain a mixed alloy powder; molding and sintering the resultant mixture alloy; and performing a thermal treatment on the resultant mixture alloy. In the step of obtaining the mixed alloy powder, the hydrogen-occluding R-Ga alloy is pulverized with hydrogen occluded by the alloy, and the mass ratio of the R-Ga alloy powder to a mass of the mixed alloy powder is 1-5%.SELECTED DRAWING: Figure 1A

Description

  The present disclosure relates to a method for manufacturing an RTB-based sintered magnet.

R-T-B based sintered magnet (R is at least one of rare earth elements and includes at least one of Nd and Pr, T is at least one of transition metal elements and must contain Fe) _It consists of a main phase composed of a compound having a ₂ T ₁₄ B-type crystal structure and a grain boundary phase located at the grain boundary portion of this main phase, and is known as the most powerful magnet among permanent magnets. Yes.

  For this reason, it is used for various applications such as various motors such as voice coil motors (VCM) for hard disk drives, motors for electric vehicles (EV, HV, PHV), motors for industrial equipment, and home appliances.

  As the application expands in this way, for example, when used in an electric vehicle motor, it may be exposed to a high temperature such as 100 ° C. to 160 ° C., and stable operation is required even at a high temperature. .

However, the conventional _RTB -based sintered magnet has a _problem that the coercive force H _cJ (hereinafter sometimes simply referred to as “H _cJ ”) decreases at a high temperature and irreversible thermal demagnetization occurs. is there. When an R-T-B sintered magnet is used for a motor for an electric vehicle, _HcJ decreases due to use at a high temperature, and there is a possibility that stable operation of the motor cannot be obtained. Therefore, an _RTB -based sintered magnet having high H _cJ at room temperature and high H _cJ even at high temperature is required.

In order to improve _HcJ at room temperature, a heavy rare earth element RH (mainly Dy) has been added to a conventional RTB-based sintered magnet, but the residual magnetic flux density B _r (hereinafter simply referred to as “B _r ”). There is a problem that it may decrease). Furthermore, Dy has problems such as supply being unstable and price fluctuating due to the limited production area. Therefore, there is a demand for a technique for improving _HcJ of an R-T-B based sintered magnet without using a heavy rare earth element RH such as Dy as _much as possible.

As such a technique, for example, Patent Document 1 contains a metal element M that is one or more selected from Al, Ga, and Cu while lowering the B amount than a normal RTB-based alloy. The R ₂ T ₁₇ phase is generated by making the R ₂ T ₁₇ phase a raw material, and the volume ratio of the transition metal rich phase (R-T-Ga phase) generated using the R ₂ T ₁₇ phase as a raw material is sufficiently ensured. It discloses that an RTB-based sintered magnet having a high coercive force can be obtained while suppressing the amount.

International Publication No. 2013/008756

However, although the _RTB -based sintered magnet described in Patent Document 1 has improved _HcJ , it is insufficient to satisfy recent requirements.

Then, an _object of this invention is to provide the manufacturing method of the _RTB system sintered magnet which has high coercive force _HcJ .

Aspect 1 of the present invention
R1: 28.5-33.5% by mass (R1 is at least one of rare earth elements and includes at least one of Nd and Pr),
B: 0.84 to 0.92 mass%,
Ga: 0.3-0.7 mass%,
Cu: 0.05 to 0.35 mass%,
Al: 0.02-0.50 mass%,
Production of RTB-based sintered magnet including T: 61.0% by mass or more (T is Fe and Co, and 90% by mass or more of T is Fe) and satisfies the following formula (1) A method,

14 [B] /10.8 <[T] /55.85 (1)
([B] is the B content in mass%, and [T] is the T content in mass%)

R2: 80 to 95% by mass (R2 is at least one of rare earth elements),
Ga: 5 to 20% by mass (40% by mass or less of Ga can be replaced with Cu),
Preparing one or more R-Ga alloys including Fe: 0 to 1% by mass (part or all of Fe can be replaced with Co) and one or more main alloys;
A hydrogen storage step of heating the R-Ga alloy to a temperature of 200 ° C. or higher and 450 ° C. or lower in a hydrogen atmosphere to obtain a hydrogen storage R-Ga alloy;
Using the one or more hydrogen storage R-Ga alloys and the one or more main alloys to obtain a mixed alloy powder including the R-Ga alloy powder and the main alloy powder;
A molding step of molding the mixed alloy powder to obtain a molded body;
A sintering step of sintering the molded body to obtain a sintered body;
A heat treatment step for heat-treating the sintered body;
Including
In the step of obtaining the mixed alloy powder, at least the one or more hydrogen storage R-Ga alloys are pulverized in a state of storing hydrogen,
It is a manufacturing method of the RTB system sintered magnet whose ratio of the mass of the R-Ga alloy powder to the mass of the mixed alloy powder is 1 to 5%.

Aspect 2 of the present invention is the production of the RTB-based sintered magnet according to aspect 1, wherein the step of obtaining the mixed alloy powder obtains the mixed alloy powder according to the following (Condition a) or (Condition b). Is the method.
(Condition a) Obtained by pulverizing the main alloy with R-Ga alloy powder obtained by pulverizing the hydrogen-occluded R-Ga alloy in a state where the hydrogen-occlusion R-Ga alloy occludes hydrogen. Main alloy powder is mixed.
(Condition b) Obtaining a mixed alloy obtained by mixing the hydrogen storage R-Ga alloy and the coarsely pulverized powder of the main alloy, and in the state where the hydrogen storage R-Ga alloy stores hydrogen, Smash.

  Aspect 3 of the present invention is the method for producing an RTB-based sintered magnet according to aspect 1 or 2, wherein the hydrogen content in the hydrogen storage R-Ga alloy is 2600 ppm or more.

Aspect 4 of the present invention
R1: 28.5-33.5% by mass (R1 is at least one of rare earth elements and includes at least one of Nd and Pr),
B: 0.84 to 0.92 mass%,
Ga: 0.3-0.7 mass%,
Cu: 0.05 to 0.35 mass%,
Al: 0.02-0.50 mass%,
Including
The balance is T (T is Fe and Co, and 90% by mass or more of T is Fe) and inevitable impurities, and the manufacturing method of the RTB-based sintered magnet satisfying the following formula (1) Because

14 [B] /10.8 <[T] /55.85 (1)
([B] is the B content in mass%, and [T] is the T content in mass%)

R2: 80 to 95% by mass (R2 is at least one of rare earth elements),
Ga: 5 to 20% by mass (40% by mass or less of Ga can be replaced with Cu),
Preparing one or more R-Ga alloys including Fe: 0 to 1% by mass (part or all of Fe can be replaced with Co) and one or more main alloys;
A hydrogen storage step of heating the R-Ga alloy to a temperature of 200 ° C. or higher and 450 ° C. or lower in a hydrogen atmosphere to obtain a hydrogen storage R-Ga alloy;
A step of obtaining a mixed alloy powder containing an R-Ga alloy powder and a main alloy powder according to the following (condition a) or (condition b);
(Condition a) Obtained by pulverizing the main alloy with R-Ga alloy powder obtained by pulverizing the hydrogen-occluded R-Ga alloy in a state where the hydrogen-occlusion R-Ga alloy occludes hydrogen. (Condition b) A mixed alloy obtained by mixing the hydrogen storage R-Ga alloy and the coarsely pulverized powder of the main alloy is obtained, and the hydrogen storage R-Ga alloy stores hydrogen. In a state where the mixed alloy is pulverized, a forming step of forming the mixed alloy powder to obtain a formed body,
A sintering step of sintering the molded body to obtain a sintered body;
A heat treatment step for heat-treating the sintered body;
And the ratio of the mass of the R-Ga alloy powder to the mass of the mixed alloy powder is 1 to 5%.

  Aspect 5 of the present invention is the method for producing an RTB-based sintered magnet according to aspect 4, wherein the hydrogen content in the hydrogen storage R—Ga alloy is 2600 ppm or more.

Aspect 6 of the present invention
In (condition a) in the step of obtaining the mixed alloy powder, after the hydrogen storage step, the hydrogen storage R-Ga alloy is pulverized without heating the hydrogen storage R-Ga alloy to a temperature exceeding 450 ° C. The method for producing an RTB-based sintered magnet according to aspect 2 or 4, characterized in that:

  In aspect 7 of the present invention, in the step (condition a) of obtaining the mixed alloy powder, the hydrogen storage R-Ga alloy is pulverized without heating the hydrogen storage R-Ga alloy after the hydrogen storage step. It is a manufacturing method of the RTB type | system | group sintered magnet of aspect 2 or 4 characterized by these.

  Aspect 8 of the present invention provides the mixed alloy powder without heating the hydrogen storage R—Ga alloy to a temperature exceeding 450 ° C. after the hydrogen storage step in the condition (b) of obtaining the mixed alloy powder. The method for producing an RTB-based sintered magnet according to the aspect 2 or 4, characterized in that:

  Aspect 9 of the present invention is characterized in that, in (condition b) of the step of obtaining the mixed alloy powder, after the hydrogen storage step, the mixed alloy is pulverized without heating the hydrogen storage R-Ga alloy. It is a manufacturing method of the RTB type sintered magnet of the aspect 2 or 4.

_ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the _{RTB type |} system _| group sintered magnet which has high coercive force _HcJ can be provided.

FIG. 1A is a flowchart showing an example of the process of the present invention under (condition a). FIG. 1B is a flowchart showing an example of the process of the present invention in (Condition b).

  Embodiment shown below illustrates the manufacturing method of the RTB type sintered magnet for materializing the technical idea of this invention, Comprising: This invention is not limited below.

As described in Patent Document 1, the amount of B is smaller than that of a general RTB-based sintered magnet (less than the amount of B in the stoichiometric ratio of the R ₂ T ₁₄ B type compound), By adding Ga or the like, a transition metal rich phase (RT-Ga phase) can be generated and _HcJ can be improved. However, as a result of intensive studies by the present inventors, the RT-Ga phase has a slight magnetization, and the first grain boundary existing between the two main phases in the RTB-based sintered magnet. (Hereinafter sometimes referred to as “two-grain grain boundaries”) and second grain boundaries existing between three or more main phases (hereinafter sometimes referred to as “triple-grain grain boundaries”) , especially when R-T-Ga phase is often present in the second grain boundaries that would mainly affect H _cJ, it was found to hinder _{H cJ} increased. Further, it was found that, along with the generation of the R—T—Ga phase, an R—Ga phase considered to have a magnetization lower than that of the R—T—Ga phase was generated at the grain boundary. Therefore, in order to obtain an _RTB -based sintered magnet having high _HcJ , it is necessary to generate an RT-Ga phase, but a large amount of R-Ga phase is generated at the grain boundary. Was assumed to be important.

  In order to produce a large amount of R-Ga phase at the two-particle grain boundary, the present inventors prepare R-Ga alloy powder and main alloy powder, and mix these alloy powders by a so-called blending method. It was considered effective to produce a -T-B based sintered magnet.

However, the R-Ga alloy has poor grindability, and even in the blending method, even when the R-Ga alloy is ground using a normal method such as hydrogen grinding to obtain the R-Ga alloy powder, D ₅₀ (according to the air flow dispersion type laser diffraction method). It could only be pulverized to a volume median value (volume reference median diameter) obtained by measurement, which is the same hereinafter) of about 20 μm. When an R-T-B system sintered magnet is manufactured by a blend method using an R-Ga alloy having such a size, an R-Ga phase is formed at the two-particle grain boundary of the R-T-B system sintered magnet. It can not be sufficiently produced, and further, the first place the particle size is too large (high H _cJ and high to obtain a B _r has to be ground to 8μm or less) for high coercivity H _cJ and remanence B _{An RTB} -based sintered magnet having _r could not be obtained. Although the grindability could be improved by adding excessive Fe to the R-Ga alloy, in this case, it has magnetization at the two-grain boundary of the obtained RTB-based sintered magnet. The Fe concentration increased and it was still _impossible to obtain high _HcJ .

As a result of further intensive studies, the present inventors have determined that in the blending method, hydrogen is occluded at a specific temperature with respect to an R—Ga alloy having a specific composition, and hydrogen is occluded (hydrogen content is 2600 ppm or more). It was found that by pulverizing the —Ga alloy, the size of the obtained R—Ga alloy powder can be reduced to D ₅₀ of 8 μm or less. Accordingly, the R—Ga alloy can be pulverized to 8 μm or less without excessively adding Fe that causes _HcJ to decrease. And many R-Ga phases are produced | generated in a two-particle grain boundary by producing a RTB system sintered magnet using the R-Ga alloy of the specific composition of this invention, and the main alloy powder. it is conceivable that. This makes it possible to obtain the R-T-B based sintered magnet having a high coercive force H _cJ of and high residual magnetic flux density B _r.
The manufacturing method according to the embodiment of the present invention will be described in detail below.

[RTB-based sintered magnet]
First, the RTB system sintered magnet obtained by the manufacturing method according to the embodiment of the present invention will be described.

[Composition of RTB-based sintered magnet]
The composition of the RTB-based sintered magnet according to this embodiment is
R1: 28.5-33.5% by mass (R1 is at least one of rare earth elements and includes at least one of Nd and Pr),
B: 0.84 to 0.92 mass%,
Ga: 0.3-0.7 mass%,
Cu: 0.05 to 0.35 mass%,
Al: 0.02-0.50 mass%,
T: 61.0 mass% or more (T is Fe and Co, and 90 mass% or more of T is Fe), and satisfies the following formula (1).

14 [B] /10.8 <[T] /55.85 (1)
([B] is the B content in mass%, and [T] is the T content in mass%.)

In addition, the composition of the RTB-based sintered magnet according to a preferred embodiment of the present invention is:
R1: 28.5 to 33.5 mass% (R1 is at least one rare earth element and includes at least one of Nd and Pr),
B: 0.84 to 0.92 mass%,
Ga: 0.3-0.7 mass%,
Cu: 0.05 to 0.35 mass%,
Al: 0.02-0.50 mass%,
Including
The balance is T (T is Fe and Co, 90% by mass or more of T is Fe) and inevitable impurities, and satisfies the following formula (1).

14 [B] /10.8 <[T] /55.85 (1)
([B] is the B content in mass%, and [T] is the T content in mass%)

With the above composition, the amount of B is smaller than that of a general RTB-based sintered magnet, and Ga and the like are contained. Therefore, an RT-Ga phase is generated at the two-grain grain boundary, _Can have a high H _cJ . Here, the R—T—Ga phase is typically an Nd ₆ Fe ₁₃ Ga compound. The R ₆ T ₁₃ Ga compound has a La ₆ Co ₁₁ Ga ₃ type crystal structure. Moreover, the R ₆ T ₁₃ Ga compound may be an R ₆ T _13-δ Ga _{1 + δ} compound (δ is typically 2 or less) depending on the state. For example, relatively large Cu in R-T-B based sintered magnet, if the Al is _contained, may have been the _{R 6 T 13-δ (Ga} 1-x-y Cu x Al y) 1 + δ is there.
Below, each composition is explained in full detail.

(R1: 28.5-33.5% by mass)
R1 is at least one of rare earth elements and includes at least one of Nd and Pr. Content of R1 is 28.5-33.5 mass%. R1 is may become difficult to densification during sintering is less than 28.5% by mass, there is a possibility that the main phase proportion exceeds 33.5% by weight can not be obtained a high B _r drops . The content of R1 is preferably 29.5 to 32.5% by mass. If R1 is in such a range, higher _Br can be obtained.

(B: 0.84-0.92 mass%)
Content of B is 0.84-0.92 mass%. If B is less than 0.84% by mass, R ₂ T ₁₇ phase may be produced and high H _cJ may not be obtained. If it exceeds 0.92% by mass, the amount of R—T—Ga phase produced is small. _Therefore, there is a possibility that high _HcJ cannot be obtained. The content of B is preferably 0.85 to 0.92% by mass. A part of B can be replaced with C.

The content of B satisfies the following formula (1).

14 [B] /10.8 <[T] /55.85 (1)

By satisfying the formula (1), the content of B becomes smaller than that of a general RTB-based sintered magnet. A general R-T-B type sintered magnet has [T] /55.85 (so that an R ₂ T ₁₇ phase, which is a soft magnetic phase, is not generated in addition to an R ₂ T ₁₄ B phase, which is a main phase. The atomic weight of Fe is less than 14 [B] /10.8 (the atomic weight of B) ([T] is the Fe content expressed in mass%). The R-T-B system sintered magnet of the present invention is different from a general R-T-B system sintered magnet in that [T] /55.85 is larger than 14 [B] /10.8. Is defined by equation (1). Since the main component of T in the RTB-based sintered magnet of the present invention is Fe, the atomic weight of Fe was used.

(Ga: 0.3-0.7 mass%)
The Ga content is 0.3 to 0.7% by mass. If Ga is less than 0.3% by mass, the amount of R—T—Ga phase produced is so small that the R ₂ T ₁₇ phase cannot be lost and high H _cJ may not be obtained. It will be present unnecessary Ga exceeds 0.7 weight%, there is a possibility that B _r decreases to decrease the main phase proportion.

(Cu: 0.05 to 0.35 mass%)
The content of Cu is 0.05 to 0.35 mass%. If Cu is less than 0.05% by mass, high H _cJ may not be obtained, and if it exceeds 0.35% by mass, sinterability may deteriorate and high H _cJ may not be obtained.

(Al: 0.02-0.50 mass%)
The Al content is 0.02 to 0.50 mass%. By containing Al, _HcJ can be improved. Al is usually contained in an amount of 0.02% by mass or more as an inevitable impurity in the production process, but it may be contained in an amount of 0.50% by mass or less in total of the amount contained in the inevitable impurity and the amount intentionally added. Good.

(T: 61.0 mass% or more (T is Fe and Co, and 90 mass% or more of T is Fe))
T is at least one of transition metal elements and necessarily contains Fe. In addition, 10% by mass or less of Fe can be replaced with Co. That is, 90% by mass or more of T is Fe. Although the corrosion resistance can be improved by containing Co, if the substitution amount of Co exceeds 10% by mass of Fe, high _Br may not be obtained. The content of T is 61.0% by mass or more and satisfies the above-described formula (1). When the content of T is less than 61.0% by mass may greatly B _r drops. Preferably, T is the balance.

Furthermore, the RTB-based sintered magnet of the present invention includes Cr, Mn, Si, La, Ce, Sm, unavoidable impurities normally contained in didymium alloy (Nd-Pr), electrolytic iron, ferroboron, and the like. Ca, Mg and the like can be contained. Furthermore, O (oxygen), N (nitrogen), C (carbon), etc. can be illustrated as an inevitable impurity in a manufacturing process. In addition, the RTB-based sintered magnet of the present invention may contain one or more other elements (elements intentionally added other than unavoidable impurities). For example, as such an element, a small amount (each about 0.1% by mass) of V, Ni, Mo, Hf, Ta, W, Nb, Zr and the like may be contained. Such elements may be included in a total amount of 0.5% by mass or less, for example. If it is this grade, it is fully possible to obtain the _RTB system sintered magnet which has high _HcJ .

The RTB-based sintered magnet having the composition according to the present embodiment described above can be manufactured by a blend method using one or more main alloys and one or more R-Ga alloys. Specifically, a step of preparing a main alloy and an R—Ga alloy, a hydrogen storage step of obtaining a hydrogen storage R—Ga alloy, and a step of obtaining a mixed alloy powder including the R—Ga alloy powder and the main alloy powder. In addition, the manufacturing process includes a forming step of forming a mixed alloy powder to obtain a formed body, a sintering step of sintering the formed body to obtain a sintered body, and a heat treatment step of applying a heat treatment to the sintered body.
Below, the detail of the manufacturing method of the RTB type | system | group sintered magnet which concerns on embodiment of this invention is demonstrated.

1. Step of preparing main alloy and R-Ga alloy [main alloy]
In the main alloy according to an aspect of the present invention, R _m (R _m is at least one rare earth element and includes at least one of Nd and Pr) is 27.5% by mass or more. R _m can be any composition which is adjusted so that the R-T-B based sintered magnet having a composition described above was mixed with R-Ga alloy to be described later. Typically, R _m it is possible to use a 27.5 wt% or more of the known R-T-B based sintered magnet alloys. R _m there is a possibility that the densification becomes difficult at the time of sintering of the R-T-B based sintered magnet of the present invention is less than 27.5 wt%. The main alloy may be one type of alloy, or may be composed of two or more types of alloys having different compositions.

  The main alloy having the above-described composition is, for example, a flaky alloy slab that can be obtained by an ingot method by die casting, a strip cast method in which a molten alloy is rapidly cooled using a cooling roll, or the like.

[R-Ga alloy]
The composition of the R—Ga alloy according to an embodiment of the present invention is as follows:
R2: 80 to 95% by mass (R2 is at least one of rare earth elements),
Ga: 5 to 20% by mass (40% by mass or less of Ga can be replaced with Cu),
Fe: 0 to 1% by mass (some or all of Fe can be replaced with Co).

Such an R-Ga alloy having a composition by heating to a specific temperature to occlude hydrogen, by grinding remain occluded hydrogen, fine R-Ga alloy powder D ₅₀ is 8μm or less Can be obtained. The mixed alloy powder containing the R-Ga alloy powder thus obtained and the main alloy powder obtained by pulverizing the main alloy described above in a specific mass ratio is molded, sintered and heat treated to increase the An _RTB -based sintered magnet having _HcJ can be obtained.

In addition, a mixed alloy obtained by mixing a hydrogen storage R-Ga alloy obtained by heating an R-Ga alloy having such a composition to a specific temperature to occlude hydrogen and a coarsely pulverized powder of the main alloy is obtained. Te, hydrogen storage R-Ga alloy remain occluded hydrogen, by grinding a mixed alloy, mixing the alloy powder containing fine R-Ga alloy powder D ₅₀ is 8μm or less is obtained. An _RTB -based sintered magnet having high _HcJ can be obtained by molding, sintering and heat-treating the mixed alloy powder.
The reason for limitation of each element is described below.

(R2: 80 to 95% by mass)
R2 is at least one rare earth element. The content of R2 is 80 to 95% by mass. If R2 is less than 80% by mass, an R-T-B system sintered magnet having high _HcJ may not be obtained, and if it exceeds 95% by mass, the amount of R2 is too large, which causes oxidation problems. Occurring may cause a decrease in magnetic properties, a risk of ignition, and the like, which may cause production problems.

(Ga: 5 to 20% by mass)
The Ga content is 5 to 20% by mass. If Ga is less than 5% by mass, an R—T—B-based sintered magnet having high H _cJ may not be obtained, and if it exceeds 20% by mass, H _cJ may decrease. 40% by mass or less of Ga can be replaced with Cu.

(Fe: 0 to 1% by mass)
The content of Fe is 0 to 1% by mass. When Fe exceeds 1 mass%, high _HcJ cannot be obtained. Also, some or all of Fe can be replaced with Co. Preferably, the R—Ga alloy does not contain Fe and Co.

  The R—Ga alloy preferably contains R2, Ga, and Fe in the above-described range, and the balance is made of inevitable impurities. As unavoidable impurities, for example, Cr, Mn, Si, La, Ce, Sm, Ca, Mg and the like can be contained. Furthermore, O (oxygen), N (nitrogen), C (carbon), etc. can be illustrated as an inevitable impurity in a manufacturing process. Moreover, you may contain a small amount (about 0.1 mass%) of V, Ni, Mo, Hf, Ta, W, Nb, Zr, etc.

  The R—Ga alloy having the above-described composition can be manufactured by the same method as the manufacturing method of the known RTB-based sintered magnet. For example, a flake-shaped alloy slab is produced by an ingot method using die casting, a strip casting method in which a molten alloy is rapidly cooled using a cooling roll, or the like. Note that the R—Ga alloy may be one type of alloy or may be composed of two or more types of alloys having different compositions.

2. Hydrogen storage process for obtaining a hydrogen storage R-Ga alloy [hydrogen storage process]
The R—Ga alloy having the above composition is heated to a temperature of 200 ° C. or more and 450 ° C. or less in a hydrogen atmosphere to obtain a hydrogen storage R—Ga alloy (coarse pulverized powder). Specifically, a flaky R-Ga alloy slab is accommodated in a hydrogen furnace and a hydrogen storage process is performed. In the hydrogen storage treatment, the inside of the hydrogen furnace is evacuated, the furnace temperature is set to 200 ° C. or higher and 450 ° C. or lower, and hydrogen gas having a pressure of 30 kPa to 1.0 MPa is supplied into the hydrogen furnace (that is, In a hydrogen atmosphere), and hydrogen is occluded in the R—Ga alloy slab. The heating temperature for the R—Ga alloy can be confirmed by attaching a thermocouple to the R—Ga alloy. Due to the occlusion of hydrogen, the R-Ga alloy slab spontaneously collapses and becomes brittle (partially pulverized) to obtain a coarsely powdered hydrogen occlusion R-Ga alloy of, for example, 1.0 mm or less. When the hydrogen occlusion treatment is performed at a temperature lower than 200 ° C., the hydrogen occlusion amount is too small, so that it cannot be embrittled. Moreover, if it heats to the temperature over 450 degreeC, a R-Ga alloy will fuse | melt and it cannot grind | pulverize. Accordingly, the R—Ga alloy is subjected to hydrogen storage treatment at a temperature of 200 ° C. or higher and 450 ° C. or lower. By performing the hydrogen occlusion treatment in such a temperature range, a fine R—Ga alloy powder having a D ₅₀ of 8 μm or less can be obtained in the pulverization step described later, and the R—Ga alloy powder is used for the production. The _RTB -based sintered magnet can have a high _HcJ .
In the present specification, the “hydrogen storage R—Ga alloy” means a coarse powdered R—Ga alloy obtained by hydrogen storage treatment of an R—Ga alloy.

3. Step of obtaining mixed alloy powder Next, using the one or more hydrogen storage R-Ga alloys (coarse pulverized powder) and the one or more main alloys, R-Ga alloy powder (fine pulverized powder) and main A mixed alloy powder (fine pulverized powder) containing an alloy powder (fine pulverized powder) is obtained. In the step of obtaining a mixed alloy powder (fine pulverized powder), at least the one or more hydrogen storage R-Ga alloys (coarse pulverized powder) are pulverized (fine pulverized) in a state of storing hydrogen. The mixed alloy powder (finely pulverized powder) may be obtained by mixing a hydrogen storage R-Ga alloy (coarse pulverized powder) and the main alloy and then pulverizing, or the hydrogen storage R-Ga alloy and the main alloy. You may obtain by mixing after grind | pulverizing separately (coarse grinding | pulverization and fine grinding | pulverization). For example, a mixed alloy powder containing an R—Ga alloy powder and a main alloy powder is obtained under the following condition (a) or condition (b).

(Condition a) R-Ga alloy obtained by pulverizing (finely pulverizing) a hydrogen storage R-Ga alloy (coarse pulverized powder) in a state where the hydrogen storage R-Ga alloy (coarse pulverized powder) occludes hydrogen The powder (finely pulverized powder) and the main alloy powder (finely pulverized powder) obtained by pulverizing (roughly and finely pulverizing) the main alloy are mixed.
(Condition b) A mixed alloy (coarse pulverized powder) obtained by mixing a hydrogen storage R-Ga alloy (coarse pulverized powder) and a main alloy coarse pulverized powder is obtained, and the hydrogen storage R-Ga alloy (coarse pulverized powder) is hydrogen. The mixed alloy (coarse pulverized powder) is pulverized (finely pulverized) while occluded.

(Conditions a) and by any method (condition b), D ₅₀ can be obtained a mixed alloy powder containing the following R-Ga alloy powder pulverized powdery 8 [mu] m (pulverized powder). Such mixed alloy powder forming the (pulverized powder), by sintering and heat treatment, to obtain a R-T-B based sintered magnet having a high residual magnetic flux density B _r and a high coercive force H _cJ it can.
Hereinafter, (Condition a) and (Condition b) will be described.

[(Condition a) R-Ga obtained by pulverizing (finely pulverizing) a hydrogen storage R-Ga alloy (coarse pulverized powder) in a state where the hydrogen storage R-Ga alloy (coarse pulverized powder) occludes hydrogen The alloy powder (finely pulverized powder) and the main alloy powder (finely pulverized powder) obtained by pulverizing (roughly and finely pulverizing) the main alloy are mixed.
The mixed alloy powder (finely pulverized powder) according to the present invention may be obtained by mixing the prepared R-Ga alloy powder (finely pulverized powder) and the main alloy powder (finely pulverized powder).
FIG. 1A is a flowchart showing an example of the process of the present invention under (condition a). As shown in FIG. 1A, in the case of (Condition a), the main alloy and R-Ga alloy coarsely pulverized powder (main alloy coarsely pulverized powder and hydrogen storage R-Ga alloy (coarse pulverized powder)) were prepared separately. Further, finely pulverized powders (main alloy powder and R-Ga alloy powder) are produced separately. Then, the produced main alloy powder (finely pulverized powder) and R-Ga alloy powder (finely pulverized powder) are mixed to obtain a mixed alloy powder (finely pulverized powder).

Step of pulverizing (finely pulverizing) hydrogen storage R-Ga alloy (coarse pulverized powder) to obtain R-Ga alloy powder (fine pulverized powder) First, the obtained hydrogen storage R-Ga alloy (coarse pulverized powder) By pulverizing (pulverizing), an R-Ga alloy powder (fine pulverized powder) is obtained. Specifically, in the state where the obtained hydrogen storage R-Ga alloy (coarse pulverized powder) occludes hydrogen, the R-Ga alloy powder (fine A pulverized powder is obtained. Here, in the present invention, the hydrogen occlusion R-Ga alloy occludes hydrogen means that the hydrogen content (hydrogen content) contained in the hydrogen occlusion R-Ga alloy is 2600 ppm or more. By milling in a state where hydrogen storage R-Ga alloy is occluded hydrogen can be D ₅₀ to obtain a R-Ga alloy powder 8μm following finely pulverized powder form. The _RTB -based sintered magnet manufactured using the R-Ga alloy powder can have a high _HcJ .

In addition, when the hydrogen storage R-Ga alloy (coarse pulverized powder) is dehydrogenated by heating to a temperature of, for example, about 500 ° C to 800 ° C, the hydrogen storage R-Ga alloy (coarse pulverized powder) is almost hydrogenated. no longer contain, for thereby further melting hydrogen storage R-Ga alloy (coarsely pulverized powder), by the grinding process, D ₅₀ can not get 8μm following R-Ga alloy powder (pulverized powder) .

After obtaining the hydrogen occlusion R-Ga alloy (coarse pulverized powder) in the hydrogen occlusion process described above (that is, from the time when the hydrogen occlusion R-Ga alloy is taken out from the hydrogen furnace), until the fine pulverization is completed, It is preferable to pulverize the hydrogen storage R—Ga alloy (coarse pulverized powder) without heating to a temperature exceeding 450 ° C. With such a condition, since the hydrogen storage R-Ga alloy (coarsely pulverized powder) is not melted, D ₅₀ can be obtained reliably following R-Ga alloy powder pulverized powdery 8 [mu] m.
More preferably, the hydrogen storage R-Ga alloy (coarse pulverized powder) after the hydrogen storage step is pulverized (fine pulverized) without heating the hydrogen storage R-Ga alloy (coarse pulverized powder). (However, since the temperature of the hydrogen storage R-Ga alloy may increase during fine pulverization, the temperature increase due to its own heat generation is not included in the heating.)
In the present specification, “alloy powder” means a finely pulverized powder having a D ₅₀ of 8 μm or less.

  A known lubricant may be added as an auxiliary agent to the coarsely pulverized powder (that is, hydrogen storage R—Ga alloy) before jet mill pulverization, and to the alloy powder during and after jet mill pulverization.

As described above, the R—Ga alloy is subjected to a hydrogen occlusion treatment at a temperature of 200 ° C. or higher and 450 ° C. or lower, and pulverized in a state where the hydrogen is occluded, whereby an R—Ga alloy powder having a D ₅₀ of 8 μm or less. (Finely pulverized powder) can be obtained. By using such a fine R-Ga alloy powder to produce an R-T-B system sintered magnet by a blend method in which it is mixed with the main alloy powder, many R-Ga phases are present at the two-grain grain boundaries. An _RTB -based sintered magnet having a high H _cJ can be obtained. Here, the R-Ga phase includes R: 70% by mass or more and 95% by mass or less, Ga: 5% by mass or more and 30% by mass or less, and T (Fe): 20% by mass or less (including 0). When a relatively large amount of Cu is contained in the RTB-based sintered magnet, a part of Ga is substituted with Cu, so that it may be, for example, an R ₃ (Ga, Cu) ₁ compound.

Step of mixing R-Ga alloy powder (finely pulverized powder) and main alloy powder (finely pulverized powder) The R-Ga alloy powder (finely pulverized powder) thus obtained and the main alloy are pulverized ( A mixed alloy powder (finely pulverized powder) containing a main alloy powder (finely pulverized powder) obtained by coarse pulverization and fine pulverization) is obtained.
Specifically, the mixed alloy powder (finely pulverized powder) includes an R-Ga alloy powder (finely pulverized powder) obtained by pulverizing a hydrogen storage R-Ga alloy (coarsely pulverized powder), and a main alloy pulverized (roughly). The main alloy powder (finely pulverized powder) obtained by pulverization and fine pulverization is prepared and mixed. The R-Ga alloy powder (finely pulverized powder) and the main alloy powder (finely pulverized powder) may be mixed with a known mixer such as a V-type mixer, for example.
In this case, apart from the step of obtaining the R-Ga alloy powder (finely pulverized powder), the main alloy powder (finely pulverized powder) is prepared using a known pulverization method as described above. Specifically, the main alloy is coarsely pulverized by hydrogen pulverization or the like to prepare a coarsely pulverized powder (coarse powder of the main alloy) having an average particle size of 1.0 mm or less. Next, the coarsely pulverized powder is finely pulverized by a jet mill in an inert gas, for example, the particle size D ₅₀ of obtained finely pulverized powder 3~5μm (mainly alloy powder). By mixing the main alloy powder (finely pulverized powder) thus obtained and the R-Ga alloy powder (finely pulverized powder) obtained in the step of obtaining the R-Ga alloy powder (finely pulverized powder). A mixed alloy powder (finely pulverized powder) can be obtained.

[(Condition b) A mixed alloy (coarse pulverized powder) obtained by mixing the hydrogen storage R-Ga alloy (coarse pulverized powder) and the main alloy coarse pulverized powder was obtained, and the hydrogen storage R-Ga alloy (coarse pulverized) The mixed alloy (coarse pulverized powder) is pulverized (finely pulverized) while the powder) is storing hydrogen.]
Moreover, the mixed alloy powder (finely pulverized powder) according to the embodiment of the present invention is a pulverized mixed alloy (coarse pulverized powder) obtained by mixing a hydrogen storage R-Ga alloy (coarsely pulverized powder) and a coarsely pulverized powder of the main alloy. It may be obtained by (pulverization).
FIG. 1B is a flowchart showing an example of the process of the present invention under (condition b). As shown in FIG. 1B, in the case of (Condition b), the main alloy and R-Ga alloy coarsely pulverized powder (main alloy coarsely pulverized powder and hydrogen storage R-Ga alloy (coarse pulverized powder)) were prepared separately. Thereafter, the coarsely pulverized powder of the main alloy and the hydrogen storage R-Ga alloy (coarse pulverized powder) are mixed to obtain a mixed alloy (coarse pulverized powder). The obtained mixed alloy (coarse pulverized powder) is pulverized (fine pulverized) to obtain a mixed alloy powder (fine pulverized powder).

-Step of obtaining mixed alloy First, the main alloy is pulverized using a known pulverization method (for example, hydrogen pulverization) to obtain coarsely pulverized powder of the main alloy having a size of 1.0 mm or less, for example. Next, a mixed alloy is obtained by mixing the coarsely pulverized powder of the obtained main alloy and the hydrogen storage R—Ga alloy.

-The process of grind | pulverizing a mixed alloy The mixed alloy powder is obtained by grind | pulverizing the mixed alloy obtained in this way.
Specifically, mixing is performed by pulverizing the mixed alloy with a jet mill or the like in an inert gas in a state where the hydrogen storage R-Ga alloy (coarse pulverized powder) contained in the mixed alloy stores hydrogen. An alloy powder is obtained. Here, the state where the hydrogen storage R-Ga alloy (coarse pulverized powder) contained in the mixed alloy occludes hydrogen means the hydrogen contained in the hydrogen storage R-Ga alloy (coarse pulverized powder) contained in the mixed alloy. The amount (hydrogen content) is 2600 ppm or more. In a state where hydrogen storage R-Ga alloy mixture contained in the alloy (coarsely pulverized powder) (coarsely pulverized powder) is storing hydrogen by mixing alloy (coarsely pulverized powder) is finely pulverized, D ₅₀ is 8μm or less A mixed alloy powder containing the finely pulverized powdered R-Ga alloy powder can be obtained. The _RTB -based sintered magnet manufactured using the mixed alloy powder can have a high _HcJ .

In addition, when the dehydrogenation process heated to the temperature of about 500 to 800 degreeC is performed with respect to the mixed alloy (coarse pulverized powder) containing a hydrogen storage R-Ga alloy (coarse pulverized powder), it will be contained in the mixed alloy. The hydrogen occlusion R-Ga alloy (coarse pulverized powder) hardly contains hydrogen, and the hydrogen occlusion R-Ga alloy (coarse pulverized powder) is melted. Therefore, R ₅₀ having a D50 of 8 μm or less is obtained by the pulverization step. A mixed alloy powder (finely pulverized powder) containing a Ga alloy powder (finely pulverized powder) cannot be obtained.

After obtaining the hydrogen occlusion R-Ga alloy (coarse pulverized powder) in the hydrogen occlusion process described above (that is, from when the hydrogen occlusion R-Ga alloy is taken out from the hydrogen furnace), the mixed alloy (coarse pulverized powder) is finely mixed. Until the pulverization is completed, the mixed alloy (coarse pulverized powder) is pulverized without heating the hydrogen storage R-Ga alloy (coarse pulverized powder) contained in the mixed alloy (coarse pulverized powder) to a temperature exceeding 450 ° C. ( It is preferable to pulverize. With such a condition, since the hydrogen storage R-Ga alloy contained in the mixed alloy (coarsely pulverized powder) (coarsely pulverized powder) is not melted, D ₅₀ of 8μm or less finely ground powder like R-Ga alloy powder A mixed alloy powder (finely pulverized powder) containing can be reliably obtained.
More preferably, the hydrogen storage R-Ga alloy (coarse powder) contained in the mixed alloy (coarse pulverized powder) after the hydrogen storage R-Ga alloy (coarse pulverized powder) is obtained until the fine pulverization of the mixed alloy is completed. The mixed alloy (coarse pulverized powder) is pulverized (fine pulverized) without heating the pulverized powder). (However, since the temperature of the hydrogen storage R-Ga alloy may increase during fine pulverization, the temperature increase due to its own heat generation is not included in the heating.)

  A known lubricant may be added as an auxiliary agent to the mixed alloy before jet mill grinding, and to the mixed alloy powder during jet mill grinding and after jet mill grinding.

As described above, the hydrogen storage treatment is performed on the R—Ga alloy at a temperature of 200 ° C. or more and 450 ° C. or less, and the hydrogen storage R-Ga alloy (coarse pulverized powder) stores the hydrogen in the state of storing the hydrogen. by -Ga alloy (coarsely pulverized powder) mixed alloy containing a (coarsely pulverized powder) grinding (milling), mixing the alloy powder D ₅₀ comprises 8μm following R-Ga alloy powder (pulverized powder) (fine Pulverized powder) can be obtained. It is thought that many R-Ga phases exist at the two-grain grain boundary by producing an RTB-based sintered magnet using such a mixed alloy powder containing a fine R-Ga alloy powder. _Thus , an _RTB -based sintered magnet having high H _cJ can be obtained.

In the step of obtaining the mixed alloy powder, the mass of the R-Ga alloy powder (finely pulverized powder) relative to the mass of the mixed alloy powder, regardless of whether the mixed alloy is obtained by any of the methods (Condition a) and (Condition b) The R—Ga alloy powder (finely pulverized powder) and the main alloy powder (finely pulverized powder) are mixed so that the ratio is 1 to 5%. By setting the ratio of the mass of the R—Ga alloy powder (finely pulverized powder) to the mass of the mixed alloy powder in such a range, high H _cJ can be obtained. In addition, when performing the process of obtaining mixed alloy powder (finely pulverized powder) by said (condition b), it is with respect to the mass of the mixture which mixed hydrogen storage R-Ga alloy (coarsely pulverized powder) and the coarsely pulverized powder of the main alloy. What is necessary is just to adjust so that the mass ratio of a hydrogen storage R-Ga alloy (coarse pulverized powder) may be 1 to 5%.

4). Forming Step Using the obtained mixed alloy powder, forming in a magnetic field is performed to obtain a formed body. Molding in a magnetic field is a dry molding method in which a dry alloy powder is inserted into a mold cavity and molding is performed while a magnetic field is applied. The slurry is injected into the mold cavity and the slurry dispersion medium is discharged. Any known forming method in a magnetic field may be used, including a wet forming method.

5. Sintering process A sintered compact (sintered magnet) is obtained by sintering a molded object. A known method can be used for sintering the molded body. In order to prevent oxidation due to the atmosphere during sintering, sintering is preferably performed in a vacuum atmosphere or in an inert gas. As the inert gas, an inert gas such as helium or argon is preferably used.

6). Heat treatment step The obtained sintered magnet is preferably subjected to heat treatment for the purpose of improving magnetic properties. Known conditions can be used for the heat treatment temperature, the heat treatment time, and the like. For example, heat treatment (one-step heat treatment) only at a relatively low temperature (400 ° C. or more and 600 ° C. or less) may be performed, or heat treatment is performed at a relatively high temperature (700 ° C. or more and sintering temperature or less (eg, 1050 ° C. or less)). After performing, heat treatment (two-stage heat treatment) may be performed at a relatively low temperature (400 ° C. or more and 600 ° C. or less). Preferable conditions are as follows: heat treatment at 730 ° C. to 1020 ° C. for 5 minutes to 500 minutes, cooling (after cooling to room temperature or after cooling to 440 ° C. to 550 ° C.), and further at 440 ° C. to 550 ° C. Heat treatment for about 500 minutes to 500 minutes. The heat treatment atmosphere is preferably a vacuum atmosphere or an inert gas (such as helium or argon).

  For the purpose of obtaining a final product shape, the obtained sintered magnet may be subjected to machining such as grinding. In that case, the heat treatment may be performed before or after machining. Furthermore, you may surface-treat to the obtained sintered magnet. The surface treatment may be a known surface treatment, and for example, a surface treatment such as Al deposition, electric Ni plating, or resin coating can be performed.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1
In the inventive example of Example 1, the step of obtaining the mixed alloy powder was performed under the condition b.
Sample No. in Table 1 Each element was weighed so as to have the composition of the RTB-based sintered magnet shown in 1-4 (both were comparative examples), and each alloy was produced by strip casting. Each of the obtained alloys was subjected to known hydrogen pulverization to obtain coarsely pulverized powder. Specifically, dehydrogenation is performed by charging each of the above alloys into a hydrogen furnace and applying a vacuum, introducing hydrogen until the absolute pressure reaches 295 kPa at room temperature, hydrogen embrittlement, and heating and cooling to 550 ° C. in vacuum. Treatment was performed to obtain a coarsely pulverized powder.

The coarsely pulverized powders were each finely pulverized by a jet mill to prepare finely pulverized powders having a particle diameter D ₅₀ (volume center value obtained by a laser diffraction method by an air flow dispersion method) of 4.5 μm. To the finely pulverized powder, 0.05 part by mass of zinc stearate as a lubricant with respect to 100 parts by mass of the finely pulverized powder was added and mixed. Then, it shape | molded in the magnetic field and obtained the molded object. In addition, what was called a right-angle magnetic field shaping | molding apparatus (lateral magnetic field shaping | molding apparatus) in which the magnetic field application direction and the pressurization direction orthogonally cross was used for the shaping | molding apparatus. The obtained molded body was sintered in vacuum at 1030 to 1070 ° C. for 4 hours according to the composition to obtain an RTB-based sintered magnet. The density of the sintered magnet was 7.5 Mg / m ³ or more. The sintered R-T-B sintered magnet is subjected to a heat treatment in which it is kept at 900 ° C. for 2 hours in a vacuum, then cooled to room temperature, then kept at 500 ° C. in a vacuum for 2 hours, and then cooled to room temperature. gave. Table 1 shows the analysis results of the components of the obtained RTB-based sintered magnet.

  Nd, Pr, B, Zr, Co, Al, Cu, Ga, and Fe in Table 1 were measured using high frequency inductively coupled plasma optical emission spectrometry (ICP-OES). O (oxygen amount) is a gas melting-infrared absorption method, N (nitrogen amount) is a gas melting-heat conduction method, and C (carbon amount) is a combustion-infrared absorption method. Measured. The same applies to Tables 5 and 10 below. Moreover, in Table 1, when satisfy | filling Formula (1) in this invention, it described as "(circle)" and not satisfy | filled with "x". The same applies to Table 5, Table 10, Table 15, Table 17, and Table 21 below.

Furthermore, each element was weighed so as to have a composition of a main alloy (No. A to J) and an R—Ga alloy (No. a to d) shown in Table 2, and an alloy was produced by a strip casting method. Table 2 shows the analysis results of the components of the obtained main alloy and R-Ga alloy. Nd, Pr, B, Zr, Co, Al, Cu, Ga and Fe in Table 2 were measured using high frequency inductively coupled plasma optical emission spectrometry (ICP-OES). The same applies to Table 7 below. The obtained main alloy was subjected to hydrogen pulverization under the same conditions as the known hydrogen pulverization described above to obtain a coarsely pulverized powder of the main alloy. Further, a hydrogen storage step was performed on the obtained R-Ga alloy under the conditions shown in Table 3 to obtain a hydrogen storage R-Ga alloy (coarse pulverized powder). For example, the hydrogen storage R-Ga alloy No. b-2 is alloy No. 2 in Table 2. After charging the R-Ga alloy of b into a hydrogen furnace, it was heated to 250 ° C. in a vacuum, hydrogen was introduced until the absolute pressure became 295 kPa, hydrogen embrittled, cooled, and further cooled to 400 ° C. in vacuum. This is an additional process of heating and cooling.
Other hydrogen storage R-Ga alloys described in Table 3 (Alloy Nos. A-1, a-2, b-1, c-1, d-1 to d-4), and Tables 8, 13 and Tables For each of the hydrogen storage R-Ga alloys described in 19, the conditions of the hydrogen storage process are described in accordance with the same description rule. In addition, the heating temperature to R-Ga alloy was confirmed by attaching a thermocouple to R-Ga alloy.

  Further, hydrogen storage R—Ga alloy No. The hydrogen content (amount of hydrogen) in a-1, a-2, b-2, and d-3 was measured. Table 3 shows the measurement results. The hydrogen content was measured by heating / dissolving column separation-thermal conductivity method (TCD) in an Ar atmosphere using an apparatus manufactured by Horiba, Ltd .: EMGA-621W. In addition, hydrogen storage R-Ga alloy No. a-1, a-2, b-1, b-2, c-1 and d-1 were able to be finely pulverized in the subsequent process. d-2 and No. Since d-4 was too high in heating temperature (both heated at a temperature exceeding 450 ° C.), the R—Ga alloy was dissolved and could not be finely pulverized. Furthermore, hydrogen storage R—Ga alloy No. In d-3, since the heating temperature of the alloy was too low (150 ° C.), the R—Ga alloy was not hydrogen embrittled (hydrogen content was as low as 50 ppm) and could not be finely pulverized. Therefore, as shown in Table 3, the hydrogen storage R-Ga alloy must be pulverized with at least 2600 ppm (a-2) or more of hydrogen stored.

The obtained coarsely pulverized powder of the main alloy and the hydrogen storage R-Ga alloy (coarsely pulverized powder) were introduced into a V-type mixer at the ratios shown in Table 4 and mixed, and finely pulverized by a jet mill. D ₅₀ (volume center value obtained by laser diffraction method by airflow dispersion method) was prepared as finely pulverized powder (mixed alloy powder in which main alloy powder and R-Ga alloy powder were mixed) (condition b) . For example, sample No. 5 is alloy No. shown in Table 2. The coarsely pulverized powder of A and the hydrogen storage R-Ga alloy No. a-1 is mixed to produce a mixed alloy powder, and the ratio of the mass of the R-Ga alloy powder to the mass of the mixed alloy powder (in this case, the alloy No. A and the hydrogen storage R-Ga alloy No. 1). The ratio of the mass of the hydrogen storage R-Ga alloy No. a-1 to the total mass of the mixed alloy obtained by mixing a-1) is 2.5% by mass.
For the other samples (sample Nos. 6 to 15) described in Table 4 and the samples described in Table 9, Table 14, and Table 20, the conditions of each alloy and the mixing ratio are described according to the same description rule. doing.

To the finely pulverized powder, 0.05 part by mass of zinc stearate as a lubricant with respect to 100 parts by mass of the finely pulverized powder was added and mixed, and then molded in a magnetic field to obtain a molded body. In addition, what was called a right-angle magnetic field shaping | molding apparatus (lateral magnetic field shaping | molding apparatus) in which the magnetic field application direction and the pressurization direction orthogonally cross was used for the shaping | molding apparatus. The obtained molded body was sintered in vacuum at 1030 to 1070 ° C. for 4 hours according to the composition to obtain a sintered body (RTB-based sintered magnet). The density of the sintered magnet was 7.5 Mg / m ³ or more. The sintered R-T-B sintered magnet is subjected to a heat treatment in which it is kept at 900 ° C. for 2 hours in a vacuum, then cooled to room temperature, then kept at 500 ° C. in a vacuum for 2 hours, and then cooled to room temperature. gave. Table 5 shows the analysis results of the components of the obtained RTB-based sintered magnet.

The sintered magnets (sample Nos. 1 to 15) after heat treatment are machined to prepare samples having a length of 7 mm, a width of 7 mm, and a thickness of 7 mm, and characteristics of each sample (B _r and H _cJ ) by a BH tracer Was measured. Table 6 shows the measurement results.

As shown in Table 6, Sample No. 1-4 are comparative examples produced using a single alloy. Sample No. 6, 8, 9, and 13 are sample Nos. Prepared by using mixed alloy powder containing main alloy powder and R-Ga alloy powder so as to have almost the same composition as that of 1-4 (composition of RTB-based sintered magnet) (that is, the production method of the present invention) This is an example of the present invention prepared by the above method. Sample No. 6 (substantially the same composition as sample No. 1), sample no. 8 (same composition as sample No. 2), sample no. 9 (substantially the same composition as sample No. 3), sample no. 13 (substantially the same composition as sample No. 4). Comparing the 1-4 and properties, respectively, both of which can obtain high _{B r} and a high _{H cJ} towards the sample of the present invention examples (Sample No.6,8,9,13).

On the other hand, Sample No. deviating from the composition range of the present invention (composition range of the RTB-based sintered magnet). 5 (Formula 1 is outside the scope of the present invention), Sample No. Although the comparative examples of 10 and 14 (the amount of B is outside the range of the present invention) are produced by the production method of the present invention, the _HcJ is greatly reduced.

Example 2
In Example 2, the step of obtaining the mixed alloy powder was performed under condition b.
Each element was weighed so as to have a composition of a main alloy (No. K to Q) and an R—Ga alloy (No. e to j) shown in Table 7, and an alloy was produced by a strip casting method. Table 7 shows the analysis results of the components of the obtained main alloy and R-Ga alloy. The obtained main alloy was subjected to hydrogen pulverization under the same conditions as the known hydrogen pulverization described above to obtain a coarsely pulverized powder of the main alloy. Moreover, the hydrogen storage process of this invention shown in Table 8 was performed with respect to the obtained said R-Ga alloy, and the hydrogen storage R-Ga alloy (coarse pulverized powder) was obtained. The obtained coarsely pulverized powder of the main alloy and the hydrogen occlusion R-Ga alloy (coarsely pulverized powder) were introduced into a V-type mixer at the ratios shown in Table 9 and mixed, and finely pulverized by a jet mill. D ₅₀ (volume center value obtained by laser diffraction method by airflow dispersion method) was prepared as finely pulverized powder (mixed alloy powder in which main alloy powder and R-Ga alloy powder were mixed) (condition b) . The obtained finely pulverized powder was molded in the same manner as in Example 1 to obtain a molded body. Furthermore, the obtained molded body was sintered and heat-treated in the same manner as in Example 1. Table 10 shows the analysis results of the components of the obtained sintered body (RTB-based sintered magnet). As shown in Table 10, sample no. 16-22 all have substantially the same composition.

Sintered magnet after the heat treatment by machining (Sample Nanba16～22), vertical 7mm, horizontal 7mm, the sample thickness 7mm produced, the characteristics of each sample by the B-H tracer _{(B r} and _{H cJ)} Was measured. Table 11 shows the measurement results.

Sample No. 17, 19, 20, and 22 are examples of the present invention. Sample No. 16 is a comparative example, and the composition of the R—Ga alloy is out of the scope of the present invention (Fe in the R—Ga alloy is out of the scope of the present invention). Sample No. 18 is a comparative example, and the R amount and the Ga amount in the R—Ga alloy are out of the scope of the present invention. Sample No. 21 is a comparative example, and the mixing amount of the R—Ga alloy powder is out of the scope of the present invention. As shown in Table 11, sample No. As for the characteristics of 17, 19, 20, and ₂₂ , all _HcJs are higher than those of the special samples of Comparative Sample Nos. _{16, 18, and 21} .

Example 3
In Example 3, the step of obtaining the mixed alloy powder was performed under the condition a.
Each element was weighed so that the compositions of the main alloy (No. T, U) and the R—Ga alloy (No. t, u) were the compositions shown in Table 12, and an alloy was produced by strip casting. Table 12 shows the analysis results of the components of the obtained main alloy and R-Ga alloy. The obtained main alloy was hydrogen crushed under the same conditions as in Example 1 to obtain a coarsely pulverized powder of the main alloy. Further, the coarsely pulverized powder of the obtained main alloy was finely pulverized by a jet mill, and the finely pulverized powder (main alloy powder) having a particle diameter D ₅₀ (volume center value obtained by laser diffraction method by airflow dispersion method) of 4.5 μm. Was made. Moreover, the hydrogen storage process of this invention shown in Table 13 was performed with respect to the obtained said R-Ga alloy, and the hydrogen storage R-Ga alloy (coarse pulverized powder) was obtained. Further resulting hydrogen storage R-Ga alloy was finely pulverized by a jet mill, a particle diameter D _{50 (volume} center values obtained by the laser diffraction method using a stream of dispersion method) of 4.5 [mu] m R-Ga alloy powder (milled Powder). The obtained main alloy powder (finely pulverized powder) and R-Ga alloy powder (finely pulverized powder) were mixed in a V-type mixer at the ratios shown in Table 14, respectively, and mixed alloy powder (finely pulverized powder) (Condition a). The obtained mixed alloy powder was molded in the same manner as in Example 1 to obtain a molded body. Furthermore, the obtained molded body was sintered and heat-treated in the same manner as in Example 1. Table 15 shows the analysis results of the components of the obtained sintered body (RTB-based sintered magnet).

Sintered magnet after the heat treatment by machining (Sample No.23 and 24), vertical 7mm, horizontal 7mm, the sample thickness 7mm produced, the characteristics of each sample by the B-H tracer _{(B r} and _{H cJ)} Was measured. The measurement results are shown in Table 16.

As shown in Table 16, is also obtained a high _{B r} and a high _{H cJ} in the present invention example of manufacturing a mixed alloy powder in (Conditions a) (Sample No.23 and 24).

Example 4
In the inventive example of Example 4, the step of obtaining the mixed alloy powder was performed under the condition b.
Sample No. in Table 17 Each element was weighed so as to have the composition of the RTB-based sintered magnet shown in 25 to 28 (all are comparative examples), and each alloy was produced by strip casting. The obtained alloy was subjected to known hydrogen pulverization in the same manner as in Example 1 to obtain coarsely pulverized powder. Specifically, dehydrogenation is performed by charging each of the above alloys into a hydrogen furnace and applying a vacuum, introducing hydrogen until the absolute pressure reaches 295 kPa at room temperature, hydrogen embrittlement, and heating and cooling to 550 ° C. in vacuum. Treatment was performed to obtain a coarsely pulverized powder.

The coarsely pulverized powders were each finely pulverized by a jet mill to prepare finely pulverized powders having a particle diameter D ₅₀ (volume center value obtained by a laser diffraction method by an air flow dispersion method) of 4.5 μm. To the finely pulverized powder, 0.05 part by mass of zinc stearate as a lubricant with respect to 100 parts by mass of the finely pulverized powder was added and mixed. Then, it shape | molded by the method similar to Example 1, and obtained the molded object. Furthermore, the obtained molded body was sintered and heat-treated in the same manner as in Example 1. Table 17 shows the analysis results of the components of the obtained sintered body (R-T-B system sintered magnet).

Each element was weighed so as to have a composition of a main alloy (No. V to Y) and an R—Ga alloy (No. k to n) shown in Table 18, and an alloy was produced by strip casting. Table 18 shows the analysis results of the components of the obtained main alloy and R-Ga alloy. The obtained main alloy was subjected to hydrogen pulverization under the same conditions as the known hydrogen pulverization described above to obtain a coarse pulverized powder of the main alloy. Moreover, the hydrogen storage process of this invention shown in Table 19 was performed with respect to the obtained said R-Ga alloy, and the hydrogen storage R-Ga alloy (coarse pulverized powder) was obtained.
Further, hydrogen storage R—Ga alloy No. The hydrogen content at k-1 and n-1 was measured. The measurement results are shown in Table 19.

The obtained coarsely pulverized powder of the main alloy and the hydrogen storage R-Ga alloy (coarse pulverized powder) were respectively introduced into a V-type mixer at the ratios shown in Table 20, mixed, finely pulverized by a jet mill, D ₅₀ (volume center value obtained by laser diffraction method by airflow dispersion method) was prepared as finely pulverized powder (mixed alloy powder in which main alloy powder and R-Ga alloy powder were mixed) (condition b) . In Table 20, the hydrogen storage R-Ga alloy No. a-1 and alloy no. B is the same as in Example 1. The obtained finely pulverized powder was molded in the same manner as in Example 1 to obtain a molded body. Furthermore, the obtained molded body was sintered and heat-treated in the same manner as in Example 1. Table 21 shows the analysis results of the components of the obtained RTB-based sintered magnet. As shown in Table 17 and Table 21, Sample No. Except for the contents of heavy rare earth elements (Dy and Tb), 25 to 37 have almost the same composition.

The sintered magnets (sample Nos. 25 to 37) after heat treatment are machined to produce samples having a length of 7 mm, a width of 7 mm, and a thickness of 7 mm, and the characteristics of each sample (B _r and H _cJ ) using a BH _tracer Was measured. The measurement results are shown in Table 22.

As shown in Table 22, combinations of samples containing the same heavy rare earth element in the same amount are as follows. Sample No. All of 25, 29 and 33 contain Dy: 0.5% by mass. Sample No. 26, 30 and 34 all contain 0.2% by mass of Tb. Sample No. 27, 31 and 35 all contain 0.5% by mass of Tb. And sample no. 28, 32, 36 and 37 all have Tb: 1.0 mass%. Compared with samples containing the same heavy rare earth element in the same amount, produced using a mixed alloy powder including a main alloy powder and an RG alloy powder compared to a sample of a comparative example produced using a single alloy towards the samples of the present invention example of the both high B _r and a high H _cJ are achieved.

In addition, when the inventive examples were compared with each other, sample No. 2 was prepared by containing a heavy rare earth element on the main alloy side. Samples Nos. 29 to 32 were prepared by containing a heavy rare earth element on the R-Ga alloy side. Who 33-37 are higher _{B r} and a high _{H cJ} are achieved. Sample No. No. 36 contains heavy rare earth elements in both the main alloy and the RG alloy, but the content of the R-Ga alloy is greater than that of the main alloy.
Therefore, when the R-T-B system sintered magnet contains a heavy rare earth element, it is preferable to contain a larger amount of heavy rare earth element on the R-Ga alloy side than on the main alloy side.

Claims (9)

R1: 28.5-33.5% by mass (R1 is at least one of rare earth elements and includes at least one of Nd and Pr),
B: 0.84 to 0.92 mass%,
Ga: 0.3-0.7 mass%,
Cu: 0.05 to 0.35 mass%,
Al: 0.02-0.50 mass%,
Production of RTB-based sintered magnet including T: 61.0% by mass or more (T is Fe and Co, and 90% by mass or more of T is Fe) and satisfies the following formula (1) A method,

14 [B] /10.8 <[T] /55.85 (1)
([B] is the B content in mass%, and [T] is the T content in mass%)

R2: 80 to 95% by mass (R2 is at least one of rare earth elements),
Ga: 5 to 20% by mass (40% by mass or less of Ga can be replaced with Cu),
Preparing one or more R-Ga alloys including Fe: 0 to 1% by mass (part or all of Fe can be replaced with Co) and one or more main alloys;
A hydrogen storage step of heating the R-Ga alloy to a temperature of 200 ° C. or higher and 450 ° C. or lower in a hydrogen atmosphere to obtain a hydrogen storage R-Ga alloy;
Using the one or more hydrogen storage R-Ga alloys and the one or more main alloys to obtain a mixed alloy powder including the R-Ga alloy powder and the main alloy powder;
A molding step of molding the mixed alloy powder to obtain a molded body;
A sintering step of sintering the molded body to obtain a sintered body;
A heat treatment step for heat-treating the sintered body;
Including
In the step of obtaining the mixed alloy powder, at least the one or more hydrogen storage R-Ga alloys are pulverized in a state of storing hydrogen,
The manufacturing method of the RTB system sintered magnet whose ratio of the mass of the R-Ga alloy powder to the mass of the mixed alloy powder is 1 to 5%. The process for obtaining the mixed alloy powder according to claim 1, wherein the mixed alloy powder is obtained according to the following (Condition a) or (Condition b).
(Condition a) Obtained by pulverizing the main alloy with R-Ga alloy powder obtained by pulverizing the hydrogen-occluded R-Ga alloy in a state where the hydrogen-occlusion R-Ga alloy occludes hydrogen. (Condition b) A mixed alloy obtained by mixing the hydrogen storage R-Ga alloy and the coarsely pulverized powder of the main alloy is obtained, and the hydrogen storage R-Ga alloy stores hydrogen. Crush the mixed alloy   The manufacturing method of the RTB system sintered magnet according to claim 1 or 2 whose hydrogen content in said hydrogen occlusion R-Ga alloy is 2600 ppm or more. R1: 28.5-33.5% by mass (R1 is at least one of rare earth elements and includes at least one of Nd and Pr),
B: 0.84 to 0.92 mass%,
Ga: 0.3-0.7 mass%,
Cu: 0.05 to 0.35 mass%,
Al: 0.02-0.50 mass%,
Including
The balance is T (T is Fe and Co, and 90% by mass or more of T is Fe) and inevitable impurities, and the manufacturing method of the RTB-based sintered magnet satisfying the following formula (1) Because

14 [B] /10.8 <[T] /55.85 (1)
([B] is the B content in mass%, and [T] is the T content in mass%)

R2: 80 to 95% by mass (R2 is at least one of rare earth elements),
Ga: 5 to 20% by mass (40% by mass or less of Ga can be replaced with Cu),
Preparing one or more R-Ga alloys including Fe: 0 to 1% by mass (part or all of Fe can be replaced with Co) and one or more main alloys;
A hydrogen storage step of heating the R-Ga alloy to a temperature of 200 ° C. or higher and 450 ° C. or lower in a hydrogen atmosphere to obtain a hydrogen storage R-Ga alloy;
A step of obtaining a mixed alloy powder containing an R-Ga alloy powder and a main alloy powder according to the following (condition a) or (condition b);
(Condition a) Obtained by pulverizing the main alloy with R-Ga alloy powder obtained by pulverizing the hydrogen-occluded R-Ga alloy in a state where the hydrogen-occlusion R-Ga alloy occludes hydrogen. (Condition b) A mixed alloy obtained by mixing the hydrogen storage R-Ga alloy and the coarsely pulverized powder of the main alloy is obtained, and the hydrogen storage R-Ga alloy stores hydrogen. In a state where the mixed alloy is pulverized, a forming step of forming the mixed alloy powder to obtain a formed body,
A sintering step of sintering the molded body to obtain a sintered body;
A heat treatment step for heat-treating the sintered body;
And the ratio of the mass of the R-Ga alloy powder to the mass of the mixed alloy powder is 1 to 5%.   The manufacturing method of the RTB system sintered magnet according to claim 4 whose hydrogen content in said hydrogen occlusion R-Ga alloy is 2600 ppm or more.   In (condition a) in the step of obtaining the mixed alloy powder, after the hydrogen storage step, the hydrogen storage R-Ga alloy is pulverized without heating the hydrogen storage R-Ga alloy to a temperature exceeding 450 ° C. The manufacturing method of the RTB type | system | group sintered magnet of Claim 2 or 4 characterized by the above-mentioned.   In (condition a) of the step of obtaining the mixed alloy powder, the hydrogen storage R-Ga alloy is pulverized after the hydrogen storage step without heating the hydrogen storage R-Ga alloy. The manufacturing method of the RTB system sintered magnet of Claim 2 or 4.   (Condition b) in the step of obtaining the mixed alloy powder, the mixed alloy is pulverized after the hydrogen storage step without heating the hydrogen storage R-Ga alloy to a temperature exceeding 450 ° C. The manufacturing method of the RTB type | system | group sintered magnet of Claim 2 or 4.   In the (condition b) of the step of obtaining the mixed alloy powder, the mixed alloy is pulverized after the hydrogen storage step without heating the hydrogen storage R-Ga alloy. 4. A method for producing an RTB-based sintered magnet according to 4.

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