JP2015103681A - Rare earth-transition metal-boron based sintered magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an R-T-B based sintered magnet having high Band high Hwhile keeping the content of Dy down.SOLUTION: The R-T-B based sintered magnet comprises uR, wB, xIn, yCu, zAl, qM and the balance of T (where R consists of RL and RH; RL represents Nd and/or Pr; RH represents Dy and/or Tb; T represents Fe, of which no more than 10% may be substituted with Co; M represents Nb and/or Zr; and u, w, x, y, z and q each represent a figure in units of mass%, provided that the R-T-B based sintered magnet includes inevitable impurities). RH accounts for 5 mass% or less of the R-T-B-based sintered magnet, and the figures x, y, z and q satisfy the following conditions: 0.3≤x≤1.5; 0.07≤y≤0.2; 0.05≤z≤0.5; and 0≤q≤0.1. Supposing that the quantity of oxygen (mass%) is α, the quantity of nitrogen (mass%) is β, and the quantity of carbon (mass%) is γ, the relation, v=u-(6α+10β+8γ) holds, and v and w satisfy the following expressions: 50w-18.5≤v≤50w-14; and -12.5w+38.75≤v≤-62.5w+86.125.

Description

  The present invention relates to an RTB-based sintered magnet.

R-T-B based sintered magnet having R ₂ T ₁₄ B type compound as a main phase (R is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy and / or Tb and T are at least one of transition metal elements and must contain Fe), and are known as the most powerful magnets among permanent magnets. Various motors for hybrid vehicles, electric vehicles, and home appliances Etc. are used.

The _RTB -based sintered magnet has a _reduced coercive force H _cJ (hereinafter sometimes simply referred to as “H _cJ ”) at high temperatures, causing irreversible thermal demagnetization. Therefore, especially when used for a hybrid vehicle or an electric vehicle motor, it is required to maintain a high _HcJ even at high temperatures.

Conventionally, in order to improve _HcJ , a large amount of heavy rare earth element (mainly Dy) has been added to the 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). Therefore, in recent years, while suppressing a decrease in B _r was concentrated heavy rare earth element in the outer shell of the main phase crystal grains by diffusing a heavy rare earth elements from the surface of the R-T-B based sintered magnet therein, A method of obtaining high H _cJ has been adopted.

However, Dy has problems such as unstable supply and fluctuating prices due to the limited production area. Therefore, there is a demand for a technique for improving the _HcJ of an _RTB -based sintered magnet without using a heavy rare earth element such as Dy as _much as possible.

Patent Document 1 discloses that R ₂ T ₁₇ by lowering the amount of B than a normal R-T-B alloy and containing one or more metal elements M selected from Al, Ga, and Cu. The coercive force is suppressed while the content of Dy is suppressed by sufficiently securing the volume fraction of the transition metal rich phase (R ₆ T ₁₃ M) generated by using the R ₂ T ₁₇ phase as a raw material. It is described that an R-T-B rare earth sintered magnet having a high C can be obtained.

International Publication No. 2013/008756

However, since Patent Document 1 has a larger R amount and a smaller B amount than in the prior art, there is a problem that the abundance ratio of the main phase is lowered and _Br is significantly reduced.

The present invention has been made to solve the above problems, aims while suppressing the content of Dy, provides R-T-B based sintered magnet having a high B _r and high H _cJ And

Aspect 1 of the present invention
Formula uRwBxInyCuzAlqM (100-u-w-xy-z-q) T (R is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy and / or Tb , T is Fe and up to 10% of Fe can be replaced by Co, M is Nb and / or Zr, u, w, x, y, z, q and 100-u-wxyz -Q represents mass% and includes inevitable impurities)
The RH is 5% by mass or less of the R-T-B system sintered magnet,
0.3 ≦ x ≦ 1.5,
0.07 ≦ y ≦ 0.2,
0.05 ≦ z ≦ 0.5,
0 ≦ q ≦ 0.1,
When the oxygen content (mass%) of the RTB-based sintered magnet is α, the nitrogen content (mass%) is β, and the carbon content (mass%) is γ, v = u− (6α + 10β + 8γ) , V, w
50w-18.5 ≦ v ≦ 50w-14,
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125,
Is an RTB-based sintered magnet.

  In aspect 1, it is preferable that the amount of oxygen is 0.15 mass% or less.

Aspect 2 of the present invention
Formula uRwBxInyCuzAlqM (100-u-w-xy-z-q) T (R is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy and / or Tb , T is Fe and up to 10% of Fe can be replaced by Co, M is Nb and / or Zr, u, w, x, y, z, q and 100-u-wxyz -Q represents mass% and includes inevitable impurities)
The RH is 5% by mass or less of the R-T-B system sintered magnet,
0.3 ≦ x ≦ 1.5,
0.07 ≦ y ≦ 0.2,
0.05 ≦ z ≦ 0.5
0 ≦ q ≦ 0.1,
When the oxygen content (mass%) of the RTB-based sintered magnet is α, the nitrogen content (mass%) is β, and the carbon content (mass%) is γ, v = u− (6α + 10β + 8γ) , V, w
50w-18.5 ≦ v ≦ 50w-16.25,
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125,
Is an RTB-based sintered magnet.

The present invention, while suppressing the content of Dy and Tb, it is possible to provide a R-T-B based sintered magnet having a high B _r and high H _cJ.

It is explanatory drawing which shows the range of v and w of this invention.

The present inventors have made intensive studies in order to solve the above problems, by a composition represented by the formula shown in embodiment 1 or embodiment 2 of the present invention, a high B _r and high H _cJ It has been found that an RTB-based sintered magnet is obtained. That is, the present invention is an RTB-based sintered magnet containing R, B, In, Cu, Al, and optionally M, in a specific ratio shown in the first or second aspect.

With the composition of the particular proportions shown in embodiment 1 or embodiment 2 of the present invention, there is also still questions about the mechanism by which the R-T-B based sintered magnet can be obtained with a high B _r and high H _cJ . The mechanism considered by the present inventors based on the knowledge obtained so far will be described below. It should be noted that the following description of the mechanism is not intended to limit the technical scope of the present invention.

R-T-B based sintered magnet can be improved B _r by increasing the existence ratio of R _{2 T} 14 _B type compound as the main phase. To increase the abundance ratio of the R ₂ T ₁₄ B type compound is, R amount, T amounts, although the B amount should brought close to the stoichiometric ratio of _R 2 _{T 14} B type _compound, R _{2 T 14} B-type When the amount of B for forming the compound is lower than the stoichiometric ratio, a soft magnetic R ₂ T ₁₇ phase is precipitated at the grain boundary, and H _cJ is rapidly decreased. However, when Ga is contained in the magnet composition, an R—T—Ga phase is generated instead of the R ₂ T ₁₇ phase, and a decrease in H _cJ can be prevented.

However, as a result of the study by the present inventors, even when In is used instead of Ga, an R—T—In phase is generated instead of the R ₂ T ₁₇ phase as in the case of using Ga, and H _cJ It was found that the decrease can be prevented. Further, since the R-T-In phase has some magnetism, the grain boundary in the R-T-B system sintered magnet, particularly the grains existing between two main phases that are considered to mainly affect _HcJ. It was found that the presence of a large amount of RT-In phase at the boundary (hereinafter sometimes referred to as a two-grain grain boundary) hinders the improvement of _HcJ . Further, it was found that an R-In phase and an R-In-Cu phase were generated at the grain boundary along with the generation of the R-T-In phase. Therefore, the present inventors assumed that _HcJ is improved by the presence of the R-In phase and the R-In-Cu phase at the two-particle grain boundary of the _RTB -based sintered magnet. In addition, in order to generate the R—In phase and the R—In—Cu phase, and in order to eliminate the R ₂ T ₁₇ phase, it is necessary to generate the R—T—In phase, _but to obtain a high H _cJ. Assumed that it was necessary to keep the production amount low. If the generation of the R-T-In phase can be suppressed as much as possible while generating the R-In phase and the R-In-Cu phase, especially at the two-grain grain boundary, the _HcJ can be further improved. Assumed.

In the R-T-B system sintered magnet, in order to keep the production amount of the R-T-In phase low, the production amount of the R ₂ T ₁₇ phase is reduced by setting the R amount and the B amount in an appropriate range. In addition to lowering, it is necessary to set the R amount and the In amount within an optimum range according to the amount of R ₂ T ₁₇ phase generated. However, since a part of R is consumed by combining with oxygen, nitrogen and carbon in the manufacturing process of the RTB-based sintered magnet, it is actually used for the R ₂ T ₁₇ phase and the RT-In phase. The amount of R changes in the manufacturing process. Therefore, it is difficult to suppress the generation amount of the R ₂ T ₁₇ phase and the R-T-In phase by adjusting the R amount in order to suppress the generation amount while generating the R-T-In phase. I understood it. As a result of repeated studies, the inventors have changed the amount of oxygen (mass%) in the R-T-B system sintered magnet from the amount of R (u) to α, nitrogen as described in Aspect 1 or Aspect 2. When the amount (mass%) is β and the carbon content (mass%) is γ, the value (v) obtained by subtracting 6α + 10β + 8γ is used to adjust the production amount of the R ₂ T ₁₇ phase and the R-T-In phase. It was found that it was possible. Then, it was found that be contained minus the 6α + 10β + 8γ from R amount (u) and (v) B and In, Cu and Al in a specific ratio, high _{B r} and high _{H cJ} are obtained. As a result, in the entire RTB-based sintered magnet, the R—In phase and the R—In—Cu phase are present at the two grain boundaries, and the R—T—In phase is almost absent. It is thought that the organization that there are many can be obtained. By obtaining such a structure, the decrease in _HcJ due to the R-T-In phase is suppressed, and furthermore, as a result of suppressing the amount of R-T-In phase generated, the R amount and the B amount are changed to the abundance ratio of the main phase. Therefore, it is considered that high _Br can be obtained. In the technique described in Patent Document 1, since the oxygen amount, the nitrogen amount, and the carbon amount are not considered with respect to the R amount, it is difficult to suppress the generation amount of the R ₂ T ₁₇ phase or the R—T—In phase. . In the first place, the technique described in Patent Document 1 improves _HcJ by promoting the generation of the RT-Ga phase, and the technical idea of suppressing the generation amount of the RT-Ga (In) phase. There is no. Therefore, in Patent Document 1, in order to promote the generation of the R ₂ T ₁₇ phase that is the raw material of the R—T—Ga phase, the amount of B is made lower than before, and the generation of the R—T—Ga phase is promoted. In addition, since it is necessary to increase the amount of R, it is considered that the existence ratio of the main phase is greatly reduced and high _Br is not obtained.

[RTB-based sintered magnet]
The present invention has the formula uRwBxInyCuzAlqM (100-u-w-x-yz-q) T, where R is a light rare earth element RL and a heavy rare earth element RH, where RL is Nd and / or Pr, RH is Dy and / Or Tb, T is Fe and up to 10% of Fe can be replaced by Co, M is Nb and / or Zr, u, w, x, y, z, q and 100-u-w-x -Y-z-q represents% by mass and contains inevitable impurities)
The RH is 5% by mass or less of the R-T-B system sintered magnet,
0.3 ≦ x ≦ 1.5,
0.07 ≦ y ≦ 0.2,
0.05 ≦ z ≦ 0.5,
0 ≦ q ≦ 0.1,
When the oxygen content (mass%) of the RTB-based sintered magnet is α, the nitrogen content (mass%) is β, and the carbon content (mass%) is γ, v = u− (6α + 10β + 8γ) , V, w
50w-18.5 ≦ v ≦ 50w-14,
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125,
R-T-B system sintered magnet characterized by satisfying
Or
Formula uRwBxInyCuzAlqM (100-u-w-xy-z-q) T (R is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy and / or Tb , T is Fe and up to 10% of Fe can be replaced by Co, M is Nb and / or Zr, u, w, x, y, z, q and 100-u-wxyz -Q represents mass% and includes inevitable impurities)
The RH is 5% by mass or less of the R-T-B system sintered magnet,
0.3 ≦ x ≦ 1.5,
0.07 ≦ y ≦ 0.2,
0.05 ≦ z ≦ 0.5,
0 ≦ q ≦ 0.1,
When the oxygen content (mass%) of the RTB-based sintered magnet is α, the nitrogen content (mass%) is β, and the carbon content (mass%) is γ, v = u− (6α + 10β + 8γ) , V, w
50w-18.5 ≦ v ≦ 50w-16.25,
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125,
R-T-B system sintered magnet characterized by satisfying
It is.
The RTB-based sintered magnet of the present invention contains inevitable impurities. For example, the effect of the present invention can be achieved even if it contains inevitable impurities normally contained in didymium alloy (Nd—Pr), electrolytic iron, ferroboron, and the like. Inevitable impurities include, for example, trace amounts of La, Ce, Cr, Mn, Si and the like.

The present invention can achieve the effect that by the R-T-B based sintered magnet composition represented by the above formula, a high B _r and high H _cJ are obtained. This will be described in detail below.

R in the RTB-based sintered magnet of the present invention is composed of a light rare earth element RL and a heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy and / or Tb, and RH is R- It is 5 mass% or less of a TB type sintered magnet. Because the present invention can obtain a high B _r and high H _cJ without using a heavy rare-earth element, it can be reduced the amount of RH even be asked a higher H _cJ. T is Fe, and 10% or less of Fe can be substituted with Co. B is boron.

In is preferably contained in an amount of 0.3% by mass to 1.5% by mass. If the content of In is less than 0.3% by mass, the amount of R-T-In phase produced is too small to eliminate the R2T17 phase, and in the entire R-T-B system sintered magnet, Since the R—In phase and the R—In—Cu phase are not sufficiently generated at the two grain boundaries, high _HcJ cannot be obtained. When the content of In is more than 1.5 wt%, will be unnecessary In the presence, abundance ratio of the main phase may be decreased is B _r drops.

It is preferable to contain Cu 0.07 mass% or more and 0.2 mass% or less. If the Cu content is less than 0.07% by mass, the R—In phase and the R—In—Cu phase are hardly generated at the two-grain grain boundaries, and high _HcJ may not be obtained. Moreover, when it exceeds 0.2 mass%, since there is too much content of Cu, there exists a possibility that it becomes impossible to sinter. The Cu content is more preferably 0.08% by mass or more and 0.15% by mass or less.

Furthermore, Al (0.05 mass% or more and 0.5 mass% or less) of the grade normally contained is contained. By containing Al, _HcJ can be improved. Al is usually contained in an amount of 0.05% by mass or more as an inevitable impurity in the production process, but it may be contained in an amount of 0.5% by mass or less in total of the amount contained by the inevitable impurity and the amount intentionally added. Good.

In general, it is known that an RTB-based sintered magnet contains Nb and / or Zr to suppress abnormal grain growth during sintering. Also in the present invention, Nb and / or Zr may be contained in a total amount of 0.1% by mass or less. By the content of Nb and / or Zr is present unwanted Nb and Zr exceeds 0.1 mass% in total, there is a possibility that the volume ratio of the main phase is lowered B _r drops.

Moreover, the oxygen content (mass%), the nitrogen content (mass%), and the carbon content (mass%) in the present invention are the contents in the RTB-based sintered magnet, and the oxygen content is gas melting-infrared radiation. The absorption method, the nitrogen amount can be measured by using a gas analyzer by a gas melting-heat conduction method, and the carbon amount can be measured by a combustion-infrared absorption method. The present invention uses a value (v) obtained by subtracting the amount consumed by combining with oxygen, nitrogen and carbon from the amount of R (u) by the method described below. This makes it possible to adjust the amount of R ₂ T ₁₇ phase and R-T-In phase generated. The v is determined by subtracting 6α + 10β + 8γ from the R amount (u), where α is the oxygen amount (% by mass), β is the nitrogen amount (% by mass), and γ is the carbon amount (% by mass). 6α is defined because R having a mass approximately six times that of oxygen is consumed as an oxide, assuming that an oxide of R ₂ O ₃ is mainly produced as an impurity. 10β is defined by the fact that R having a mass approximately 10 times that of nitrogen is consumed as nitride, assuming that RN nitride is mainly produced. 8γ is defined because R, which is approximately eight times the mass of carbon, is consumed as carbides, assuming that R ₂ C ₃ carbides are mainly produced.

The amount of oxygen in the RTB-based sintered magnet is preferably 0.15% by mass or less. v is a value obtained by subtracting 6α + 10β + 8γ from the R amount, assuming that the oxygen amount (mass%) is α, the nitrogen amount (mass%) is β, and the carbon amount (mass%) is γ. It is necessary to increase the amount of R in the raw material alloy stage. In particular, among regions 1 and 2 of the present invention shown in FIG. 1 described later, region 1 has a relatively higher v than region 2, and therefore, when the amount of oxygen α is large, the amount of R in the raw material alloy stage is very high. There is a risk of increasing. As a result, the abundance ratio of the main phase is lowered and _Br may be lowered. In particular, in the region 1 of the present invention shown in FIG. 1, the oxygen amount is preferably 0.15% by mass or less.

Further, in the present invention, v and w are related as follows.
50w-18.5 ≦ v ≦ 50w-14,
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125,
FIG. 1 shows the scope of the present invention of v and w contained in the above relationship. In FIG. 1, v is a value obtained by subtracting 6α + 10β + 8γ from the R amount (u), where the oxygen amount (% by mass) is α, the nitrogen amount (% by mass) is β, and the carbon amount (% by mass) is γ. , B value. 50w-18.5 ≦ v ≦ 50w-14 is a range between the straight line including point A and point B and the straight line including point C and point D in FIG. 1, and is −12.5w + 38.75 ≦ v ≦ −. 62.5w + 86.125 is a range sandwiched between a straight line including point D, point F, point B, and point G, and a straight line including point C, point E, point A, and point G. Regions 1 and 2 (regions surrounded by point A, point B, point D, and point C) that satisfy both of these conditions are within the scope of the present invention. v and w to by the range of the region 1 and 2, it is possible to obtain a high B _r and high H _cJ. The region 10 deviated from the range of the regions 1 and 2 (the lower region in the drawing from the straight line including the point D, the point F, the point B, and the point G) has too little v with respect to w, and thus the RT-In phase the amount is _{small, and} may not be able to eliminate the R _{2 T 17} phase is considered that the amount of R-an in-phase and R-in-Cu phase is reduced. Thereby, high _HcJ cannot be obtained. On the other hand, the region 20 outside the range of the regions 1 and 2 (the region in the figure from the straight line including the point C, the point E, the point A, and the point G) has too many vs relative to w. Insufficient Fe content. If the amount of Fe is insufficient, R and B will remain, and as a result, it is considered that the R ₁ Fe ₄ B ₄ phase is likely to be generated without generating the RT-In phase. As a result, the amount of R-In phase and R-In-Cu phase produced is reduced, and high _HcJ cannot be obtained. Further, the region 30 (the region in the figure from the straight line including the point C and the point D) deviated from the range of the regions 1 and 2 has too much v and too little w, so that the R-T-In phase and R Although the -In phase and the R-In-Cu phase are produced, the abundance ratio of the main phase is lowered, and high _Br cannot be obtained. Further, the region 40 (the region excluding the regions 1 and 2 from the region surrounded by the points C, D, and G) deviated from the regions 1 and 2 has a small amount of R and a large amount of B. Although the abundance ratio is high, the R—T—In phase is hardly generated, and the generation amount of the R—In phase and the R—In—Cu phase is reduced, so that a high H _cJ cannot be obtained.

More preferably, in the present invention, v and w have the following relationship.
50w-18.5 ≦ v ≦ 50w-16.25,
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125
FIG. 1 shows the scope of the present invention of v and w contained in the above relationship. 50w-18.5 ≦ v ≦ 50w-16.25 is a range sandwiched between a straight line including point A and point B and a straight line including point E and point F, and −12.5w + 38.75 ≦ v ≦ −62. .5w + 86.125 is a range sandwiched between a straight line including point D, point F, point B, and point G, and a straight line including point C, point E, point A, and point G. And the area | region 2 (area | region enclosed by the point A, the point B, the point F, and the point E) which satisfy | fills both is the range of this invention. By setting the above range, v can be lowered and w can be increased while securing the amount of R—T—In phase generated, so that the main phase abundance ratio is not lowered and a higher _Br is obtained. be able to.

In the present invention, the R-T-In phase includes R 15 mass% to 65 mass%, T 20 mass% to 80 mass%, In 2 mass% to 20 mass%, for example, R ₆ Fe ₁₃ In ₁ compound is mentioned. The R-In phase includes R70 mass% or more and 95 mass% or less, In 5 mass% or more and 30 mass% or less, and T20 mass% or less (including 0). For example, the R ₃ In ₁ compound includes Can be mentioned. Furthermore, the R—In—Cu phase is a portion in which part of In in the R—In phase is substituted with Cu, and includes, for example, an R ₃ (In, Cu) ₁ compound.

[Method for producing RTB-based sintered magnet]
An example of the manufacturing method of the RTB system sintered magnet of this invention is demonstrated. The manufacturing method of a RTB system sintered magnet has a process of obtaining alloy powder, a forming process, a sintering process, and a heat treatment process. Hereinafter, each step will be described.

(1) Step of obtaining alloy powder A metal or alloy of each element is prepared so as to have a predetermined composition, and a flaky alloy is manufactured using the strip casting method or the like. The obtained flaky raw material alloy is hydrogen pulverized so that the size of the coarsely pulverized powder is 1.0 mm or less, for example. Next, the coarsely pulverized powder is finely pulverized by a jet mill or the like, for example, finely pulverized powder (alloy powder) having a particle diameter D50 (volume-based median diameter obtained by a laser diffraction method by an air flow dispersion method) of 3 to 7 μm. Get. A known lubricant may be used as an auxiliary agent for the coarsely pulverized powder before jet mill pulverization and the alloy powder during and after jet mill pulverization.

(2) Forming step Using the obtained 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.

(3) Sintering process A sintered magnet is obtained by sintering a molded object. A well-known method can be used for sintering of a molded object. In addition, in order to prevent the oxidation by the atmosphere at the time of sintering, it is preferable to perform sintering in a vacuum atmosphere or atmospheric gas. The atmosphere gas is preferably an inert gas such as helium or argon.

(4) Heat treatment process It is preferable to perform the heat processing for the purpose of improving a magnetic characteristic with respect to the obtained sintered magnet. Known conditions can be adopted for the heat treatment temperature, the heat treatment time, and the like. The obtained sintered magnet may be subjected to machining such as grinding in order to adjust the magnet dimensions. 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 vapor 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.

  Using Nd metal, Pr metal, Dy metal, Tb metal, ferroboron alloy, electrolytic Co, Al metal, Cu metal, In metal, ferroniobium alloy, ferrozirconium alloy and electrolytic iron (all metals have a purity of 99% or more) It mix | blended so that it might become a predetermined | prescribed composition, those raw materials were melt | dissolved, and it casted by the strip cast method, and obtained the flaky raw material alloy of thickness 0.2-0.4mm. The obtained flaky raw material alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere, and then subjected to a dehydrogenation treatment in which it was heated and cooled in vacuum to 550 ° C. to obtain coarsely pulverized powder. Next, after adding and mixing 0.04% by mass of zinc stearate as a lubricant with respect to 100% by mass of the coarsely pulverized powder, the resulting coarsely pulverized powder was mixed with an airflow pulverizer (jet mill device). Then, dry pulverization was performed in a nitrogen stream to obtain finely pulverized powder (alloy powder) having a particle diameter D50 of 4 μm. Note that the oxygen concentration in the nitrogen gas during pulverization was adjusted by mixing the atmosphere with nitrogen gas during pulverization. When the atmosphere is not mixed, the oxygen concentration in the nitrogen gas during pulverization is 50 ppm or less, and by mixing the air, the oxygen concentration in the nitrogen gas is increased to a maximum of 4100 ppm to produce finely pulverized powders with various oxygen amounts. did. The particle diameter D50 is a volume-based median diameter obtained by a laser diffraction method using an airflow dispersion method. In Table 1, 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.

  To the finely pulverized powder, 0.05% by mass of zinc stearate as a lubricant was added to and mixed with 100% by mass of the finely pulverized powder, 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 (transverse magnetic field shaping | molding apparatus) in which the magnetic field application direction and the pressurization direction orthogonally crossed was used for the shaping | molding apparatus.

The obtained compact was sintered in vacuum at 1020 ° C. for 4 hours and then rapidly cooled to obtain an RTB-based sintered magnet. The density of the sintered magnet was 7.5 Mg / m ³ or more. Table 1 shows the components and gas analysis results of the obtained sintered magnet. The obtained sintered body was held at 800 ° C. for 2 hours and then cooled to room temperature, and then held at 500 ° C. for 2 hours and then cooled to room temperature. By machining the sintered magnet after the heat treatment, vertical 7 mm, transverse 7 mm, to prepare a sample having a thickness of 7 mm, were measured _{B r} and _{H cJ} of the sample by B-H tracer. The measurement results are shown in Table 2.

  In Table 2, u is a value obtained by summing the amounts (mass%) of Nd, Pr, Dy, and Tb in Table 1, and v is the oxygen content (mass%) in Table 1 and the nitrogen content (mass%). Is the value obtained by subtracting 6α + 10β + 8γ from u, where β is β and the carbon content (% by mass) is γ. For w, the amount of B in Table 1 is directly transferred. The area in Table 2 indicates where the ratio of v and w is in FIG. 1. In the case of 1 area in FIG. 1, 1 and 2 area in FIG. In the case of 2. Furthermore, when it exists in the area | region other than 1 and 2 area | region in FIG. 1, any one of 10, 20, 30, 40 was described according to the position. For example, no. 1 is the region 2 in FIG. 1 because v is 28.3% by mass and w is 0.91% by mass. Therefore, it was described as 2. No. 10 is the region 1 in FIG. 1 because v is 29.4 mass% and w is 0.88 mass%. Therefore, it was described as 1. Furthermore, no. 11 is the region 20 in FIG. 1 because v is 29.9% by mass and w is 0.91% by mass. Therefore, it was described as 20.

As described above, the present invention contains v and w in the following proportions.
50w-18.5 ≦ v ≦ 50w-14,
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125,
Preferably,
50w-18.5 ≦ v ≦ 50w-16.25
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125
The range of v and w when contained in the proportion corresponds to the region 1 and 2 or 2 in FIG.

As shown in Table 2, when the raw material alloy does not contain Dy and Tb, the relationship between v and w is located in the region of the present invention (regions 1 and 2 in FIG. 1), and 0.3 ≦ In ≦ 1.5, 0.07 ≦ Cu ≦ 0.2, 0.05 ≦ Al ≦ 0.5, 0 ≦ M (Nb and / or Zr) ≦ 0.1 (Sample No. 12) The present invention other than 13) has high magnetic properties of B _r ≧ 1.37T and H _cJ ≧ 1450 kA / m. On the other hand, even if the amounts of In, Cu, and Al are within the scope of the present invention, v and w are outside the scope of the present invention (regions other than 1 or 2 in FIG. 1) ( Sample Nos. 7, 8, 9, and 11), and even if v and w are within the scope of the present invention (area 1 or 2 in FIG. 1), the amounts of In and Cu are outside the scope of the present invention. In the comparative examples (sample Nos. 4 to 6), high magnetic properties of B _r ≧ 1.37T and H _cJ ≧ 1450 kA / m are not obtained.

Dy in the raw material alloy, if containing Tb is Dy, and _{B r} decreases in accordance with the content of _{Tb, H cJ} can be increased. In this case, _{B r} decreases approximately 0.024T when containing 1 mass% of Dy and Tb. _HcJ increases by about 160 kA / m when 1% by mass of Dy is contained, and increases by about 240 kA / m when 1% by mass of Tb is contained.
Therefore, the present invention has magnetic properties of B _r ≧ 1.37T and H _cJ ≧ 1450 kA / m when the raw material alloy does not contain Dy and Tb as described above. Depending on the content, B _r (T) ≧ 1.37−0.024 Dy (mass%) − 0.024 Tb (mass%) and H _cJ (kA / m) ≧ 1450 + 160 Dy (mass%) + 240 Tb (mass%) ) Magnetic properties.

As shown in Table 2, in the present invention (sample Nos. 12 and 13) containing Dy and Tb in the raw material alloy, B _r (T) ≧ 1.37−0.024 Dy (mass%)-0. It has high magnetic properties of 024 Tb (mass%) and H _cJ (kA / m) ≧ 1450 + 160 Dy (mass%) + 240 Tb (mass%). In contrast, Comparative Example (Sample Nanba14,15) are both _B r (T) ≧ 1.37-0.024Dy (wt%) - 0.024Tb (wt%), _and, H cJ (kA / M) ≧ 1450 + 160 Dy (mass%) + 240 Tb (mass%).

Furthermore, as shown in Table 2, the 1 2 (1 region in FIG. 1) region than towards the (second region in FIG. 1) is higher B _{r (material} alloy regions in the present invention Dy When Tb is not contained, B _r ≧ 1.38T, and when Dy and Tb are contained, B _r ≧ 1.38T−0.024 [Dy] −0.024 [Tb]) can be obtained. [Dy] [Tb] indicates the content (% by mass) of Dy and Tb, respectively.

  The RTB-based sintered magnet according to the present invention can be suitably used for a hybrid vehicle motor or an electric vehicle motor.

Claims (3)

Formula uRwBxInyCuzAlqM (100-u-w-xy-z-q) T (R is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy and / or Tb , T is Fe and up to 10% of Fe can be replaced by Co, M is Nb and / or Zr, u, w, x, y, z, q and 100-u-wxyz -Q represents mass% and includes inevitable impurities)
The RH is 5% by mass or less of the R-T-B system sintered magnet,
0.3 ≦ x ≦ 1.5,
0.07 ≦ y ≦ 0.2,
0.05 ≦ z ≦ 0.5,
0 ≦ q ≦ 0.1,
When the oxygen content (mass%) of the RTB-based sintered magnet is α, the nitrogen content (mass%) is β, and the carbon content (mass%) is γ, v = u− (6α + 10β + 8γ) , V, w
50w-18.5 ≦ v ≦ 50w-14,
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125,
R-T-B system sintered magnet characterized by satisfying   The RTB-based sintered magnet according to claim 1, wherein the oxygen content is 0.15% by mass or less. Formula uRwBxInyCuzAlqM (100-u-w-xy-z-q) T (R is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy and / or Tb , T is Fe and up to 10% of Fe can be replaced by Co, M is Nb and / or Zr, u, w, x, y, z, q and 100-u-wxyz -Q represents mass% and includes inevitable impurities)
The RH is 5% by mass or less of the R-T-B system sintered magnet,
0.3 ≦ x ≦ 1.5,
0.07 ≦ y ≦ 0.2,
0.05 ≦ z ≦ 0.5,
0 ≦ q ≦ 0.1,
When the oxygen content (mass%) of the RTB-based sintered magnet is α, the nitrogen content (mass%) is β, and the carbon content (mass%) is γ, v = u− (6α + 10β + 8γ) , V, w
50w-18.5 ≦ v ≦ 50w-16.25,
−12.5w + 38.75 ≦ v ≦ −62.5w + 86.125,
R-T-B system sintered magnet characterized by satisfying

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