JP2020155657A - Method for manufacturing r-t-b based sintered magnet - Google Patents
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/64—Electric machine technologies in electromobility
Abstract
Description
本発明は、Ｒ−Ｔ−Ｂ系焼結磁石の製造方法に関する。 The present invention relates to a method for manufacturing 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る。Ｔは遷移金属元素のうち少なくとも一種でありＦｅを必ず含む。Ｂは硼素である）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や家電製品などに使用されている。本明細書において希土類元素とは、スカンジウム（Ｓｃ）、イットリウム（Ｙ）、およびランタノイドからなる群から選択された少なくとも１つの元素をいう。ここで、ランタノイドとは、ランタンからルテチウムまでの１５の元素の総称である。 R-TB-based sintered magnets (R is at least one of the rare earth elements, T is at least one of the transition metal elements and always contains Fe, and B is boron) are the most permanent magnets. Known as a high-performance magnet, it is used in various motors such as voice coil motors (VCM) for hard disk drives, motors for electric vehicles (EV, HV, PHV, etc.), motors for industrial equipment, and home appliances. .. As used herein, the rare earth element means at least one element selected from the group consisting of scandium (Sc), yttrium (Y), and lanthanoids. Here, lanthanoid is a general term for 15 elements from lanthanum to lutetium.
Ｒ−Ｔ−Ｂ系焼結磁石は主としてＲ２Ｔ１４Ｂ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（以下、単に「粒界」という場合がある）とから構成されている。Ｒ２Ｔ１４Ｂ化合物は高い磁化を持つ強磁性相でありＲ−Ｔ−Ｂ系焼結磁石の特性の根幹をなしている。 R-T-B based sintered magnet is mainly grain boundary phase located in the grain boundary of the main phase and the main phase consisting of R 2 T 14 B compound (hereinafter, simply referred to as "grain boundary") from the It is configured. R 2 T 14 B compound has the foundation characteristics of high magnetization are ferromagnetic phase with an R-T-B based sintered magnet.
Ｒ−Ｔ−Ｂ系焼結磁石は、高温で保磁力ＨｃＪ（以下、単に「保磁力」又は「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という問題がある。そのため、特に電気自動車用モータに使用されるＲ−Ｔ−Ｂ系焼結磁石では、高温下でも高いＨｃＪを有する、すなわち室温においてより高いＨｃＪを有することが要求されている。 The RTB -based sintered magnet has a problem that irreversible thermal demagnetization occurs because the coercive force H cJ (hereinafter, may be simply referred to as “coercive force” or “H cJ ”) decreases at a high temperature. Therefore, in a particularly R-T-B based sintered magnet used in an electric vehicle motor, having a high H cJ even at high temperatures, that is, required to have a higher H cJ at room temperature.
Ｒ−Ｔ−Ｂ系焼結磁石において、Ｒ２Ｔ１４Ｂ化合物中のＲに含まれる軽希土類元素（主としてＮｄ及び／又はＰｒ）の一部を重希土類元素（主としてＤｙ及び／又はＴｂ）で置換すると、ＨｃＪが向上することが知られている。重希土類元素の置換量の増加に伴いＨｃＪは向上する。 In the RTB-based sintered magnet, a part of the light rare earth elements (mainly Nd and / or Pr) contained in R in the R 2 T 14 B compound is a heavy rare earth element (mainly Dy and / or Tb). Substitution is known to improve H cJ . H cJ improves as the amount of replacement of heavy rare earth elements increases.
しかし、Ｒ２Ｔ１４Ｂ化合物中の軽希土類元素を重希土類元素で置換するとＲ−Ｔ−Ｂ系焼結磁石のＨｃＪが向上する一方、残留磁束密度Ｂｒ（以下、単に「Ｂｒ」という場合がある）が低下する。また、重希土類元素、特にＤｙなど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、ユーザーから重希土類元素をできるだけ使用することなくＨｃＪを向上させることが求められている。 However, while improving the H cJ of R 2 T 14 B when the light rare earth element in the compound is replaced with the heavy rare-earth element R-T-B based sintered magnet, the remanence B r (hereinafter, simply "B r" In some cases) decreases. In addition, heavy rare earth elements, especially Dy, have problems such as unstable supply due to a small amount of resources present and limited production areas, and prices fluctuate significantly. Therefore, in recent years, users have requested to improve HcJ without using heavy rare earth elements as much as possible.
特許文献１には、Ｄｙの含有量を低減しつつ保磁力を高めたＲ−Ｔ−Ｂ系希土類焼結磁石が開示されている。この焼結磁石の組成は、一般に用いられてきたＲ−Ｔ−Ｂ系合金に比べてＢ量が相対的に少ない特定の範囲に限定され、かつ、Ａｌ、Ｇａ、Ｃｕのうちから選ばれる１種以上の金属元素Ｍを含有している。その結果、粒界にＲ２Ｔ１７相が生成され、このＲ２Ｔ１７相から粒界に形成される遷移金属リッチ相（Ｒ６Ｔ１３Ｍ）の体積比率が増加することにより、ＨｃＪが向上する。 Patent Document 1 discloses an RTB-based rare earth sintered magnet in which the coercive force is increased while reducing the Dy content. The composition of this sintered magnet is limited to a specific range in which the amount of B is relatively small as compared with the generally used RTB-based alloy, and is selected from Al, Ga, and Cu1. It contains more than one kind of metal element M. As a result, an R 2 T 17 phase is generated at the grain boundary, and the volume ratio of the transition metal rich phase (R 6 T 13 M) formed at the grain boundary from this R 2 T 17 phase increases, so that H cJ Is improved.
特許文献１に記載されている方法は、重希土類元素の含有量を抑制しつつＲ−Ｔ−Ｂ系焼結磁石を高保磁力化できる点で注目に値する。しかし、Ｂｒが大幅に低下するという問題があった。また、近年、電気自動車用モータ等の用途において更に高いＨｃＪを有するＲ−Ｔ−Ｂ系焼結磁石が求められている。また、Ｒ−Ｔ−Ｂ系焼結磁石は、特に電気自動車用モータ向けなどで需要が今後大きく拡大することが予想されている。そのため、重希土類元素の低減だけでなく、希土類元素使用の多様化もはかる必要がある。具体的な手段として希土類元素の中で存在量が比較的豊富なＬａ（ほかにＣｅ）などを使用することが挙げられる。 It is noteworthy that the method described in Patent Document 1 can increase the coercive magnetic force of the RTB-based sintered magnet while suppressing the content of heavy rare earth elements. However, there is a problem that Br is significantly reduced. Further, in recent years, RTB -based sintered magnets having a higher HcJ have been demanded for applications such as motors for electric vehicles. Demand for RTB-based sintered magnets is expected to grow significantly in the future, especially for motors for electric vehicles. Therefore, it is necessary not only to reduce heavy rare earth elements but also to diversify the use of rare earth elements. As a specific means, La (in addition to Ce), which is relatively abundant among rare earth elements, may be used.
本開示の実施形態は、Ｌａを使用し、重希土類元素の含有量を低減しつつ、高いＢｒ及び高いＨｃＪを有するＲ−Ｔ−Ｂ系焼結磁石の製造方法を提供する。 Embodiments of the present disclosure, using La, while reducing the content of heavy rare earth elements, to provide a method of manufacturing a R-T-B based sintered magnet having a high B r and a high H cJ.
本開示のＲ−Ｔ−Ｂ系焼結磁石の製造方法は、例示的な実施形態において、Ｒ１−Ｔ１−Ｂ系焼結体を準備する工程と、Ｒ２−Ｇａ−Ｃｕ系合金を準備する工程と、前記Ｒ１−Ｔ１−Ｂ系焼結体の表面の少なくとも一部に、前記Ｒ２−Ｇａ−Ｃｕ系合金の少なくとも一部を接触させ、真空又は不活性ガス雰囲気中、４５０℃以上５００℃以下の温度で熱処理を実施する工程を含み、前記Ｒ１−Ｔ１−Ｂ系焼結体において、Ｒ１は希土類元素のうち少なくとも一種であり、Ｎｄ及びＰｒの少なくとも一方を必ず含み、Ｒ１の含有量は、Ｒ１−Ｔ１−Ｂ系焼結体全体の２７ｍａｓｓ％以上３５ｍａｓｓ％以下であり、Ｔ１はＦｅ又はＣｏ、Ａｌ、Ｍｎ、Ｓｉの少なくとも１つとＦｅであり、Ｔ１全体に対するＦｅの含有量が８０ｍａｓｓ％以上であり、Ｂに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）が１４．０超１５．０以下であり、前記Ｒ２−Ｇａ−Ｃｕ系合金において、Ｒ２は希土類元素のうち少なくとも一種であり、Ｌａを必ず含み、Ｒ２の含有量は、Ｒ２−Ｇａ−Ｃｕ系合金全体の７０ｍｏｌ％以上９０ｍｏｌ％以下であり、かつ、希土類元素全体に対するＬａの比率が、Ｒ１−Ｔ１―Ｂ系焼結体の希土類元素全体に対するＬａの比率よりも高く、Ｇａの含有量は、Ｒ２−Ｇａ−Ｃｕ系合金全体の５ｍｏｌ％以上２０ｍｏｌ％以下であり、Ｃｕの含有量は、Ｒ２−Ｇａ−Ｃｕ系合金全体の５ｍｏｌ％以上２０ｍｏｌ％以下である。 The method for producing an R-TB-based sintered magnet of the present disclosure is a step of preparing an R1-T1-B-based sintered body and a step of preparing an R2-Ga-Cu-based alloy in an exemplary embodiment. And, at least a part of the R2-Ga-Cu alloy is brought into contact with at least a part of the surface of the R1-T1-B-based sintered body, and in a vacuum or an inert gas atmosphere, 450 ° C. or more and 500 ° C. or less In the R1-T1-B-based sintered body, R1 is at least one of rare earth elements, and always contains at least one of Nd and Pr, and the content of R1 is determined by the above-mentioned step of performing heat treatment at the above temperature. It is 27 mass% or more and 35 mass% or less of the whole R1-T1-B-based sintered body, T1 is Fe or at least one of Co, Al, Mn, and Si and Fe, and the content of Fe with respect to the whole T1 is 80 mass% or more. The mol ratio of T1 to B ([T1] / [B]) is more than 14.0 and 15.0 or less, and in the R2-Ga—Cu alloy, R2 is at least one of the rare earth elements. , La is always contained, the content of R2 is 70 mol% or more and 90 mol% or less of the whole R2-Ga-Cu alloy, and the ratio of La to the whole rare earth element is R1-T1-B-based sintered body. The content of Ga is 5 mol% or more and 20 mol% or less of the whole R2-Ga-Cu alloy, and the content of Cu is the whole R2-Ga-Cu alloy, which is higher than the ratio of La to the whole rare earth element. 5 mol% or more and 20 mol% or less.
ある実施形態において、前記Ｒ２−Ｇａ−Ｃｕ系合金中のＬａがＲ２全体の５０ｍｏｌ％以上である。 In a certain embodiment, La in the R2-Ga—Cu based alloy is 50 mol% or more of the total amount of R2.
ある実施形態において、前記Ｒ２−Ｇａ−Ｃｕ系合金中のＲ２はＬａである（不純物は含む）。 In certain embodiments, R2 in the R2-Ga—Cu based alloy is La (including impurities).
ある実施形態において、前記Ｒ２−Ｇａ−Ｃｕ系合金におけるＲ２、Ｇａ，Ｃｕの合計の含有量が８０ｍａｓｓ％以上である。 In a certain embodiment, the total content of R2, Ga, and Cu in the R2-Ga—Cu based alloy is 80 mass% or more.
ある実施形態において、前記Ｒ１−Ｔ１−Ｂ系焼結体を準備する工程は、原料合金を粒径Ｄ５０が３μｍ以上１０μｍ以下になるように粉砕した後、磁界中で配向させて焼結を行うことを含む。 In a certain embodiment, in the step of preparing the R1-T1-B-based sintered body, the raw material alloy is pulverized so that the particle size D 50 is 3 μm or more and 10 μm or less, and then oriented in a magnetic field for sintering. Including doing.
本開示の実施形態によると、Ｌａを使用し、重希土類元素の含有量を低減しつつ、高いＢｒ及び高いＨｃＪを有するＲ−Ｔ−Ｂ系焼結磁石の製造方法を提供することができる。 According to embodiments of the present disclosure, it is possible to use La, while reducing the content of heavy rare earth elements, to provide a method of manufacturing a R-T-B based sintered magnet having a high B r and a high H cJ it can.
本開示において、希土類元素を総称して「Ｒ」と表記する場合がある。希土類元素Ｒのうちの特定の元素または元素群を指すとき、例えば「Ｒ１」及び「Ｒ２」の符号を用いて他の希土類元素から区別する。また、本開示において、Ｆｅを含む遷移金属元素の全体を「Ｔ」と表記する。遷移金属元素Ｔのうちの特定の元素または元素群及び主相のＦｅサイトと容易に置換される遷移金属元素以外の特定の元素または元素群の両方を含むとき、「Ｔ１」の符号を用いて他の遷移金属元素から区別する。 In the present disclosure, rare earth elements may be collectively referred to as "R". When referring to a specific element or group of elements in the rare earth element R, for example, the symbols "R1" and "R2" are used to distinguish it from other rare earth elements. Further, in the present disclosure, the entire transition metal element including Fe is referred to as "T". When both a specific element or element group of the transition metal element T and a specific element or element group other than the transition metal element that is easily replaced with the Fe site of the main phase are included, the reference numeral "T1" is used. Distinguish from other transition metal elements.
本開示によるＲ−Ｔ−Ｂ系焼結磁石の製造方法は、図１に示すように、Ｒ１−Ｔ１−Ｂ系焼結体を準備する工程Ｓ１０と、Ｒ２−Ｇａ−Ｃｕ系合金を準備する工程Ｓ２０とを含む。Ｒ１−Ｔ１−Ｂ系焼結体を準備する工程Ｓ１０と、Ｒ２−Ｇａ−Ｃｕ系合金を準備する工程Ｓ２０との順序は任意であり、それぞれ、異なる場所で製造されたＲ１−Ｔ１−Ｂ系焼結体及びＲ２−Ｇａ−Ｃｕ系合金を用いてもよい。 As shown in FIG. 1, the method for producing an R-TB-based sintered magnet according to the present disclosure includes a step S10 for preparing an R1-T1-B-based sintered body and an R2-Ga-Cu-based alloy. Includes step S20. The order of the step S10 for preparing the R1-T1-B-based sintered body and the step S20 for preparing the R2-Ga-Cu-based alloy is arbitrary, and the R1-T1-B-based alloys are manufactured at different locations. A sintered body and an R2-Ga—Cu based alloy may be used.
本開示において、熱処理前及び熱処理中のＲ−Ｔ−Ｂ系焼結磁石をＲ１−Ｔ１−Ｂ系焼結体と称し、熱処理後のＲ１−Ｔ１−Ｂ系焼結体を単にＲ−Ｔ−Ｂ系焼結磁石と称する。 In the present disclosure, the R-TB-based sintered magnet before and during the heat treatment is referred to as an R1-T1-B-based sintered body, and the R1-T1-B-based sintered body after the heat treatment is simply RT-. It is called a B-based sintered magnet.
Ｒ１−Ｔ１−Ｂ系焼結体においては、下記（１）〜（３）が成立している。
（１）Ｒ１は希土類元素のうち少なくとも一種でありＮｄ及びＰｒの少なくとも一方を必ず含み、Ｒ１の含有量は、Ｒ１−Ｔ１−Ｂ系焼結体全体の２７ｍａｓｓ％以上３５ｍａｓｓ％以下である。
（２）Ｔ１はＦｅ又はＣｏ、Ａｌ、Ｍｎ、Ｓｉの少なくとも１つとＦｅであり、Ｔ１全体に対するＦｅの含有量が８０ｍａｓｓ％以上である。
（３）Ｂに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）が１４．０超１５．０以下である。
In the R1-T1-B-based sintered body, the following (1) to (3) are established.
(1) R1 is at least one of rare earth elements and always contains at least one of Nd and Pr, and the content of R1 is 27 mass% or more and 35 mass% or less of the entire R1-T1-B-based sintered body.
(2) T1 is Fe or at least one of Co, Al, Mn, and Si and Fe, and the content of Fe with respect to the whole T1 is 80 mass% or more.
(3) The mol ratio of T1 to B ([T1] / [B]) is more than 14.0 and 15.0 or less.
本開示におけるＢに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）とは、Ｔ１を構成する各元素（Ｆｅ又はＣｏ、Ａｌ、Ｍｎ、Ｓｉの少なくとも１つとＦｅ）の分析値（ｍａｓｓ％）をそれぞれの元素の原子量で除したものを求め、それらの値を合計したもの（ａ）と、Ｂの分析値（ｍａｓｓ％）をＢの原子量で除したもの（ｂ）との比（ａ／ｂ）である。 The mol ratio of T1 to B ([T1] / [B]) in the present disclosure is an analytical value (mass%) of each element (Fe or at least one of Co, Al, Mn, Si and Fe) constituting T1. Was divided by the atomic weight of each element, and the ratio (a /) of the sum of those values (a) and the analytical value of B (mass%) divided by the atomic weight of B (b). b).
Ｂに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）が１４．０を超えるということは、Ｂの含有比率がＲ２Ｔ１４Ｂ化合物の化学量論組成比よりも低いことを意味している。言い換えると、Ｒ１−Ｔ１−Ｂ系焼結体において、主相（Ｒ２Ｔ１４Ｂ化合物）の形成に使われるＴ１の量に対して相対的にＢ量が少ない。 Mol ratio of T1 for B ([T1] / [B ]) that is greater than 14.0, the content ratio of B is meant that less than the stoichiometric composition ratio of R 2 T 14 B compound There is. In other words, the R1-T1-B based sintered body, relative B amount relative to the amount of T1 to be used in the formation of the main phase (R 2 T 14 B compound) is small.
Ｒ２−Ｇａ−Ｃｕ系合金においては、以下の（４）〜（６）が成立している。
（４）Ｒ２は希土類元素のうち少なくとも一種であり、Ｌａを必ず含み、Ｒ２の含有量は、Ｒ２−Ｇａ−Ｃｕ系合金全体の７０ｍｏｌ％以上９０ｍｏｌ％以下であり、かつ、希土類元素全体に対するＬａの比率が、Ｒ１−Ｔ１―Ｂ系焼結体の希土類元素全体に対するＬａの比率よりも高い。
（５）Ｇａの含有量は、Ｒ２−Ｇａ−Ｃｕ系合金全体の５ｍｏｌ％以上２０ｍｏｌ％以下である。
（６）Ｃｕの含有量は、Ｒ２−Ｇａ−Ｃｕ系合金全体の５ｍｏｌ％以上２０ｍｏｌ％以下である。
In the R2-Ga—Cu based alloy, the following (4) to (6) are established.
(4) R2 is at least one of rare earth elements and always contains La, and the content of R2 is 70 mol% or more and 90 mol% or less of the whole R2-Ga—Cu based alloy, and La with respect to the whole rare earth element. Is higher than the ratio of La to the total rare earth elements of the R1-T1-B based sintered body.
(5) The Ga content is 5 mol% or more and 20 mol% or less of the entire R2-Ga—Cu based alloy.
(6) The Cu content is 5 mol% or more and 20 mol% or less of the entire R2-Ga—Cu based alloy.
本開示によるＲ−Ｔ−Ｂ系焼結磁石の製造方法は、主相（Ｒ２Ｔ１４Ｂ化合物）形成に使われるＴの量に対して化学量論比で相対的にＢ量が少ないＲ１−Ｔ１−Ｂ系焼結体の表面の少なくとも一部にＲ２−Ｇａ−Ｃｕ系合金を接触させ、図１に示すように、真空又は不活性ガス雰囲気中、４５０℃以上５００℃以下の温度で熱処理を実施する工程Ｓ３０を行う。これにより、高いＢｒ及び高いＨｃＪを有するＲ−Ｔ−Ｂ系焼結磁石を得ることが出来る。 Method for producing R-T-B based sintered magnet according to the present disclosure, the main phase (R 2 T 14 B compound) relatively B amount in stoichiometric ratio to the amount of T used for forming a small R1 An R2-Ga—Cu alloy is brought into contact with at least a part of the surface of the −T1-B-based sintered body, and as shown in FIG. 1, at a temperature of 450 ° C. or higher and 500 ° C. or lower in a vacuum or an inert gas atmosphere. The step S30 for carrying out the heat treatment is performed. Thus, it is possible to obtain the R-T-B based sintered magnet having a high B r and a high H cJ.
まず、Ｒ−Ｔ−Ｂ系焼結磁石の基本構造を説明する。 First, the basic structure of the RTB-based sintered magnet will be described.
Ｒ−Ｔ−Ｂ系焼結磁石は、原料合金の粉末粒子が焼結によって結合した構造を有しており、主としてＲ２Ｔ１４Ｂ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。 R-T-B based sintered magnet, the powder particles of the raw material alloy has a structure bonded by sintering, mainly a main phase consisting of R 2 T 14 B compound, the grain boundary portion of the main phase It is composed of the positioned grain boundary phase.
図２Ａは、Ｒ−Ｔ−Ｂ系焼結磁石の主相と粒界相を示す模式図であり、図２Ｂは図２Ａの破線矩形領域内を更に拡大した模式図である。図２Ａには、一例として長さ５μｍの矢印が大きさを示す基準の長さとして参考のために記載されている。図２Ａ及び図２Ｂに示されるように、Ｒ−Ｔ−Ｂ系焼結磁石は、主としてＲ２Ｔ１４Ｂ化合物からなる主相１２と、主相１２の粒界部分に位置する粒界相１４とから構成されている。また、粒界相１４は、図２Ｂに示されるように、２つのＲ２Ｔ１４Ｂ化合物粒子（グレイン）が隣接する二粒子粒界相１４ａと、３つ以上のＲ２Ｔ１４Ｂ化合物粒子が隣接する粒界三重点１４ｂとを含む。 FIG. 2A is a schematic view showing the main phase and the grain boundary phase of the RTB-based sintered magnet, and FIG. 2B is a schematic view further enlarging the inside of the broken line rectangular region of FIG. 2A. In FIG. 2A, as an example, an arrow having a length of 5 μm is shown for reference as a reference length indicating the size. As shown in FIGS. 2A and 2B, R-T-B based sintered magnet includes a main phase 12 mainly composed of R 2 T 14 B compound, the grain boundary phase located grain boundary of the main phase 12 14 It is composed of and. Further, as shown in FIG. 2B, the grain boundary phase 14 is a two-particle grain boundary phase 14a in which two R 2 T 14 B compound particles (grains) are adjacent to each other, and three or more R 2 T 14 B compound particles. Includes adjacent grain boundary triple points 14b.
主相１２であるＲ２Ｔ1４Ｂ化合物は高い飽和磁化と異方性磁界を持つ強磁性相である。したがって、Ｒ−Ｔ−Ｂ系焼結磁石では、主相１２であるＲ２Ｔ１４Ｂ化合物の存在比率を高めることによってＢｒを向上させることができる。Ｒ２Ｔ１４Ｂ化合物の存在比率を高めるためには、原料合金中のＲ量、Ｔ量、Ｂ量を、Ｒ２Ｔ１４Ｂ化合物の化学量論比（Ｒ量：Ｔ量：Ｂ量＝２：１４：１）に近づければよい。Ｒ２Ｔ１４Ｂ化合物を形成するためのＢ量又はＲ量が化学量論比を下回ると、一般的には、粒界相１４にＦｅ相又はＲ２Ｔ１７相等の強磁性体が生成し、ＨｃＪが急激に低下する。しかし、特許文献１に記載されている方法のように、Ｂ量をＲ２Ｔ１４Ｂ化合物の化学量論比よりも少なくし、且つ、Ａｌ、Ｇａ、Ｃｕのうちから選ばれる１種以上の金属元素Ｍを含有させると、Ｒ２Ｔ１７相から粒界に遷移金属リッチ相（例えばＲ−Ｔ−Ｇａ相）が生成されて高いＨｃＪを得ることできる。しかし、特許文献１に記載されている方法では、Ｂｒが大幅に低下してしまう。 The R 2 T 14 B compound, which is the main phase 12, is a ferromagnetic phase having a high saturation magnetization and an anisotropic magnetic field. Therefore, in the R-T-B based sintered magnet, it is possible to improve the B r by increasing the existence ratio of R 2 T 14 B compound is the main phase 12. In order to increase the abundance ratio of the R 2 T 14 B compound, the R amount, T amount, and B amount in the raw material alloy are changed to the stoichiometric ratio of the R 2 T 14 B compound (R amount: T amount: B amount = It should be close to 2:14: 1). When the amount of B or R for forming the R 2 T 14 B compound is less than the stoichiometric ratio, generally, a ferromagnet such as Fe phase or R 2 T 17 phase is generated in the grain boundary phase 14. , H cJ drops sharply. However, as in the method described in Patent Document 1, the B amount is less than the stoichiometric ratio of R 2 T 14 B compound, and, Al, Ga, of one or more selected among Cu When the metal element M is contained, a transition metal rich phase (for example, R-T-Ga phase) is generated from the R 2 T 17 phase to the grain boundary, and a high H cJ can be obtained. However, with the method described in Patent Document 1, Br is significantly reduced.
本開示のＲ−Ｔ−Ｂ系焼結磁石の製造方法は、低Ｂ組成である特定の組成を有するＲ１−Ｔ１−Ｂ系焼結体の表面の少なくとも一部に、希土類元素の中でも存在量が比較的豊富なＬａをＲ２として含有するＲ２−Ｇａ−Ｃｕ系合金を接触させて熱処理を行うことで、Ｌａを含むＲ２とＧａ及びＣｕを磁石内部に拡散させている。発明者らは検討の結果、Ｒ２−Ｇａ−Ｃｕ系合金におけるＲ２の含有量は、希土類元素全体に対するＬａの比率が、Ｒ１−Ｔ１−Ｂ系焼結磁石体の希土類元素全体に対するＬａの比率よりも高くする。そして、このような比率でＲ２中にＬａを存在させたうえで、非常に狭い特定の温度（４５０℃以上５００℃以下）で熱処理を行うと粒界拡散が促進されて、Ｇａを含む厚い二粒子粒界を焼結体の内部にまで容易に形成させることができることがわかった。これによりＬａを使用し、重希土類元素の含有量を低減しつつ、高いＢｒと高いＨｃＪを得ることができる。また、Ｌａと同じく希土類元素の中で存在量が比較的豊富なＣｅの場合は、本開示と同様な効果（高いＢｒと高いＨｃＪ）を実現することが困難であることも分かった。すなわち、本開示は、Ｌａを含むＲ２とＧａ及びＣｕを含む合金を非常に狭い特定の温度で熱処理を行い上記特定組成の焼結体へ拡散させることで、高いＢｒと高いＨｃＪを実現できることを見出したものである。 The method for producing an R-TB-based sintered magnet of the present disclosure has an abundance among rare earth elements on at least a part of the surface of an R1-T1-B-based sintered body having a specific composition having a low B composition. By contacting an R2-Ga—Cu alloy containing a relatively abundant La as R2 and performing heat treatment, R2 containing La, Ga and Cu are diffused inside the magnet. As a result of examination by the inventors, the content of R2 in the R2-Ga-Cu alloy is such that the ratio of La to the whole rare earth element is higher than the ratio of La to the whole rare earth element of the R1-T1-B-based sintered magnet body. Also raise. Then, when La is present in R2 at such a ratio and heat treatment is performed at a very narrow specific temperature (450 ° C. or higher and 500 ° C. or lower), grain boundary diffusion is promoted and a thick second containing Ga is contained. It was found that the grain boundaries can be easily formed even inside the sintered body. Thus using La, while reducing the content of heavy rare earth elements, it is possible to obtain a high B r and high H cJ. In the case of relatively rich Ce is abundance in the same rare earth elements and La, also it has been found that it is difficult to realize the present disclosure similar effect (high B r and high H cJ). That is, the present disclosure is that to diffuse into the sintered body of the specific composition subjected to heat treatment the alloy containing R2 and Ga and Cu containing La in a very narrow specific temperature, realizing a high B r and high H cJ I found out what I could do.
（Ｒ１−Ｔ１−Ｂ系焼結体を準備する工程）
まず、Ｒ１−Ｔ１−Ｂ系焼結体（以下、単に「焼結体」という場合がある）を準備する工程における焼結体の組成を説明する。
(Step of preparing R1-T1-B-based sintered body)
First, the composition of the sintered body in the step of preparing the R1-T1-B-based sintered body (hereinafter, may be simply referred to as “sintered body”) will be described.
Ｒ１は希土類元素のうち少なくとも一種であり、Ｎｄ及びＰｒの少なくとも一方を必ず含む。Ｒ１−Ｔ１−Ｂ系焼結体のＨｃＪを向上させるために、一般的に用いられるＤｙ、Ｔｂ、Ｇｄ、Ｈｏなどの重希土類元素を少量含有してもよい。ただし、本開示による製造方法によれば、重希土類元素を多量に用いずとも十分に高いＨｃＪを得ることができる。そのため、前記重希土類元素の含有量は、Ｒ１−Ｔ１−Ｂ系焼結体の１ｍａｓｓ％以下であることが好ましく、０．５ｍａｓｓ％以下であることがより好ましく、含有しない（実質的に０ｍａｓｓ％）ことがさらに好ましい。 R1 is at least one of rare earth elements and always contains at least one of Nd and Pr. In order to improve the HcJ of the R1-T1-B-based sintered body, a small amount of commonly used heavy rare earth elements such as Dy, Tb, Gd, and Ho may be contained. However, according to the production method according to the present disclosure, a sufficiently high HcJ can be obtained without using a large amount of heavy rare earth elements. Therefore, the content of the heavy rare earth element is preferably 1 mass% or less, more preferably 0.5 mass% or less, and not contained (substantially 0 mass%) of the R1-T1-B-based sintered body. ) Is even more preferable.
Ｒ１の含有量は、Ｒ１−Ｔ１−Ｂ系焼結体全体の２７ｍａｓｓ％以上３５ｍａｓｓ％以下である。Ｒ１の含有量が２７ｍａｓｓ％未満では焼結過程で液相が十分に生成せず、Ｒ１−Ｔ１−Ｂ系焼結体を十分に緻密化することが困難になる。一方、Ｒ１の含有量が３５ｍａｓｓ％を超えても本開示の効果を得ることはできるが、Ｒ１−Ｔ１−Ｂ系焼結体の製造工程中における合金粉末が非常に活性になる。その結果、合金粉末の著しい酸化や発火などを生じることがあるため、３５ｍａｓｓ％以下が好ましい。Ｒ１の含有量は、２７．５ｍａｓｓ％以上３３ｍａｓｓ％以下であることがより好ましく、２８ｍａｓｓ％以上３２ｍａｓｓ％以下であることがさらに好ましい。 The content of R1 is 27 mass% or more and 35 mass% or less of the entire R1-T1-B-based sintered body. If the content of R1 is less than 27 mass%, a liquid phase is not sufficiently formed in the sintering process, and it becomes difficult to sufficiently densify the R1-T1-B-based sintered body. On the other hand, although the effect of the present disclosure can be obtained even if the content of R1 exceeds 35 mass%, the alloy powder in the manufacturing process of the R1-T1-B-based sintered body becomes very active. As a result, significant oxidation or ignition of the alloy powder may occur, so 35 mass% or less is preferable. The content of R1 is more preferably 27.5 mass% or more and 33 mass% or less, and further preferably 28 mass% or more and 32 mass% or less.
Ｔ１はＦｅ又はＣｏ、Ａｌ、Ｍｎ、Ｓｉの少なくとも１つとＦｅであり、Ｔ１全体に対するＦｅの含有量が８０ｍａｓｓ％以上である。すなわち、Ｔ１はＦｅのみであってもよいし、Ｃｏ、Ａｌ、Ｍｎ、Ｓｉの少なくとも１つとＦｅからなってもよい。但し、Ｔ１全体に対するＦｅの含有量は８０ｍａｓｓ％以上である。Ｆｅの含有量が８０ｍａｓｓ％未満であると、Ｂｒ及びＨｃＪが低下する可能性がある。ここで、「Ｔ１全体に対するＦｅの含有量は８０ｍａｓｓ％以上」とは、例えばＲ１−Ｔ１−Ｂ系焼結体中におけるＴ１の含有量が７０ｍａｓｓ％である場合、Ｒ１−Ｔ１−Ｂ系焼結体の５６ｍａｓｓ％以上がＦｅであることを言う。好ましくはＴ１全体に対するＦｅの含有量は９０ｍａｓｓ％以上である。より高いＢｒと高いＨｃＪを得ることができるからである。Ｃｏ、Ａｌ、Ｍｎ、Ｓｉを含有する場合の好ましい含有量は、Ｃｏは５．０ｍａｓｓ％以下、Ａｌは１．５ｍａｓｓ％以下、Ｍｎ及びＳｉはそれぞれ０．２ｍａｓｓ％以下である。 T1 is Fe or at least one of Co, Al, Mn, and Si and Fe, and the content of Fe with respect to the entire T1 is 80 mass% or more. That is, T1 may be Fe alone, or may be composed of at least one of Co, Al, Mn, and Si and Fe. However, the content of Fe with respect to the whole T1 is 80 mass% or more. When the content of Fe is less than 80 mass%, B r and H cJ may be reduced. Here, "the content of Fe with respect to the entire T1 is 80 mass% or more" means, for example, when the content of T1 in the R1-T1-B-based sintered body is 70 mass%, the R1-T1-B-based sintered body. It means that 56 mass% or more of the body is Fe. Preferably, the Fe content with respect to the entire T1 is 90 mass% or more. This is because it is possible to obtain a higher B r and a high H cJ. When Co, Al, Mn, and Si are contained, the preferable contents of Co are 5.0 mass% or less, Al is 1.5 mass% or less, and Mn and Si are 0.2 mass% or less, respectively.
Ｂに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）は１４．０超１５．０以下である。 The mol ratio of T1 to B ([T1] / [B]) is more than 14.0 and 15.0 or less.
Ｂに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）が１４．０以下であると高いＨｃＪを得ることができない。一方、Ｂに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）が１５．０を超えるとＢｒが低下する可能性がある。Ｂに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）は１４．３以上１５．０以下であることが好ましい。さらに高いＢｒと高いＨｃＪを得ることができる。また、Ｂの含有量はＲ１−Ｔ１−Ｂ系焼結体全体の０．８５ｍａｓｓ％以上０．９５ｍａｓｓ％未満が好ましい。 If the mol ratio of T1 to B ([T1] / [B]) is 14.0 or less, a high H cJ cannot be obtained. On the other hand, if the mol ratio of T1 to B ([T1] / [B]) exceeds 15.0, Br may decrease. The mol ratio of T1 to B ([T1] / [B]) is preferably 14.3 or more and 15.0 or less. It is possible to obtain a higher B r and a high H cJ. The B content is preferably 0.85 mass% or more and less than 0.95 mass% of the entire R1-T1-B-based sintered body.
Ｒ１−Ｔ１−Ｂ系焼結体は、上記元素の他にＧａ、Ｃｕ、Ａｇ、Ｚｎ、Ｉｎ、Ｓｎ、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、Ｇａ、Ｃｕ、Ａｇ、Ｚｎ、Ｉｎ、Ｓｎ、Ｚｒ、Ｎｂ、及びＴｉはそれぞれ０．５ｍａｓｓ％以下、Ｎｉ、Ｈｆ、Ｔａ、Ｗ、Ｇｅ、Ｍｏ、Ｖ、Ｙ、Ｌａ、Ｃｅ、Ｓｍ、Ｃａ、Ｍｇ、Ｃｒはそれぞれ０．２ｍａｓｓ％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、Ｒ１−Ｔ１−Ｂ系焼結体全体の５ｍａｓｓ％以下が好ましい。これらの元素の合計の含有量がＲ１−Ｔ１−Ｂ系焼結体全体の５ｍａｓｓ％を超えると高いＢｒと高いＨｃＪを得ることができない可能性がある。 In addition to the above elements, the R1-T1-B-based sintered body includes Ga, Cu, Ag, Zn, In, Sn, Zr, Nb, Ti, Ni, Hf, Ta, W, Ge, Mo, V, Y, It may contain La, Ce, Sm, Ca, Mg, Cr, H, F, P, S, Cl, O, N, C and the like. The contents of Ga, Cu, Ag, Zn, In, Sn, Zr, Nb, and Ti are 0.5 mass% or less, respectively, and Ni, Hf, Ta, W, Ge, Mo, V, Y, La, Ce, It is preferable that Sm, Ca, Mg and Cr are 0.2 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 mass% or less of the entire R1-T1-B-based sintered body. The total content of these elements may not be able to obtain the high B r and high H cJ exceeds 5 mass% of the total R1-T1-B based sintered body.
次にＲ１−Ｔ１−Ｂ系焼結体を準備する工程について説明する。Ｒ１−Ｔ１−Ｂ系焼結体を準備する工程は、Ｒ−Ｔ−Ｂ系焼結磁石に代表される一般的な製造方法を用いて準備することができる。Ｒ１−Ｔ１−Ｂ系焼結体は、原料合金を粒径Ｄ５０（気流分散式レーザー回折法による測定で得られる体積中心値＝Ｄ５０）が３μｍ以上１０μｍ以下になるように粉砕した後、磁界中で配向させて焼結を行うことが好ましい。一例を挙げると、ストリップキャスト法などで作製された原料合金を、ジェットミル装置などを用いて粒径Ｄ５０が３μｍ以上１０μｍ以下になるように粉砕した後、磁界中で成形し、９００℃以上１１００℃以下の温度で焼結することにより準備することができる。原料合金の粒径Ｄ５０が３μｍ未満では粉砕粉を作製するのが非常に困難であり、生産効率が大幅に低下するため好ましくない。一方、粒径Ｄ５０が１０μｍを超えると最終的に得られるＲ１−Ｔ１−Ｂ系焼結体の結晶粒径が大きくなり過ぎ、高いＨｃＪを得ることが困難となるため好ましくない。粒径Ｄ５０は好ましくは、３μｍ以上５μｍ以下である。 Next, a step of preparing the R1-T1-B-based sintered body will be described. The step of preparing the R1-T1-B-based sintered body can be prepared by using a general manufacturing method typified by the R-TB-based sintered magnet. In the R1-T1-B-based sintered body, the raw material alloy is pulverized so that the particle size D 50 (volume center value obtained by measurement by the air flow dispersion laser diffraction method = D 50 ) is 3 μm or more and 10 μm or less, and then the raw material alloy is pulverized. It is preferable to perform sintering by orienting in a magnetic field. As an example, a raw material alloy produced by a strip casting method or the like is pulverized using a jet mill device or the like so that the particle size D 50 is 3 μm or more and 10 μm or less, and then molded in a magnetic field at 900 ° C. or higher. It can be prepared by sintering at a temperature of 1100 ° C. or lower. If the particle size D 50 of the raw material alloy is less than 3 μm, it is very difficult to produce pulverized powder, and the production efficiency is significantly reduced, which is not preferable. On the other hand, if the particle size D 50 exceeds 10 μm, the crystal particle size of the finally obtained R1-T1-B-based sintered body becomes too large, and it becomes difficult to obtain a high H cJ, which is not preferable. The particle size D 50 is preferably 3 μm or more and 5 μm or less.
Ｒ１−Ｔ１−Ｂ系焼結体は、前記の各条件を満たしていれば、一種類の原料合金（単一原料合金）から作製してもよいし、二種類以上の原料合金を用いてそれらを混合する方法（ブレンド法）によって作製してもよい。また、得られたＲ１−Ｔ１−Ｂ系焼結体は、必要に応じて切断や切削など公知の機械加工を行った後、後述する熱処理を実施してもよい。 The R1-T1-B-based sintered body may be produced from one kind of raw material alloy (single raw material alloy) as long as each of the above conditions is satisfied, or two or more kinds of raw material alloys are used for them. May be produced by a method of mixing (blending method). Further, the obtained R1-T1-B-based sintered body may be subjected to known machining such as cutting or cutting if necessary, and then heat treatment described later may be performed.
（Ｒ２−Ｇａ−Ｃｕ系合金を準備する工程）
まず、Ｒ２−Ｇａ−Ｃｕ系合金を準備する工程におけるＲ２−Ｇａ−Ｃｕ系合金の組成を説明する。以下に説明する特定の範囲でＲ２及びＧａ、Ｃｕを含有することにより、後述する熱処理を実施する工程においてＲ２−Ｇａ−Ｃｕ系合金中のＲ２及びＧａ、ＣｕをＲ１−Ｔ１−Ｂ系焼結体内部に導入することができる。
(Step of preparing R2-Ga-Cu alloy)
First, the composition of the R2-Ga-Cu-based alloy in the step of preparing the R2-Ga-Cu-based alloy will be described. By containing R2, Ga, and Cu in a specific range described below, R2, Ga, and Cu in the R2-Ga—Cu alloy are sintered by R1-T1-B in the step of performing the heat treatment described later. It can be introduced inside the body.
Ｒ２は希土類元素のうち少なくとも一種であり、Ｌａを必ず含み、Ｒ２の含有量はＲ２−Ｇａ−Ｃｕ系合金全体の７０ｍｏｌ％以上９０ｍｏｌ％以下である。Ｒ２の含有量が７０ｍｏｌ％未満では後述する熱処理で拡散が十分に進行しない可能性がある。一方、Ｒ２の含有量が９０ｍｏｌ％を超えても本開示の効果を得ることはできるが、Ｒ２−Ｇａ−Ｃｕ系合金の製造工程中における合金粉末が非常に活性になる。その結果、合金粉末の著しい酸化や発火などを生じることがあるため、Ｒ２の含有量はＲ２−Ｇａ−Ｃｕ系合金全体の９０ｍｏｌ％以下が好ましい。Ｒ２の含有量は７５ｍｏｌ％以上８５ｍｏｌ％以下であることがより好ましい。より高いＨｃＪを得ることができるからである。また、上述したように、Ｎｄの供給不足が懸念されている中、希土類元素使用の多様化の観点から前記Ｒ２−Ｇａ−Ｃｕ系合金中のＬａがＲ２全体の５０ｍｏｌ％以上であることが好ましく、さらに好ましくは、前記Ｒ２−Ｇａ−Ｃｕ系合金中のＲ２はＬａである（不純物は含む）。 R2 is at least one of rare earth elements and always contains La, and the content of R2 is 70 mol% or more and 90 mol% or less of the entire R2-Ga—Cu based alloy. If the content of R2 is less than 70 mol%, diffusion may not proceed sufficiently by the heat treatment described later. On the other hand, although the effect of the present disclosure can be obtained even if the content of R2 exceeds 90 mol%, the alloy powder in the manufacturing process of the R2-Ga—Cu based alloy becomes very active. As a result, the alloy powder may be significantly oxidized or ignited. Therefore, the R2 content is preferably 90 mol% or less of the total R2-Ga—Cu alloy. The content of R2 is more preferably 75 mol% or more and 85 mol% or less. This is because a higher H cJ can be obtained. Further, as described above, while there is a concern that the supply of Nd will be insufficient, it is preferable that La in the R2-Ga-Cu alloy is 50 mol% or more of the total amount of R2 from the viewpoint of diversifying the use of rare earth elements. More preferably, R2 in the R2-Ga—Cu based alloy is La (including impurities).
Ｒ２は、希土類元素全体に対するＬａの比率が、Ｒ１−Ｔ１―Ｂ系焼結体の希土類元素全体に対するＬａの比率よりも高い。これにより粒界拡散が促進され、磁石内部にＧａやＣｕを拡散させることができる。Ｌａの比率がＲ１−Ｔ１―Ｂ系焼結体の希土類元素全体に対するＬａの比率よりも低いと、粒界拡散が促進されずＧａやＣｕの拡散は焼結体の表面近傍にとどまる可能性がある。そのため、Ｇａ−Ｃｕの磁石表面から内部への導入量が不十分となり、高いＢｒと高いＨｃＪを有するＲ−Ｔ−Ｂ系焼結磁石を得ることができない可能性がある。好ましくは、前記Ｒ１−Ｔ１−Ｂ系焼結体中の［Ｌａ］／［Ｒ１］をα、Ｒ２−Ｇａ−Ｃｕ系合金中の［Ｌａ］／［Ｒ２］をβとしたとき、β／α≧１．５である。 In R2, the ratio of La to the whole rare earth element is higher than the ratio of La to the whole rare earth element of the R1-T1-B-based sintered body. As a result, grain boundary diffusion is promoted, and Ga and Cu can be diffused inside the magnet. If the ratio of La is lower than the ratio of La to the total rare earth elements of the R1-T1-B-based sintered body, the intergranular diffusion is not promoted and the diffusion of Ga and Cu may stay near the surface of the sintered body. is there. Therefore, the introduction amount to the inside from the magnet surface of the Ga-Cu is insufficient, there is a possibility that it is impossible to obtain a R-T-B based sintered magnet having a high B r and high H cJ. Preferably, when [La] / [R1] in the R1-T1-B-based sintered body is α and [La] / [R2] in the R2-Ga-Cu-based alloy is β, β / α ≧ 1.5.
Ｇａは、Ｒ２−Ｇａ−Ｃｕ系合金全体の５ｍｏｌ％以上２０ｍｏｌ％以下である。Ｇａが５ｍｏｌ％未満では、後述する熱処理を実施する工程においてＲ２−Ｇａ−Ｃｕ系合金中のＧａやＣｕがＲ１−Ｔ１−Ｂ系焼結体の内部に導入され難くなり高いＨｃＪを得ることが出来ない。一方、Ｇａが２０ｍｏｌ％超であると、Ｂｒが大幅に低下する可能性がある。Ｇａは５ｍｏｌ％以上２０ｍｏｌ％以下であることがより好ましい。より高いＢｒと高いＨｃＪを得ることができるからである。 Ga is 5 mol% or more and 20 mol% or less of the whole R2-Ga—Cu based alloy. If Ga is less than 5 mol%, it becomes difficult for Ga and Cu in the R2-Ga-Cu-based alloy to be introduced into the R1-T1-B-based sintered body in the step of performing the heat treatment described later, and a high HcJ is obtained. I can't. On the other hand, if Ga is a 20 mol% excess, B r may be lowered significantly. Ga is more preferably 5 mol% or more and 20 mol% or less. This is because it is possible to obtain a higher B r and a high H cJ.
Ｃｕは、Ｒ２−Ｇａ−Ｃｕ系合金全体の５ｍｏｌ％以上２０ｍｏｌ％以下含有する。５ｍｏｌ％未満であると高いＨｃＪを得ることが出来ない可能性があり、Ｃｕが２０ｍｏｌ％を超えると、粒界におけるＧａの存在比率が低下する可能性があるため、２０ｍｏｌ％以下が好ましい。 Cu is contained in an amount of 5 mol% or more and 20 mol% or less of the entire R2-Ga—Cu based alloy. If it is less than 5 mol%, high H cJ may not be obtained, and if Cu exceeds 20 mol%, the abundance ratio of Ga at the grain boundary may decrease. Therefore, 20 mol% or less is preferable.
Ｒ２−Ｇａ−Ｃｕ系合金は、上記元素の他にＣｏ、Ａｌ、Ａｇ、Ｚｎ、Ｓｉ、Ｉｎ、Ｓｎ、Ｚｒ、Ｎｂ、Ｔｉ、Ｎｉ、Ｈｆ、Ｔａ、Ｗ、Ｇｅ、Ｍｏ、Ｖ、Ｙ、Ｌａ、Ｃｅ、Ｓｍ、Ｃａ、Ｍｇ、Ｍｎ、Ｃｒ、Ｈ、Ｆ、Ｐ、Ｓ、Ｃｌ、Ｏ、Ｎ、Ｃ等を含有してもよい。 In addition to the above elements, R2-Ga—Cu alloys include Co, Al, Ag, Zn, Si, In, Sn, Zr, Nb, Ti, Ni, Hf, Ta, W, Ge, Mo, V, Y, It may contain La, Ce, Sm, Ca, Mg, Mn, Cr, H, F, P, S, Cl, O, N, C and the like.
Ｃｏは、耐食性の向上のために０．５ｍａｓｓ％以上１０ｍａｓｓ％以下含有してもよい。また、Ａｌは１．０ｍａｓｓ％以下、Ａｇ、Ｚｎ、Ｓｉ、Ｉｎ、Ｓｎ、Ｚｒ、Ｎｂ、及びＴｉはそれぞれ０．５ｍａｓｓ％以下、Ｎｉ、Ｈｆ、Ｔａ、Ｗ、Ｇｅ、Ｍｏ、Ｖ、Ｙ、Ｌａ、Ｃｅ、Ｓｍ、Ｃａ、Ｍｇ、Ｍｎ、Ｓｉ、Ｃｒはそれぞれ０．２ｍａｓｓ％以下、Ｈ、Ｆ、Ｐ、Ｓ、Ｃｌは５００ｐｐｍ以下、Ｏは６０００ｐｐｍ以下、Ｎは１０００ｐｐｍ以下、Ｃは１５００ｐｐｍ以下の含有量が好ましい。但し、これらの元素の合計の含有量が２０ｍａｓｓ％を超えると、Ｒ２−Ｇａ−Ｃｕ系合金におけるＲ２、Ｇａ、Ｃｕの含有量が少なくなり、高いＢｒと高いＨｃＪを得ることが出来ない可能性がある。そのため、Ｒ２−Ｇａ−Ｃｕ系合金におけるＲ２、Ｇａ、Ｃｕの合計の含有量は８０ｍａｓｓ％以上が好ましく、９０ｍａｓｓ％以上がさらに好ましい。 Co may be contained in an amount of 0.5 mass% or more and 10 mass% or less in order to improve corrosion resistance. Al is 1.0 mass% or less, Ag, Zn, Si, In, Sn, Zr, Nb, and Ti are 0.5 mass% or less, respectively, Ni, Hf, Ta, W, Ge, Mo, V, Y, La, Ce, Sm, Ca, Mg, Mn, Si, Cr are 0.2 mass% or less, H, F, P, S, Cl are 500 ppm or less, O is 6000 ppm or less, N is 1000 ppm or less, C is 1500 ppm or less. Content is preferred. However, the total content of these elements exceeds 20 mass%, R2 in R2-Ga-Cu-based alloy, Ga, then the amount of Cu, it is impossible to obtain a high B r and high H cJ there is a possibility. Therefore, the total content of R2, Ga, and Cu in the R2-Ga—Cu alloy is preferably 80 mass% or more, and more preferably 90 mass% or more.
次にＲ２−Ｇａ−Ｃｕ系合金を準備する工程について説明する。Ｒ２−Ｇａ−Ｃｕ系合金は、Ｎｄ−Ｆｅ−Ｂ系焼結磁石に代表される一般的な製造方法において採用されている原料合金の作製方法、例えば、金型鋳造法やストリップキャスト法や単ロール超急冷法（メルトスピニング法）やアトマイズ法などを用いて準備することができる。また、Ｒ２−Ｇａ−Ｃｕ系合金は、前記によって得られた合金をピンミルなどの公知の粉砕手段によって粉砕されたものであってもよい。また、前記によって得られた合金の粉砕性を向上させるために、水素雰囲気中で７００℃以下の熱処理を行って水素を含有させてから粉砕を行っても良い。 Next, the step of preparing the R2-Ga—Cu based alloy will be described. The R2-Ga-Cu based alloy is a method for producing a raw material alloy adopted in a general manufacturing method represented by an Nd-Fe-B based sintered magnet, for example, a mold casting method, a strip casting method, or a simple method. It can be prepared by using a roll ultra-quenching method (melt spinning method) or an atomizing method. Further, the R2-Ga—Cu based alloy may be an alloy obtained by pulverizing the alloy obtained by the above by a known pulverizing means such as a pin mill. Further, in order to improve the pulverizability of the alloy obtained as described above, pulverization may be performed after heat treatment at 700 ° C. or lower is performed in a hydrogen atmosphere to contain hydrogen.
（熱処理を実施する工程）
前記によって準備したＲ１−Ｔ１−Ｂ系焼結体の表面の少なくとも一部に、前記Ｒ２−Ｇａ−Ｃｕ系合金の少なくとも一部を接触させ、真空又は不活性ガス雰囲気中、４５０℃以上５００℃以下の温度で熱処理をする。これにより、Ｒ２−Ｇａ−Ｃｕ系合金からＬａを含むＲ２及びＧａ、Ｃｕを含む液相が生成し、その液相がＲ１−Ｔ１−Ｂ系焼結体の粒界を経由して焼結体表面から内部に拡散導入され、粒界にＲ−Ｔ−Ｇａ相が生成される。熱処理温度が４５０℃未満であると、Ｌａを含むＲ２及びＧａ，Ｃｕを含む液相量が少なすぎて、高いＢｒと高いＨｃＪを得ることが出来ない可能性がある。一方、５００℃を超えると、理由は不明であるが、Ｒ１−Ｔ１−Ｂ系焼結体へのＲ２−Ｇａ−Ｃｕ系合金の拡散が阻害されて高いＨｃＪが得られない可能性がある。熱処理温度は、４６０℃以上４９０℃以下が好ましい。より高いＢｒと高いＨｃＪを得ることができるからである。なお、熱処理時間はＲ１−Ｔ１−Ｂ系焼結体やＲ２−Ｇａ−Ｃｕ系合金の組成や寸法、熱処理温度などによって適正値を設定するが、５分以上２４時間以下が好ましく、１０分以上２０時間以下がより好ましく、３０分以上１６時間以下がさらに好ましい。また、熱処理は１回だけ行ってもよく、複数回行ってもよい。また、Ｒ２−Ｇａ−Ｃｕ系合金は、Ｒ１−Ｔ１−Ｂ系焼結体の重量に対し２ｍａｓｓ％以上３０ｍａｓｓ％以下準備することが好ましい。Ｒ２−Ｇａ−Ｃｕ系合金がＲ１−Ｔ１−Ｂ系焼結体の重量に対し２ｍａｓｓ％未満であると高いＨｃＪが得られない可能性がある。一方、３０ｍａｓｓ％を超えるとＢｒが大幅に低下する可能性がある。
(Step of performing heat treatment)
At least a part of the R2-Ga—Cu alloy is brought into contact with at least a part of the surface of the R1-T1-B-based sintered body prepared as described above, and the temperature is 450 ° C. or higher and 500 ° C. in a vacuum or an inert gas atmosphere. Heat treatment is performed at the following temperature. As a result, a liquid phase containing R2 containing La and Ga and Cu is generated from the R2-Ga—Cu based alloy, and the liquid phase passes through the grain boundaries of the R1-T1-B based sintered body and is sintered. It is diffusely introduced from the surface to the inside, and an RT-Ga phase is generated at the grain boundaries. If the heat treatment temperature is lower than 450 ° C., R2 and Ga containing La, and too small amount of liquid phase containing Cu, it may not be able to obtain a high B r and high H cJ. On the other hand, if the temperature exceeds 500 ° C., for unknown reasons, the diffusion of the R2-Ga—Cu alloy into the R1-T1-B sintered body may be inhibited and a high HcJ may not be obtained. .. The heat treatment temperature is preferably 460 ° C. or higher and 490 ° C. or lower. This is because it is possible to obtain a higher B r and a high H cJ. The heat treatment time is set to an appropriate value depending on the composition and dimensions of the R1-T1-B-based sintered body and the R2-Ga-Cu-based alloy, the heat treatment temperature, etc., but is preferably 5 minutes or more and 24 hours or less, preferably 10 minutes or more. 20 hours or less is more preferable, and 30 minutes or more and 16 hours or less is further preferable. Further, the heat treatment may be performed only once or a plurality of times. Further, it is preferable to prepare the R2-Ga—Cu based alloy in an amount of 2 mass% or more and 30 mass% or less based on the weight of the R1-T1-B based sintered body. If the R2-Ga—Cu alloy is less than 2 mass% with respect to the weight of the R1-T1-B sintered body, high HcJ may not be obtained. On the other hand, there is a possibility that B r exceeds 30 mass% is greatly reduced.
前記熱処理は、Ｒ１−Ｔ１−Ｂ系焼結体表面に、任意形状のＲ２−Ｇａ−Ｃｕ系合金を配置し、公知の熱処理装置を用いて行うことができる。例えば、Ｒ１−Ｔ１−Ｂ系焼結体表面をＲ２−Ｇａ−Ｃｕ系合金の粉末層で覆い、熱処理を行うことができる。例えば、Ｒ２−Ｇａ−Ｃｕ系合金を分散媒中に分散させたスラリーをＲ１−Ｔ１−Ｂ系焼結体表面に塗布した後、分散媒を蒸発させてＲ２−Ｇａ−Ｃｕ系合金とＲ１−Ｔ１−Ｂ系焼結体とを接触させてもよい。また、後述する実験例に示すように、Ｒ２−Ｇａ−Ｃｕ系合金は、少なくともＲ１−Ｔ１−Ｂ系焼結体の配向方向に対して垂直な表面に接触させるように配置することが好ましい。なお、分散媒として、アルコール（エタノール等）、ＮＭＰ（Ｎ−メチルピロリドン）、アルデヒド及びケトンを例示できる。また、熱処理が実施されたＲ１−Ｔ１−Ｂ系焼結体に対して切断や切削など公知の機械加工を行ってもよい。 The heat treatment can be performed by arranging an R2-Ga-Cu alloy having an arbitrary shape on the surface of the R1-T1-B-based sintered body and using a known heat treatment apparatus. For example, the surface of the R1-T1-B-based sintered body can be covered with a powder layer of an R2-Ga-Cu-based alloy to perform heat treatment. For example, a slurry in which an R2-Ga-Cu alloy is dispersed in a dispersion medium is applied to the surface of an R1-T1-B-based sintered body, and then the dispersion medium is evaporated to form an R2-Ga-Cu alloy and R1-. It may be brought into contact with the T1-B based sintered body. Further, as shown in an experimental example described later, it is preferable that the R2-Ga-Cu alloy is arranged so as to be in contact with the surface perpendicular to the orientation direction of at least the R1-T1-B sintered body. Examples of the dispersion medium include alcohol (ethanol and the like), NMP (N-methylpyrrolidone), aldehyde and ketone. Further, the R1-T1-B-based sintered body that has been heat-treated may be subjected to known machining such as cutting or cutting.
本発明を実施例によりさらに詳細に説明するが、本発明はそれらに限定されるものではない。 The present invention will be described in more detail by way of examples, but the present invention is not limited thereto.
実験例１
［Ｒ１−Ｔ１−Ｂ系焼結体の準備］
Ｎｄメタル、Ｐｒメタル、フェロボロン合金、電解鉄を用いて（メタルはいずれも純度９９％以上）、焼結体がおよそ表１に示す符号１−Ａから１−Ｃの組成となるように配合し、それらの原料を溶解してストリップキャスト法により鋳造し、厚さ０．２〜０．４ｍｍのフレーク状の原料合金を得た。得られたフレーク状の原料合金を水素粉砕した後、５５０℃まで真空中で加熱後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１００ｍａｓｓ％に対して０．０４ｍａｓｓ％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、粉砕粒径Ｄ５０が４μｍの微粉砕粉（合金粉末）を得た。なお、粉砕粒径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。
Experimental Example 1
[Preparation of R1-T1-B-based sintered body]
Using Nd metal, Pr metal, ferrobolon alloy, and electrolytic iron (all metals have a purity of 99% or more), the sintered body is blended so as to have a composition of reference numerals 1-A to 1-C shown in Table 1. , These raw materials were melted and cast by a strip casting method to obtain a flake-shaped raw material alloy having a thickness of 0.2 to 0.4 mm. The obtained flake-shaped raw material alloy was pulverized with hydrogen, and then subjected to a dehydrogenation treatment of heating to 550 ° C. in a vacuum and then cooling to obtain a coarsely pulverized powder. Next, zinc stearate as a lubricant was added to the obtained coarsely pulverized powder in an amount of 0.04 mass% with respect to 100 mass% of the coarsely pulverized powder, mixed, and then nitrogen was used using an airflow type pulverizer (jet mill device). Dry pulverization was performed in an air stream to obtain a finely pulverized powder (alloy powder) having a pulverized particle size D 50 of 4 μm. The pulverized particle size D 50 is a volume center value (volume-based median diameter) obtained by a laser diffraction method based on an air flow dispersion method.
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１００ｍａｓｓ％に対して０．０５ｍａｓｓ％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。 Zinc stearate as a lubricant was added to the finely pulverized powder in an amount of 0.05 mass% based on 100 mass% of the finely pulverized powder, mixed, and then molded in a magnetic field to obtain a molded product. As the molding apparatus, a so-called right-angled magnetic field forming apparatus (transverse magnetic field forming apparatus) in which the magnetic field application direction and the pressurizing direction are orthogonal to each other was used.
得られた成形体を、真空中、１０００℃以上１０４０℃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、Ｒ１−Ｔ１−Ｂ系焼結体を得た。得られた焼結体の密度は７．５Ｍｇ／ｍ３以上であった。得られた焼結体の組成を表１に示す。なお、表１における各成分は、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。なお、焼結体の酸素量をガス融解−赤外線吸収法で測定した結果、すべて０．４ｍａｓｓ％前後であることを確認した。表１における「［Ｔ１］／［Ｂ］」は、Ｔ１を構成する各元素（不可避の不純物を含む、本実験例ではＦｅ、Ａｌ、Ｓｉ、Ｍｎ）に対し、分析値（ｍａｓｓ％）をその元素の原子量で除したものを求め、それらの値を合計したもの（ａ）と、Ｂの分析値（ｍａｓｓ％）をＢの分析値（ｍａｓｓ％）をＢの原子量で除したもの（ｂ）との比（ａ／ｂ）である。以下の全ての表も同様である。なお、表１の各組成を合計しても１００ｍａｓｓ％にはならない。これは、前記の通り、各成分によって分析方法が異なるため、さらには、表１に挙げた成分以外の成分（例えばＣ（カーボン）やＮ（窒素）など）が存在するためである。その他表についても同様である。 The obtained molded product was sintered in vacuum at 1000 ° C. or higher and 1040 ° C. or lower (select a temperature at which sufficient densification by sintering occurs for each sample) for 4 hours, and then rapidly cooled, and then R1-T1-B-based sintering. I got a body. The density of the obtained sintered body was 7.5 Mg / m 3 or more. The composition of the obtained sintered body is shown in Table 1. Each component in Table 1 was measured using high frequency inductively coupled plasma emission spectroscopy (ICP-OES). As a result of measuring the amount of oxygen in the sintered body by the gas melting-infrared absorption method, it was confirmed that all of them were around 0.4 mass%. “[T1] / [B]” in Table 1 indicates the analytical value (mass%) of each element (including unavoidable impurities, Fe, Al, Si, Mn in this experimental example) constituting T1. Divided by the atomic weight of the element, the sum of those values (a) and the analytical value of B (mass%) divided by the atomic weight of B (mass%) divided by the atomic weight of B (b) Is the ratio (a / b) with. The same applies to all the tables below. The total composition of Table 1 does not reach 100 mass%. This is because, as described above, the analysis method differs depending on each component, and further, there are components other than the components listed in Table 1 (for example, C (carbon), N (nitrogen), etc.). The same applies to other tables.
［Ｒ２−Ｇａ−Ｃｕ系合金の準備］
Ｌａメタル、Ｇａメタル、Ｃｕメタルを用いて（メタルはいずれも純度９９％以上）、合金がおよそ表２に示す符号１−ａの組成になるように配合し、それらの原料を溶解して、単ロール超急冷法（メルトスピニング法）により、リボンまたはフレーク状の合金を得た。得られた合金を乳鉢を用いてアルゴン雰囲気中で粉砕した後、目開き４２５μｍの篩を通過させ、Ｒ２−Ｇａ−Ｃｕ系合金を準備した。得られたＲ２−Ｇａ−Ｃｕ系合金の組成を表２に示す。
[Preparation of R2-Ga-Cu alloy]
Using La metal, Ga metal, and Cu metal (all metals have a purity of 99% or more), the alloys are blended so as to have a composition of reference numeral 1-a shown in Table 2, and the raw materials thereof are dissolved. A ribbon or flake-shaped alloy was obtained by a single-roll ultra-quenching method (melt spinning method). The obtained alloy was pulverized in an argon atmosphere using a mortar and then passed through a sieve having an opening of 425 μm to prepare an R2-Ga—Cu based alloy. The composition of the obtained R2-Ga—Cu based alloy is shown in Table 2.
［熱処理］
表１の符号１−Ａから１−ＣのＲ１−Ｔ１−Ｂ系焼結体を切断、切削加工し、４．４ｍｍ×４．４ｍｍ×４．４ｍｍ（配向方向）の直方体とした。次に、図３に示すように、ニオブ箔により作製した処理容器３中に、主にＲ１−Ｔ１−Ｂ系焼結体１の配向方向（図中の矢印方向）と垂直な面がＲ２−Ｓｉ系合金２と接触するように、表２に示す符号１−ａのＲ２−Ｇａ−Ｃｕ系合金を、符号１−Ａから１−ＩのＲ１−Ｔ１−Ｂ系焼結体のそれぞれの上下に配置した。
[Heat treatment]
The R1-T1-B-based sintered bodies of reference numerals 1-A to 1-C in Table 1 were cut and machined to obtain a rectangular parallelepiped of 4.4 mm × 4.4 mm × 4.4 mm (orientation direction). Next, as shown in FIG. 3, in the processing container 3 made of niobium foil, the plane perpendicular to the orientation direction (arrow direction in the figure) of the R1-T1-B-based sintered body 1 is mainly R2-. The R2-Ga-Cu alloys of reference numerals 1-a shown in Table 2 are placed above and below the R1-T1-B-based sintered bodies of reference numerals 1-A to 1-I so as to come into contact with the Si-based alloy 2. Placed in.
その後、管状流気炉を用いて、２００Ｐａに制御した減圧アルゴン中で、表３に示す熱処理温度及び時間で熱処理を行った後、冷却した。熱処理後の各サンプルの表面近傍に存在するＲ２−Ｇａ−Ｃｕ系合金の濃化部を除去するため、表面研削盤を用いて各サンプルの全面を０．２ｍｍずつ切削加工し、４．０ｍｍ×４．０ｍｍ×４．０ｍｍの立方体状のサンプル（Ｒ−Ｔ−Ｂ系焼結磁石）を得た。 Then, using a tubular air-flow furnace, heat treatment was performed in reduced pressure argon controlled at 200 Pa at the heat treatment temperature and time shown in Table 3, and then cooled. In order to remove the concentrated portion of the R2-Ga-Cu alloy existing near the surface of each sample after heat treatment, the entire surface of each sample is cut by 0.2 mm using a surface grinding machine, and 4.0 mm × A cubic sample (RTB-based sintered magnet) having a size of 4.0 mm × 4.0 mm was obtained.
［サンプル評価］
ＢＨトレーサーにより得られたサンプルの残留磁束密度（Ｂｒ）および保磁力（ＨｃＪ）を測定した。測定結果を表３に示す。表３の通り、Ｒ１−Ｔ１−Ｂ系焼結体におけるＢに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）を１４．０以上とし、熱処理温度を４５０℃以上５００℃以下に設定したとき、高い特性が得られた。
[Sample evaluation]
Residual magnetic flux density of the sample obtained by the BH tracer (B r) and coercivity (H cJ) were measured. The measurement results are shown in Table 3. As shown in Table 3, when the mol ratio of T1 to B ([T1] / [B]) in the R1-T1-B-based sintered body is set to 14.0 or more and the heat treatment temperature is set to 450 ° C or higher and 500 ° C or lower. , High characteristics were obtained.
表３に示すサンプルのうち、Ｎｏ．１−４（本発明例）の焼結体表面近傍、表面から８００μｍ領域、および中心部の断面を走査電子顕微鏡（ＳＥＭ：日本電子製ＪＳＭ−７８００Ｆ）にて、加速電圧５ｋＶで反射電子像を取得した。結果を図４Ａ〜図４Ｃに示す。磁石表面近傍から磁石の中央部まで１００ｎｍ以上の厚い二粒子粒界が形成されていた。 Among the samples shown in Table 3, No. A scanning electron microscope (SEM: JSM-7800F manufactured by JEOL Ltd.) is used to scan the cross section of 1-4 (example of the present invention) near the surface of the sintered body, 800 μm from the surface, and the center of the sintered body. Obtained. The results are shown in FIGS. 4A-4C. A thick two-particle boundary of 100 nm or more was formed from the vicinity of the magnet surface to the central portion of the magnet.
さらに、本発明例であるＮｏ．１−４の焼結体について、表面近傍、表面から８００μｍ領域、および中心部の断面をＳＥＭ（日本電子製ＪＳＭ−７８００Ｆ）付属装置(日本電子製ＪＥＤ−２３００ ＳＤ３０)によるエネルギー分散Ｘ線分光分析（ＥＤＳ）を実施した。分析箇所は、図４Ａ及び図４Ｂは、1、４、６、７及び８、図４Ｃでは、１、４、５、７及び８である。ＥＤＸ分析のプローブ径は１μｍとし、観察領域の平均組成は２００μｍ角の分析結果から得た。結果を図５Ａ〜図５Ｃに示す。図５Ａ〜図５Ｃに示すように、主相へのＬａの置換はほとんど確認できなかった。また、各観察領域において複数の組成の粒界相が観察されたが、それぞれの相の希土類元素Ｒに対するＬａのモル比は、Ｒ−Ｔ−Ｂ系焼結磁石表面のほうが内部よりも高くなっていた。また、各観察領域において領域では、Ｒが２５ｍｏｌ％以上３５ｍｏｌ％以下、Ｆｅが５５ｍｏｌ％以上６５ｍｏｌ％以下の相が確認された。この相はＧａおよびＣｕを含んでいることから、Ｒ６Ｆｅ１３Ｍ（ＭはＧａ，Ｃｕなど）相であると推定され、かつ、同一視野内でＬａ量の異なる２種類以上の組成の相が存在していた。 Furthermore, No. 1 which is an example of the present invention. Energy dispersive X-ray spectroscopic analysis of the sintered body 1-4 in the vicinity of the surface, 800 μm region from the surface, and the cross section of the central part by SEM (JSM-7800F manufactured by JEOL Ltd.) accessory device (JED-2300 SD30 manufactured by JEOL Ltd.). (EDS) was carried out. The analysis points are 1, 4, 6, 7 and 8 in FIGS. 4A and 4B, and 1, 4, 5, 7 and 8 in FIG. 4C. The probe diameter for EDX analysis was 1 μm, and the average composition of the observation area was obtained from the analysis results of 200 μm square. The results are shown in FIGS. 5A-5C. As shown in FIGS. 5A to 5C, the substitution of La with the main phase could hardly be confirmed. In addition, although multiple grain boundary phases were observed in each observation region, the molar ratio of La to the rare earth element R in each phase was higher on the surface of the RTB-based sintered magnet than on the inside. Was there. Further, in each observation region, a phase in which R was 25 mol% or more and 35 mol% or less and Fe was 55 mol% or more and 65 mol% or less was confirmed. Since this phase contains Ga and Cu, it is presumed to be the R 6 Fe 13 M (M is Ga, Cu, etc.) phase, and two or more types of phases having different La amounts within the same field of view. Was present.
実験例２
焼結体がおよそ表４に示す符号２−Ａの組成となるように配合する以外は実験例１と同様の方法でＲ１−Ｔ１−Ｂ系焼結体を複数個作製した。得られた焼結体の成分分析の結果を表４に示す。
Experimental Example 2
A plurality of R1-T1-B-based sintered bodies were prepared in the same manner as in Experimental Example 1 except that the sintered bodies were blended so as to have the composition of reference numeral 2-A shown in Table 4. Table 4 shows the results of component analysis of the obtained sintered body.
合金組成がおよそ表５に示す符号２−ａから２−ｍとなるように配合する以外は実験例１と同様の方法でＲ２−Ｇａ−Ｃｕ系合金を作製した。 An R2-Ga-Cu based alloy was prepared in the same manner as in Experimental Example 1 except that the alloy compositions were blended so as to have a code number of 2-a to 2-m shown in Table 5.
複数個のＲ１−Ｔ１−Ｂ系焼結体を実験例１と同様に加工した後、実験例１と同様に符号２−ａから２−ｍのＲ２−Ｇａ−Ｃｕ系合金と符号２−ＡのＲ１−Ｔ１−Ｂ系焼結体とが接触するよう配置し、実験例１と同様に熱処理および加工を行い、サンプル（Ｒ−Ｔ−Ｂ系焼結磁石）を得た。得られたサンプルを実験例１と同様な方法により測定し、残留磁束密度（Ｂｒ）および保磁力（ＨｃＪ）を求めた。その結果を表６に示す。表６の通り、Ｒ２−Ｇａ−Ｃｕ系合金を特定の範囲に設定することで、高い磁気特性を有するＲ−Ｔ−Ｂ系焼結磁石が得られた。 After processing a plurality of R1-T1-B-based sintered bodies in the same manner as in Experimental Example 1, R2-Ga-Cu-based alloys of reference numerals 2-a to 2-m and reference numerals 2-A as in Experimental Example 1 The sample (RTB-based sintered magnet) was obtained by arranging the above-mentioned R1-T1-B-based sintered body in contact with the above and performing heat treatment and processing in the same manner as in Experimental Example 1. The obtained sample was measured in the same manner as in Experimental Example 1 was determined remanence (B r) and coercivity (H cJ). The results are shown in Table 6. As shown in Table 6, by setting the R2-Ga—Cu alloy in a specific range, an RTB-based sintered magnet having high magnetic properties was obtained.
本発明の実施形態により得られたＲ−Ｔ−Ｂ系焼結磁石は、ハードディスクドライブのボイスコイルモータ（ＶＣＭ）や、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や家電製品などに好適に利用することができる。 The RTB-based sintered magnets obtained by the embodiment of the present invention include voice coil motors (VCMs) for hard disk drives, motors for electric vehicles (EV, HV, PHV, etc.), motors for industrial equipment, and the like. It can be suitably used for various motors and home appliances.
１ Ｒ１−Ｔ１−Ｂ系焼結体
２ Ｒ２−Ｇａ−Ｃｕ系合金
３ 処理容器
1 R1-T1-B-based sintered body 2 R2-Ga-Cu-based alloy 3 Processing container
Claims (5)
Ｒ２−Ｇａ−Ｃｕ系合金を準備する工程と、
前記Ｒ１−Ｔ１−Ｂ系焼結体の表面の少なくとも一部に、前記Ｒ２−Ｇａ−Ｃｕ系合金の少なくとも一部を接触させ、真空又は不活性ガス雰囲気中、４５０℃以上５００℃以下の温度で熱処理を実施する工程を含み、
前記Ｒ１−Ｔ１−Ｂ系焼結体において、
Ｒ１は希土類元素のうち少なくとも一種であり、Ｎｄ及びＰｒの少なくとも一方を必ず含み、Ｒ１の含有量は、Ｒ１−Ｔ１−Ｂ系焼結体全体の２７ｍａｓｓ％以上３５ｍａｓｓ％以下であり、
Ｔ１はＦｅ又はＣｏ、Ａｌ、Ｍｎ、Ｓｉの少なくとも１つとＦｅであり、Ｔ１全体に対するＦｅの含有量が８０ｍａｓｓ％以上であり、
Ｂに対するＴ１のｍｏｌ比（［Ｔ１］／［Ｂ］）が１４．０超１５．０以下であり、
前記Ｒ２−Ｇａ−Ｃｕ系合金において、
Ｒ２は希土類元素のうち少なくとも一種であり、Ｌａを必ず含み、Ｒ２の含有量は、Ｒ２−Ｇａ−Ｃｕ系合金全体の７０ｍｏｌ％以上９０ｍｏｌ％以下であり、かつ、希土類元素全体に対するＬａの比率が、Ｒ１−Ｔ１―Ｂ系焼結体の希土類元素全体に対するＬａの比率よりも高く、
Ｇａの含有量は、Ｒ２−Ｇａ−Ｃｕ系合金全体の５ｍｏｌ％以上２０ｍｏｌ％以下であり、
Ｃｕの含有量は、Ｒ２−Ｇａ−Ｃｕ系合金全体の５ｍｏｌ％以上２０ｍｏｌ％以下である、Ｒ−Ｔ−Ｂ系焼結磁石の製造方法。 The process of preparing the R1-T1-B-based sintered body and
The process of preparing R2-Ga-Cu alloy and
At least a part of the R2-Ga—Cu alloy is brought into contact with at least a part of the surface of the R1-T1-B-based sintered body, and the temperature is 450 ° C. or higher and 500 ° C. or lower in a vacuum or an inert gas atmosphere. Including the process of performing heat treatment in
In the R1-T1-B-based sintered body,
R1 is at least one of rare earth elements and always contains at least one of Nd and Pr, and the content of R1 is 27 mass% or more and 35 mass% or less of the entire R1-T1-B-based sintered body.
T1 is Fe or at least one of Co, Al, Mn, and Si and Fe, and the content of Fe with respect to the whole T1 is 80 mass% or more.
The mol ratio of T1 to B ([T1] / [B]) is more than 14.0 and 15.0 or less.
In the R2-Ga—Cu based alloy,
R2 is at least one of the rare earth elements and always contains La, the content of R2 is 70 mol% or more and 90 mol% or less of the whole R2-Ga-Cu alloy, and the ratio of La to the whole rare earth element is , Higher than the ratio of La to the total rare earth elements of the R1-T1-B based sintered body,
The content of Ga is 5 mol% or more and 20 mol% or less of the entire R2-Ga—Cu based alloy.
A method for producing an RTB-based sintered magnet, wherein the Cu content is 5 mol% or more and 20 mol% or less of the entire R2-Ga—Cu-based alloy.
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