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JP2018125445A - R-T-B based sintered magnet - Google Patents

R-T-B based sintered magnet Download PDF

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JP2018125445A
JP2018125445A JP2017017213A JP2017017213A JP2018125445A JP 2018125445 A JP2018125445 A JP 2018125445A JP 2017017213 A JP2017017213 A JP 2017017213A JP 2017017213 A JP2017017213 A JP 2017017213A JP 2018125445 A JP2018125445 A JP 2018125445A
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sintered magnet
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JP6702215B2 (en
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鉄兵 佐藤
Teppei Sato
鉄兵 佐藤
國吉 太
Futoshi Kuniyoshi
太 國吉
倫太郎 石井
Rintaro Ishii
倫太郎 石井
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Proterial Ltd
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Hitachi Metals Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047Alloys characterised by their composition
    • H01F1/053Alloys characterised by their composition containing rare earth metals
    • H01F1/055Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Hard Magnetic Materials (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide an R-T-B based sintered magnet having a high Band a high Hwithout using RH such as Dy as far as possible (or with an amount of use of RH minimized).SOLUTION: An R-T-B based sintered magnet comprises R of 27.5% or more and 34.0% or less (R is at least one kind of rare earth elements, always including at least one of Nd and Pr), B of 0.85% or more and 0.93% or less, Ga of 0.20% or more and 0.75% or less, Sn of 0.05% or more and 0.60% or less, Cu of 0.05% or more and 0.70% or less, Al of 0.05% or more and 0.40% or less, and T of 61.5% or more (T represents Fe and Co, and by mass percentage, Fe accounts for no less than 90% of T), which are represented by mass%. The R-T-B based sintered magnet satisfies the following requirements (1) to (4): 0<[T]-72.3×[B] (1); 0.2≤[Cu]/([Ga]+[Cu])≤0.5 (2); 0.5≤[Ga]/[Sn] (3); and 0.25≤[Ga]+[Sn]≤0.80 (4).SELECTED DRAWING: None

Description

本開示は、R−T−B系焼結磁石に関する。   The present disclosure relates to an RTB-based sintered magnet.

R−T−B系焼結磁石(Rは、希土類元素のうち少なくとも一種でありNdおよびPrの少なくとも一方を必ず含む)は永久磁石の中で最も高性能な磁石として知られており、ハードディスクドライブのボイスコイルモータ(VCM)、電気自動車用(EV、HV、PHVなど)モータ、産業機器用モータなどの各種モータおよび家電製品などに使用されている。   An RTB-based sintered magnet (R is at least one of rare earth elements and always includes at least one of Nd and Pr) is known as the most powerful magnet among permanent magnets, and is a hard disk drive. Used in various motors such as voice coil motors (VCM), motors for electric vehicles (EV, HV, PHV, etc.), motors for industrial equipment, and home appliances.

R−T−B系焼結磁石は、主としてR14B化合物からなる主相と、この主相の粒界部分に位置する粒界相とから構成されている。主相であるR14B化合物は、高い飽和磁化と異方性磁界を持つ強磁性材料であり、R−T−B系焼結磁石の特性の根幹をなしている。 The RTB-based sintered magnet is composed of a main phase mainly composed of an R 2 T 14 B compound and a grain boundary phase located at the grain boundary portion of the main phase. The main phase R 2 T 14 B compound is a ferromagnetic material having a high saturation magnetization and an anisotropic magnetic field, and forms the basis of the characteristics of the R—T—B system sintered magnet.

R−T−B系焼結磁石は、高温において保磁力HcJ(以下、単に「HcJ」という場合がある)が低下するため、不可逆熱減磁が起こる。そのため、特に電気自動車用モータに使用される場合、高いHcJを有することが要求されている。 The RTB -based sintered magnet has irreversible thermal demagnetization because the coercive force H cJ (hereinafter sometimes simply referred to as “H cJ ”) decreases at high temperatures. Therefore, it is required to have a high H cJ especially when used for an electric vehicle motor.

R−T−B系焼結磁石において、主相であるR14B化合物中のRに含まれる軽希土類元素RL(以下、単に「RL」という場合がある)の一部を重希土類元素RH(以下、単に「RH」という場合がある)で置換するとHcJが向上することが知られており、RHの置換量の増加に伴いHcJは向上する。 In the R-T-B based sintered magnet, a part of the light rare earth element RL (hereinafter sometimes simply referred to as “RL”) contained in R in the main phase R 2 T 14 B compound is a heavy rare earth element. RH (hereinafter simply is referred to as "RH") is known to H cJ is enhanced when substituted by, H cJ with increasing RH replacement amount is improved.

しかし、R14B化合物中のRLをRHで置換すると、R−T−B系焼結磁石のHcJが向上する一方、残留磁束密度B(以下、単に「B」という場合がある)が低下する。また、特にDyは資源存在量が少ないうえ産出地が限定されているなどの理由から供給が安定しておらず、価格が大きく変動するなどの問題を有している。そのため、近年、RHをできるだけ使用することなく(使用量をできるだけ少なくして)、HcJを向上させることが求められている。 However, when RL in the R 2 T 14 B compound is replaced with RH, the H cJ of the RTB -based sintered magnet is improved, while the residual magnetic flux density B r (hereinafter simply referred to as “B r ”). There is). In particular, Dy has a problem that its supply is not stable and its price fluctuates greatly because of its low resource abundance and limited production area. Therefore, in recent years, it has been demanded to improve HcJ without using RH as much as possible (with the least amount used).

特許文献1には、従来一般に用いられてきたR−T−B系合金に比べB量が相対的に少ない特定の範囲に限定するとともに、Al、GaおよびCuのうちから選ばれる1種以上の金属元素Mを含有させることによりR17相を生成させ、該R17相を原料として生成させた遷移金属リッチ相(R13M)の体積率を充分に確保することにより、Dyの含有量を抑制しつつ保磁力の高いR−T−B系希土類焼結磁石が得られることが記載されている。 In Patent Document 1, the amount of B is limited to a specific range relatively smaller than that of an R-T-B alloy that has been generally used in the past, and at least one selected from Al, Ga, and Cu. By containing the metal element M, the R 2 T 17 phase is generated, and the volume ratio of the transition metal rich phase (R 6 T 13 M) generated using the R 2 T 17 phase as a raw material is sufficiently secured. It is described that an RTB-based rare earth sintered magnet having a high coercive force while suppressing the Dy content can be obtained.

国際公開第2013/008756号International Publication No. 2013/008756

特許文献1に記載のように、一般的なR−T−B系焼結磁石よりもB量を少なく(R14B型化合物の化学量論比のB量よりも少なく)し、Ga等を添加することにより製造したR−T−B系焼結磁石では、遷移金属リッチ相(R−T−Ga相)が生成され、それによりHcJをある程度高めることができる。しかし、特許文献1に開示されているR−T−B系希土類焼結磁石は、Dyの含有量を低減しつつある程度高いHcJを発揮することができるものの、近年、電気自動車用モータ等の用途において要求される十分に高いHcJを満足するには不十分であった。 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), and Ga In an RTB -based sintered magnet manufactured by adding, for example, a transition metal-rich phase (RT-Ga phase), HcJ can be increased to some extent. However, although the RTB-based rare earth sintered magnet disclosed in Patent Document 1 can exhibit a high HcJ to some extent while reducing the Dy content, in recent years, such as motors for electric vehicles, etc. It was insufficient to satisfy the sufficiently high HcJ required in the application.

そこで本発明は、Dy等のRHをできるだけ使用することなく(すなわち、RHの使用量をできるだけ低減して)、高いBと高いHcJを有するR−T−B系焼結磁石を提供することを目的とする。 The present invention, without using as much as possible RH of Dy or the like (i.e., by reducing as much as possible the amount of RH), to provide R-T-B based sintered magnet having a high B r and high H cJ For the purpose.

本発明の態様1は、
R:27.5質量%以上、34.0質量%以下(Rは、希土類元素のうち少なくとも一種でありNdおよびPrの少なくとも一方を必ず含む)、
B:0.85質量%以上、0.93質量%以下、
Ga:0.20質量%以上、0.75質量%以下、
Sn:0.05質量%以上、0.60質量%以下、
Cu:0.05質量%以上、0.70質量%以下、
Al:0.05質量%以上、0.40質量%以下、および
T:61.5質量%以上(Tは、FeとCoであり、質量比でTの90%以上がFeである)を含み、下記式(1)〜(4)を満足する、R−T−B系焼結磁石である。

0<[T]−72.3×[B] (1)
0.2≦[Cu]/([Ga]+[Cu])≦0.5 (2)
0.5≦[Ga]/[Sn] (3)
0.25≦[Ga]+[Sn]≦0.80 (4)
([T]は質量%で示すTの含有量であり、[B]は質量%で示すBの含有量であり、[Ga]は質量%で示すGaの含有量であり、[Cu]は質量%で示すCuの含有量であり、[Sn]は質量%で示すSnの含有量である)
Aspect 1 of the present invention
R: 27.5% by mass or more and 34.0% by mass or less (R is at least one of rare earth elements and always includes at least one of Nd and Pr),
B: 0.85 mass% or more, 0.93 mass% or less,
Ga: 0.20 mass% or more, 0.75 mass% or less,
Sn: 0.05 mass% or more, 0.60 mass% or less,
Cu: 0.05 mass% or more, 0.70 mass% or less,
Al: 0.05 mass% or more, 0.40 mass% or less, and T: 61.5 mass% or more (T is Fe and Co, and 90% or more of T is Fe by mass ratio) The RTB-based sintered magnet satisfies the following formulas (1) to (4).

0 <[T] -72.3 × [B] (1)
0.2 ≦ [Cu] / ([Ga] + [Cu]) ≦ 0.5 (2)
0.5 ≦ [Ga] / [Sn] (3)
0.25 ≦ [Ga] + [Sn] ≦ 0.80 (4)
([T] is the content of T expressed in mass%, [B] is the content of B expressed in mass%, [Ga] is the content of Ga expressed in mass%, and [Cu] is (The content of Cu in mass%, and [Sn] is the content of Sn in mass%)

本発明の態様2は、Ga:0.20質量%以上、0.60質量%以下である、態様1に記載のR−T−B系焼結磁石である。   Aspect 2 of the present invention is the RTB-based sintered magnet according to aspect 1, wherein Ga: 0.20% by mass or more and 0.60% by mass or less.

本発明の態様3は、Sn:0.05質量%以上、0.38質量%以下である、態様1または2に記載のR−T−B系焼結磁石である。   Aspect 3 of the present invention is the RTB-based sintered magnet according to aspect 1 or 2, wherein Sn: 0.05% by mass or more and 0.38% by mass or less.

本発明の態様4は、0.20≦[Cu]/([Ga]+[Cu])≦0.38である、態様1〜3のいずれかに記載のR−T−B系焼結磁石である。   Aspect 4 of the present invention is the RTB-based sintered magnet according to any one of aspects 1 to 3, wherein 0.20 ≦ [Cu] / ([Ga] + [Cu]) ≦ 0.38. It is.

本発明の態様5は、0.94≦[Ga]/[Sn]である、態様1〜4のいずれかに記載のR−T−B系焼結磁石である。   Aspect 5 of the present invention is the RTB-based sintered magnet according to any one of aspects 1 to 4, wherein 0.94 ≦ [Ga] / [Sn].

本発明の態様6は、Ga:0.25質量%以上、0.60質量%以下である、態様1〜5のいずれかに記載のR−T−B系焼結磁石である。   Aspect 6 of the present invention is the RTB-based sintered magnet according to any one of aspects 1 to 5, which is Ga: 0.25 mass% or more and 0.60 mass% or less.

本発明の態様7は、0.43≦[Ga]+[Sn]≦0.80である、態様1〜6のいずれかに記載のR−T−B系焼結磁石である。   Aspect 7 of the present invention is the RTB-based sintered magnet according to any one of aspects 1 to 6, wherein 0.43 ≦ [Ga] + [Sn] ≦ 0.80.

本発明は、RHをできるだけ使用することなく(すなわち、RHの使用量をできるだけ低減して)、高いBと高いHcJを有するR−T−B系焼結磁石を提供することができる。 The present invention can provide (i.e., by reducing as much as possible the amount of RH), R-T-B based sintered magnet having a high B r and high H cJ without using as much as possible RH.

本発明者らは、特許文献1に開示されるR−T−B系焼結磁石では、遷移金属リッチ相(R−T−Ga相)を生成することによりHcJをある程度高めることができるものの、当該R−T−Ga相が若干の磁性を有しており、R−T−B系焼結磁石における粒界、特に主にHcJに影響すると考えられる、二つの主相間に存在する粒界(以下、「二粒子粒界」と記載する場合がある)にR−T−Ga相が多く存在することでHcJ向上を妨げていることに着眼した。
本発明者らはまた、特許文献1に開示されているような、一般的なR−T−B系焼結磁石よりもB量を少なくしてGa等を添加したR−T−B系焼結磁石では、R−T−Ga相が生成されるとともに、二粒子粒界にR−Ga−Cu相が生成されており、当該R−Ga−Cu相を二粒子粒界に多く存在させることにより、HcJを向上できることに着眼した。これは、製造過程の熱処理工程において、生成した液相中にCuが存在することで主相と液相の界面エネルギーを低下させることができ、そのため二粒子粒界に効率的に液相を導入することができ、そして、二粒子粒界に導入された液相中にGaが存在することにより、主相の表面近傍を溶解して厚い二粒子粒界を形成することができ、そのため主相間の磁気的な結合が弱められ、HcJを向上できると考えられる。
そこで、本発明者らは、二粒子粒界に形成されるR−Ga−Cu相の量を多くすることにより、R−T−B系焼結磁石のHcJを高めることを考えた。
本発明者らが鋭意検討した結果、一般的なR−T−B系焼結磁石よりもB量を少なく(R14B型化合物の化学量論比のB量よりも少なく)し、Ga等を添加することにより製造したR−T−B系焼結磁石では、二粒子粒界に遷移金属リッチ相(R−T−Ga相)が生成されると、R−T−Ga相の生成によってGaが消費され、そのためR−Ga−Cu相を形成するためのGa量が少なくなり、R−Ga−Cu相の生成が抑制されていることがわかった。また、二粒子粒界におけるR−Ga−Cu相の生成が抑制されないように、添加するGa量を多くした場合には、遷移金属リッチ相(R−T−Ga相)が二粒子粒界に多く生成されてしまい、HcJ向上の妨げとなることがわかった。
Although the present inventors can raise HcJ to some extent by producing | generating a transition metal rich phase (RT-Ga phase) in the RTB type | system | group sintered magnet disclosed by patent document 1. The R-T-Ga phase has some magnetism, and is present in the grain boundary in the R-T-B system sintered magnet, particularly a grain existing between two main phases, which is considered to mainly affect HcJ. It was noticed that the HcJ improvement was hindered by the presence of a large amount of RT-Ga phase at the boundary (hereinafter sometimes referred to as “two-particle grain boundary”).
The inventors of the present invention also have an RTB-based sintered body in which the amount of B is reduced and Ga or the like is added as compared with a general RTB-based sintered magnet as disclosed in Patent Document 1. In the magnet, an R—T—Ga phase is generated, an R—Ga—Cu phase is generated at the two-grain grain boundary, and a large amount of the R—Ga—Cu phase is present at the two-grain grain boundary. Thus , it was noted that HcJ could be improved. This is because, in the heat treatment step of the manufacturing process, the presence of Cu in the generated liquid phase can reduce the interfacial energy between the main phase and the liquid phase, so that the liquid phase is efficiently introduced into the two-particle grain boundary. And the presence of Ga in the liquid phase introduced into the two-grain grain boundary can dissolve the vicinity of the surface of the main phase to form a thick two-grain grain boundary. It is considered that the magnetic coupling is weakened and HcJ can be improved.
Therefore, the present inventors considered increasing the HcJ of the RTB -based sintered magnet by increasing the amount of the R—Ga—Cu phase formed at the two-grain grain boundary.
As a result of intensive studies by the present inventors, 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), In an RTB-based sintered magnet manufactured by adding Ga or the like, when a transition metal rich phase (RT-Ga phase) is generated at the two-particle grain boundary, the RT-Ga phase It was found that Ga was consumed by the generation, and therefore the amount of Ga for forming the R—Ga—Cu phase was reduced, and the generation of the R—Ga—Cu phase was suppressed. In addition, when the amount of Ga to be added is increased so that the generation of the R—Ga—Cu phase at the two-grain grain boundary is not suppressed, the transition metal rich phase (R—T—Ga phase) becomes the two-grain grain boundary. It was found that a large amount was generated, hindering the improvement of HcJ .

そこで、本発明者らは、遷移金属リッチ相(R−T−Ga相)の形成に消費されるGa量を抑制することにより、二粒子粒界に形成されるR−Ga−Cu相の量を多くでき、それによりHcJを向上させることを考えた。
本発明者らは、さらに鋭意検討を重ねた結果、Gaの添加量に対して適切な割合でSnを添加することにより、二粒子粒界におけるR−T−Ga相の生成を抑制することができ、これによりR−Ga−Cu相を形成するためのGa量を十分に確保することができ、R−Ga−Cu相を二粒子粒界に多く形成して、HcJを向上できることを見出した。これは、Gaの添加量に対して適切な割合でSnを含有させることにより、具体的には、0.5≦[Ga]/[Sn]かつ0.25≦[Ga]+[Sn]≦0.80の関係を満たすことによりR−T−Ga相よりもR−T−Sn相を優先的に生成することができる。そのため、R−T−Ga相の生成を抑制することができ、R−T−Ga相の形成に用いられるGa量を低減することができると考えられる。その結果、R−Ga−Cu相を形成するためのGa量を十分に確保することができ、R−Ga−Cu相を二粒子粒界に多く生成することができ、HcJを向上できると考えられる。
以下に、本発明の実施形態について詳述する。
Therefore, the present inventors suppress the amount of Ga consumed for the formation of the transition metal rich phase (RT-Ga phase), thereby the amount of the R-Ga-Cu phase formed at the grain boundary. It was considered that HcJ could be improved.
As a result of further earnest studies, the present inventors can suppress the generation of the RT-Ga phase at the two-grain grain boundary by adding Sn at an appropriate ratio with respect to the Ga addition amount. It was found that the amount of Ga for forming the R—Ga—Cu phase can be sufficiently secured, and a large amount of R—Ga—Cu phase can be formed at the grain boundary to improve HcJ. It was. Specifically, by adding Sn at an appropriate ratio with respect to the added amount of Ga, specifically, 0.5 ≦ [Ga] / [Sn] and 0.25 ≦ [Ga] + [Sn] ≦ By satisfying the relationship of 0.80, the RT-Sn phase can be preferentially generated over the RT-Ga phase. Therefore, it is considered that the generation of the R—T—Ga phase can be suppressed and the amount of Ga used for forming the R—T—Ga phase can be reduced. As a result, a sufficient amount of Ga for forming the R—Ga—Cu phase can be secured, many R—Ga—Cu phases can be generated at the two-grain grain boundaries, and HcJ can be improved. Conceivable.
Hereinafter, embodiments of the present invention will be described in detail.

[R−T−B系焼結磁石]
本発明の実施形態に係るR−T−B系焼結磁石について説明する。
本発明の実施形態に係るR−T−B系焼結磁石は、R−T−B系焼結磁石全体を100質量%としたとき、
R:27.5質量%以上、34.0質量%以下(Rは、希土類元素のうち少なくとも一種でありNdおよびPrの少なくとも一方を必ず含む)、
B:0.85質量%以上、0.93質量%以下、
Ga:0.20質量%以上、0.75質量%以下、
Sn:0.05質量%以上、0.60質量%以下、
Cu:0.05質量%以上、0.70質量%以下、
Al:0.05質量%以上、0.40質量%以下、および
T:61.5質量%以上(Tは、FeとCoであり、質量比でTの90%以上がFeである)を含み、下記式(1)〜(4)を満足する。
0<[T]−72.3×[B] (1)
0.2≦[Cu]/([Ga]+[Cu])≦0.5 (2)
0.5≦[Ga]/[Sn] (3)
0.25≦[Ga]+[Sn]≦0.80 (4)
([T]は質量%で示すTの含有量であり、[B]は質量%で示すBの含有量であり、[Ga]は質量%で示すGaの含有量であり、[Cu]は質量%で示すCuの含有量であり、[Sn]は質量%で示すSnの含有量である)
[RTB-based sintered magnet]
An RTB-based sintered magnet according to an embodiment of the present invention will be described.
When the R-T-B system sintered magnet according to the embodiment of the present invention is 100% by mass of the entire R-T-B system sintered magnet,
R: 27.5% by mass or more and 34.0% by mass or less (R is at least one of rare earth elements and always includes at least one of Nd and Pr),
B: 0.85 mass% or more, 0.93 mass% or less,
Ga: 0.20 mass% or more, 0.75 mass% or less,
Sn: 0.05 mass% or more, 0.60 mass% or less,
Cu: 0.05 mass% or more, 0.70 mass% or less,
Al: 0.05 mass% or more, 0.40 mass% or less, and T: 61.5 mass% or more (T is Fe and Co, and 90% or more of T is Fe by mass ratio) The following formulas (1) to (4) are satisfied.
0 <[T] -72.3 × [B] (1)
0.2 ≦ [Cu] / ([Ga] + [Cu]) ≦ 0.5 (2)
0.5 ≦ [Ga] / [Sn] (3)
0.25 ≦ [Ga] + [Sn] ≦ 0.80 (4)
([T] is the content of T expressed in mass%, [B] is the content of B expressed in mass%, [Ga] is the content of Ga expressed in mass%, and [Cu] is (The content of Cu in mass%, and [Sn] is the content of Sn in mass%)

また、本発明の別の好ましい実施形態の1つでは、R−T−B系焼結磁石の組成は、R−T−B系焼結磁石全体を100質量%としたとき、
R:27.5質量%以上、34.0質量%以下(Rは、希土類元素のうち少なくとも一種でありNdおよびPrの少なくとも一方を必ず含む)、
B:0.85質量%以上、0.93質量%以下、
Ga:0.20質量%以上、0.75質量%以下、
Sn:0.05質量%以上、0.60質量%以下、
Cu:0.05質量%以上、0.70質量%以下、および
Al:0.05質量%以上、0.40質量%以下、
を含み、残部がT(Tは、FeとCoであり、質量比でTの90%以上がFeである)および不可避不純物であり、下記式(1)〜(4)を満足する。
0<[T]−72.3×[B] (1)
0.2≦[Cu]/([Ga]+[Cu])≦0.5 (2)
0.5≦[Ga]/[Sn] (3)
0.25≦[Ga]+[Sn]≦0.80 (4)
([T]は質量%で示すTの含有量であり、[B]は質量%で示すBの含有量であり、[Ga]は質量%で示すGaの含有量であり、[Cu]は質量%で示すCuの含有量であり、[Sn]は質量%で示すSnの含有量である。)
In another preferred embodiment of the present invention, when the composition of the R-T-B system sintered magnet is 100% by mass of the entire R-T-B system sintered magnet,
R: 27.5% by mass or more and 34.0% by mass or less (R is at least one of rare earth elements and always includes at least one of Nd and Pr),
B: 0.85 mass% or more, 0.93 mass% or less,
Ga: 0.20 mass% or more, 0.75 mass% or less,
Sn: 0.05 mass% or more, 0.60 mass% or less,
Cu: 0.05 mass% or more, 0.70 mass% or less, and Al: 0.05 mass% or more, 0.40 mass% or less,
The balance is T (T is Fe and Co, and 90% or more of T is Fe by mass) and inevitable impurities, and satisfies the following formulas (1) to (4).
0 <[T] -72.3 × [B] (1)
0.2 ≦ [Cu] / ([Ga] + [Cu]) ≦ 0.5 (2)
0.5 ≦ [Ga] / [Sn] (3)
0.25 ≦ [Ga] + [Sn] ≦ 0.80 (4)
([T] is the content of T expressed in mass%, [B] is the content of B expressed in mass%, [Ga] is the content of Ga expressed in mass%, and [Cu] is (The Cu content in mass%, and [Sn] is the Sn content in mass%.)

次に各元素の詳細を説明する。   Next, details of each element will be described.

(1)希土類元素(R)
本発明の実施形態に係るR−T−B系焼結磁石におけるRは、希土類元素の少なくとも一種でありNdおよびPrの少なくとも一方を必ず含む。本発明の実施形態に係るR−T−B系焼結磁石は重希土類元素(RH)を含有しなくても高いBと高いHcJを得ることができるため、より高いHcJを求められる場合でもRHの添加量を削減でき、典型的にはRHの含有量を5質量%以下とすることができる。しかし、このことは、本発明の実施形態に係るR−T−B系焼結磁石のRH含有量が5質量%以下に限定されることを意味するものではない。
Rの含有量は、27.5質量%以上、34.0質量%以下である。
R含有量が27.5質量%未満では、焼結過程で液相が十分に生成せず、R−T−B系焼結体を十分に緻密化することが困難になるおそれがあり、34.0質量%を超えると主相比率が低下して高いBを得ることができないおそれがある。Rは、より高いBを得るには、31.0質量%以下が好ましい。
(1) Rare earth element (R)
R in the RTB-based sintered magnet according to the embodiment of the present invention is at least one kind of rare earth element and always includes at least one of Nd and Pr. R-T-B based sintered magnet according to an embodiment of the present invention it is possible to obtain a high B r and high H cJ also contain no heavy rare-earth element (RH), obtained higher H cJ Even in this case, the amount of RH added can be reduced, and the content of RH can be typically 5% by mass or less. However, this does not mean that the RH content of the RTB-based sintered magnet according to the embodiment of the present invention is limited to 5% by mass or less.
Content of R is 27.5 mass% or more and 34.0 mass% or less.
When the R content is less than 27.5% by mass, a liquid phase is not sufficiently generated in the sintering process, and it may be difficult to sufficiently densify the R-T-B system sintered body. more than 2.0 wt%, the main phase ratio it may be impossible to obtain a high B r drops. R is, in order to obtain a higher B r is preferably not more than 31.0 wt%.

(2)ボロン(B)
Bの含有量は、0.85質量%以上、0.93質量%以下である。
Bの含有量が0.85質量%未満では、R17相が析出して高いHcJが得られない。さらに、主相比率が低下して高いBを得ることができないおそれがある。一方、Bの含有量が0.93質量%を超えるとR−T−Ga相の生成量が少なすぎて高いHcJが得られない。
(2) Boron (B)
Content of B is 0.85 mass% or more and 0.93 mass% or less.
When the B content is less than 0.85 mass%, the R 2 T 17 phase is precipitated and high H cJ cannot be obtained. Furthermore, there is a possibility that the main phase ratio can not be obtained a high B r drops. On the other hand, if the B content exceeds 0.93% by mass, the amount of R—T—Ga phase produced is too small to obtain high H cJ .

(3)ガリウム(Ga)
Gaの含有量は、0.20質量%以上、0.75質量%以下である。
Gaの含有量が0.20質量%未満であると、R−T−Ga相の生成量が少なすぎて、R17相を消失させることができず、高いHcJを得ることができない。一方、Gaの含有量が0.75質量%を超えると、不要なGaが存在することになり、主相比率が低下してBが低下する恐れがある。
Ga含有量は、0.20質量%以上、0.60質量%以下であることが好ましく、0.25質量%以上、0.60質量%以下がさらに好ましい。
(3) Gallium (Ga)
The Ga content is 0.20% by mass or more and 0.75% by mass or less.
If the Ga content is less than 0.20% by mass, the amount of R—T—Ga phase produced is too small to eliminate the R 2 T 17 phase, and high H cJ cannot be obtained. . On the other hand, when the content of Ga is more than 0.75 wt%, will be unnecessary Ga is present, there is a possibility that B r decreases to decrease the main phase proportion.
The Ga content is preferably 0.20% by mass or more and 0.60% by mass or less, and more preferably 0.25% by mass or more and 0.60% by mass or less.

(4)スズ(Sn)
Snの含有量は、0.05質量%以上、0.60質量%以下である。
Snの含有量が0.05質量%未満であると、R−T−Sn相の生成量が少なくなり、R−T−Ga相の生成を抑制することができず、HcJが低下する。
一方、Snの含有量が0.60質量%を超えると、不要なSnが存在することになり、主相比率が低下してBが低下する恐れがある。Sn含有量は、0.05質量%以上、0.55質量%以下が好ましく、0.05質量%以上、0.38質量%以下であることが更に好ましい。
(4) Tin (Sn)
The Sn content is 0.05% by mass or more and 0.60% by mass or less.
When the Sn content is less than 0.05% by mass, the amount of R—T—Sn phase generated decreases, the generation of R—T—Ga phase cannot be suppressed, and H cJ decreases.
On the other hand, when the content of Sn is more than 0.60 wt%, will be unnecessary Sn is present, there is a possibility that B r decreases to decrease the main phase proportion. The Sn content is preferably 0.05% by mass or more and 0.55% by mass or less, and more preferably 0.05% by mass or more and 0.38% by mass or less.

(5)銅(Cu)
Cuの含有量は、0.05質量%以上、0.70質量%以下である。
Cuの含有量が0.05質量%未満であると、R−Ga−Cu相の生成量が少なすぎて高いHcJを得ることができない。また、Cuの含有量が0.70質量%を超えると、Bが低下する恐れがある。
(5) Copper (Cu)
The Cu content is 0.05% by mass or more and 0.70% by mass or less.
If the Cu content is less than 0.05 mass%, the amount of R-Ga-Cu phase produced is too small to obtain high HcJ . Further, when the Cu content exceeds 0.70 mass%, B r may be reduced.

(6)アルミニウム(Al)
Alの含有量は、0.05質量%以上、0.40質量%以下である。Alを含有することにより、HcJを向上させることができる。Alは不可避的不純物として含有されてもよいし、積極的に添加して含有させてもよい。不可避的不純物として含有される量と積極的に添加した量の合計で0.05質量%以上0.40質量%以下含有させる。
(6) Aluminum (Al)
The Al content is 0.05% by mass or more and 0.40% by mass or less. By containing Al, HcJ can be improved. Al may be contained as an inevitable impurity, or may be positively added and contained. The total of the amount contained as an unavoidable impurity and the amount positively added is 0.05 mass% or more and 0.40 mass% or less.

(7)遷移金属元素(T)
Tは、FeとCoであり、質量比でTの90%以上がFeである。
Tが61.5質量%未満では、Bが大幅に低下するおそれがある。そのためTの含有量は61.5質量%以上である。TにおけるFeの割合が質量比で90%未満の場合、Bが低下するおそれがある。そのため、T含有量におけるCo含有量の割合は、T含有量全体の10%以下が好ましく、2.5%以下がより好ましい。
(7) Transition metal element (T)
T is Fe and Co, and 90% or more of T is Fe by mass ratio.
T is less than 61.5 mass%, there is a possibility that B r is greatly reduced. Therefore, the content of T is 61.5% by mass or more. When the ratio of Fe in T is less than 90% by mass, Br may be lowered. Therefore, the ratio of the Co content in the T content is preferably 10% or less, more preferably 2.5% or less of the entire T content.

(8)式(1)〜(4)
本発明の実施形態に係るR−T−B系焼結磁石は、上述した成分組成範囲を満足した上で、さらに以下の式(1)〜(4)を満足する。
0<[T]−72.3×[B] (1)
0.2≦[Cu]/([Ga]+[Cu])≦0.5 (2)
0.5≦[Ga]/[Sn] (3)
0.25≦[Ga]+[Sn]≦0.80 (4)
([T]は質量%で示すTの含有量であり、[B]は質量%で示すBの含有量であり、[Ga]は質量%で示すGaの含有量であり、[Cu]は質量%で示すCuの含有量であり、[Sn]は質量%で示すSnの含有量である)
以下に、式(1)〜(4)について詳細に説明する。
(8) Expressions (1) to (4)
The RTB-based sintered magnet according to the embodiment of the present invention further satisfies the following formulas (1) to (4) after satisfying the component composition range described above.
0 <[T] -72.3 × [B] (1)
0.2 ≦ [Cu] / ([Ga] + [Cu]) ≦ 0.5 (2)
0.5 ≦ [Ga] / [Sn] (3)
0.25 ≦ [Ga] + [Sn] ≦ 0.80 (4)
([T] is the content of T expressed in mass%, [B] is the content of B expressed in mass%, [Ga] is the content of Ga expressed in mass%, and [Cu] is (The content of Cu in mass%, and [Sn] is the content of Sn in mass%)
Below, Formula (1)-(4) is demonstrated in detail.

(0<[T]−72.3×[B])
本発明の実施形態に係るR−T−B系焼結磁石の組成は、式(1)を満足することにより、B含有量が一般的なR−T−B系焼結磁石よりも低くなっている。一般的なR−T−B系焼結磁石は、主相であるR14B相以外に軟磁性相であるR17相が析出しないよう、[Fe]/55.847(Feの原子量)が[B]/10.811(Bの原子量)×14よりも少ない組成となっている([ ]は、その内部に記載された元素の質量%で示した含有量を意味する。例えば、[Fe]は質量%で示したFeの含有量を意味する)。本発明の実施形態に係るR−T−B系焼結磁石は、一般的なR−T−B系焼結磁石と異なり、[Fe]/55.847(Feの原子量)が[B]/10.811(Bの原子量)×14よりも多くなるように、式(1)を満足する組成とする。なお、TはFeとCoであるが、本発明の実施形態におけるTはFeが主成分(質量比で90%以上)であることから、Feの原子量を用いた。これにより、Dyなどの重希土類元素をできるだけ使用せず、高いHcJを得ることができる。
(0 <[T] -72.3 × [B])
The composition of the RTB-based sintered magnet according to the embodiment of the present invention is such that the B content is lower than that of a general RTB-based sintered magnet by satisfying the formula (1). ing. A general R-T-B type sintered magnet has [Fe] /55.847 (Fe) so that the R 2 T 17 phase, which is a soft magnetic phase, does not precipitate in addition to the R 2 T 14 B phase, which is a main phase. The atomic weight of the element is less than [B] /10.811 (the atomic weight of B) × 14 ([] means the content expressed in mass% of the element described therein. For example, [Fe] means the Fe content expressed in mass%). The RTB-based sintered magnet according to the embodiment of the present invention is different from a general RTB-based sintered magnet in that [Fe] /55.847 (the atomic weight of Fe) is [B] / The composition satisfies Formula (1) so as to be larger than 10.811 (atomic weight of B) × 14. Although T is Fe and Co, T in the embodiment of the present invention uses the atomic weight of Fe since Fe is a main component (mass ratio of 90% or more). Thereby, high HcJ can be obtained without using heavy rare earth elements such as Dy as much as possible.

(0.2≦[Cu]/([Ga]+[Cu])≦0.5)
本発明の実施形態に係るR−T−B系焼結磁石は、[Cu]/([Ga]+[Cu])が0.2以上、0.5以下となるように、Cu含有量およびGa含有量を制御する。[Cu]/([Ga]+[Cu])をこのような範囲にすることにより、二粒子粒界の厚みを大きくすることができ、高いHcJと高いBとを得ることができる。[Cu]/([Ga]+[Cu])は、好ましくは、0.20以上、0.38以下である。
[Cu]/([Ga]+[Cu])が0.2未満の場合には、Ga量に対してCu量が少なすぎるため、熱処理時に二粒子粒界へ液相を十分に導入することができず、R−Ga−Cu相を適切に形成することができない。また、二粒子粒界へのGaの導入が少なくなるため、三つ以上の主相間に存在する第二の粒界に存在するGaを含む液相の量が多くなる。これにより、Gaを含む液相による第二の粒界近傍の主相の溶解が促進され、HcJが十分向上しないだけでなく、Bの低下を招く。
一方、[Cu]/([Ga]+[Cu])の質量比が0.5を超える場合には、液相中のGaの存在比が小さすぎ、二粒子粒界に導入された液相による主相の溶解が十分に起こらない。そのため、二粒子粒界が十分に厚くならず、高いHcJが得られない。
(0.2 ≦ [Cu] / ([Ga] + [Cu]) ≦ 0.5)
In the RTB-based sintered magnet according to the embodiment of the present invention, the Cu content and the [Cu] / ([Ga] + [Cu]) are 0.2 or more and 0.5 or less. The Ga content is controlled. The [Cu] / ([Ga] + [Cu]) With such a range, it is possible to increase the thickness of the second grain grain boundary, it is possible to obtain a high H cJ and high B r. [Cu] / ([Ga] + [Cu]) is preferably 0.20 or more and 0.38 or less.
When [Cu] / ([Ga] + [Cu]) is less than 0.2, the amount of Cu is too small relative to the amount of Ga, so that a sufficient liquid phase should be introduced into the grain boundary during heat treatment. And the R—Ga—Cu phase cannot be formed properly. Moreover, since the introduction of Ga into the two-grain grain boundary is reduced, the amount of the liquid phase containing Ga present at the second grain boundary existing between three or more main phases is increased. Thereby, dissolution of the main phase of the second near the grain boundary by a liquid phase containing Ga is promoted not only H cJ is not sufficiently improved, leading to reduction in B r.
On the other hand, when the mass ratio of [Cu] / ([Ga] + [Cu]) exceeds 0.5, the abundance ratio of Ga in the liquid phase is too small, and the liquid phase introduced into the two-particle grain boundary The main phase is not sufficiently dissolved by Therefore, the two-grain grain boundary is not sufficiently thick, and high HcJ cannot be obtained.

(0.5≦[Ga]/[Sn])
本発明の実施形態に係るR−T−B系焼結磁石は、[Ga]/[Sn]が0.5以上になるように、Ga含有量およびSn含有量を制御する。[Ga]/[Sn]をこのような範囲に設定することにより、高いHcJを得ることができる。[Ga]/[Sn]が0.5未満であると、Gaに対してSnの添加量が多すぎるため、R−T−Sn相に加えてR−Sn相が生成され、R−Sn相の生成にRが消費されることでR−Ga−Cu相の生成量が少なくなり高いHcJが得られない。[Ga]/[Sn]は、好ましくは0.94以上である。
(0.5 ≦ [Ga] / [Sn])
The RTB-based sintered magnet according to the embodiment of the present invention controls the Ga content and the Sn content so that [Ga] / [Sn] is 0.5 or more. By setting [Ga] / [Sn] in such a range, high HcJ can be obtained. If [Ga] / [Sn] is less than 0.5, the amount of Sn added is too large relative to Ga, so that an R—Sn phase is generated in addition to the R—T—Sn phase, and the R—Sn phase. Since R is consumed for the production of R, the production amount of the R—Ga—Cu phase is reduced, and high HcJ cannot be obtained. [Ga] / [Sn] is preferably 0.94 or more.

(0.25≦[Ga]+[Sn]≦0.80)
本発明の実施形態に係るR−T−B系焼結磁石は、[Ga]+[Sn](Ga含有量とSn含有量との合計)が0.25質量%以上、0.80質量%以下になるように、Ga含有量とSn含有量とを制御する。[Ga]+[Sn]をこのような範囲に設定することにより、Gaの働きにより主相の表面近傍が溶解され、溶解された際にできた液相とSnが反応し、R−T−Sn相が生成することでR−T−Ga相の生成が抑制され、二粒子粒界にR−Ga−Cu相を多く形成させることができるため、高いHcJを有することができる。
GaとSnの合計含有量が0.25質量%未満であると、GaおよびSnの少なくとも一方の含有量が少なすぎるため、R−T−Sn相の生成量およびR−Ga−Cu相の少なくとも一方の生成量が少なくなり、高いHcJを得ることができない。
一方、GaとSnの合計含有量が0.80質量%を超えると、GaおよびSnの少なくとも一方が粒界に過剰に存在し、主相の体積比率が低下し、Bが低下する恐れがある。
[Ga]+[Sn]は、0.30質量%以上、0.80質量%以下が好ましく、0.43質量%以上、0.80質量%以下が更に好ましい。
(0.25 ≦ [Ga] + [Sn] ≦ 0.80)
In the RTB-based sintered magnet according to the embodiment of the present invention, [Ga] + [Sn] (total of Ga content and Sn content) is 0.25% by mass or more and 0.80% by mass. The Ga content and the Sn content are controlled so as to be as follows. By setting [Ga] + [Sn] in such a range, the vicinity of the surface of the main phase is dissolved by the action of Ga, the liquid phase formed when dissolved and Sn react, and RT- Since the generation of the Sn phase suppresses the generation of the R—T—Ga phase and a large number of R—Ga—Cu phases can be formed at the two-grain grain boundaries, it can have high H cJ .
When the total content of Ga and Sn is less than 0.25% by mass, the content of at least one of Ga and Sn is too small, so that the amount of R-T-Sn phase generated and at least of the R-Ga-Cu phase On the other hand, the amount of production decreases, and high HcJ cannot be obtained.
On the other hand, when the total content of Ga and Sn exceeds 0.80% by mass, at least one of Ga and Sn is excessively present at the grain boundary, the volume ratio of the main phase may be reduced, and Br may be reduced. is there.
[Ga] + [Sn] is preferably 0.30 mass% or more and 0.80 mass% or less, more preferably 0.43 mass% or more and 0.80 mass% or less.

(9)残部
本発明の実施形態に係るR−T−B系焼結磁石の組成は、上述した元素に限定されるものではない。上述した元素の他にAg、Zn、In、Zr、Nb、Ti、Ni、Hf、Ta、W、Ge、Mo、V、Y、La、Ce、Sm、Ca、Mg、Cr、H、F、P、S、Cl、O、N、C等を含有してもよい。含有量は、Ni、Ag、Zn、In、Zr、Nb、およびTiはそれぞれ0.5質量%以下、Hf、Ta、W、Ge、Mo、V、Y、La、Ce、Sm、Ca、Mg、Crはそれぞれ0.2質量%以下、H、F、P、S、Clは500ppm以下、Oは6000ppm以下、Nは1000ppm以下、Cは1500ppm以下が好ましい。これらの元素の合計の含有量は、R−T−B系焼結磁石全体の5質量%以下が好ましい。これらの元素の合計の含有量がR−T−B系焼結磁石全体の5質量%を超えると高いBと高いHcJを得ることができない可能性がある。
(9) Remainder The composition of the RTB-based sintered magnet according to the embodiment of the present invention is not limited to the elements described above. In addition to the elements described above, Ag, Zn, In, Zr, Nb, Ti, Ni, Hf, Ta, W, Ge, Mo, V, Y, La, Ce, Sm, Ca, Mg, Cr, H, F, P, S, Cl, O, N, C, etc. may be contained. The contents of Ni, Ag, Zn, In, Zr, Nb, and Ti are each 0.5 mass% or less, Hf, Ta, W, Ge, Mo, V, Y, La, Ce, Sm, Ca, Mg Cr is preferably 0.2% by mass or less, H, F, P, S, and Cl are 500 ppm or less, O is 6000 ppm or less, N is 1000 ppm or less, and C is 1500 ppm or less. The total content of these elements is preferably 5% by mass or less of the entire RTB-based sintered magnet. The total content of these elements may not be able to obtain a R-T-B based sintered magnet exceeds 5% by weight of the total the high B r and high H cJ.

また、上述したように、好ましい1つの実施形態では、残部はTおよび不可避的不純物であってよい。例えば、ジジム合金(Nd−Pr)、電解鉄およびフェロボロン等の溶解原料に通常不可避的に含有される不純物等に起因した不可避的不純物を含有していても、本発明の実施形態の効果を十分に奏することができる。このような不可避的不純物は、例えば、La、Ce、Cr、Mn、Si、Sm、CaおよびMgである。さらに、製造工程中の不可避的不純物として、O(酸素)、N(窒素)、C(炭素)などを例示できる。   Also, as described above, in one preferred embodiment, the balance may be T and inevitable impurities. For example, the effects of the embodiments of the present invention are sufficiently obtained even if unavoidable impurities due to impurities inevitably contained in dissolved raw materials such as didymium alloy (Nd—Pr), electrolytic iron and ferroboron are contained. Can be played. Such inevitable impurities are, for example, La, Ce, Cr, Mn, Si, Sm, Ca and Mg. Furthermore, O (oxygen), N (nitrogen), C (carbon), etc. can be illustrated as an inevitable impurity in a manufacturing process.

[R−T−B系焼結磁石の製造方法]
R−T−B系焼結磁石の製造方法の一例を説明する。R−T−B系焼結磁石の製造方法は、合金粉末を得る工程、成形工程、焼結工程、熱処理工程を有する。以下、各工程について説明する。
[Method for producing RTB-based sintered magnet]
An example of a manufacturing method of the RTB-based sintered magnet will be described. 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)合金粉末を得る工程
上述した組成となるようにそれぞれの元素の金属または合金を準備し、これらをストリップキャスティング法等を用いてフレーク状の合金を製造する。得られたフレーク状の合金を水素粉砕し、粗粉砕粉のサイズを例えば1.0mm以下とする。次に、粗粉砕粉をジェットミル等により微粉砕することで、例えば粒径D50(気流分散法によるレーザー回折法で得られた値(メジアン径))が3〜7μmの微粉砕粉(合金粉末)を得る。なお、ジェットミル粉砕前の粗粉砕粉、ジェットミル粉砕中およびジェットミル粉砕後の合金粉末に助剤として公知の潤滑剤を使用してもよい。
(1) Step of obtaining alloy powder A metal or alloy of each element is prepared so as to have the above-described composition, and a flaky alloy is produced using the strip casting method or the like. The obtained flaky alloy is hydrogen crushed 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, so that, for example, a finely pulverized powder (alloy having a particle diameter D 50 (value (median diameter) obtained by a laser diffraction method by an air flow dispersion method) of 3 to 7 μm Powder). 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)成形工程
得られた合金粉末に対して磁界中成形を行い、成形体を得る。磁界中成形は、金型のキャビティー内に乾燥した合金粉末を挿入し、磁界を印加しながら成形する乾式成形法、金型のキャビティー内に該合金粉末を分散させたスラリーを注入し、スラリーの分散媒を排出しながら成形する湿式成形法を含む既知の任意の磁界中成形方法を用いてよい。成形中に印加する磁界の方向は、加圧方向と直交する方向(いわゆる直角磁界成形法)でもよく、加圧方向に平行方向(いわゆる平行磁界成形法)でもよい。
(2) Forming step The obtained alloy powder is formed in a magnetic field to obtain a formed body. In the magnetic field molding, a dry alloy method in which a dry alloy powder is inserted into a mold cavity and molded while applying a magnetic field, a slurry in which the alloy powder is dispersed is injected into the mold cavity, Any known forming method in a magnetic field may be used, including a wet forming method of forming while discharging the slurry dispersion medium. The direction of the magnetic field applied during molding may be a direction orthogonal to the pressing direction (so-called perpendicular magnetic field forming method) or a direction parallel to the pressing direction (so-called parallel magnetic field forming method).

(3)焼結工程
成形体を焼結することにより焼結体(焼結磁石)を得る。成形体の焼結は既知の方法を用いることができる。なお、焼結時の雰囲気による酸化を防止するために、焼結は、真空雰囲気中または雰囲気ガス中で行うことが好ましい。雰囲気ガスは、ヘリウム、アルゴンなどの不活性ガスを用いることが好ましい。
(3) 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 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)熱処理工程
得られた焼結磁石に対し、磁気特性を向上させることを目的とした熱処理を行うことが好ましい。熱処理温度、熱処理時間などは既知の条件を用いることができる。例えば、比較的低い温度(400℃以上600℃以下)のみでの熱処理(一段熱処理)をしてもよく、あるいは比較的高い温度(700℃以上焼結温度以下(例えば1050℃以下))で熱処理を行った後比較的低い温度(400℃以上600℃以下)で熱処理(二段熱処理)をしてもよい。好ましい条件は、750℃以上850℃以下で5分から500分程度の熱処理を施し、冷却後(室温まで冷却後、または440℃以上550℃以下まで冷却後)、さらに440℃以上550℃以下で5分から500分程度熱処理をすることが挙げられる。熱処理雰囲気は、真空雰囲気あるいは不活性ガス(ヘリウムやアルゴンなど)で行うことが好ましい。
得られた焼結磁石に磁石寸法の調整のため、研削などの機械加工を施してもよい。その場合、熱処理は機械加工前でも機械加工後でもよい。さらに、得られた焼結磁石に、表面処理を施してもよい。表面処理は、公知の表面処理で良く、例えばAl蒸着、電気Niめっきまたは樹脂塗装等の表面処理を行うことができる。
(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 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 that heat treatment is performed at 750 ° C. to 850 ° C. for about 5 minutes to 500 minutes, and after cooling (after cooling to room temperature or after cooling to 440 ° C. to 550 ° C.), 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).
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.

本開示に係るR−T−B系焼結磁石を実験例によりさらに詳細に説明するが、本開示はそれらに限定されるものではない。   The RTB-based sintered magnet according to the present disclosure will be described in more detail by experimental examples, but the present disclosure is not limited thereto.

(1)実験例1
R−T−B系焼結磁石がおよそ表1のNo.1〜16に示す組成となるように、各元素を秤量しストリップキャスト法により鋳造し、フレーク状の合金を得た。なお、表1の「TRE」は、希土類元素の合計含有量(Total amount of Rear Earth)、つまり、Nd、PrおよびDyの合計含有量を意味している。得られた合金を水素粉砕した後、550℃まで真空中で加熱冷却する脱水素処理を施し粗粉砕粉を得た。次に、得られた粗粉砕粉に、潤滑剤としてステアリン酸亜鉛を粗粉砕粉100質量%に対して0.04質量%添加、混合した後、気流式粉砕機(ジェットミル装置)を用いて、窒素気流中で乾式粉砕し、粒径D50が4μmの微粉砕粉(合金粉末)を得た。なお、粒径D50は、気流分散法によるレーザー回折法で得られた体積中心値(体積基準メジアン径)である。
(1) Experimental example 1
The R-T-B system sintered magnet is approximately No. 1 in Table 1. Each element was weighed so as to have the composition shown in 1 to 16 and cast by a strip casting method to obtain a flaky alloy. Note that “TRE” in Table 1 means the total amount of rare earth elements (Total amount of Rear Earth), that is, the total content of Nd, Pr and Dy. The obtained alloy was pulverized with hydrogen and then subjected to dehydrogenation treatment by heating and cooling to 550 ° C. in a vacuum 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). was dry milled in a nitrogen stream, the particle size D 50 was obtained finely pulverized powder of 4μm (the alloy powder). The particle diameter D 50 is the volume center value obtained by the laser diffraction method by air flow dispersion method (volume-based median diameter).

前記微粉砕粉に、潤滑剤としてステアリン酸亜鉛を微粉砕粉100質量%に対して0.05質量%添加、混合した後磁界中で成形し成形体を得た。なお、成形装置には、磁界印加方向と加圧方向とが直交するいわゆる直角磁界成形装置(横磁界成形装置)を用いた。   To the finely pulverized powder, zinc stearate as a lubricant was added in an amount of 0.05% by mass with respect to 100% by mass of the finely pulverized powder, mixed, and then molded in a magnetic field to obtain a molded body. In addition, what was called a perpendicular magnetic field shaping | molding apparatus (transverse magnetic field shaping | molding apparatus) with which the magnetic field application direction and the pressurization direction orthogonally crossed was used for the shaping | molding apparatus.

得られた成形体を、真空中、1000℃以上1050℃以下(サンプル毎に焼結による緻密化が十分起こる温度を選定)で4時間焼結した後急冷し焼結体を得た。得られた焼結体の密度は7.5Mg/m以上であった。得られた焼結体に対し真空中、800℃で2時間保持した後室温まで冷却し、次いで真空中で430℃で2時間保持した後、室温まで冷却する熱処理を施しR−T−B系焼結磁石(No.1〜16)を得た。得られたR−T−B系焼結磁石の成分を表1に示す。なお、表1における各成分(O、NおよびC以外)は、高周波誘導結合プラズマ発光分光分析法(ICP−OES)を使用して測定した。また、O(酸素)含有量は、ガス融解−赤外線吸収法、N(窒素)含有量は、ガス融解−熱伝導法、C(炭素)含有量は、燃焼−赤外線吸収法によるガス分析装置を使用して測定した。熱処理後のR−T−B系焼結磁石(試料No.1〜16)にそれぞれ機械加工を施し、縦7mm、横7mm、厚み7mmの試料を作製し、B−Hトレーサによって各試料の磁気特性を測定した。測定結果を表2に示す。なお、H/HcJ(角形比)において、HはI(磁化の大きさ)−H(磁界の強さ)曲線の第2象限において、Iが0.9×J(Jは残留磁化、J=B)の値になる位置のHの値である。 The obtained molded body was sintered at 1000 ° C. or higher and 1050 ° C. or lower (a temperature at which densification by sintering was sufficiently selected for each sample) for 4 hours, and then rapidly cooled to obtain a sintered body. The density of the obtained sintered body was 7.5 Mg / m 3 or more. The obtained sintered body was held in vacuum at 800 ° C. for 2 hours, then cooled to room temperature, then held in vacuum at 430 ° C. for 2 hours, and then subjected to a heat treatment to cool to room temperature to obtain an RTB system Sintered magnets (No. 1 to 16) were obtained. Table 1 shows components of the obtained RTB-based sintered magnet. In addition, each component (except O, N, and C) in Table 1 was measured using a high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES). The O (oxygen) content is a gas melting-infrared absorption method, the N (nitrogen) content is a gas melting-thermal conduction method, and the C (carbon) content is a gas analysis device by a combustion-infrared absorption method. Measured using. Each of the R-T-B sintered magnets (sample Nos. 1 to 16) after heat treatment is machined to prepare samples having a length of 7 mm, a width of 7 mm, and a thickness of 7 mm, and each sample is magnetized by a B-H tracer. Characteristics were measured. The measurement results are shown in Table 2. Note that, in H k / H cJ (square ratio), H k is in the second quadrant of the I (magnetization magnitude) -H (magnetic field strength) curve, and I is 0.9 × J r (J r is This is the value of H at the position where the value of remanent magnetization, J r = B r ).

Figure 2018125445
Figure 2018125445

Figure 2018125445
Figure 2018125445

表2に示す様に、本開示の範囲内である本発明例はいずれもB:1.174T以上、且つ、HcJ:2323kA/m以上の高いBと高いHcJが得られている。これに対し、Snの含有量が本開示の範囲外であるNo.1、Bの含有量及び式(1)が本開示の範囲外であるNo.7、Bの含有量が本開示の範囲外であるNo.8、Gaの含有量が本開示の範囲外であるNo.9、Gaの含有量及び式(4)が本開示の範囲外であるNo.12、式(2)が本開示の範囲外であるNo.13及び14、式(3)が本開示の範囲外であるNo.15、Sn及び式(4)が本開示の範囲外であるNo.6、式(4)が本開示の範囲外であるNo.16は、いずれもB:1.174T以上、且つ、HcJ:2323kA/m以上の高いBと高いHcJが得られていない。 As shown in Table 2, the present invention embodiment are within the scope of the present disclosure are both B r: 1.174T above, and, H cJ: 2323kA / m or more high B r and high H cJ are obtained . On the other hand, the content of Sn is outside the scope of the present disclosure. No. 1, content of B and formula (1) are outside the scope of the present disclosure. 7, No. B content is outside the scope of the present disclosure. No. 8, Ga content is outside the scope of the present disclosure. No. 9, Ga content and formula (4) are outside the scope of the present disclosure. 12, No. 2 in which equation (2) is outside the scope of the present disclosure. No. 13 and 14, No. 3 in which formula (3) is outside the scope of the present disclosure 15, Sn and formula (4) are outside the scope of the present disclosure. 6, No. 4 in which equation (4) is outside the scope of the present disclosure. 16, both B r: 1.174T above, and, H cJ: 2323kA / m or more high B r and high H cJ can not be obtained.

Claims (7)

R:27.5質量%以上、34.0質量%以下(Rは、希土類元素のうち少なくとも一種でありNdおよびPrの少なくとも一方を必ず含む)、
B:0.85質量%以上、0.93質量%以下、
Ga:0.20質量%以上、0.75質量%以下、
Sn:0.05質量%以上、0.60質量%以下、
Cu:0.05質量%以上、0.70質量%以下、
Al:0.05質量%以上、0.40質量%以下、および
T:61.5質量%以上(Tは、FeとCoであり、質量比でTの90%以上がFeである)を含み、下記式(1)〜(4)を満足する、R−T−B系焼結磁石。
0<[T]−72.3×[B] (1)
0.2≦[Cu]/([Ga]+[Cu])≦0.5 (2)
0.5≦[Ga]/[Sn] (3)
0.25≦[Ga]+[Sn]≦0.80 (4)
([T]は質量%で示すTの含有量であり、[B]は質量%で示すBの含有量であり、[Ga]は質量%で示すGaの含有量であり、[Cu]は質量%で示すCuの含有量であり、[Sn]は質量%で示すSnの含有量である)
R: 27.5% by mass or more and 34.0% by mass or less (R is at least one of rare earth elements and always includes at least one of Nd and Pr),
B: 0.85 mass% or more, 0.93 mass% or less,
Ga: 0.20 mass% or more, 0.75 mass% or less,
Sn: 0.05 mass% or more, 0.60 mass% or less,
Cu: 0.05 mass% or more, 0.70 mass% or less,
Al: 0.05 mass% or more, 0.40 mass% or less, and T: 61.5 mass% or more (T is Fe and Co, and 90% or more of T is Fe by mass ratio) An RTB-based sintered magnet satisfying the following formulas (1) to (4).
0 <[T] -72.3 × [B] (1)
0.2 ≦ [Cu] / ([Ga] + [Cu]) ≦ 0.5 (2)
0.5 ≦ [Ga] / [Sn] (3)
0.25 ≦ [Ga] + [Sn] ≦ 0.80 (4)
([T] is the content of T expressed in mass%, [B] is the content of B expressed in mass%, [Ga] is the content of Ga expressed in mass%, and [Cu] is (The content of Cu in mass%, and [Sn] is the content of Sn in mass%)
Ga:0.20質量%以上、0.60質量%以下である、
請求項1に記載のR−T−B系焼結磁石。
Ga: 0.20% by mass or more and 0.60% by mass or less,
The RTB-based sintered magnet according to claim 1.
Sn:0.05質量%以上、0.38質量%以下である、
請求項1または2に記載のR−T−B系焼結磁石。
Sn: 0.05% by mass or more and 0.38% by mass or less,
The RTB-based sintered magnet according to claim 1 or 2.
0.20≦[Cu]/([Ga]+[Cu])≦0.38である、
請求項1〜3のいずれか1項に記載のR−T−B系焼結磁石。
0.20 ≦ [Cu] / ([Ga] + [Cu]) ≦ 0.38,
The RTB-based sintered magnet according to any one of claims 1 to 3.
0.94≦[Ga]/[Sn]である、
請求項1〜4のいずれか1項に記載のR−T−B系焼結磁石。
0.94 ≦ [Ga] / [Sn],
The RTB-based sintered magnet according to any one of claims 1 to 4.
Ga:0.25質量%以上、0.60質量%以下である、
請求項1〜5のいずれか1項に記載のR−T−B系焼結磁石。
Ga: 0.25 mass% or more and 0.60 mass% or less,
The RTB-based sintered magnet according to any one of claims 1 to 5.
0.43≦[Ga]+[Sn]≦0.80である、
請求項1〜6のいずれか1項に記載のR−T−B系焼結磁石。
0.43 ≦ [Ga] + [Sn] ≦ 0.80,
The RTB-based sintered magnet according to any one of claims 1 to 6.
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