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JP2005197533A - R-t-b-based rare earth permanent magnet - Google Patents

R-t-b-based rare earth permanent magnet Download PDF

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JP2005197533A
JP2005197533A JP2004003435A JP2004003435A JP2005197533A JP 2005197533 A JP2005197533 A JP 2005197533A JP 2004003435 A JP2004003435 A JP 2004003435A JP 2004003435 A JP2004003435 A JP 2004003435A JP 2005197533 A JP2005197533 A JP 2005197533A
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rare earth
earth permanent
permanent magnet
magnetization
rtb
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JP3728316B2 (en
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Tetsuya Hidaka
徹也 日▲高▼
Kazuya Sakamoto
一也 坂元
Kazuo Sato
和生 佐藤
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TDK Corp
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TDK Corp
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Priority to US10/807,889 priority patent/US7199690B2/en
Priority to CN200410032256.7A priority patent/CN1277277C/en
Priority to EP04007468A priority patent/EP1462531B1/en
Priority to EP07016095A priority patent/EP1884574B1/en
Priority to EP07017978A priority patent/EP1860203B1/en
Priority to DE602004009979T priority patent/DE602004009979T2/en
Priority to HK05103338A priority patent/HK1070740A1/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an R-T-B-based rare earth permanent magnet that obtains a higher magnetization rate by a low magnetization magnetic field and allows the magnetization rate to rise fast until a magnetization rate reaches the vicinity of 100%, for example about 90%. <P>SOLUTION: In the R-T-B-based rare earth permanent magnet having a high coercive force by containing many heavy rare earth elements, the average crystal particle diameter of a sintered body and the amount of contained oxygen are controlled, and further an element such as Nb is contained. Regarding magnetization characteristics, the calculation result of (f1/f3×100) is equal to or higher than 60%, and the result of (f2/f3×100) is equal to or higher than 85%, when total flux by applying an effective magnetic field of 240 kA/m is set to f1, when total flux by applying an effective magnetic field of 400 kA/m is set to f2, and when total flux by applying an effective magnetic field of 2,000 kA/m is set to f3 if Pc is equal to 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、R−T−B(ただし、Rは希土類元素の1種又は2種以上、TはFe又はFe及びCoを必須とする1種又は2種以上の遷移金属元素)系希土類永久磁石に関し、特に着磁特性の高いR−T−B系希土類永久磁石に関する。   The present invention relates to an R-T-B (where R is one or more rare earth elements and T is one or more transition metal elements in which Fe, Fe and Co are essential) based rare earth permanent magnets. In particular, the present invention relates to an R-T-B rare earth permanent magnet having high magnetization characteristics.

希土類磁石の中でもR−T−B系希土類永久磁石は、磁気特性に優れていること、主成分であるNdが資源的に豊富で比較的安価であることから、各種電気機器に採用されている。
これまで、R−T−B系希土類永久磁石の磁気特性、具体的には残留磁束密度、保磁力あるいは最大エネルギー積の向上のための研究、開発が主になされてきた。しかし、近時、着磁特性に着目した研究、開発が行なわれている。R−T−B系希土類永久磁石は、フェライト磁石に比べて高い着磁磁界を必要とする。例えば、リング状のR−T−B系希土類永久磁石をモータの回転子として用いる場合に、モータにR−T−B系希土類永久磁石を組み込んだ後にリング状のR−T−B系希土類永久磁石に捲き回したモータ用コイルを用いて着磁させることがある。モータが小型の場合には所定の捲き回し数を得るためにコイルの線径が細くなり、大電流を流すことができず、そのためにR−T−B系希土類永久磁石に対して十分な着磁磁界を印加することができない。したがって、以上のような用途に用いられるR−T−B系希土類永久磁石としては、低い着磁磁界で可能な限り高い着磁特性を有することが要求される。
Among rare earth magnets, R-T-B rare earth permanent magnets are used in various electric devices because they have excellent magnetic properties and Nd as a main component is abundant in resources and relatively inexpensive. .
Until now, research and development have been mainly conducted for improving the magnetic characteristics of the RTB rare earth permanent magnet, specifically, the residual magnetic flux density, the coercive force, or the maximum energy product. However, recently, research and development focusing on magnetizing characteristics have been conducted. R-T-B rare earth permanent magnets require a higher magnetizing magnetic field than ferrite magnets. For example, when a ring-shaped RTB-based rare earth permanent magnet is used as a rotor of a motor, the ring-shaped RTB-based rare earth permanent magnet is incorporated into the motor after the RTB-based rare earth permanent magnet is incorporated. Magnetization may be performed using a motor coil wound around a magnet. When the motor is small, the coil wire diameter is reduced to obtain a predetermined number of turns, and a large current cannot be flowed. Therefore, sufficient attachment to the R-T-B system rare earth permanent magnet is possible. A magnetic field cannot be applied. Therefore, the RTB-based rare earth permanent magnet used for the above-described applications is required to have as high a magnetization characteristic as possible with a low magnetization magnetic field.

例えば、特開2002−356701号公報(特許文献1)には、着磁特性の優れるR−T−B系希土類永久磁石として、主相の平均組成が、(LR1-xHRx214A(Tは、Fe、又はFeとFe以外の遷移金属元素の少なくとも1種との混合物、Aはボロン又はボロンと炭素との混合物、LRは軽希土類元素の少なくとも1種、HRは重希土類元素の少なくとも1種、0<x<1)で表される希土類合金焼結体であって、(LR1-pHRp214A(0≦p<x)で表される組成の第1の主相と、(LR1-qHRq214A(x<q≦1)で表される組成の第2の主相との少なくとも一方を複数有する結晶粒を含んでいる希土類合金焼結体が開示されている。 For example, in Japanese Patent Laid-Open No. 2002-356701 (Patent Document 1), an R-T-B rare earth permanent magnet having excellent magnetization characteristics has an average main phase composition of (LR 1-x HR x ) 2 T 14 A (T is Fe or a mixture of Fe and at least one transition metal element other than Fe, A is boron or a mixture of boron and carbon, LR is at least one light rare earth element, and HR is heavy rare earth A rare earth alloy sintered body represented by at least one element, 0 <x <1, and having a composition represented by (LR 1-p HR p ) 2 T 14 A (0 ≦ p <x) It includes crystal grains having a plurality of at least one of the first main phase and the second main phase having a composition represented by (LR 1-q HR q ) 2 T 14 A (x <q ≦ 1). A rare earth alloy sintered body is disclosed.

また、特開2003−217918号公報(特許文献2)には、着磁特性の向上を目的として、重量%で、R(RはYを含む希土類元素の少なくとも1種であり、Rに占めるNdが50原子%以上である):25〜35%、B:0.8〜1.5%、必要によりM(Ti、Cr、Ga、Mn、Co、Ni、Cu、Zn、Nb、Alから選ばれる少なくとも1種):8%以下、及び残部T(Fe又はFe及びCo)、ならびに不可避的不純物を含有し、80at%以上をFeCo1−AとするFe相が0.01〜300μmの大きさで焼結体中に残存している結晶組織を有する希土類焼結磁石において、残留磁束密度で評価される着磁率Br(0.2MA/m)/Br(2.0MA/m)が59%以上、フラックスで評価される着磁率Φ(0.3MA/m)/Φ(4.0MA/m)が4%以上であることが開示されている。 Japanese Patent Laid-Open No. 2003-217918 (Patent Document 2) describes, for the purpose of improving the magnetizing characteristics, in weight%, R (R is at least one kind of rare earth element including Y, and Nd occupies R). Is 25-35%, B: 0.8-1.5%, M (Ti, Cr, Ga, Mn, Co, Ni, Cu, Zn, Nb, Al if necessary) At least one selected from the group consisting of 8% or less and the balance T (Fe or Fe and Co) and unavoidable impurities, and Fe phase having an Fe A Co 1-A content of 80 at% or more is 0.01 to 300 μm. In a rare earth sintered magnet having a size and a crystal structure remaining in the sintered body, the magnetization rate Br (0.2 MA / m) / Br (2.0 MA / m) evaluated by the residual magnetic flux density is 59. % Or more, the magnetic permeability Φ (0. 3MA / m) / Φ (4.0 MA / m) is disclosed to be 4% or more.

特開2002−356701号公報JP 2002-356701 A 特開2003−217918号公報JP 2003-217918 A

特許文献1に開示された技術によれば、磁気特性を低下させることなく着磁特性を改善することができる。しかし、50%程度の着磁率を得るために0.8MA/m(10kOe)程度の着磁磁界が必要であり、さらに低い着磁磁界で50%程度の着磁率を得ることが望まれる。また、特許文献2における残留磁束密度で評価される着磁率Br(0.2MA/m)/Br(2.0MA/m)が59%以上、フラックスで評価される着磁率Φ(0.3MA/m)/Φ(4.0MA/m)が4%以上という値は、着磁特性が良いとはいえない。   According to the technique disclosed in Patent Document 1, the magnetization characteristics can be improved without deteriorating the magnetic characteristics. However, a magnetizing magnetic field of about 0.8 MA / m (10 kOe) is necessary to obtain a magnetizing ratio of about 50%, and it is desirable to obtain a magnetizing ratio of about 50% with a lower magnetizing field. In addition, the magnetization rate Br (0.2 MA / m) / Br (2.0 MA / m) evaluated by the residual magnetic flux density in Patent Document 2 is 59% or more, and the magnetization rate Φ (0.3 MA / m) evaluated by the flux. When the value of m) / Φ (4.0 MA / m) is 4% or more, it cannot be said that the magnetization characteristics are good.

一方で、本発明者等の検討によると、低い磁界でより高い着磁率が得られるR−T−B系希土類永久磁石は、着磁率の着磁磁界による変動を表す着磁特性曲線がなだらかな傾斜を示す傾向にある。つまり、着磁率特性曲線が緩やかなため100%近傍の着磁率に到達するまでに、より大きな着磁磁界が必要であった。
本発明は、このような技術的課題に基づいてなされたもので、低い着磁磁界でより高い着磁率を得るとともに、100%近傍、例えば90%程度の着磁率に到達するまで、より着磁率の立ち上がりが早いR−T−B系希土類永久磁石を提供することを目的とする。
On the other hand, according to the study by the present inventors, an R-T-B rare earth permanent magnet that can obtain a higher magnetization rate with a low magnetic field has a gentle magnetization characteristic curve that represents a variation in the magnetization rate due to the magnetization magnetic field. It tends to show an inclination. That is, since the magnetization characteristic curve is gentle, a larger magnetizing magnetic field is required to reach a magnetization rate near 100%.
The present invention has been made on the basis of such a technical problem, and obtains a higher magnetization rate with a low magnetization magnetic field, and further increases the magnetization rate until reaching a magnetization rate of around 100%, for example, about 90%. It is an object of the present invention to provide an R-T-B rare earth permanent magnet having a quick rise.

かかる目的のもと、本発明者はR14B相からなる主相と、主相よりRを多く含む粒界相とを備えた焼結体からなる磁石について検討を行なった。その結果、重希土類元素を多く含むことにより保磁力の高いタイプのR−T−B系希土類永久磁石において、焼結体の平均結晶粒径及び含有酸素量を制御すること、さらにはNb等の元素を含有させることにより、従来にない優れた着磁特性が得られることを確認した。
すなわち本発明のR−T−B系希土類永久磁石は、R14B相(ただし、Rは希土類元素の1種又は2種以上、TはFe又はFe及びCoを必須とする1種又は2種以上の遷移金属元素。以下同じ。)からなる主相と、主相よりRを多く含む粒界相とを備えた焼結体からなり、Pc(パーミアンス係数)が2において、240kA/mの有効磁場(ただし、有効磁場=印加磁場−反磁場)を印加したときのトータルフラックスをf1、400kA/mの有効磁場を印加したときのトータルフラックスをf2、2000kA/mの有効磁場を印加したときのトータルフラックスをf3とすると、着磁率a(=f1/f3×100)が60%以上、かつ、着磁率b(=f2/f3×100)が85%以上の着磁特性を有していることを特徴としている。
本発明のR−T−B系希土類永久磁石は、Pcが0.5において、着磁率aが40%以上で、かつ、着磁率bが70%以上であり、さらにPcが1において、着磁率aが55%以上で、かつ、着磁率bが80%以上という高い着磁特性を実現することができる。
For this purpose, the present inventor has studied a magnet made of a sintered body having a main phase composed of an R 2 T 14 B phase and a grain boundary phase containing more R than the main phase. As a result, in the R-T-B type rare earth permanent magnet of a type having a high coercive force by containing a large amount of heavy rare earth elements, it is possible to control the average crystal grain size and the amount of oxygen contained in the sintered body, and further, Nb or the like It was confirmed that by including an element, an excellent magnetization characteristic that has never been obtained can be obtained.
That is, the R-T-B rare earth permanent magnet of the present invention has an R 2 T 14 B phase (where R is one or more of rare earth elements, and T is one or more essential elements of Fe, Fe, and Co). A sintered body having a main phase composed of two or more transition metal elements (the same shall apply hereinafter) and a grain boundary phase containing more R than the main phase, and a Pc (permeance coefficient) of 2 is 240 kA / m The total flux when applying an effective magnetic field (where effective magnetic field = applied magnetic field-demagnetizing field) is f1, the total flux when applying an effective magnetic field of 400 kA / m is f2, and the effective magnetic field of 2000 kA / m is applied. When the total flux is f3, the magnetization rate a (= f1 / f3 × 100) is 60% or more and the magnetization rate b (= f2 / f3 × 100) is 85% or more. Features that It is.
The RTB-based rare earth permanent magnet of the present invention has a magnetization rate of 40% or more, a magnetization rate b of 70% or more at Pc of 0.5, and a magnetization rate of b of 70% or more. It is possible to realize a high magnetization characteristic such that a is 55% or more and the magnetization rate b is 80% or more.

ところで従来から、R−T−B系希土類永久磁石は、高い保磁力を得ようとする場合には残留磁束密度が低くなり、逆に高い残留磁束密度を得ようとする場合には保磁力が低くなることが知られている。例えば、希土類元素として含有されるDyの量を調整すること、具体的には高保磁力を得たいときにはDy量を増やし、高残留磁束密度を得たいときにはDy量を減らすことにより、所望する特性を得ていた。そして、高い保磁力を有するタイプのR−T−B系希土類永久磁石は高い着磁特性が得られることは概念的には知られていた。そのため、高保磁力タイプのR−T−B系希土類永久磁石においては、それ以上の高い着磁特性を追求することが行われていなかった。ところが、本発明によると、保磁力(HcJ)が1680kA/m(21Oe)、さらには2000kA/m(25Oe)を超える高保磁力タイプにおいても低い着磁磁界における着磁特性を向上させることができるという利点がある。このR−T−B系希土類永久磁石は、残留磁束密度(Br)が1.20T以上、最大エネルギー積((BH)max)が240kJ/m以上、角形比(Hk/HcJ)が90%以上の特性を確保することができる。 Conventionally, an RTB-based rare earth permanent magnet has a low residual magnetic flux density when trying to obtain a high coercive force, and conversely, when an attempt is made to obtain a high residual magnetic flux density, the coercive force is low. It is known to be lower. For example, by adjusting the amount of Dy contained as a rare earth element, specifically, increasing the Dy amount when it is desired to obtain a high coercive force, and decreasing the Dy amount when obtaining a high residual magnetic flux density, the desired characteristics can be obtained. I was getting. And, it has been conceptually known that an RTB-based rare earth permanent magnet of a type having a high coercive force can obtain a high magnetization characteristic. Therefore, in the high coercive force type R-T-B type rare earth permanent magnet, it has not been attempted to pursue a higher magnetizing characteristic. However, according to the present invention, even in a high coercive force type in which the coercive force (HcJ) exceeds 1680 kA / m (21 Oe), and further exceeds 2000 kA / m (25 Oe), it is possible to improve the magnetization characteristics in a low magnetization field. There are advantages. This RTB-based rare earth permanent magnet has a residual magnetic flux density (Br) of 1.20 T or more, a maximum energy product ((BH) max) of 240 kJ / m 3 or more, and a squareness ratio (Hk / HcJ) of 90%. The above characteristics can be ensured.

本発明のR−T−B系希土類永久磁石において、焼結体中の酸素量が1500ppm以下であること、焼結体中の平均結晶粒径が3.5〜5.0μmであることが、以上の優れた着磁特性を得るために重要である。さらに、焼結体中にNbが分散していることが、以上の優れた着磁特性を得るために重要である。   In the RTB-based rare earth permanent magnet of the present invention, the amount of oxygen in the sintered body is 1500 ppm or less, and the average crystal grain size in the sintered body is 3.5 to 5.0 μm. It is important to obtain the above excellent magnetization characteristics. Further, it is important for Nb to be dispersed in the sintered body in order to obtain the above excellent magnetization characteristics.

本発明は、R:25〜35wt%、B:0.5〜4.5wt%、Al及びCuの1種又は2種:0.02〜0.5wt%、Nb:0.2〜1.5wt%及びZr:0.03〜0.25wt%の1種又は2種 、Co:2wt%以下(0を含まず)、残部実質的にFeからなる組成を有する焼結体からなるR−T−B系希土類永久磁石に適用することが望ましい。また、保磁力や温度特性の向上、生産性の向上、低コスト化などのためにTi、V、Cr、Mn、Bi、Ta、Mo、W、Sb、Ge、Sn、Ni、Si、Hf、Ga等を1種以上添加してもよい。この中でGaは着磁特性向上にとって有効であり、0.02〜1.5wt%、さらには0.1〜1wt%の範囲で添加することが望ましい。
このR−T−B系希土類永久磁石において、焼結体中の酸素量を2000ppm以下、焼結体の平均結晶粒径を3.5〜5.0μmとすることにより、優れた着磁特性を得ることができる。
In the present invention, R: 25 to 35 wt%, B: 0.5 to 4.5 wt%, one or two of Al and Cu: 0.02 to 0.5 wt%, Nb: 0.2 to 1.5 wt% % And Zr: 0.03 to 0.25 wt%, 1 type or 2 types, Co: 2 wt% or less (not including 0), and the balance being a sintered body having a composition substantially consisting of Fe It is desirable to apply to B-based rare earth permanent magnets. In addition, Ti, V, Cr, Mn, Bi, Ta, Mo, W, Sb, Ge, Sn, Ni, Si, Hf, etc. for improving coercive force and temperature characteristics, improving productivity, and reducing costs. One or more types of Ga or the like may be added. Among these, Ga is effective for improving the magnetization characteristics, and it is desirable to add in the range of 0.02 to 1.5 wt%, and further 0.1 to 1 wt%.
In this R-T-B rare earth permanent magnet, the amount of oxygen in the sintered body is 2000 ppm or less, and the average crystal grain size of the sintered body is 3.5 to 5.0 μm. Can be obtained.

本発明によるR−T−B系希土類永久磁石は、Rとして4.0〜12.0wt%のDyを含むことができる。また、Rとして1.0〜6.0wt%のTbを含むことができる。Dy及びTbは単独又は複合で含むことができることはいうまでもない。
また、本発明によるR−T−B系希土類永久磁石にNbを含む場合、このNbは焼結体中の主相(R14B相)及び結晶粒界に分散する。また、R−T−B系希土類永久磁石にZrを含む場合、このZrは焼結体中の結晶粒界に分散する。
本発明によるR−T−B系希土類永久磁石は、種々の形態の磁石に用いることができるが、多極着磁される磁石に用いた場合にその効果を顕著に発揮することができる。
本発明によるR−T−B系希土類永久磁石は、高い磁気特性を有するためには、焼結体中の窒素量を20〜600ppm、炭素量を1500ppm以下に規制することが望ましい。
The RTB-based rare earth permanent magnet according to the present invention may contain 4.0 to 12.0 wt% Dy as R. Further, R may contain 1.0 to 6.0 wt% of Tb. It goes without saying that Dy and Tb can be contained alone or in combination.
Further, when the RTB-based rare earth permanent magnet according to the present invention contains Nb, the Nb is dispersed in the main phase (R 2 T 14 B phase) and the crystal grain boundary in the sintered body. Further, when the RTB-based rare earth permanent magnet contains Zr, the Zr is dispersed at the grain boundaries in the sintered body.
The RTB-based rare earth permanent magnet according to the present invention can be used for various types of magnets, but the effect can be remarkably exhibited when used for a magnet that is multipolarly magnetized.
In order for the RTB-based rare earth permanent magnet according to the present invention to have high magnetic properties, it is desirable to regulate the amount of nitrogen in the sintered body to 20 to 600 ppm and the amount of carbon to 1500 ppm or less.

本発明によれば、400kA/m(5kOe)程度の低い着磁磁界での着磁率が向上されるとともに、800kA/m(10kOe)以上の着磁磁界における着磁率も向上されたR−T−B系希土類永久磁石を提供する。このような着磁特性に優れたR−T−B系希土類永久磁石は、多極着磁磁石に用いた場合には、ニュートラルゾーンの幅を狭くすることができる。このようなリング磁石を用いたモータは、高い回転性能を保持することができる。また、着磁率の高い磁石は、材質的に高コストで高磁気特性であるが着磁率の低い磁石に比べて、実際に発生するトータルフラックスが多い場合がある。したがって、本発明は、所定のトータルフラックスを低コストの磁石で実現することができる。または磁石のサイズを小型化することができる。   According to the present invention, the magnetization rate in a magnetization field as low as about 400 kA / m (5 kOe) is improved and the magnetization rate in a magnetization field of 800 kA / m (10 kOe) or more is also improved. A B-based rare earth permanent magnet is provided. Such an R-T-B rare earth permanent magnet having excellent magnetization characteristics can reduce the width of the neutral zone when used in a multipolar magnet. A motor using such a ring magnet can maintain high rotational performance. In addition, a magnet with a high magnetization rate has a high cost and high magnetic properties as a material, but there are cases where a total flux actually generated is larger than a magnet with a low magnetization rate. Therefore, the present invention can realize a predetermined total flux with a low-cost magnet. Alternatively, the size of the magnet can be reduced.

以下、本発明によるR−T−B系希土類永久磁石及びその製造方法について詳細に説明する。
<着磁特性>
本発明によって得られるR−T−B系希土類永久磁石は、よく知られているように、R14B結晶粒(Rは希土類元素の1種又は2種以上、TはFe又はFe及びCoを主体とする遷移金属元素の1種以上)からなる主相と、この主相よりRを多く含む粒界相とを少なくとも含んでいる。
そして、Pc(パーミアンス係数)が2において、240kA/mの有効磁場(ただし、有効磁場=印加磁場−反磁場)を印加したときのトータルフラックスをf1、400kA/mの有効磁場を印加したときのトータルフラックスをf2、2000kA/mの有効磁場を印加したときのトータルフラックスをf3とすると、着磁率a(=f1/f3×100)が60%以上、かつ、着磁率b(=f2/f3×100)が85%以上である。さらに、本発明のR−T−B系希土類永久磁石は、800kA/mの有効磁場を印加したときのトータルフラックスをf4とすると、着磁率c(=f4/f3×100)が95%以上となり、極めて着磁率が高い。なお、本発明におけるPcは、「希土類永久磁石」俵好夫、大橋健共著(森北出版)第146頁の図5−4に基づいて定めている。また、着磁率は以下によって測定した。評価する磁石をポールピースに挟み込んで閉磁路を形成した後、電磁石に電流を流し着磁を行なった。この場合、印加磁場=有効磁場となる。着磁後、フラックスメータによりトータルフラックスを測定した。
Hereinafter, the RTB system rare earth permanent magnet and the manufacturing method thereof according to the present invention will be described in detail.
<Magnetic properties>
As is well known, the R-T-B rare earth permanent magnet obtained by the present invention has R 2 T 14 B crystal grains (R is one or more rare earth elements, T is Fe or Fe and A main phase composed of one or more transition metal elements mainly composed of Co) and a grain boundary phase containing more R than the main phase.
When the effective magnetic field of 240 kA / m (where effective magnetic field = applied magnetic field−demagnetizing field) is applied at Pc (permeance coefficient) of 2, the total flux is f1, when the effective magnetic field of 400 kA / m is applied. If the total flux is f2, and the total flux when an effective magnetic field of 2000 kA / m is applied is f3, the magnetization a (= f1 / f3 × 100) is 60% or more and the magnetization b (= f2 / f3 ×). 100) is 85% or more. Furthermore, the RTB-based rare earth permanent magnet of the present invention has a magnetization rate c (= f4 / f3 × 100) of 95% or more when the total flux when an effective magnetic field of 800 kA / m is applied is f4. The magnetization rate is extremely high. Note that Pc in the present invention is determined based on FIG. 5-4 on page 146 of “rare earth permanent magnet” by Yoshio Tsuji and Kenji Ohashi (Morita Kita Publishing). The magnetization rate was measured as follows. A magnet to be evaluated was sandwiched between pole pieces to form a closed magnetic circuit, and then an electric current was passed through the electromagnet for magnetization. In this case, the applied magnetic field = effective magnetic field. After magnetization, the total flux was measured with a flux meter.

ここで着磁特性についていえば、前述したように、低磁界でより大きな着磁率を有し、かつ着磁率の立ち上がり急峻であることが理想的である。ところが、従来、この両者を満足することは容易ではなかった。しかるに、本発明は、着磁率a(=f1/f3×100)が60%以上、かつ、着磁率b(=f2/f3×100)が85%以上、さらには着磁率c(=f4/f3×100)が95%以上という、従来にはない低磁界で高着磁率で、かつ着磁率の立ち上がりの早いR−T−B系希土類永久磁石を提供する。   Here, regarding the magnetization characteristics, as described above, it is ideal that the magnetic field has a larger magnetization rate in a low magnetic field and that the magnetization rate rises steeply. However, conventionally, it has not been easy to satisfy both. However, according to the present invention, the magnetization a (= f1 / f3 × 100) is 60% or more, the magnetization b (= f2 / f3 × 100) is 85% or more, and the magnetization c (= f4 / f3). The present invention provides an RTB-based rare earth permanent magnet having a low magnetic field, a high magnetization rate, and a rapid rise in magnetization rate, which is unprecedented (x100) is 95% or more.

以上の着磁特性を得るためには、焼結体の結晶粒が平均粒径で3.5〜5.0μmという限られた範囲にあることが重要である。後述する第1実施例で説明するように、結晶粒の平均粒径が3.5μm未満あるいは5.0μmを超えると、上述した着磁率a、着磁率bを得ることができない。
また、以上の着磁特性を得るための組成的な要因としては、焼結体中の酸素含有量を規制すること、さらにNb及びZrの1種又は2種を含むことが掲げられる。この点については、以下の<化学組成>の欄で述べることにする。
In order to obtain the above magnetization characteristics, it is important that the crystal grains of the sintered body are in a limited range of 3.5 to 5.0 μm in average grain size. As will be described in the first embodiment described later, when the average grain size of the crystal grains is less than 3.5 μm or more than 5.0 μm, the above-described magnetization rate a and magnetization rate b cannot be obtained.
Moreover, as a compositional factor for obtaining the above magnetizing characteristics, it is mentioned that the oxygen content in the sintered body is regulated and that one or two of Nb and Zr are included. This point will be described in the section <Chemical composition> below.

<化学組成>
次に、本発明によるR−T−B系希土類永久磁石の望ましい化学組成について説明する。ここでいう化学組成は焼結後における最終組成をいう。
本発明のR−T−B系希土類永久磁石は、希土類元素(R)を25〜35wt%含有する。
ここで、本発明におけるRはYを含む概念を有しており、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Yb、Lu及びYの1種又は2種以上である。Rの量が25wt%未満であると、R−T−B系希土類永久磁石の主相となるR14B結晶粒の生成が十分ではなく軟磁性を持つα−Feなどが析出し、保磁力が著しく低下する。一方、Rの量が35wt%を超えると主相であるR14B結晶粒の体積比率が低下し、残留磁束密度が低下する。またRが酸素と反応し、含有する酸素量が増え、これに伴い保磁力発生に有効なR−リッチ相が減少し、保磁力の低下を招く。したがって、Rの量は25〜35wt%とする。望ましいRの量は28〜33wt%、さらに望ましいRの量は29〜32wt%である。
Ndは資源的に豊富で比較的安価であることから、希土類元素としての主成分をNdとすることが好ましい。また、Dy及びTbは保磁力を向上させる上で有効である。よって、希土類元素としてNd及びDyを選択し、NdとDy及び/又はTbの合計を25〜35wt%とすることが望ましい。Dy及びTbは、残留磁束密度及び保磁力のいずれを重視するかによって上記範囲内においてその量を定めることが望ましい。つまり、高い保磁力を得たい場合にはDy量を4.0〜12.0wt%、Tb量を1.0〜6.0wt%とすることが望ましい。なお、保磁力向上の効果はTbがDyよりも高く、Tbは同じ量を含む場合にDyの2倍程度の保磁力向上効果を発揮する。
<Chemical composition>
Next, the desirable chemical composition of the RTB-based rare earth permanent magnet according to the present invention will be described. The chemical composition here refers to the final composition after sintering.
The RTB-based rare earth permanent magnet of the present invention contains 25 to 35 wt% of a rare earth element (R).
Here, R in the present invention has a concept including Y, and one or two of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, and Y More than a seed. When the amount of R is less than 25 wt%, the formation of R 2 T 14 B crystal grains serving as the main phase of the R—T—B system rare earth permanent magnet is not sufficient, and α-Fe having soft magnetism is precipitated, The coercive force is significantly reduced. On the other hand, when the amount of R exceeds 35 wt%, the volume ratio of the R 2 T 14 B crystal grains as the main phase decreases, and the residual magnetic flux density decreases. Further, R reacts with oxygen, the amount of oxygen contained increases, and accordingly, the R-rich phase effective for the generation of coercive force decreases, leading to a decrease in coercive force. Therefore, the amount of R is set to 25 to 35 wt%. A desirable amount of R is 28 to 33 wt%, and a more desirable amount of R is 29 to 32 wt%.
Since Nd is abundant in resources and relatively inexpensive, it is preferable to use Nd as the main component as a rare earth element. Dy and Tb are effective in improving the coercive force. Therefore, it is desirable that Nd and Dy are selected as the rare earth elements, and the total of Nd, Dy and / or Tb is 25 to 35 wt%. It is desirable to determine the amounts of Dy and Tb within the above range depending on which of the residual magnetic flux density and the coercive force is important. That is, when it is desired to obtain a high coercive force, it is desirable to set the Dy amount to 4.0 to 12.0 wt% and the Tb amount to 1.0 to 6.0 wt%. The effect of improving the coercive force is that Tb is higher than Dy, and when Tb contains the same amount, the effect of improving the coercive force is about twice that of Dy.

本発明は、前述したように、保磁力が比較的高いタイプのR−T−B系希土類永久磁石においても優れた着磁特性を有している点に特徴がある。したがって、Dy及び/Tbが上述した範囲にある場合に本発明の効果が十分発揮することができる。その場合の保磁力(HcJ)は1680kA/mを超え、また1750kA/m以上、さらには2000kA/m以上となる。   As described above, the present invention is characterized in that it has excellent magnetization characteristics even in a type of R-T-B rare earth permanent magnet having a relatively high coercive force. Therefore, the effects of the present invention can be sufficiently exerted when Dy and / Tb are in the above-described range. In this case, the coercive force (HcJ) exceeds 1680 kA / m, is 1750 kA / m or more, and further is 2000 kA / m or more.

また、本発明のR−T−B系希土類永久磁石は、ホウ素(B)を0.5〜4.5wt%含有する。Bが0.5wt%未満の場合には高い保磁力を得ることができない。ただし、Bが4.5wt%を超えると残留磁束密度が低下する傾向がある。したがって、上限を4.5wt%とする。望ましいBの量は0.5〜1.5wt%、さらに望ましいBの量は0.8〜1.2wt%である。   The RTB-based rare earth permanent magnet of the present invention contains 0.5 to 4.5 wt% of boron (B). When B is less than 0.5 wt%, a high coercive force cannot be obtained. However, when B exceeds 4.5 wt%, the residual magnetic flux density tends to decrease. Therefore, the upper limit is 4.5 wt%. A desirable amount of B is 0.5 to 1.5 wt%, and a more desirable amount of B is 0.8 to 1.2 wt%.

本発明のR−T−B系希土類永久磁石は、Al及びCuの1種又は2種を0.02〜0.5wt%の範囲で含有することができる。この範囲でAl及びCuの1種又は2種を含有させることにより、得られるR−T−B系希土類永久磁石の高保磁力化、温度特性の改善が可能となる。Alを添加する場合において、望ましいAlの量は0.03〜0.3wt%、さらに望ましいAlの量は0.05〜0.25wt%である。また、Cuを添加する場合において、望ましいCuの量は0.15wt%以下(0を含まず)、さらに望ましいCuの量は0.03〜0.08wt%である。   The RTB-based rare earth permanent magnet of the present invention can contain one or two of Al and Cu in the range of 0.02 to 0.5 wt%. By containing one or two of Al and Cu within this range, it is possible to increase the coercive force and improve the temperature characteristics of the R-T-B rare earth permanent magnet obtained. In the case of adding Al, a desirable amount of Al is 0.03 to 0.3 wt%, and a more desirable amount of Al is 0.05 to 0.25 wt%. In addition, in the case of adding Cu, the desirable amount of Cu is 0.15 wt% or less (not including 0), and the more desirable amount of Cu is 0.03 to 0.08 wt%.

本発明のR−T−B系希土類永久磁石は、0.2〜1.5wt%のNb及び0.03〜0.25wt%のZrの1種又は2種を含有することが望ましい。
Nb及びZrはR−T−B系希土類永久磁石の着磁特性向上を図るために有効である。また、R−T−B系希土類永久磁石の磁気特性を向上するために酸素含有量を低減する際に、焼結過程での結晶粒の異常成長を抑制する効果を発揮し、焼結体の組織を均一かつ微細にする。したがって、Nb及びZrは酸素量が低い場合にその効果が顕著になる。Nbの望ましい量は0.5〜1.3wt%、さらに望ましい量は0.5〜1.2wt%である。また、Zrの望ましい量は0.05〜0.25wt%、さらに望ましい量は0.1〜0.2wt%である。
The RTB-based rare earth permanent magnet of the present invention preferably contains one or two of 0.2 to 1.5 wt% Nb and 0.03 to 0.25 wt% Zr.
Nb and Zr are effective for improving the magnetization characteristics of the R-T-B rare earth permanent magnet. Moreover, when reducing the oxygen content in order to improve the magnetic properties of the R-T-B rare earth permanent magnet, it exhibits the effect of suppressing abnormal growth of crystal grains during the sintering process, Make the tissue uniform and fine. Therefore, Nb and Zr have a remarkable effect when the amount of oxygen is low. A desirable amount of Nb is 0.5 to 1.3 wt%, and a more desirable amount is 0.5 to 1.2 wt%. A desirable amount of Zr is 0.05 to 0.25 wt%, and a more desirable amount is 0.1 to 0.2 wt%.

本発明のR−T−B系希土類永久磁石は、その酸素量を2000ppm以下とする。酸素量が多いと非磁性成分である酸化物相が増大して、磁気特性を低下させる。そこで本発明では、焼結体中に含まれる酸素量を、2000ppm以下、望ましくは1500ppm以下、さらに望ましくは1000ppm以下とする。ただし、単純に酸素量を低下させたのでは、粒成長抑制効果を有していた酸化物相の量が不足し、焼結時に十分な密度上昇を得る過程で異常粒成長が容易に起こる。そこで、本発明では、着磁特性向上効果とともに異常粒成長抑制効果を有するNb及びZrの1種又は2種を所定量添加する。   The RTB-based rare earth permanent magnet of the present invention has an oxygen content of 2000 ppm or less. When the amount of oxygen is large, the oxide phase, which is a nonmagnetic component, increases and the magnetic properties are deteriorated. Therefore, in the present invention, the amount of oxygen contained in the sintered body is set to 2000 ppm or less, desirably 1500 ppm or less, and more desirably 1000 ppm or less. However, if the amount of oxygen is simply reduced, the amount of the oxide phase having the effect of suppressing grain growth is insufficient, and abnormal grain growth easily occurs in the process of obtaining a sufficient density increase during sintering. Therefore, in the present invention, a predetermined amount of one or two of Nb and Zr having an effect of suppressing abnormal grain growth as well as an effect of improving the magnetization characteristics is added.

本発明のR−T−B系希土類永久磁石は、Coを2wt%以下(0を含まず)、望ましくは0.1〜1wt%、さらに望ましくは0.3〜0.7wt%含有する。Coはキュリー温度の向上、粒界相の耐食性向上に効果がある。   The RTB-based rare earth permanent magnet of the present invention contains 2 wt% or less (not including 0) of Co, desirably 0.1 to 1 wt%, and more desirably 0.3 to 0.7 wt%. Co is effective in improving the Curie temperature and the corrosion resistance of the grain boundary phase.

<多極着磁磁石>
本発明は、前述したように、多極着磁が施される磁石に適用することが望ましい。
多極着磁される磁石としては、モータ用に用いられるラジアル異方性又は極異方性リング状磁石、CD、DVD等の機器のピックアップ駆動用に用いられる直方体状磁石、VCM(Voice Coil Motor)用の扇状磁石がある。これらの多極着磁磁石は、N・Sの極性を複数有している。
以上の多極着磁磁石に本発明のR−T−B系希土類永久磁石を適用すると、ニュートラルゾーンの幅を狭くすることができる。そのために、トータルフラックス量が増加し、例えばモータに用いるものであればモータの特性を向上させることができる。ここで、ニュートラルゾーンとは、磁石を着磁した際に、極性(N・S)が反転する境界においてN又はSのどちらにも着磁されない領域をいう。特に、サイズの小さな磁石や極数の多い磁石においては、ニュートラルゾーンの占める割合が増大する。したがって、本発明による着磁特性の優れるR−T−B系希土類永久磁石を多極着磁に供することにより、ニュートラルゾーンの幅を狭くすることができ、ひいては当該磁石が用いられるモータの特性を向上することができる。
<Multipolar magnetized magnet>
As described above, the present invention is preferably applied to a magnet subjected to multipolar magnetization.
The magnets magnetized with multiple poles include radial or polar anisotropic ring magnets used for motors, rectangular parallelepiped magnets used for driving pickups of devices such as CDs and DVDs, and VCM (Voice Coil Motors). ) Fan-shaped magnet. These multipolar magnets have a plurality of N · S polarities.
When the RTB-based rare earth permanent magnet of the present invention is applied to the above multipolar magnetized magnet, the width of the neutral zone can be reduced. Therefore, the total flux amount is increased. For example, if used for a motor, the characteristics of the motor can be improved. Here, the neutral zone refers to a region that is not magnetized by either N or S at the boundary where the polarity (N · S) is reversed when the magnet is magnetized. In particular, in a small-sized magnet or a magnet having a large number of poles, the ratio of the neutral zone increases. Therefore, the width of the neutral zone can be narrowed by using the R-T-B rare earth permanent magnet having excellent magnetization characteristics according to the present invention for multipolar magnetization, and the characteristics of the motor in which the magnet is used can be reduced. Can be improved.

<製造方法>
次に、本発明によるR−T−B系希土類永久磁石の好適な製造方法について説明する。
本実施の形態では、単一の原料合金を用いて製造する方法について示す。ただし、本発明によるR−T−B系希土類永久磁石は、R14B結晶粒を主体とする合金(低R合金)と、低R合金よりRを多く含む合金(高R合金)とを用いる混合法により製造することができることはいうまでもない。
<Manufacturing method>
Next, the suitable manufacturing method of the RTB system rare earth permanent magnet by this invention is demonstrated.
In this embodiment mode, a method of manufacturing using a single raw material alloy is described. However, the RTB-based rare earth permanent magnet according to the present invention includes an alloy mainly composed of R 2 T 14 B crystal grains (low R alloy) and an alloy containing more R than the low R alloy (high R alloy). Needless to say, it can be produced by a mixing method using.

はじめに、真空又は不活性ガス、好ましくはAr雰囲気中でストリップキャスティングすることにより、所定組成の原料合金を得る。
原料合金が作製された後、原料合金は粉砕される。粉砕工程には、粗粉砕工程と微粉砕工程とがある。まず、原料合金を、それぞれ粒径数百μm程度になるまで粗粉砕する。粗粉砕は、スタンプミル、ジョークラッシャー、ブラウンミル等を用い、不活性ガス雰囲気中にて行なうことが望ましい。粗粉砕性を向上させるために、水素を吸蔵させた後、粗粉砕を行なうことが効果的である。
粗粉砕工程後、微粉砕工程に移る。微粉砕は、主にジェットミルが用いられ、粒径数百μm程度の粗粉砕粉末が、平均粒径2.5〜6μm、好ましくは3〜5μmになるまで行われる。ジェットミルは、高圧の不活性ガス(例えば窒素ガス)を狭いノズルより開放して高速のガス流を発生させ、この高速のガス流により粗粉砕粉末を加速し、粗粉砕粉末同士の衝突やターゲットあるいは容器壁との衝突を発生させて粉砕する方法である。微粉砕時に、ステアリン酸亜鉛等の粉砕助剤を0.01〜0.3wt%程度添加することにより、成形時に配向性の高い微粉を得ることができる。
First, a raw material alloy having a predetermined composition is obtained by strip casting in a vacuum or an inert gas, preferably in an Ar atmosphere.
After the raw material alloy is produced, the raw material alloy is pulverized. The pulverization process includes a coarse pulverization process and a fine pulverization process. First, the raw material alloys are coarsely pulverized until each particle size becomes about several hundred μm. The coarse pulverization is desirably performed in an inert gas atmosphere using a stamp mill, a jaw crusher, a brown mill or the like. In order to improve the coarse pulverization property, it is effective to perform coarse pulverization after occlusion of hydrogen.
After the coarse pulverization process, the process proceeds to the fine pulverization process. The fine pulverization is mainly performed using a jet mill until the coarsely pulverized powder having a particle size of about several hundreds of μm has an average particle size of 2.5 to 6 μm, preferably 3 to 5 μm. The jet mill opens a high-pressure inert gas (for example, nitrogen gas) from a narrow nozzle to generate a high-speed gas flow, and the high-speed gas flow accelerates the coarsely pulverized powder. Or it is the method of generating and colliding with a container wall. By adding about 0.01 to 0.3 wt% of a grinding aid such as zinc stearate at the time of fine grinding, a fine powder with high orientation can be obtained at the time of molding.

次いで、微粉末を磁場印加によってその結晶軸を配向させた状態で磁場中成形する。この磁場中成形は、12〜20kOe(960〜1600kA/m)前後の磁場中で、0.3〜3.0t/cm(30〜300MPa)前後の圧力で行なえばよい。また、磁場印加方法は前述の他に、パルス印加磁場を用いてもよい。 Next, the fine powder is molded in a magnetic field with its crystal axis oriented by applying a magnetic field. The forming in the magnetic field may be performed at a pressure of about 0.3 to 3.0 t / cm 2 (30 to 300 MPa) in a magnetic field of about 12 to 20 kOe (960 to 1600 kA / m). In addition to the above-described magnetic field application method, a pulse application magnetic field may be used.

磁場中成形後、その成形体を真空又は不活性ガス雰囲気中で焼結する。焼結温度は、組成、粉砕方法、粒度と粒度分布の違い等、諸条件により調整する必要があるが、1000〜1100℃で1〜5時間程度焼結すればよい。焼結工程の前に成形体に含まれている粉砕助剤、ガスなどを除去する処理を行なってもよい。焼結後、得られた焼結体に時効処理を施すことができる。この工程は、保磁力を制御する重要な工程である。時効処理を2段に分けて行なう場合には、800℃近傍、600℃近傍での所定時間の保持が有効である。800℃近傍での熱処理を焼結後に行なうと、保磁力が増大するため、混合法においては特に有効である。また、600℃近傍の熱処理で保磁力が大きく増加するため、時効処理を1段で行なう場合には、600℃近傍の時効処理を施すとよい。   After molding in a magnetic field, the compact is sintered in a vacuum or an inert gas atmosphere. Although it is necessary to adjust sintering temperature by various conditions, such as a composition, a grinding | pulverization method, a particle size, and a particle size distribution difference, what is necessary is just to sinter at 1000-1100 degreeC for about 1 to 5 hours. You may perform the process which removes the grinding | pulverization adjuvant, gas, etc. which are contained in the molded object before a sintering process. After sintering, the obtained sintered body can be subjected to an aging treatment. This process is an important process for controlling the coercive force. In the case where the aging treatment is performed in two stages, holding for a predetermined time at around 800 ° C. and around 600 ° C. is effective. When the heat treatment at around 800 ° C. is performed after sintering, the coercive force increases, which is particularly effective in the mixing method. In addition, since the coercive force is greatly increased by the heat treatment at around 600 ° C., the aging treatment at around 600 ° C. is preferably performed when the aging treatment is performed in one stage.

以下本発明を具体的な実施例に基づいて説明する。
<第1実施例>
ストリップキャスト法により、表1に示す組成の原料合金を作製した。
得られた各々の原料合金に対して室温にて水素を吸蔵させた後、Ar雰囲気中で600℃×1時間の脱水素を行なう、水素粉砕処理を行なった。
高磁気特性を得るべく、本実験では焼結体酸素量を1000ppm以下に抑えるために、水素粉砕(粉砕処理後の回収)から焼結(焼結炉に投入する)までの各工程の雰囲気を100ppm未満の酸素濃度に抑えてある。
Hereinafter, the present invention will be described based on specific examples.
<First embodiment>
Raw material alloys having the compositions shown in Table 1 were produced by strip casting.
After each of the obtained raw material alloys was occluded with hydrogen at room temperature, hydrogen pulverization treatment was performed in which dehydrogenation was performed at 600 ° C. for 1 hour in an Ar atmosphere.
In order to obtain high magnetic properties, in this experiment, in order to keep the amount of oxygen in the sintered body to 1000 ppm or less, the atmosphere of each step from hydrogen pulverization (recovery after pulverization treatment) to sintering (put into the sintering furnace) was changed. The oxygen concentration is suppressed to less than 100 ppm.

通常、粗粉砕と微粉砕による2段粉砕を行っているが、本実施例では粗粉砕工程を省いている。
水素粉砕された合金に粉砕助剤としてオレイン酸アミドを0.1%添加し、ジェットミルにて微粉砕を行ない、平均粒径(d)3.3μm、3.7μm、4.1μm、4.4μm、4.8μm及び5.3μmの6種類の微粉末を得た。なお、粒径の測定はレーザ回折式粒度分布計(Malvern Instruments社製Mastersizer)により行なった。
Usually, two-stage pulverization by coarse pulverization and fine pulverization is performed, but the coarse pulverization step is omitted in this embodiment.
0.1% oleic acid amide was added to the hydrogen pulverized alloy as a pulverization aid and pulverized with a jet mill to obtain an average particle size (d) of 3.3 μm, 3.7 μm, 4.1 μm, and 4. Six types of fine powders of 4 μm, 4.8 μm, and 5.3 μm were obtained. The particle size was measured with a laser diffraction particle size distribution meter (Mastersizer manufactured by Malvern Instruments).

得られた微粉末を1320kA/m(16.5kOe)の磁場中で加圧成形を行って成形体を得た。成形体の密度は4.2Mg/mである。
得られた成形体を真空中において1040℃で4時間焼結した後、急冷した。次いで得られた焼結体に800℃×1時間と530℃×2.5時間(ともにAr雰囲気中)の2段時効処理を施した。
The obtained fine powder was subjected to pressure molding in a magnetic field of 1320 kA / m (16.5 kOe) to obtain a molded body. The density of the compact is 4.2 Mg / m 3 .
The obtained molded body was sintered in vacuum at 1040 ° C. for 4 hours and then rapidly cooled. Next, the obtained sintered body was subjected to a two-stage aging treatment of 800 ° C. × 1 hour and 530 ° C. × 2.5 hours (both in an Ar atmosphere).

Figure 2005197533
Figure 2005197533

得られたR−T−B系希土類永久磁石についてB−Hトレーサにより磁気特性を測定するとともに、焼結体の密度、平均結晶粒径、酸素含有量、窒素含有量及び炭素含有量を測定した。その結果を表2に示す。表2において、dは焼結体の平均結晶粒径、ρは焼結体の密度、Brは残留磁束密度、HcJは保磁力、(BH)maxは最大エネルギー積を、Hk/HcJは角形比を示す。なお、角形比(Hk/HcJ)は磁石性能の指標となるものであり、磁気ヒステリシスル−プの第2象限における角張の度合いを表す。またHkは、磁気ヒステリシスル−プの第2象限において、磁束密度が残留磁束密度の90%になるときの外部磁界強度である。焼結体の平均結晶粒径は、焼結体の研磨面を簡易偏光顕微鏡(オリンパス光学工業(株)製BX60M)で観察し、それを画像処理装置(旭化成工業(株)製IP−1000)にて評価した。この評価により、粒子面積が得られるので、それを円相当径に換算して結晶粒径とした。   The R-T-B rare earth permanent magnet obtained was measured for magnetic properties by a BH tracer, and the density, average crystal grain size, oxygen content, nitrogen content and carbon content of the sintered body were measured. . The results are shown in Table 2. In Table 2, d is the average grain size of the sintered body, ρ is the density of the sintered body, Br is the residual magnetic flux density, HcJ is the coercive force, (BH) max is the maximum energy product, and Hk / HcJ is the square ratio. Indicates. The squareness ratio (Hk / HcJ) is an index of magnet performance and represents the degree of angulation in the second quadrant of the magnetic hysteresis loop. Hk is the external magnetic field strength when the magnetic flux density is 90% of the residual magnetic flux density in the second quadrant of the magnetic hysteresis loop. The average crystal grain size of the sintered body was determined by observing the polished surface of the sintered body with a simple polarizing microscope (BX60M manufactured by Olympus Optical Co., Ltd.) and image processing apparatus (IP-1000 manufactured by Asahi Kasei Kogyo Co., Ltd.). Evaluated. By this evaluation, the particle area was obtained, and it was converted to the equivalent circle diameter to obtain the crystal grain size.

表2に示すように、試料1〜6のいずれのR−T−B系希土類永久磁石も1.3T以上の残留磁束密度、2000kA/m以上の保磁力、340kJ/m近傍又はそれ以上という最大エネルギー積、90%以上の角形比(Hk/HcJ)を有していることがわかる。また、いずれのR−T−B系希土類永久磁石も酸素量が1000ppm以下、窒素量が500ppm以下、炭素量が1000ppm以下と、不純物量が低いレベルにあることがわかる。 As shown in Table 2, any of the R-T-B rare earth permanent magnets of Samples 1 to 6 has a residual magnetic flux density of 1.3 T or more, a coercive force of 2000 kA / m or more, and around 340 kJ / m 3 or more. It can be seen that the maximum energy product has a squareness ratio (Hk / HcJ) of 90% or more. In addition, it can be seen that all of the R-T-B rare earth permanent magnets have low levels of impurities, such as an oxygen content of 1000 ppm or less, a nitrogen content of 500 ppm or less, and a carbon content of 1000 ppm or less.

Figure 2005197533
Figure 2005197533

次に、試料1〜6のR−T−B系希土類永久磁石について、着磁率(Pc=2)を測定した。その結果を表3に示す。表3に示すように、平均結晶粒径が最も小さい試料1(3.3μm)及び最も大きい試料5(5.3μm)のR−T−B系希土類永久磁石は、240kA/mの着磁磁界で60%未満の着磁率しか得られないことがわかる。   Next, the magnetization rate (Pc = 2) of the R-T-B rare earth permanent magnets of Samples 1 to 6 was measured. The results are shown in Table 3. As shown in Table 3, the RTB rare earth permanent magnets of Sample 1 (3.3 μm) and Sample 5 (5.3 μm) having the smallest average crystal grain size have a magnetizing magnetic field of 240 kA / m. It can be seen that only a magnetization rate of less than 60% can be obtained.

Figure 2005197533
Figure 2005197533

以上より、焼結体の平均結晶粒径が3.5〜5.0μm、望ましくは4.0〜4.5μmの範囲とすることにより、240kA/mという低い着磁磁界で60%以上の着磁率を得ることができるとともに、400kA/mという低い着磁磁界で85%以上の着磁率を得ることができる。さらに、800kA/mの着磁磁界で95%以上の着磁率が得られることからわかるように、本発明によるR−T−B系希土類永久磁石は、着磁率の立ち上がりが早い。   From the above, by setting the average grain size of the sintered body in the range of 3.5 to 5.0 μm, preferably 4.0 to 4.5 μm, it is possible to achieve a magnetization of 60% or more with a low magnetic field of 240 kA / m. A magnetic permeability can be obtained, and a magnetization rate of 85% or more can be obtained with a magnetic field as low as 400 kA / m. Furthermore, as can be seen from the fact that a magnetization rate of 95% or more can be obtained with a magnetization field of 800 kA / m, the R-T-B rare earth permanent magnet according to the present invention has a rapid rise in magnetization rate.

<第2実施例>
表4に示す組成の原料合金を用いること及び微粉末を作製する際の粉砕ガス(窒素)中の酸素含有量を制御することによって最終の焼結体の酸素含有量を変動させた以外は第1実施例と同様にして5種類のR−T−B系希土類永久磁石(試料7〜11)を得た。得られたR−T−B系希土類永久磁石について、第1実施例と同様に磁気特性等を測定した。その結果を表5に示す。
<Second embodiment>
Except for using the raw material alloy having the composition shown in Table 4 and controlling the oxygen content in the pulverized gas (nitrogen) when producing the fine powder, the oxygen content of the final sintered body was varied. Five types of RTB-based rare earth permanent magnets (samples 7 to 11) were obtained in the same manner as in Example 1. About the obtained RTB-based rare earth permanent magnet, the magnetic characteristics and the like were measured in the same manner as in the first example. The results are shown in Table 5.

表5に示すように、試料7〜11のいずれのR−T−B系希土類永久磁石も1.3T以上の残留磁束密度、2300kA/m以上の保磁力、330kJ/m近傍の最大エネルギー積を有していることがわかる。 As shown in Table 5, any of the R-T-B rare earth permanent magnets of Samples 7 to 11 has a residual magnetic flux density of 1.3 T or more, a coercive force of 2300 kA / m or more, and a maximum energy product near 330 kJ / m 3. It can be seen that

Figure 2005197533
Figure 2005197533

Figure 2005197533
Figure 2005197533

次に、試料7〜11のR−T−B系希土類永久磁石について、着磁率(Pc=2)を測定した。その結果を表6に示す。表6に示すように、焼結体の酸素量が490ppmと最も低い試料7のR−T−B系希土類永久磁石が低い着磁磁界における着磁率が最も高いことがわかる。また、試料7〜10は、240kA/m(3kOe)の着磁磁界で70%以上の着磁率、400kA/m(5kOe)の着磁磁界で90%以上の着磁率、800kA/m(10kOe)の着磁磁界でほぼ100%の着磁率を得ることができる。これに対して、試料11は240kA/m(3kOe)の着磁磁界で60%を超える着磁率を得ることができない。同様に400kA/m(5kOe)の着磁磁界における着磁率が85%に達しない。   Next, the magnetization rate (Pc = 2) of the R-T-B rare earth permanent magnets of Samples 7 to 11 was measured. The results are shown in Table 6. As shown in Table 6, it can be seen that the RTB-based rare earth permanent magnet of Sample 7 having the lowest oxygen content of the sintered body of 490 ppm has the highest magnetization rate in a low magnetization field. Samples 7 to 10 have a magnetization rate of 70% or more in a magnetizing magnetic field of 240 kA / m (3 kOe), a magnetization rate of 90% or more in a magnetizing magnetic field of 400 kA / m (5 kOe), and 800 kA / m (10 kOe). A magnetization rate of almost 100% can be obtained with a magnetization field of. On the other hand, the sample 11 cannot obtain a magnetization rate exceeding 60% in a magnetization magnetic field of 240 kA / m (3 kOe). Similarly, the magnetization rate in a magnetizing magnetic field of 400 kA / m (5 kOe) does not reach 85%.

Figure 2005197533
Figure 2005197533

以上のように、着磁率はR−T−B系希土類永久磁石に含まれる酸素の量と関連があり、低い着磁磁界から高い着磁磁界まで着磁率を向上させるためには、酸素含有量は2000ppm以下、望ましくは1500ppm以下、さらに望ましくは1000ppm以下とすべきである。   As described above, the magnetization rate is related to the amount of oxygen contained in the R-T-B rare earth permanent magnet, and in order to improve the magnetization rate from a low magnetization field to a high magnetization field, the oxygen content Should be 2000 ppm or less, desirably 1500 ppm or less, more desirably 1000 ppm or less.

<第3実施例>
表7に示す原料合金を用いた以外は第1実施例と同様にして8種類のR−T−B系希土類永久磁石(試料12〜19)を得た。得られたR−T−B系希土類永久磁石について、第1実施例と同様に磁気特性等を測定した。その結果を表8に示す。なお、第1実施例における試料1も表7、8に示している。
表8に示すように、M元素を含まない試料12は角形比(Hk/HcJ)が93.6%と他の試料に比べて低い。これに対してM元素を含む試料1、13〜19は95%を超える角形比(Hk/HcJ)を有しており、特にNbを含む試料13、Gaを含む試料17及びZrとNbを含む試料19の角形比(Hk/HcJ)が高くかつ保磁力(HcJ)も高いことがわかる。
<Third embodiment>
Eight types of R-T-B rare earth permanent magnets (samples 12 to 19) were obtained in the same manner as in the first example except that the raw material alloys shown in Table 7 were used. About the obtained RTB-based rare earth permanent magnet, the magnetic characteristics and the like were measured in the same manner as in the first example. The results are shown in Table 8. Samples 1 in the first example are also shown in Tables 7 and 8.
As shown in Table 8, Sample 12 containing no M element has a squareness ratio (Hk / HcJ) of 93.6%, which is lower than those of other samples. On the other hand, Samples 1 and 13 to 19 containing M element have a squareness ratio (Hk / HcJ) exceeding 95%, and in particular, Sample 13 containing Nb, Sample 17 containing Ga, and Zr and Nb. It can be seen that the squareness ratio (Hk / HcJ) of the sample 19 is high and the coercive force (HcJ) is also high.

試料12について組織観察を行なったところ、試料12は焼結体中に100μm程度まで異常に成長した結晶粒が観察された。これは、酸素含有量が1000ppm程度と低く、結晶粒成長を抑制していた酸化物の量が低減されたためである。この異常成長した結晶粒の存在が低い角形比の原因と推測される。
試料1、13〜19についても同様に組織観察を行なったが、試料12で観察された異常成長した結晶粒は観察されなかった。試料1、13及び19ではNbが主相結晶粒及び粒界相に、また試料14、19ではZrが粒界相に分散していることが確認されており、Nb又はZrが何らかの化合物を形成し、この化合物が結晶粒の異常成長を抑制しているものと解される。
When the structure of the sample 12 was observed, crystal grains abnormally grown to about 100 μm in the sintered body were observed in the sample 12. This is because the oxygen content was as low as about 1000 ppm, and the amount of oxide that suppressed crystal grain growth was reduced. The existence of the abnormally grown crystal grains is presumed to be the cause of the low squareness ratio.
The samples 1 and 13 to 19 were similarly observed for the structure, but the abnormally grown crystal grains observed in the sample 12 were not observed. Samples 1, 13, and 19 confirm that Nb is dispersed in the main phase crystal grains and grain boundary phase, and Samples 14 and 19 confirm that Zr is dispersed in the grain boundary phase. Nb or Zr forms some compound. It is understood that this compound suppresses abnormal growth of crystal grains.

Figure 2005197533
Figure 2005197533

Figure 2005197533
Figure 2005197533

次に、試料1、試料12〜19のR−T−B系希土類永久磁石について、着磁率(Pc=2)を測定した。その結果を表9に示す。なお、試料1の結果についても表9に示してある。表9に示すように、M元素を含まない試料12は240kA/mの着磁磁界で50%以下の着磁率しか得られないのに対して、M元素を含む試料1、13〜18は240kA/mの着磁磁界で60%以上の着磁率が得られることがわかる。また、M元素を含まない試料12は400kA/mの着磁磁界で85%以下の着磁率しか得られないのに対して、M元素を含む試料1、13〜19は400kA/mの着磁磁界で85%以上の着磁率が得られることがわかる。   Next, the magnetization rate (Pc = 2) of the R-T-B rare earth permanent magnets of Sample 1 and Samples 12 to 19 was measured. The results are shown in Table 9. The results for Sample 1 are also shown in Table 9. As shown in Table 9, sample 12 containing no M element can obtain only a magnetization rate of 50% or less in a magnetizing magnetic field of 240 kA / m, whereas samples 1 and 13 to 18 containing M element are 240 kA. It can be seen that a magnetization rate of 60% or more can be obtained with a magnetizing magnetic field of / m. Sample 12 containing no M element can obtain only a magnetization rate of 85% or less in a magnetizing magnetic field of 400 kA / m, whereas Samples 1 and 13 to 19 containing M element are magnetized at 400 kA / m. It can be seen that a magnetization rate of 85% or more can be obtained with a magnetic field.

Figure 2005197533
Figure 2005197533

以上より、M元素は異常粒成長を抑制することにより磁気特性、特に角形比(Hk/HcJ)の向上にとって有効な元素であるとともに、着磁特性の向上にとっても有効な元素であることがわかる。特に、Nb、Zr及びGaは磁気特性及び着磁特性の両者を高いレベルにするために有効な元素である。   From the above, it can be seen that the M element is an element effective for improving magnetic characteristics, particularly the squareness ratio (Hk / HcJ) by suppressing abnormal grain growth, and also effective for improving the magnetization characteristics. . In particular, Nb, Zr, and Ga are effective elements for setting both magnetic characteristics and magnetization characteristics to high levels.

<第4実施例>
表10に示す原料合金を用いた以外は第1実施例と同様にして4種類のR−T−B系希土類永久磁石(試料20〜23)を得た。試料20〜23について、第1実施例と同様に磁気特性、焼結体の平均結晶粒径等を測定した。その結果を表11に示す。Dy量が多くなるにつれて保磁力(HcJ)が高くなる一方、残留磁束密度(Br)が低下することがわかる。試料20〜23の着磁率(Pc=2)を第1実施例と同様に測定した。その結果を表12に示す。表12に示すように、Dy量が多くなるにつれて着磁率が向上することがわかる。特に、その差異は400kA/m以下の着磁磁界において顕著である。
<Fourth embodiment>
Four types of RTB-based rare earth permanent magnets (samples 20 to 23) were obtained in the same manner as in the first example except that the raw material alloys shown in Table 10 were used. For Samples 20 to 23, the magnetic properties, the average crystal grain size of the sintered body, and the like were measured in the same manner as in the first example. The results are shown in Table 11. It can be seen that as the amount of Dy increases, the coercive force (HcJ) increases while the residual magnetic flux density (Br) decreases. The magnetization rate (Pc = 2) of samples 20 to 23 was measured in the same manner as in the first example. The results are shown in Table 12. As shown in Table 12, it can be seen that the magnetization increases as the Dy amount increases. In particular, the difference is remarkable in a magnetizing magnetic field of 400 kA / m or less.

Figure 2005197533
Figure 2005197533

Figure 2005197533
Figure 2005197533

Figure 2005197533
Figure 2005197533

また、試料20及び試料23から図1に示す形状の試験片(厚さ2.1mm)を作製するとともに、図1に示すようにコの字状に着磁を行なった。なお、着磁条件を以下の4条件とした。
800μF×350V、800μF×600V、800μF×900V、800μF×1500V
各着磁条件において、図1の一点鎖線上のトータルフラックスを測定した。図2は、一点鎖線上の位置とトータルフラックス(B)との関係を着磁電圧ごとに示したグラフである。
フル着磁に近い着磁電圧が1500Vのときには試料20及び試料23は同等のトータルフラックス(B)を示している。しかし、着磁電圧が350Vの時には試料23は試料20の1.3倍以上のトータルフラックス(B)を有している。同様に、着磁電圧が600Vの時には試料23は試料20の1.1倍以上のトータルフラックス(B)を有している。また、着磁電圧が350Vの場合、極性が反転すべき3.5mmの位置近傍の試料20及び試料23の曲線を比較すると、後者の傾きに比べて前者の傾きが小さく、ニュートラルゾーンの発生を示唆している。
Further, a test piece (thickness: 2.1 mm) having the shape shown in FIG. 1 was prepared from the sample 20 and the sample 23, and magnetized in a U-shape as shown in FIG. The magnetization conditions were the following four conditions.
800μF × 350V, 800μF × 600V, 800μF × 900V, 800μF × 1500V
Under each magnetization condition, the total flux on the one-dot chain line in FIG. 1 was measured. FIG. 2 is a graph showing the relationship between the position on the alternate long and short dash line and the total flux (B) for each magnetization voltage.
When the magnetization voltage close to full magnetization is 1500 V, Sample 20 and Sample 23 show equivalent total flux (B). However, when the magnetization voltage is 350 V, the sample 23 has a total flux (B) 1.3 times or more that of the sample 20. Similarly, when the magnetization voltage is 600 V, the sample 23 has a total flux (B) 1.1 times or more that of the sample 20. Further, when the magnetization voltage is 350 V, when comparing the curves of the sample 20 and the sample 23 in the vicinity of the position of 3.5 mm where the polarity is to be reversed, the former inclination is smaller than the latter inclination, and a neutral zone is generated. Suggests.

以上の結果より、着磁特性の優れた試料を用いることにより、ニュートラルゾーンの幅を小さくすることができるため、アクチュエータに優れた動作特性を与えることができる。   From the above results, it is possible to reduce the width of the neutral zone by using a sample having excellent magnetization characteristics, so that excellent operating characteristics can be given to the actuator.

<第5実施例>
表13に示す原料合金を用いた以外は第1実施例と同様にして4種類のR−T−B系希土類永久磁石(試料24〜27)を得た。試料24〜27について、第1実施例と同様に磁気特性、焼結体の平均結晶粒径等を測定した。その結果を表14に示す。Tb量が多くなるにつれて保磁力(HcJ)が高くなる一方、残留磁束密度(Br)が低下することがわかる。試料24〜27の着磁率(Pc=2)を第1実施例と同様に測定した。その結果を表15に示す。表15に示すように、Tb量が多くなるにつれて着磁率が向上することがわかる。特に、400kA/m以下の着磁磁界においてその差異が顕著である。また、第4実施例と比較すると、Tbはより少ない含有量でDyと同等の効果を得ることができる。
<Fifth embodiment>
Four types of RTB-based rare earth permanent magnets (samples 24-27) were obtained in the same manner as in the first example except that the raw material alloys shown in Table 13 were used. For Samples 24-27, the magnetic properties, the average crystal grain size of the sintered body, and the like were measured as in the first example. The results are shown in Table 14. It can be seen that as the amount of Tb increases, the coercive force (HcJ) increases while the residual magnetic flux density (Br) decreases. The magnetization rates (Pc = 2) of samples 24-27 were measured in the same manner as in the first example. The results are shown in Table 15. As shown in Table 15, it can be seen that the magnetization increases as the amount of Tb increases. In particular, the difference is remarkable in a magnetizing magnetic field of 400 kA / m or less. Moreover, compared with 4th Example, Tb can acquire the effect equivalent to Dy with less content.

Figure 2005197533
Figure 2005197533

Figure 2005197533
Figure 2005197533

Figure 2005197533
Figure 2005197533

<第6実施例>
実施例1の試料2について、Pc=1.0、0.5の試料をさらに作製し、第1実施例と同様に着磁率を測定した。その結果を表16に示す。
<Sixth embodiment>
For sample 2 of Example 1, samples with Pc = 1.0 and 0.5 were further prepared, and the magnetization rate was measured in the same manner as in the first example. The results are shown in Table 16.

Figure 2005197533
Figure 2005197533

表16に示すように、Pcが小さくなるにつれて着磁率は低下する傾向にあるが、240kA/mの着磁磁界において、Pc=1.0の着磁率が55%以上、Pc=0.5の着磁率が40%以上と低磁界で高い着磁率を示している。また、400kA/mの着磁磁界において、Pc=1.0の着磁率が80%以上、Pc=0.5の着磁率が70%以上の着磁率を示していることがわかる。   As shown in Table 16, the magnetization rate tends to decrease as Pc decreases. However, in a magnetization field of 240 kA / m, the magnetization rate of Pc = 1.0 is 55% or more, and Pc = 0.5. The magnetization rate is 40% or more, indicating a high magnetization rate in a low magnetic field. It can also be seen that in a magnetized magnetic field of 400 kA / m, the magnetization rate of Pc = 1.0 is 80% or more, and the magnetization rate of Pc = 0.5 is 70% or more.

第4実施例によるR−T−B系希土類永久磁石から作製した試験片の形状を示す平面図である。It is a top view which shows the shape of the test piece produced from the RTB system rare earth permanent magnet by 4th Example. 図1の試験片の一点鎖線上の位置とトータルフラックス(B)との関係を着磁電圧ごとに示したグラフである。It is the graph which showed the relationship between the position on the dashed-dotted line of the test piece of FIG. 1, and total flux (B) for every magnetization voltage.

Claims (12)

14B相(ただし、Rは希土類元素の1種又は2種以上、TはFe又はFe及びCoを必須とする1種又は2種以上の遷移金属元素)からなる主相と、
前記主相よりRを多く含む粒界相とを備えた焼結体からなり、
Pc(パーミアンス係数)が2において、
240kA/mの有効磁場(ただし、有効磁場=印加磁場−反磁場)を印加したときのトータルフラックスをf1、
400kA/mの有効磁場を印加したときのトータルフラックスをf2、
2000kA/mの有効磁場を印加したときのトータルフラックスをf3とすると、
着磁率a(=f1/f3×100)が60%以上、かつ、
着磁率b(=f2/f3×100)が85%以上であることを特徴とするR−T−B系希土類永久磁石。
A main phase composed of an R 2 T 14 B phase (where R is one or more rare earth elements, and T is one or more transition metal elements in which Fe or Fe and Co are essential);
A sintered body having a grain boundary phase containing more R than the main phase,
When Pc (permeance coefficient) is 2,
The total flux when an effective magnetic field of 240 kA / m (where effective magnetic field = applied magnetic field−demagnetizing field) is applied is f1,
The total flux when an effective magnetic field of 400 kA / m is applied is f2,
If the total flux when an effective magnetic field of 2000 kA / m is applied is f3,
Magnetization rate a (= f1 / f3 × 100) is 60% or more, and
An RTB-based rare earth permanent magnet having a magnetization rate b (= f2 / f3 × 100) of 85% or more.
保磁力(HcJ)が1680kA/mを超えることを特徴とする請求項1に記載のR−T−B系希土類永久磁石。 The R-T-B rare earth permanent magnet according to claim 1, wherein the coercive force (HcJ) exceeds 1680 kA / m. 残留磁束密度(Br)が1.20T以上、最大エネルギー積((BH)max)が240kJ/m以上、角形比(Hk/HcJ)が90%以上であることを特徴とする請求項1又は2に記載のR−T−B系希土類永久磁石。 The residual magnetic flux density (Br) is 1.20 T or more, the maximum energy product ((BH) max) is 240 kJ / m 3 or more, and the squareness ratio (Hk / HcJ) is 90% or more. 2. An RTB-based rare earth permanent magnet according to 2. 前記焼結体中の平均結晶粒径が3.5〜5.0μmであることを特徴とする請求項1〜3のいずれかに記載のR−T−B系希土類永久磁石。 4. The RTB-based rare earth permanent magnet according to claim 1, wherein an average crystal grain size in the sintered body is 3.5 to 5.0 μm. 前記焼結体中の酸素量が1500ppm以下であることを特徴とする請求項1〜4のいずれかに記載のR−T−B系希土類永久磁石。 The RTB-based rare earth permanent magnet according to any one of claims 1 to 4, wherein the amount of oxygen in the sintered body is 1500 ppm or less. 前記焼結体中にNbが分散していることを特徴とする請求項1〜5のいずれかに記載のR−T−B系希土類永久磁石。 The RTB rare earth permanent magnet according to any one of claims 1 to 5, wherein Nb is dispersed in the sintered body. R:25〜35wt%(ただし、Rは希土類元素の1種又は2種以上)、B:0.5〜4.5wt%、Al及びCuの1種又は2種:0.02〜0.5wt%、Nb:0.2〜1.5wt%及びZr:0.03〜0.25wt%の1種又は2種、Co:2wt%以下(0を含まず)、残部実質的にFeからなる組成を有する焼結体からなり、
前記焼結体中の酸素量が2000ppm以下、前記焼結体の平均結晶粒径が3.5〜5.0μmであることを特徴とするR−T−B系希土類永久磁石。
R: 25 to 35 wt% (where R is one or more rare earth elements), B: 0.5 to 4.5 wt%, one or two of Al and Cu: 0.02 to 0.5 wt %, Nb: 0.2 to 1.5 wt% and Zr: 0.03 to 0.25 wt%, 1 or 2 types, Co: 2 wt% or less (not including 0), the balance being substantially composed of Fe Comprising a sintered body having
An RTB-based rare earth permanent magnet having an oxygen content in the sintered body of 2000 ppm or less and an average crystal grain size of the sintered body of 3.5 to 5.0 μm.
Rとして4.0〜12.0wt%のDy及び/又は1.0〜6.0wt%のTbを含むことを特徴とする請求項7に記載のR−T−B系希土類永久磁石。 The R-T-B rare earth permanent magnet according to claim 7, wherein R includes 4.0 to 12.0 wt% Dy and / or 1.0 to 6.0 wt% Tb. Nbは前記焼結体の主相及び結晶粒界に分散し、Zrは前記焼結体の結晶粒界に分散していることを特徴とする請求項7又は8に記載のR−T−B系希土類永久磁石。 9. The RTB according to claim 7, wherein Nb is dispersed in a main phase and a grain boundary of the sintered body, and Zr is dispersed in a crystal grain boundary of the sintered body. Rare earth permanent magnets. 多極着磁される磁石であることを特徴とする請求項7〜9のいずれかに記載のR−T−B系希土類永久磁石。 The RTB-based rare earth permanent magnet according to any one of claims 7 to 9, wherein the magnet is a multipolar magnet. 前記焼結体中の窒素量が20〜600ppm、炭素量が1500ppm以下であることを特徴とする請求項7〜10のいずれかに記載のR−T−B系希土類永久磁石。 The RTB rare earth permanent magnet according to any one of claims 7 to 10, wherein the sintered body has a nitrogen content of 20 to 600 ppm and a carbon content of 1500 ppm or less. Ga:0.02〜1.5wt%を含有することを特徴とする請求項7〜11のいずれかに記載のR−T−B系希土類永久磁石。 The RTB-based rare earth permanent magnet according to any one of claims 7 to 11, wherein Ga: 0.02 to 1.5 wt% is contained.
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