JP6044866B2 - Method for producing RTB-based sintered magnet - Google Patents

Method for producing RTB-based sintered magnet Download PDF

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JP6044866B2
JP6044866B2 JP2012079304A JP2012079304A JP6044866B2 JP 6044866 B2 JP6044866 B2 JP 6044866B2 JP 2012079304 A JP2012079304 A JP 2012079304A JP 2012079304 A JP2012079304 A JP 2012079304A JP 6044866 B2 JP6044866 B2 JP 6044866B2
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智機 深川
智機 深川
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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 producing an RTB-based sintered magnet.

Ｒ−Ｔ−Ｂ系焼結磁石（Ｒは希土類元素のうち少なくとも一種でありＮｄを必ず含む、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）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、ハイブリッド自動車用、電気自動車用や家電製品用の各種モータ等に使用されている。   R-T-B sintered magnets (R is at least one of rare earth elements and always contains Nd, T is at least one of transition metal elements and always contains Fe), and is the highest among permanent magnets. Known as a high performance magnet, it is used in various motors for hybrid vehicles, electric vehicles, and home appliances.

しかし、Ｒ−Ｔ−Ｂ系焼結磁石は、高温で保磁力ＨｃＪ（以下、単に「ＨｃＪ」と記載する）が低下し、不可逆熱減磁が起こる。そのため、特にハイブリッド自動車用や電気自動車用モータに使用される場合、高温下でも高いＨｃＪを維持することが要求されている。 However, the RTB -based sintered magnet has a reduced coercive force H cJ (hereinafter simply referred to as “H cJ ”) at high temperatures, causing irreversible thermal demagnetization. Therefore, especially when used for a hybrid vehicle or an electric vehicle motor, it is required to maintain a high HcJ even at high temperatures.

従来、ＨｃＪ向上のために、Ｄｙ、Ｔｂ等の重希土類元素ＲＨをＲ−Ｔ−Ｂ系焼結磁石に多量に添加していた。しかし、重希土類元素ＲＨを多量に添加すると、ＨｃＪは向上するが、残留磁束密度Ｂｒ（以下、単に「Ｂｒ」と記載する）が低下するという問題があった。また、ＤｙやＴｂは、希少で高価な元素であり、コスト面からも多量に添加することができない。 Conventionally, in order to improve HcJ , a large amount of heavy rare earth elements RH such as Dy and Tb has been added to the RTB-based sintered magnet. However, when a large amount of heavy rare earth element RH is added, HcJ is improved, but there is a problem that residual magnetic flux density B r (hereinafter simply referred to as “B r ”) is lowered. Further, Dy and Tb are rare and expensive elements, and cannot be added in a large amount from the viewpoint of cost.

前記問題を解決するため、組成が異なる２種類の合金粉末を混合した後、成形、焼結して、磁化反転の起点となる主相結晶粒の外殻部に重希土類元素ＲＨを濃縮することにより、単一合金から製造された同一組成のＲ−Ｔ−Ｂ系焼結磁石に比べて、Ｂｒを低下させずにＨｃＪを向上させる技術（以下、「２合金法」と記載する）が提案されている。 In order to solve the above problems, two kinds of alloy powders having different compositions are mixed, then molded and sintered, and the heavy rare earth element RH is concentrated in the outer shell portion of the main phase crystal grain that is the starting point of magnetization reversal. , as compared to the R-T-B based sintered magnet of the same composition manufactured from a single alloy, a technique for improving the H cJ without lowering the B r (hereinafter referred to as "2 alloy method") Has been proposed.

特許文献１は、Ｎｄ２Ｆｅ１４Ｂ金属間化合物を主成分とする第１成分粉末と、Ｒ（Ｃｕ１−ｘＴｘ）およびＲ（Ｃｕ１−ｘＴｘ）２（Ｒは、Ｄｙ＋Ｔｂを３０％以上含有する希土類元素であり、Ｔは遷移金属又は亜金属のうちの１種又は２種以上の混合）のうちの１種又は２種を主成分とする第２成分粉末とを混合した後、混合物を磁場中で成形し、焼結する方法が開示されている。これにより、Ｎｄ２Ｆｅ１４Ｂ金属間化合物の結晶粒の表面部分（外殻部）において、Ｎｄの一部をＤｙおよび／またはＴｂで置換した相が生成され、磁化反転を生じ難くなり、ＨｃＪが向上すると開示されている。 Patent Document 1 describes a first component powder mainly composed of an Nd 2 Fe 14 B intermetallic compound, R (Cu 1−x T x ), and R (Cu 1−x T x ) 2 (R is Dy + Tb). 30% or more of the rare earth element, and T is a mixture of a second component powder composed mainly of one or two of transition metals or sub-metals) Later, a method for forming and sintering the mixture in a magnetic field is disclosed. Thereby, in the surface part (outer shell part) of the crystal grain of the Nd 2 Fe 14 B intermetallic compound, a phase in which a part of Nd is substituted with Dy and / or Tb is generated, and magnetization reversal hardly occurs. It is disclosed that cJ is improved.

特許文献２は、希土類元素の全量は同じで、重希土類元素（Ｄｙ等）／軽希土類元素（Ｎｄ、Ｐｒ等）の比率が異なる以外は組成が実質的に同様な２種類以上の合金を混合し、磁場中成形、焼結する方法が開示されている。特許文献２の方法により、重希土類元素の濃度が結晶粒界相よりも高い第一のＲ２Ｔ１４Ｂ型主相結晶粒と、重希土類元素の濃度が結晶粒界相よりも低い第二のＲ２Ｔ１４Ｂ型主相結晶粒とを有する組織のＲ−Ｔ−Ｂ系焼結型永久磁石が得られ、該永久磁石が高いＢｒおよび高い最大エネルギー積（ＢＨ）ｍａｘを示すことが開示されている。 Patent Document 2 is a mixture of two or more alloys having substantially the same composition except that the total amount of rare earth elements is the same and the ratio of heavy rare earth elements (Dy, etc.) / Light rare earth elements (Nd, Pr, etc.) is different. However, a method of forming and sintering in a magnetic field is disclosed. According to the method of Patent Document 2, the first R 2 T 14 B type main phase crystal grains having a heavy rare earth element concentration higher than the grain boundary phase and the second R 2 T 14 B-type main phase crystal grains having a lower concentration than the grain boundary phase. R-T-B system sintered permanent magnet having a structure having R 2 T 14 B type main phase crystal grains of the same, and the permanent magnet exhibit high Br and high maximum energy product (BH) max Is disclosed.

特許文献３は、重希土類元素ＲＨの濃度が異なる２種類のＲ−Ｔ−Ｂ系合金粉末を焼結するに際し、重希土類元素ＲＨの濃度が高い合金粉末の粒径を小さくすることが開示されている。特許文献３の方法により、焼結後の組織において、粒度の大きいＲ−Ｔ−Ｂ系合金粉末の外周部に粒度の小さいＲ−Ｔ−Ｂ系合金粉末が取り込まれるような結晶粒成長が起こり、主相外殻部に重希土類元素ＲＨを濃縮した組織が実現され、ＨｃＪが向上すると開示されている。 Patent Document 3 discloses that when two types of RTB-based alloy powders having different heavy rare earth element RH concentrations are sintered, the particle size of the alloy powder having a high heavy rare earth element RH concentration is reduced. ing. By the method of Patent Document 3, crystal grain growth occurs in the sintered structure so that the R-T-B alloy powder having a small particle size is taken into the outer peripheral portion of the R-T-B alloy powder having a large particle size. It is disclosed that a structure in which heavy rare earth elements RH are concentrated in the main phase outer shell is realized, and HcJ is improved.

特開平６−９６９２８号公報JP-A-6-96928 特開２０００−１８８２１３号公報JP 2000-188213 A 国際公開第２０１０／０８２４９２号International Publication No. 2010/082492

しかし、特許文献１の方法は、Ｎｄ２Ｆｅ１４Ｂ金属間化合物を主成分とする第１成分粉末と、Ｒ（Ｃｕ１−ｘＴｘ）及びＲ（Ｃｕ１−ｘＴｘ）２のうちの１種又は２種を主成分とする第２成分粉末の主成分となる化合物および組成が異なり、特に、焼結時に液相となる希土類元素の含有量が大きく異なるため、混合物を焼結する際に緻密化し難く、密度不足により磁気特性が低下するという問題があった。 However, the method of Patent Document 1 includes a first component powder mainly composed of Nd 2 Fe 14 B intermetallic compound, R (Cu 1-x T x ), and R (Cu 1-x T x ) 2 . The composition and composition of the second component powder containing one or two of the above as the main components are different, and the content of rare earth elements that are in the liquid phase during sintering is particularly different, so the mixture is sintered. However, there is a problem that it is difficult to densify and the magnetic properties are deteriorated due to insufficient density.

特許文献２の方法は、Ｒに含まれる重希土類元素の濃度が異なる以外は、組成が実質的に同じ２種類のＲ２Ｔ１４Ｂ型主相結晶粒を混合し、焼結している。そのため、特許文献１のように、焼結時に緻密化し難いという問題は起こらない。しかし、得られる永久磁石の組織は、重希土類元素の濃度が結晶粒界相よりも高い第一のＲ２Ｔ１４Ｂ型主相結晶粒と、重希土類元素の濃度が結晶粒界相よりも低い第二のＲ２Ｔ１４Ｂ型主相結晶粒となっており、主相結晶粒の外殻部に重希土類元素を濃縮した組織にはなっていない。従って、Ｂｒを低下させずにＨｃＪを向上させることはできない。すなわち、特許文献２による永久磁石では、特許文献３の図２に示されるような、重希土類元素の濃度が低い部分と重希土類元素の濃度が高い部分とが半々に存在する結晶粒や、重希土類元素の濃度が高い部分のまわりが重希土類元素の濃度が低い部分で覆われた結晶粒が多数存在していると考えられる。 In the method of Patent Document 2, two types of R 2 T 14 B-type main phase crystal grains having substantially the same composition are mixed and sintered except that the concentration of heavy rare earth elements contained in R is different. Therefore, unlike patent document 1, the problem that it is difficult to densify at the time of sintering does not occur. However, the organization of the permanent magnet obtained, and R 2 T 14 B-type main-phase crystal grain concentration first higher than the grain boundary phases of the heavy rare earth elements, the concentration of the heavy rare earth element than the grain boundary phase It is a low second R 2 T 14 B type main phase crystal grain, and does not have a structure in which heavy rare earth elements are concentrated in the outer shell of the main phase crystal grain. Therefore, it is impossible to improve the H cJ without lowering the B r. That is, in the permanent magnet according to Patent Document 2, as shown in FIG. 2 of Patent Document 3, a crystal grain in which a portion having a low heavy rare earth element concentration and a portion having a high heavy rare earth element concentration exist in half, It is considered that there are many crystal grains covered around the portion where the concentration of the rare earth element is high and the portion where the concentration of the heavy rare earth element is low.

特許文献３の方法は、重希土類元素ＲＨの濃度が異なる２種類のＲ−Ｔ−Ｂ系合金粉末のうち、重希土類元素ＲＨの濃度が高い合金粉末の粒径を相対的に小さくすることで表面エネルギーを高くし、焼結時において、重希土類元素ＲＨの濃度が低い合金粉末を固相状態に維持したまま、重希土類元素ＲＨの濃度が高い合金粉末を先に液相化し、液相中における重希土類元素ＲＨの濃度を高くすることができる。その結果、重希土類元素ＲＨの低い結晶粒の外周部に重希土類元素ＲＨの濃度が高い結晶粒が取り込まれるような結晶粒成長が起きる。これにより、主相外殻部に重希土類元素ＲＨを濃縮した組織となる。   The method of Patent Document 3 is to reduce the particle size of an alloy powder having a high concentration of heavy rare earth element RH among two types of RTB alloy powders having different concentrations of heavy rare earth element RH. While the surface energy is increased and the alloy powder having a low concentration of heavy rare earth element RH is maintained in a solid phase during sintering, the alloy powder having a high concentration of heavy rare earth element RH is first liquefied, The concentration of heavy rare earth element RH in can be increased. As a result, crystal grain growth occurs such that crystal grains having a high concentration of heavy rare earth element RH are taken into the outer periphery of the crystal grains having low heavy rare earth element RH. Thereby, it becomes the structure | tissue which concentrated heavy rare earth element RH in the main phase outer shell part.

しかし、特許文献３の方法では、重希土類元素ＲＨの濃度が高い合金粉末を微細化するために、気流式粉砕機による乾式粉砕において、従来の窒素ガスに替えて、高価なＡｒガスやＨｅガスを使用する必要があり、製造コストの増加が避けられないという問題があった。また、微細化された粉末は、酸化しやすく、発火する危険性があり、安全性の面で問題があった。   However, in the method of Patent Document 3, in order to refine alloy powder having a high concentration of heavy rare earth element RH, in dry pulverization using an airflow pulverizer, instead of conventional nitrogen gas, expensive Ar gas or He gas is used. There is a problem that an increase in manufacturing cost is inevitable. Moreover, the refined powder is easy to oxidize, and there is a risk of ignition, and there is a problem in terms of safety.

本発明は、上記問題を解決するためになされたものであり、いわゆる２合金法において、焼結時の密度不足による磁気特性の低下を防止し、製造コストの増加を招くことなく、安全性に優れる製造方法によって、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織を有し、Ｂｒを低下させずにＨｃＪを向上させたＲ−Ｔ−Ｂ系焼結磁石を提供することを目的とする。 The present invention has been made to solve the above-described problems. In the so-called two-alloy method, the magnetic characteristics are prevented from being deteriorated due to insufficient density during sintering, and the production cost is not increased. by the manufacturing method is excellent, having a main phase crystal grains was concentrated heavy rare-earth element RH to the outer shell structure, provides a R-T-B based sintered magnet with improved H cJ without lowering the B r The purpose is to do.

請求項１に記載の本発明によるＲ−Ｔ−Ｂ系焼結磁石の製造方法は、
Ｒ２８質量％以上３３質量％以下（Ｒは軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ０．５質量％以上５質量％以下、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ０．５質量％以上２．５質量％以下、
残部Ｆｅおよび不可避的不純物からなるＲ−Ｔ−Ｂ系焼結磁石の製造方法において、
Ｒ１２８質量％以上３３質量％以下（Ｒ１は軽希土類元素ＲＬまたは軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ４．４質量％以下（０質量％を含む）、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ２質量％以下（０質量％を含む）、
残部Ｆｅおよび不可避的不純物からなる第一合金粉末を準備する工程と、
Ｒ２２８質量％以上３３質量％以下（Ｒ２は軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ１０質量％以上２５質量％以下、
Ｂ０．５質量以上２質量％以下、
Ｃｏ５質量％以上２０質量％以下、
残部Ｆｅおよび不可避的不純物からなる第二合金粉末を準備する工程と、
前記第一合金粉末と前記第二合金粉末を質量比７０：３０〜９７：３で混合し、混合粉末を準備する工程と、
前記混合粉末を成形し、成形体を準備する工程と、
前記成形体を焼結する工程と、を含み、
第一合金粉末に含まれる前記Ｒ１の含有量（質量％）と第二合金粉末に含まれる前記Ｒ２の含有量（質量％）との値の差が１以内であることを特徴とする。 The method for producing an RTB-based sintered magnet according to the present invention as set forth in claim 1 comprises:
R28 mass% or more and 33 mass% or less (R consists of light rare earth elements RL and heavy rare earth elements RH, RL is Nd and / or Pr, RH is Dy),
RH 0.5 mass% or more and 5 mass% or less,
B 0.5 mass% or more and 2 mass% or less,
Co 0.5 mass% or more and 2.5 mass% or less,
In the method for producing an RTB-based sintered magnet composed of the remaining Fe and inevitable impurities,
R 1 28 mass% or more and 33 mass% or less (R 1 is composed of light rare earth element RL or light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 4.4% by mass or less (including 0% by mass),
B 0.5 mass% or more and 2 mass% or less,
Co2 mass% or less (including 0 mass%),
Preparing a first alloy powder composed of the remaining Fe and inevitable impurities;
R 2 28 mass% or more and 33 mass% or less (R 2 is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 10 mass% or more and 25 mass% or less,
B 0.5 mass to 2 mass%,
Co 5 mass% or more and 20 mass% or less,
Preparing a second alloy powder comprising the balance Fe and inevitable impurities;
Mixing the first alloy powder and the second alloy powder in a mass ratio of 70:30 to 97: 3 to prepare a mixed powder;
Forming the mixed powder and preparing a molded body;
Sintering the molded body, and
A difference in value between the content (% by mass) of R 1 contained in the first alloy powder and the content (% by mass) of R 2 contained in the second alloy powder is 1 or less. .

請求項２に記載の本発明によるＲ−Ｔ−Ｂ系焼結磁石の製造方法は、
Ｒ２８質量％以上３３質量％以下（Ｒは軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ０．５質量％以上５質量％以下、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ０．５質量％以上２．５質量％以下、
Ｃｕ０．０５質量％以上０．２質量％以下、
残部Ｆｅおよび不可避的不純物からなるＲ−Ｔ−Ｂ系焼結磁石の製造方法において、
Ｒ１２８質量％以上３３質量％以下（Ｒ１は軽希土類元素ＲＬまたは軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ４．４質量％以下（０質量％を含む）、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ２質量％以下（０質量％を含む）、
Ｃｕ０．２質量％以下（０質量％を含む）、
残部Ｆｅおよび不可避的不純物からなる第一合金粉末を準備する工程と、
Ｒ２２８質量％以上３３質量％以下（Ｒ２は軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ１０質量％以上２５質量％以下、
Ｂ０．５質量以上２質量％以下、
Ｃｏ５質量％以上２０質量％以下、
Ｃｕ０．５質量％以上２質量％以下、
残部Ｆｅおよび不可避的不純物からなる第二合金粉末を準備する工程と、
前記第一合金粉末と前記第二合金粉末を質量比７０：３０〜９７：３で混合し、混合粉末を準備する工程と、
前記混合粉末を成形し、成形体を準備する工程と、
前記成形体を焼結する工程と、を含み、
第一合金粉末に含まれる前記Ｒ１の含有量（質量％）と第二合金粉末に含まれる前記Ｒ２の含有量（質量％）との値の差が１以内であることを特徴とする。 The method for producing an RTB-based sintered magnet according to the present invention as set forth in claim 2 comprises:
R28 mass% or more and 33 mass% or less (R consists of light rare earth elements RL and heavy rare earth elements RH, RL is Nd and / or Pr, RH is Dy),
RH 0.5 mass% or more and 5 mass% or less,
B 0.5 mass% or more and 2 mass% or less,
Co 0.5 mass% or more and 2.5 mass% or less,
Cu 0.05 mass% or more and 0.2 mass% or less,
In the method for producing an RTB-based sintered magnet composed of the remaining Fe and inevitable impurities,
R 1 28 mass% or more and 33 mass% or less (R 1 is composed of light rare earth element RL or light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 4.4% by mass or less (including 0% by mass),
B 0.5 mass% or more and 2 mass% or less,
Co2 mass% or less (including 0 mass%),
Cu 0.2 mass% or less (including 0 mass%),
Preparing a first alloy powder composed of the remaining Fe and inevitable impurities;
R 2 28 mass% or more and 33 mass% or less (R 2 is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 10 mass% or more and 25 mass% or less,
B 0.5 mass to 2 mass%,
Co 5 mass% or more and 20 mass% or less,
Cu 0.5 mass% or more and 2 mass% or less,
Preparing a second alloy powder comprising the balance Fe and inevitable impurities;
Mixing the first alloy powder and the second alloy powder in a mass ratio of 70:30 to 97: 3 to prepare a mixed powder;
Forming the mixed powder and preparing a molded body;
Sintering the molded body, and
A difference in value between the content (% by mass) of R 1 contained in the first alloy powder and the content (% by mass) of R 2 contained in the second alloy powder is 1 or less. .

請求項３に記載の本発明によるＲ−Ｔ−Ｂ系焼結磁石の製造方法は、
Ｒ２８質量％以上３３質量％以下（Ｒは軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ０．５質量％以上５質量％以下、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ０．５質量％以上２．５質量％以下、
Ｃｕ０．０５質量％以上０．２質量％以下、
Ｇａ０．０５質量％以上０．２質量％以下、
残部Ｆｅおよび不可避的不純物からなるＲ−Ｔ−Ｂ系焼結磁石の製造方法において、
Ｒ１２８質量％以上３３質量％以下（Ｒ１は軽希土類元素ＲＬまたは軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ４．４質量％以下（０質量％を含む）、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ２質量％以下（０質量％を含む）、
Ｃｕ０．２質量％以下（０質量％を含む）、
Ｇａ０．２質量％以下（０質量％を含む）、
残部Ｆｅおよび不可避的不純物からなる第一合金粉末を準備する工程と、
Ｒ２２８質量％以上３３質量％以下（Ｒ２は軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ１０質量％以上２５質量％以下、
Ｂ０．５質量以上２質量％以下、
Ｃｏ５質量％以上２０質量％以下、
Ｃｕ０．５質量％以上２質量％以下、
Ｇａ０．５質量％以上２質量％以下、
残部Ｆｅおよび不可避的不純物からなる第二合金粉末を準備する工程と、
前記第一合金粉末と前記第二合金粉末を質量比７０：３０〜９７：３で混合し、混合粉末を準備する工程と、
前記混合粉末を成形し、成形体を準備する工程と、
前記成形体を焼結する工程と、を含み、
第一合金粉末に含まれる前記Ｒ１の含有量（質量％）と第二合金粉末に含まれる前記Ｒ２の含有量（質量％）との値の差が１以内であることを特徴とする。 The manufacturing method of the R-T-B system sintered magnet according to the present invention according to claim 3 is:
R28 mass% or more and 33 mass% or less (R consists of light rare earth elements RL and heavy rare earth elements RH, RL is Nd and / or Pr, RH is Dy),
RH 0.5 mass% or more and 5 mass% or less,
B 0.5 mass% or more and 2 mass% or less,
Co 0.5 mass% or more and 2.5 mass% or less,
Cu 0.05 mass% or more and 0.2 mass% or less,
Ga 0.05% by mass or more and 0.2% by mass or less,
In the method for producing an RTB-based sintered magnet composed of the remaining Fe and inevitable impurities,
R 1 28 mass% or more and 33 mass% or less (R 1 is composed of light rare earth element RL or light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 4.4% by mass or less (including 0% by mass),
B 0.5 mass% or more and 2 mass% or less,
Co2 mass% or less (including 0 mass%),
Cu 0.2 mass% or less (including 0 mass%),
Ga 0.2 mass% or less (including 0 mass%),
Preparing a first alloy powder composed of the remaining Fe and inevitable impurities;
R 2 28 mass% or more and 33 mass% or less (R 2 is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 10 mass% or more and 25 mass% or less,
B 0.5 mass to 2 mass%,
Co 5 mass% or more and 20 mass% or less,
Cu 0.5 mass% or more and 2 mass% or less,
Ga 0.5 mass% or more and 2 mass% or less,
Preparing a second alloy powder comprising the balance Fe and inevitable impurities;
Mixing the first alloy powder and the second alloy powder in a mass ratio of 70:30 to 97: 3 to prepare a mixed powder;
Forming the mixed powder and preparing a molded body;
Sintering the molded body, and
A difference in value between the content (% by mass) of R 1 contained in the first alloy powder and the content (% by mass) of R 2 contained in the second alloy powder is 1 or less. .

請求項４に記載の本発明によるＲ−Ｔ−Ｂ系焼結磁石の製造方法は、
請求項１〜３のいずれかに記載のＲ−Ｔ−Ｂ系焼結磁石の製造方法において、
前記Ｒ−Ｔ−Ｂ系焼結磁石におけるＲＬがＮｄおよびＰｒであるとともに、
Ｐｒの含有量が０．６質量％以上２質量％以下であり、
前記第一合金粉末におけるＲＬがＮｄであり、
前記第二合金粉末におけるＲＬがＮｄおよびＰｒであるとともに、
Ｐｒの含有量が６質量％以上１９質量％以下である、
ことを特徴とする。 The manufacturing method of the RTB system sintered magnet by this invention of Claim 4 is the following.
In the manufacturing method of the RTB system sintered magnet in any one of Claims 1-3,
RL in the RTB-based sintered magnet is Nd and Pr,
The Pr content is 0.6 mass% or more and 2 mass% or less,
RL in the first alloy powder is Nd,
RL in the second alloy powder is Nd and Pr,
The Pr content is 6 mass% or more and 19 mass% or less,
It is characterized by that.

請求項５に記載の本発明によるＲ−Ｔ−Ｂ系焼結磁石は、
請求項４に記載のＲ−Ｔ−Ｂ系焼結磁石の製造方法によって得られることを特徴とする。 The RTB-based sintered magnet according to the present invention according to claim 5 is:
It is obtained by the manufacturing method of the RTB system sintered magnet according to claim 4.

請求項６に記載の本発明によるＲ−Ｔ−Ｂ系焼結磁石は、
請求項５に記載のＲ−Ｔ−Ｂ系焼結磁石において、
Ｒ−Ｔ−Ｂ系焼結磁石のＰｒの含有量をｘ質量％としたとき、
Ｒ−Ｔ−Ｂ系焼結磁石の主相結晶粒の外殻部におけるＰｒの含有量が０．７ｘ質量％以上であり、
Ｒ−Ｔ−Ｂ系焼結磁石の主相結晶粒の中心部におけるＰｒの含有量が０．４ｘ質量％以下であり、
前記主相結晶粒の存在量が体積比率で６０％以上９５％以下であることを特徴とする。 An RTB-based sintered magnet according to the present invention according to claim 6 is:
In the R-T-B system sintered magnet according to claim 5,
When the Pr content of the RTB-based sintered magnet is x mass%,
The Pr content in the outer shell portion of the main phase crystal grains of the RTB-based sintered magnet is 0.7x mass% or more,
The content of Pr in the central part of the main phase crystal grains of the RTB-based sintered magnet is 0.4x mass% or less,
The main phase crystal grains are present in a volume ratio of 60% to 95%.

請求項１に記載の本発明によれば、第一合金粉末よりも第二合金粉末にＲＨおよびＣｏが多く含有されているため、焼結時に第二合金粉末が第一合金粉末よりも先に液相化し、第一合金粉末の外殻部を第二合金粉末で取り囲むように粒成長する。これによって、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織を実現することができ、Ｂｒを低下させずにＨｃＪを向上させたＲ−Ｔ−Ｂ系焼結磁石を提供することができる。従って、第二合金粉末の微細化が不要であり、微細化のために高価なＡｒガスやＨｅガスを使用する必要がなく、製造コストの増加を招くことがない。また、微細化による合金粉末の発火の危険性も解消され、安全にしてＲ−Ｔ−Ｂ系焼結磁石を製造することができる。また、本発明によれば、第一合金粉末に含まれるＲ１の含有量（質量％）と第二合金粉末に含まれるＲ２の含有量（質量％）との値の差が１以内であり、組成が近似しているため、焼結時に緻密化し易く、密度不足による磁気特性の低下を招くことがない。 According to the first aspect of the present invention, since the second alloy powder contains more RH and Co than the first alloy powder, the second alloy powder is prior to the first alloy powder during sintering. A liquid phase is formed, and grain growth is performed so that the outer shell portion of the first alloy powder is surrounded by the second alloy powder. Thus, it is possible to realize the outer shell of the main phase crystal grains was concentrated heavy rare-earth element RH tissue, the R-T-B based sintered magnet with improved H cJ without lowering the B r Can be provided. Therefore, it is not necessary to refine the second alloy powder, and it is not necessary to use expensive Ar gas or He gas for the refinement, and the manufacturing cost is not increased. In addition, the risk of ignition of the alloy powder due to miniaturization is eliminated, and an RTB-based sintered magnet can be manufactured safely. Further, according to the present invention, the content of R 1 contained in the first alloy powder (mass%) and the content of R 2 contained in the second alloy powder (mass%) and the difference value is 1 less the In addition, since the compositions are close to each other, it is easy to be densified at the time of sintering, and magnetic characteristics are not deteriorated due to insufficient density.

請求項２に記載の本発明によれば、第一合金粉末よりも第二合金粉末にＲＨ、ＣｏおよびＣｕが多く含有されているため、前記請求項１に記載の本発明による効果をさらに助長し、ＨｃＪをさらに向上させることができる。 According to the second aspect of the present invention, since the second alloy powder contains more RH, Co, and Cu than the first alloy powder, the effect of the present invention according to the first aspect is further promoted. In addition, HcJ can be further improved.

請求項３に記載の本発明によれば、第一合金粉末よりも第二合金粉末にＲＨ、Ｃｏ、ＣｕおよびＧａが多く含有されているため、前記請求項２に記載の本発明による効果をさらに助長し、ＨｃＪをさらに向上させることができる。 According to the third aspect of the present invention, since the second alloy powder contains more RH, Co, Cu and Ga than the first alloy powder, the effect of the present invention according to the second aspect is achieved. Further promotion is possible, and HcJ can be further improved.

請求項４に記載の本発明によれば、請求項１〜３のいずれかに記載のＲ−Ｔ−Ｂ系焼結磁石の製造方法において、第二合金粉末のみにＰｒが含有されているため、請求項１〜３に記載の本発明による効果をさらに助長し、ＨｃＪをさらに向上させることができる。 According to this invention of Claim 4, in the manufacturing method of the RTB system sintered magnet in any one of Claims 1-3, since Pr is contained only in 2nd alloy powder. The effects of the present invention according to claims 1 to 3 can be further promoted, and HcJ can be further improved.

請求項５に記載の本発明によれば、Ｂｒを低下させずに、ＨｃＪを向上させたＲ−Ｔ−Ｂ系焼結磁石を提供することができる。 According to the present invention described in claim 5, it is possible to provide an RTB -based sintered magnet with improved HcJ without reducing Br.

請求項６に記載の本発明によれば、請求項５に記載のＲ−Ｔ−Ｂ系焼結磁石において、Ｒ−Ｔ−Ｂ系焼結磁石の主相結晶粒の外殻部に特定量のＤｙおよびＰｒを濃縮させるため、ＨｃＪをさらに向上させたＲ−Ｔ−Ｂ系焼結磁石を提供することができる。 According to the present invention described in claim 6, in the RTB-based sintered magnet according to claim 5, a specific amount is added to the outer shell portion of the main phase crystal grains of the RTB-based sintered magnet. In order to concentrate Dy and Pr, it is possible to provide an RTB -based sintered magnet with further improved HcJ .

本発明によるＲ−Ｔ−Ｂ系焼結磁石の断面ＥＰＭＡ分析結果を示す写真であり、（ａ）は反射電子線像、（ｂ）はＤｙの分布を示すマッピング写真である。It is a photograph which shows the cross-sectional EPMA analysis result of the RTB system sintered magnet by this invention, (a) is a reflected electron beam image, (b) is a mapping photograph which shows distribution of Dy. 比較例によるＲ−Ｔ−Ｂ系焼結磁石の断面ＥＰＭＡ分析結果を示す写真であり、（ａ）は反射電子線像、（ｂ）はＤｙの分布を示すマッピング写真である。It is a photograph which shows the cross-sectional EPMA analysis result of the RTB type sintered magnet by a comparative example, (a) is a reflected electron beam image, (b) is a mapping photograph which shows distribution of Dy. 本発明による他のＲ−Ｔ−Ｂ系焼結磁石の断面ＥＰＭＡ分析結果を示す写真であり、（ａ）は反射電子線像、（ｂ）はＤｙの分布を示すマッピング写真であり、（ｃ）はＰｒの分布を示すマッピング写真である。It is the photograph which shows the cross-sectional EPMA analysis result of the other RTB system sintered magnet by this invention, (a) is a reflected electron beam image, (b) is a mapping photograph which shows distribution of Dy, (c ) Is a mapping photograph showing the distribution of Pr. 本発明による他のＲ−Ｔ−Ｂ系焼結磁石のＦＥ−ＳＥＭによる反射電子線像を示す写真である。It is a photograph which shows the reflected electron beam image by the FE-SEM of the other RTB system sintered magnet by this invention.

本発明の主たる特徴は、２合金法において、第一合金粉末よりも第二合金粉末にＲＨ及びＣｏを多く含有させること、第一合金粉末に含まれるＲ１の含有量（質量％）と第二合金粉末に含まれるＲ２の含有量（質量％）との値の差が１以内であること、および、第一合金粉末と第二合金粉末を質量比７０：３０〜９７：３の割合で混合することにある。これらの特徴によって、焼結時に、第二合金粉末が第一合金粉末よりも先に液相化し、第一合金粉末の外殻部を第二合金粉末で取り囲むように粒成長し、主相結晶粒子の外殻部に重希土類元素ＲＨを濃縮した組織を実現することができ、Ｂｒを低下させずにＨｃＪを向上させたＲ−Ｔ−Ｂ系焼結磁石を得ることができる。 The main feature of the present invention is that, in the two-alloy method, the second alloy powder contains more RH and Co than the first alloy powder, the content (% by mass) of R 1 contained in the first alloy powder and the first alloy powder. The difference in value from the content (% by mass) of R 2 contained in the two alloy powder is within 1 and the mass ratio of the first alloy powder to the second alloy powder is 70:30 to 97: 3 There is to mix in. Due to these characteristics, during the sintering, the second alloy powder becomes liquid phase before the first alloy powder, and the outer shell of the first alloy powder is grown to surround the second alloy powder, and the main phase crystals are grown. it can be able to achieve a tissue concentration of the heavy rare-earth element RH on the outer shell portion of the particles, to obtain a R-T-B based sintered magnet with improved H cJ without lowering the B r.

本発明において、主相結晶粒の外殻部とは、主相結晶粒の円周から円周の中心に向かって粒径の０．１〜１５％の厚さの部分のことをいい、主相結晶粒の中心部とは、前記外殻部以外の部分のことをいう。   In the present invention, the outer shell portion of the main phase crystal grain means a portion having a thickness of 0.1 to 15% of the grain size from the circumference of the main phase crystal grain to the center of the circumference. The center part of the phase crystal grain means a part other than the outer shell part.

［Ｒ−Ｔ−Ｂ系焼結磁石］
本発明におけるＲ−Ｔ−Ｂ系焼結磁石は、
Ｒ２８質量％以上３３質量％以下（Ｒは軽希土類元素ＲＬと重希土類元素ＲＨからなり、軽希土類元素ＲＬはＮｄおよび／またはＰｒ、重希土類元素ＲＨはＤｙ）、
重希土類元素ＲＨ０．５質量％以上５質量％以下、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ０．５質量％以上２．５質量％以下、
残部Ｆｅおよび不可避的不純物からなる。 [RTB-based sintered magnet]
The RTB-based sintered magnet in the present invention is
R28 mass% or more and 33 mass% or less (R consists of light rare earth element RL and heavy rare earth element RH, light rare earth element RL is Nd and / or Pr, heavy rare earth element RH is Dy),
Heavy rare earth element RH 0.5 mass% or more and 5 mass% or less,
B 0.5 mass% or more and 2 mass% or less,
Co 0.5 mass% or more and 2.5 mass% or less,
It consists of the balance Fe and inevitable impurities.

Ｒは、軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒからなり、ＲＨはＤｙである。Ｎｄ、Ｐｒ、Ｄｙ以外の他の希土類元素を少量含有してもよい。また、ＲＬ及びＲＨは純元素でなくてもよく、工業上入手可能な範囲で、製造上不可避な不純物を含有するものでも差し支えない。Ｒの含有量は２８質量％以上３３質量％以下とする。２８質量％未満では高いＨｃＪが得られず、３３質量％を超えるとＢｒが低下する。 R is composed of a light rare earth element RL and a heavy rare earth element RH, RL is composed of Nd and / or Pr, and RH is Dy. A small amount of other rare earth elements other than Nd, Pr, and Dy may be contained. Moreover, RL and RH do not need to be pure elements, and may contain impurities that are unavoidable in production within a commercially available range. The R content is 28% by mass or more and 33% by mass or less. High H cJ can not be obtained is less than 28 mass%, more than 33% by mass, the B r drops.

重希土類元素ＲＨの含有量は０．５質量％以上５質量％以下とする。０．５質量％未満ではＨｃＪの向上効果が少なく、５質量％を超えるとＢｒが低下する。 The content of the heavy rare earth element RH is 0.5 mass% or more and 5 mass% or less. Little improvement in H cJ is less than 0.5 wt%, more than 5 wt%, the B r drops.

Ｂ（硼素）の含有量は０．５質量％以上２質量％以下とする。０．５質量％未満ではＨｃＪが低下し、２質量％を超えるとＢｒが低下する。 The content of B (boron) is 0.5 mass% or more and 2 mass% or less. It is less than 0.5 wt% reduces the H cJ, more than 2 wt%, the B r drops.

Ｃｏの含有量は０．５質量％以上２．５質量％以下とする。Ｃｏは温度特性の向上、耐食性の向上に有効であり、０．５質量％未満ではそれらの向上効果が少なく、２．５質量％を超えるとＨｃＪが低下する。 The Co content is 0.5 mass% or more and 2.5 mass% or less. Co is effective for improving temperature characteristics and corrosion resistance. If the amount is less than 0.5% by mass, the improvement effect thereof is small, and if it exceeds 2.5% by mass, HcJ decreases.

Ｆｅは前記元素の残部を占める。Ｆｅ、Ｃｏ以外の他の遷移金属元素を少量含有してもよい。   Fe occupies the remainder of the element. A small amount of transition metal elements other than Fe and Co may be contained.

前記各元素に加え、０．０５質量％以上０．２質量％以下のＣｕ、あるいはさらに０．０５質量％以上０．２質量％以下のＧａを含有させてもよい。Ｃｕを含有させることにより、Ｃｕを含有しない場合に比べＨｃＪが向上する。また、ＣｕとＧａの両方を含有させることにより、Ｃｕのみを含有させる場合に比べＨｃＪがさらに向上する。 In addition to the elements described above, 0.05 mass% or more and 0.2 mass% or less of Cu, or 0.05 mass% or more and 0.2 mass% or less of Ga may be contained. By containing Cu, HcJ improves compared with the case where Cu is not contained. Moreover, by containing both Cu and Ga, HcJ is further improved as compared with the case of containing only Cu.

本発明におけるＲ−Ｔ−Ｂ系焼結磁石は、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織を有している。そのため、単一合金から製造した同一組成のＲ−Ｔ−Ｂ系焼結磁石に比べ、Ｂｒを低下させずにＨｃＪを向上させることができる。 The RTB-based sintered magnet in the present invention has a structure in which heavy rare earth elements RH are concentrated in the outer shell portion of the main phase crystal grains. Therefore, compared to the R-T-B based sintered magnet of the same composition prepared from a single alloy, it is possible to improve the H cJ without lowering the B r.

前記Ｒ−Ｔ−Ｂ系焼結磁石は、特定組成からなる第一合金粉末を準備する工程、特定組成からなる第二合金粉末を準備する工程、第一合金粉末と第二合金粉末を特定割合で混合し混合粉末を得る工程、混合粉末を成形し成形体を得る工程、成形体を焼結する工程を経て製造される。以下、その製造方法について詳細に説明する。   The RTB-based sintered magnet includes a step of preparing a first alloy powder having a specific composition, a step of preparing a second alloy powder having a specific composition, and a specific ratio of the first alloy powder and the second alloy powder. The mixture is manufactured through a step of mixing to obtain a mixed powder, a step of forming a mixed powder to obtain a molded body, and a step of sintering the molded body. Hereinafter, the manufacturing method will be described in detail.

［第一合金粉末を準備する工程］
本発明における第一合金粉末は、
Ｒ１２８質量％以上３３質量％以下（Ｒ１は軽希土類元素ＲＬまたは軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ４．４質量％以下（０質量％を含む）、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ２質量％以下（０質量％を含む）、
残部Ｆｅおよび不可避的不純物からなる。 [Step of preparing first alloy powder]
The first alloy powder in the present invention is
R 1 28 mass% or more and 33 mass% or less (R 1 is composed of light rare earth element RL or light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 4.4% by mass or less (including 0% by mass),
B 0.5 mass% or more and 2 mass% or less,
Co2 mass% or less (including 0 mass%),
It consists of the balance Fe and inevitable impurities.

第一合金粉末は、後述する第二合金粉末よりもＲＨおよびＣｏの含有量が少なく、焼結時に、第二合金粉末よりも液相化し難い組成となっており、先に液相化した第二合金粉末が第一合金粉末の外殻部を取り囲むように粒成長するため、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織となる。   The first alloy powder has less RH and Co content than the second alloy powder described later, and has a composition that is less liable to be liquid phase than the second alloy powder during sintering. Since the two alloy powders grow so as to surround the outer shell part of the first alloy powder, a structure in which the heavy rare earth element RH is concentrated in the outer shell part of the main phase crystal grains is obtained.

Ｒ１は、軽希土類元素ＲＬまたは軽希土類元素ＲＬと重希土類元素ＲＨからなる。すなわち、Ｒ１はＲＨが含まれない場合はＲＬのみからなり、ＲＨが含まれる場合はＲＬとＲＨとからなる。ＲＬはＮｄおよび／またはＰｒであり、ＲＨはＤｙである。Ｎｄ、Ｐｒ、Ｄｙ以外の他の希土類元素を少量含有してもよい。また、ＲＬおよびＲＨは純元素でなくてもよく、工業上入手可能な範囲で、製造上不可避な不純物を含有するものでも差し支えない。Ｒ１の含有量は２８質量％以上３３質量％以下とする。２８質量％未満では得られるＲ−Ｔ−Ｂ系焼結磁石において高いＨｃＪが得られず、３３質量％を超えるとＢｒが低下する。 R 1 is composed of light rare earth element RL or light rare earth element RL and heavy rare earth element RH. That is, R 1 includes only RL when RH is not included, and includes RL and RH when RH is included. RL is Nd and / or Pr, and RH is Dy. A small amount of other rare earth elements other than Nd, Pr, and Dy may be contained. In addition, RL and RH may not be pure elements, and may contain impurities that are inevitable in the manufacturing process as long as they are industrially available. The content of R 1 is 28% by mass or more and 33% by mass or less. Not obtain a high H cJ in the R-T-B based sintered magnet obtained is less than 28 wt%, B r decreases when exceeding 33 wt%.

ＲＨの含有量は４．４質量％以下（０質量％を含む）とする。４．４質量％を超えると主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織にすることが困難になる。   The RH content is 4.4% by mass or less (including 0% by mass). If it exceeds 4.4 mass%, it becomes difficult to obtain a structure in which heavy rare earth elements RH are concentrated in the outer shell of the main phase crystal grains.

Ｂ（硼素）の含有量は０．５質量％以上２質量％以下とする。０．５質量％未満では得られるＲ−Ｔ−Ｂ系焼結磁石のＨｃＪが低下し、２質量％を超えるとＢｒが低下する。 The content of B (boron) is 0.5 mass% or more and 2 mass% or less. Obtained is less than 0.5 wt% R-T-B based sintered magnet of H cJ is reduced, more than 2 wt%, the B r drops.

Ｃｏの含有量は２質量％以下（０質量％を含む）とする。２質量％を超えると主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織にすることが困難になる。   The Co content is 2% by mass or less (including 0% by mass). If it exceeds 2 mass%, it becomes difficult to obtain a structure in which heavy rare earth elements RH are concentrated in the outer shell of the main phase crystal grains.

Ｆｅは前記元素の残部を占める。Ｆｅ、Ｃｏ以外の他の遷移金属元素を少量含有してもよい。   Fe occupies the remainder of the element. A small amount of transition metal elements other than Fe and Co may be contained.

前記各元素に加え、０．２質量％以下のＣｕ、あるいはさらに０．２質量％以下のＧａを含有させてもよい。Ｃｕを含有させる場合は、第二合金粉末に第一合金粉末よりも多くＣｕを含有させる。これにより、Ｃｕを含有しない場合に比べ、得られるＲ−Ｔ−Ｂ系焼結磁石のＨｃＪが向上する。ＣｕとＧａの両方を含有させる場合は、第二合金粉末に第一合金粉末よりも多くＣｕとＧａを含有させる。これにより、Ｃｕのみを含有する場合に比べ、得られるＲ−Ｔ−Ｂ系焼結磁石のＨｃＪがさらに向上する。 In addition to the above elements, 0.2% by mass or less of Cu, or 0.2% by mass or less of Ga may be contained. When Cu is contained, the second alloy powder contains more Cu than the first alloy powder. Thereby, compared with the case where Cu is not contained, HcJ of the RTB system sintered magnet obtained improves. When both Cu and Ga are contained, the second alloy powder contains more Cu and Ga than the first alloy powder. Thereby, HcJ of the RTB system sintered magnet obtained further improves compared with the case where it contains only Cu.

前記組成からなる第一合金粉末は、公知のＲ−Ｔ−Ｂ系焼結磁石の製造方法と同様の方法によって準備することができる。例えば、金型鋳造によるインゴット法や冷却ロールを用いて合金溶湯を急冷するストリップキャスト法等により合金を作製する。後述する混合粉末を準備する工程において、第一合金粉末と第二合金粉末を粗粉砕粉末の状態で混合した後、微粉砕を行って混合粉末を準備する場合は、第一合金粉末の合金と第二合金粉末の合金とをそれぞれ水素粉砕法等によって粗粉砕し、平均粒度が数百μｍ程度の粗粉砕粉末を準備する。また、第一合金粉末と第二合金粉末を微粉砕粉末の状態で混合する場合は、前記粗粉砕粉末をジェットミル等によって微粉砕し、平均粒径（フィッシャー法）が３〜５μｍ程度の微粉砕粉末を準備する。微粉砕は、酸化を防止するために、実質的に酸素を含有しない雰囲気中で行うことが好ましい。微粉砕中の酸化を防止することにより、得られるＲ−Ｔ−Ｂ系焼結磁石の磁気特性を向上させることができる。また、微粉砕後の微粉砕粉末の酸化を防止するために、微粉砕粉末を鉱油、合成油、植物油またはそれらの混合油中に浸漬することも好ましい。浸漬は、例えば、ジェットミルの微粉砕粉末の取出口に前記油が入った容器を設置し、直接油中へ回収する等の方法により行うことができる。   The 1st alloy powder which consists of the said composition can be prepared by the method similar to the manufacturing method of a well-known RTB type sintered magnet. For example, an alloy is produced by an ingot method by die casting or a strip cast method in which a molten alloy is rapidly cooled using a cooling roll. In the step of preparing a mixed powder to be described later, after mixing the first alloy powder and the second alloy powder in the state of coarsely pulverized powder, when preparing the mixed powder by finely pulverizing, the alloy of the first alloy powder and Each of the alloys of the second alloy powder is roughly pulverized by a hydrogen pulverization method or the like to prepare a coarsely pulverized powder having an average particle size of about several hundred μm. When the first alloy powder and the second alloy powder are mixed in the form of finely pulverized powder, the coarsely pulverized powder is finely pulverized by a jet mill or the like, and the average particle size (Fisher method) is about 3 to 5 μm. Prepare ground powder. The pulverization is preferably performed in an atmosphere substantially free of oxygen in order to prevent oxidation. By preventing oxidation during pulverization, the magnetic properties of the RTB-based sintered magnet obtained can be improved. In order to prevent oxidation of the finely pulverized powder after pulverization, it is also preferable to immerse the finely pulverized powder in mineral oil, synthetic oil, vegetable oil or a mixed oil thereof. Immersion can be performed by, for example, a method in which a container containing the oil is installed at the outlet of a finely pulverized powder of a jet mill and directly collected into the oil.

［第二合金粉末を準備する工程］
本発明における第二合金粉末は、
Ｒ２２８質量％以上３３質量％以下（Ｒ２は軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ１０質量％以上２５質量％以下、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ５質量％以上２０質量％以下、
残部Ｆｅおよび不可避的不純物からなる。 [Step of preparing second alloy powder]
The second alloy powder in the present invention is
R 2 28 mass% or more and 33 mass% or less (R 2 is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 10 mass% or more and 25 mass% or less,
B 0.5 mass% or more and 2 mass% or less,
Co 5 mass% or more and 20 mass% or less,
It consists of the balance Fe and inevitable impurities.

第二合金粉末は、前記第一合金粉末よりもＲＨ及びＣｏの含有量が多く、焼結時に、第一合金粉末よりも液相化し易い組成となっており、第二合金粉末が第一合金粉末よりも先に液相化し、第一合金粉末の外殻部を取り囲むように粒成長するため、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織となる。   The second alloy powder has a higher content of RH and Co than the first alloy powder, and has a composition that is more liable to become a liquid phase than the first alloy powder during sintering. Since the liquid phase is formed before the powder and the grains grow so as to surround the outer shell portion of the first alloy powder, a structure in which the heavy rare earth element RH is concentrated in the outer shell portion of the main phase crystal grain is obtained.

Ｒ２は、軽希土類元素ＲＬと重希土類元素ＲＨからなる。ＲＬはＮｄおよび／またはＰｒであり、ＲＨはＤｙである。Ｎｄ、Ｐｒ、Ｄｙ以外の他の希土類元素を少量含有してもよい。また、ＲＬおよびＲＨは純元素でなくてもよく、工業上入手可能な範囲で、製造上不可避な不純物を含有するものでも差し支えない。Ｒ２の含有量は２８質量％以上３３質量％以下とする。２８質量％未満では得られるＲ−Ｔ−Ｂ系焼結磁石において高いＨｃＪが得られず、３３質量％を超えるとＢｒが低下する。 R 2 is composed of a light rare earth element RL and a heavy rare earth element RH. RL is Nd and / or Pr, and RH is Dy. A small amount of other rare earth elements other than Nd, Pr, and Dy may be contained. In addition, RL and RH may not be pure elements, and may contain impurities that are inevitable in the manufacturing process as long as they are industrially available. The content of R 2 is a 33% by mass or less 28 mass% or more. Not obtain a high H cJ in the R-T-B based sintered magnet obtained is less than 28 wt%, B r decreases when exceeding 33 wt%.

ＲＨの含有量は１０質量％以上２５質量％以下とする。１０質量％未満では主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織にすることが困難になり、２５質量％を超えると、得られるＲ−Ｔ−Ｂ系焼結磁石のＨｃＪが低下する。好ましくは１５質量％以上２４質量％以下、さらに好ましくは２０質量％以上２３質量％以下である。 The content of RH is 10% by mass or more and 25% by mass or less. If it is less than 10% by mass, it becomes difficult to obtain a structure in which heavy rare earth elements RH are concentrated in the outer shell portion of the main phase crystal grains, and if it exceeds 25% by mass, H of the obtained RTB-based sintered magnet cJ decreases. Preferably they are 15 to 24 mass%, More preferably, they are 20 to 23 mass%.

Ｂ（硼素）の含有量は０．５質量％以上２質量％以下とする。０．５質量％未満では得られるＲ−Ｔ−Ｂ系焼結磁石のＨｃＪが低下し、２質量％を超えるとＢｒが低下する。 The content of B (boron) is 0.5 mass% or more and 2 mass% or less. Obtained is less than 0.5 wt% R-T-B based sintered magnet of H cJ is reduced, more than 2 wt%, the B r drops.

Ｃｏの含有量は５質量％以上２０質量％以下とする。５質量％未満では主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織にすることが困難になり、２０質量％を超えると得られるＲ−Ｔ−Ｂ系焼結磁石のＢｒが低下する。 The Co content is 5 mass% or more and 20 mass% or less. In less than 5 wt% it is difficult to the tissue concentrating the heavy rare-earth element RH on the outer shell of the main phase crystal grains, resulting in excess of 20 wt% R-T-B based sintered magnet of B r Decreases.

Ｆｅは前記元素の残部を占める。Ｆｅ、Ｃｏ以外の他の遷移金属元素を少量含有してもよい。   Fe occupies the remainder of the element. A small amount of transition metal elements other than Fe and Co may be contained.

前記各元素に加え、０．５質量％以上２質量％以下のＣｕ、あるいはさらに０．５質量％以上２質量％以下のＧａを含有させてもよい。第一合金粉末よりも第二合金粉末にＲＨおよびＣｏを多く含有させ、かつＣｕを多く含有させることにより、Ｃｕを含有しない場合に比べ焼結中の液相生成を促進できるため、得られるＲ−Ｔ−Ｂ系焼結磁石のＨｃＪが向上する。さらに、ＣｕとＧａの両方を含有させることにより、Ｃｕのみを含有する場合に比べ、得られるＲ−Ｔ−Ｂ系焼結磁石のＨｃＪがさらに向上する。 In addition to the above elements, 0.5% by mass or more and 2% by mass or less of Cu, or 0.5% by mass or more and 2% by mass or less of Ga may be contained. Since the RH and Co are contained in the second alloy powder more than the first alloy powder, and the Cu content is increased, the liquid phase generation during the sintering can be promoted compared to the case where no Cu is contained. -HcJ of the TB sintered magnet is improved. Furthermore, by including both Cu and Ga, H cJ of the obtained RTB -based sintered magnet is further improved as compared with the case of containing only Cu.

前記組成からなる第二合金粉末は、前記第一合金粉末と同様の方法によって準備することができる。本発明においては、第一合金粉末よりも第二合金粉末にＲＨおよびＣｏを多く含有させることによって、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織を実現することができるため、前記特許文献３のように、第二合金粉末の微細化が不要であり、微細化のために高価なＡｒガスやＨｅガスを使用する必要がなく、製造コストの増加を招くことがない。また、微細化による合金粉末の発火の危険性も解消され、安全にしてＲ−Ｔ−Ｂ系焼結磁石を製造することができる。   The second alloy powder having the above composition can be prepared by the same method as the first alloy powder. In the present invention, by containing more RH and Co in the second alloy powder than in the first alloy powder, a structure in which the heavy rare earth element RH is concentrated in the outer shell portion of the main phase crystal grain can be realized. As in Patent Document 3, it is not necessary to refine the second alloy powder, and it is not necessary to use expensive Ar gas or He gas for the refinement, thereby preventing an increase in manufacturing cost. In addition, the risk of ignition of the alloy powder due to miniaturization is eliminated, and an RTB-based sintered magnet can be manufactured safely.

第一合金粉末に含まれるＲ１の含有量（質量％）と第二合金粉末に含まれるＲ２の含有量（質量％）との値の差が１以内とする。Ｒ１含有量とＲ２含有量の差が大きくなるにつれ、混合粉末を焼結する際に緻密化し難くなって、密度不足により得られるＲ−Ｔ−Ｂ系焼結磁石の磁気特性が低下するためである。Ｒ１含有量とＲ２含有量の差が１を超えると急に緻密化し難くなるということはないが、Ｒ１含有量とＲ２含有量の差をできるだけ小さくすることにより、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織を実現し易くなる。 The difference in value between the content (mass%) of R 1 contained in the first alloy powder and the content (mass%) of R 2 contained in the second alloy powder is set to 1 or less. As the difference between the R 1 content and the R 2 content increases, it becomes difficult to densify when the mixed powder is sintered, and the magnetic properties of the RTB-based sintered magnet obtained due to insufficient density are reduced. Because. If the difference between the R 1 content and the R 2 content exceeds 1, it does not become difficult to be densified suddenly, but by reducing the difference between the R 1 content and the R 2 content as much as possible, the main phase crystal grains It becomes easy to realize a structure in which the heavy rare earth element RH is concentrated in the outer shell portion.

なお、前記１以内とは、第一合金粉末および第二合金粉末を準備する工程における、第一合金粉末中のＲ１の質量比（質量％）と第二合金粉末中のＲ２の質量比（質量％）との差であり、原料配合時の狙い組成にもとづくものである。Ｒ１およびＲ２の含有量は、溶解工程や粉砕工程において、酸化や分級などによって若干変化し、その変化量もＲＨの含有量や平均粒径等の違いによって異なるため、粉末の状態において含有量の差を規定することが難しいからである。 In addition, within 1 is the mass ratio (mass%) of R 1 in the first alloy powder and the mass ratio of R 2 in the second alloy powder in the step of preparing the first alloy powder and the second alloy powder. It is a difference from (mass%) and is based on a target composition at the time of blending raw materials. The contents of R 1 and R 2 are slightly changed by oxidation, classification, etc. in the dissolution process and pulverization process, and the amount of change varies depending on the difference in RH content, average particle size, etc. This is because it is difficult to define the difference in quantity.

前記のＲ−Ｔ−Ｂ系焼結磁石、第一合金粉末を準備する工程および第二合金粉末を準備する工程において、Ｒ−Ｔ−Ｂ系焼結磁石におけるＲＬがＮｄおよびＰｒであるとともに、Ｐｒの含有量が０．６質量％以上２質量％以下であり、第一合金粉末におけるＲＬがＮｄであり、第二合金粉末におけるＲＬがＮｄおよびＰｒであるとともに、Ｐｒの含有量が６質量％以上１９質量％以下とすることにより、ＨｃＪをさらに向上させることができる。この場合、第一合金粉末には基本的にＰｒは含有されない。但し、不可避的不純物として混入する場合は許容される。 In the step of preparing the RTB-based sintered magnet, the first alloy powder and the step of preparing the second alloy powder, RL in the RTB-based sintered magnet is Nd and Pr. The Pr content is 0.6 mass% or more and 2 mass% or less, the RL in the first alloy powder is Nd, the RL in the second alloy powder is Nd and Pr, and the Pr content is 6 mass%. By setting the content to not less than 19% and not more than 19% by mass, HcJ can be further improved. In this case, the first alloy powder basically does not contain Pr. However, it is allowed when it is mixed as an inevitable impurity.

［混合粉末を準備する工程］
第一合金粉末と第二合金粉末の質量比は７０：３０〜９７：３とする。第一合金粉末の質量比が７０未満または９７を超えると、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織にすることが困難になり、得られるＲ−Ｔ−Ｂ系焼結磁石のＨｃＪが低下するためである。第一合金粉末と第二合金粉末は、両粉末が粗粉砕粉末の状態で混合してもよいし、微粉砕粉末の状態で混合してもよい。粗粉砕粉末の状態で混合する場合は、両粉末を上記質量比で混合後、ジェットミル等により微粉砕して混合粉末を準備する。混合には公知の混合機等を使用することができる。また、混合は、不活性ガス雰囲気中等で行ってもよいし、粗粉砕粉または微粉砕粉末を鉱油、合成油、植物油またはそれらの混合油中に浸漬し、油中で混合してもよい。 [Process of preparing mixed powder]
The mass ratio of the first alloy powder and the second alloy powder is 70:30 to 97: 3. When the mass ratio of the first alloy powder is less than 70 or exceeds 97, it becomes difficult to obtain a structure in which the heavy rare earth element RH is concentrated in the outer shell portion of the main phase crystal grains, and the resulting RTB-based sintering is obtained. This is because the HcJ of the magnetized magnet decreases. The first alloy powder and the second alloy powder may be mixed in the state of coarsely pulverized powder or in the state of finely pulverized powder. When mixing in the state of coarsely pulverized powder, both powders are mixed at the above mass ratio and then finely pulverized by a jet mill or the like to prepare a mixed powder. A known mixer or the like can be used for mixing. The mixing may be performed in an inert gas atmosphere or the like, or coarsely pulverized powder or finely pulverized powder may be immersed in mineral oil, synthetic oil, vegetable oil, or a mixed oil thereof, and mixed in the oil.

［成形体を準備する工程］
前記混合粉末を成形し、成形体を準備する工程は、公知のＲ−Ｔ−Ｂ系焼結磁石の製造方法と同様の方法を用いることができる。例えば、磁界中で金型を用いて加圧成形する方法等である。本工程において、酸素や炭素などの不純物の混入を最小限に抑えるため、潤滑剤や離型剤等の使用は最小限にとどめることが好ましい。また、酸化を抑制ために、混合粉末を油中に浸漬してスラリー状にして、そのスラリーを磁界中で湿式成形することも好ましい。これらの好ましい方法を用いることによって、得られるＲ−Ｔ−Ｂ系焼結磁石の磁気特性を向上させることができる。 [Process for preparing molded body]
For the step of forming the mixed powder and preparing the formed body, a method similar to the method for producing a known RTB-based sintered magnet can be used. For example, there is a method of pressure molding using a mold in a magnetic field. In this step, it is preferable to minimize the use of lubricants, mold release agents, and the like in order to minimize the mixing of impurities such as oxygen and carbon. In order to suppress oxidation, it is also preferable to immerse the mixed powder in oil to form a slurry and wet-mold the slurry in a magnetic field. By using these preferable methods, the magnetic characteristics of the obtained RTB-based sintered magnet can be improved.

［成形体を焼結する工程］
前記成形体を焼結する工程は、公知のＲ−Ｔ−Ｂ系焼結磁石の製造方法と同様の方法を用いることができる。本発明においては、第一合金粉末と第二合金粉末の組成が近似しており、特に、Ｒ１含有量とＲ２含有量との差が１質量％以内であるため、焼結時に緻密化し易く、密度不足による磁気特性の低下を招くことがない。 [Step of sintering the compact]
For the step of sintering the molded body, a method similar to a known method for producing a RTB-based sintered magnet can be used. In the present invention, the compositions of the first alloy powder and the second alloy powder are close to each other. In particular, since the difference between the R 1 content and the R 2 content is within 1% by mass, it is densified during sintering. It is easy and does not cause deterioration of magnetic properties due to insufficient density.

上記の製造方法によって得られた本発明によるＲ−Ｔ−Ｂ系焼結磁石に対して、例えば、国際公開第２００７／１０２３９１号に代表されるような、Ｒ−Ｔ−Ｂ系焼結磁石に重希土類元素ＲＨを含む金属、合金、化合物等を特定手段により磁石表面に供給した後、熱処理で重希土類元素ＲＨを磁石内部に拡散させる方法を適用することもできる。これにより、さらに、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮させることができ、Ｂｒの低下を抑制しつつＨｃＪを向上させることができる。 For the RTB-based sintered magnet according to the present invention obtained by the above manufacturing method, for example, an RTB-based sintered magnet represented by International Publication No. 2007/102391 is used. A method of diffusing heavy rare earth element RH into the magnet by heat treatment after supplying a metal, alloy, compound or the like containing heavy rare earth element RH to the magnet surface by a specific means can also be applied. This further makes it possible to concentrate the heavy rare-earth element RH on the outer shell of the main phase crystal grains, the decrease in B r can be improved H cJ while suppressing.

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 with reference to examples, but the present invention is not limited thereto.

実施例１
表１に示す第一合金粉末と第二合金粉末の組成になるように各原料を配合し、それぞれを溶解し、ストリップキャスト法によって厚さ０．２ｍｍ〜０．４ｍｍの板状合金を得た。前記板状合金を水素加圧雰囲気で水素脆化させた後、６００℃まで真空中で加熱後、冷却し粗粉砕粉末を得た。得られた第一合金粉末の粗粉砕粉末と第二合金粉末の粗粉砕粉末を９０：１０の質量比でＶ型混合機に投入して混合し、混合粉末を得た。前記混合粉末をジェットミルにより窒素気流中で微粉砕し、平均粒径３．０μｍの微粉砕粉末を得た。 Example 1
Each raw material was blended so as to have the composition of the first alloy powder and the second alloy powder shown in Table 1, each was melted, and a plate-shaped alloy having a thickness of 0.2 mm to 0.4 mm was obtained by strip casting. . The plate-like alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere, heated to 600 ° C. in a vacuum, and then cooled to obtain a coarsely pulverized powder. The coarsely pulverized powder of the obtained first alloy powder and the coarsely pulverized powder of the second alloy powder were put into a V-type mixer at a mass ratio of 90:10 and mixed to obtain a mixed powder. The mixed powder was finely pulverized in a nitrogen stream by a jet mill to obtain a finely pulverized powder having an average particle size of 3.0 μm.

前記微粉砕粉末に、潤滑剤としてステアリン酸亜鉛を０．０５質量％添加混合した後、磁界中で成形し、成形体を得た。前記成形体を真空中において１０５０℃で２時間焼結し、室温まで冷却してＲ−Ｔ−Ｂ系焼結磁石を得た。得られたＲ−Ｔ−Ｂ系焼結磁石の組成分析および酸素分析の結果を表１に示す。また得られたＲ−Ｔ−Ｂ系焼結磁石の磁気特性の測定結果を表１に示す。   After adding 0.05% by mass of zinc stearate as a lubricant to the finely pulverized powder, the powder was molded in a magnetic field to obtain a molded body. The molded body was sintered in vacuum at 1050 ° C. for 2 hours and cooled to room temperature to obtain an RTB-based sintered magnet. Table 1 shows the results of composition analysis and oxygen analysis of the obtained RTB-based sintered magnet. Table 1 shows the measurement results of the magnetic properties of the obtained RTB-based sintered magnet.

表１に示すように、試料Ｎｏ．１および４の第一合金粉末よりも第二合金粉末にＤｙ及びＣｏを多く含有する本発明による焼結磁石は、試料Ｎｏ．２および３の第一合金粉末よりも第二合金粉末にＤｙのみ多く含有し、第一合金粉末と第二合金粉末のＣｏ量が同じ比較例の焼結磁石に比べて、ＨｃＪが大きく向上している。なお、以下の説明においては、「第一合金粉末よりも第二合金粉末に」の「第一合金粉末よりも」を省略し、「第二合金粉末に」と記載する。 As shown in Table 1, sample no. The sintered magnet according to the present invention, in which the second alloy powder contains more Dy and Co than the first alloy powders 1 and 4, has a sample no. Compared to the sintered magnet of the comparative example in which the second alloy powder contains only Dy more than the first alloy powders 2 and 3 and the Co amount of the first alloy powder and the second alloy powder is the same, the HcJ is greatly improved. doing. In the following description, “more than the first alloy powder” in “to the second alloy powder than the first alloy powder” is omitted, and “to the second alloy powder” is described.

また、試料Ｎｏ．１および４よりも、試料Ｎｏ．５の第二合金粉末にＤｙ、ＣｏおよびＣｕを多く含有する本発明による焼結磁石の方が、ＨｃＪが向上しており、さらに、試料Ｎｏ．６の第二合金粉末にＤｙ、Ｃｏ、ＣｕおよびＧａを多く含有する焼結磁石の方が、さらにＨｃＪが向上している。一方、試料Ｎｏ．７の第二合金粉末にＤｙおよびＣｕを多く含有し、第一合金粉末と第二合金粉末のＣｏ量が同じ比較例の焼結磁石のＨｃＪは、試料Ｎｏ．２の焼結磁石と同じ程度である。すなわち、ＨｃＪを向上させるためには、第二合金粉末にＤｙとＣｏを多く含有することが必要であり、ＤｙとＣｏに加えてＣｕ、あるいはさらにＧａを多くが含有することにより、さらにＨｃＪを向上させることができる。 Sample No. Sample No. 1 and 4 The sintered magnet according to the present invention containing a large amount of Dy, Co and Cu in the second alloy powder of No. 5 has an improved HcJ . The sintered magnet containing a large amount of Dy, Co, Cu and Ga in the second alloy powder of No. 6 is further improved in HcJ . On the other hand, sample No. The second alloy powder of No. 7 contains a large amount of Dy and Cu, and the HcJ of the sintered magnet of the comparative example in which the first alloy powder and the second alloy powder have the same amount of Co has the sample No. The same degree as the sintered magnet of No. 2. That is, in order to improve HcJ , it is necessary that the second alloy powder contains a large amount of Dy and Co, and in addition to Dy and Co, a large amount of Cu, or even Ga, further increases the HcJ. cJ can be improved.

表１の試料Ｎｏ．６の本発明による焼結磁石の断面ＥＰＭＡ分析結果を示す写真を図１に示す。また、表１の試料Ｎｏ．３の比較例の焼結磁石の断面ＥＰＭＡ分析結果を示す写真を図２に示す。図１、図２いずれも（ａ）が反射電子線像の写真、（ｂ）がＤｙの分布を示すマッピング写真であり、倍率は２０００倍である。図１（ａ）および図２（ａ）において、灰色の部分及び黒みがかった灰色の部分が主相結晶粒であり、白い部分が粒界相である。また、図１（ｂ）および図２（ｂ）において、白い部分がＤｙの濃度が高い部分、黒い部分がＤｙの濃度が低い部分である。   Sample No. in Table 1 A photograph showing the cross-sectional EPMA analysis result of the sintered magnet according to the present invention is shown in FIG. In addition, sample No. The photograph which shows the cross-sectional EPMA analysis result of the sintered magnet of 3 comparative examples is shown in FIG. In both FIG. 1 and FIG. 2, (a) is a photograph of a reflected electron beam image, (b) is a mapping photograph showing the distribution of Dy, and the magnification is 2000 times. In FIG. 1A and FIG. 2A, the gray part and the blackish gray part are main phase crystal grains, and the white part is a grain boundary phase. In FIG. 1B and FIG. 2B, the white portion is a portion having a high Dy concentration, and the black portion is a portion having a low Dy concentration.

図１（ｂ）では、多数の黒い粒子状の部分（Ｄｙ濃度が低い部分）が存在し、その周りをドーナツ状に白い部分（Ｄｙ濃度が高い部分）が取り囲んでいる。これを図１（ａ）と照らし合わせると、ドーナツ状の部分（黒い粒子状の部分を含む）が一つの主相結晶粒に相当することが分かる。すなわち、図１（ａ）に示す通り、本発明による焼結磁石は、主相結晶粒の外殻部にＤｙを濃縮した組織となっていることが分かる。   In FIG. 1B, there are a large number of black particulate portions (portions having a low Dy concentration), and white portions (portions having a high Dy concentration) are surrounded in a donut shape. When this is compared with FIG. 1A, it can be seen that a donut-shaped portion (including a black particle-shaped portion) corresponds to one main phase crystal grain. That is, as shown in FIG. 1A, it can be seen that the sintered magnet according to the present invention has a structure in which Dy is concentrated in the outer shell of the main phase crystal grains.

一方、図２（ｂ）では、黒い粒子状の部分（Ｄｙ濃度が低い部分）をドーナツ状に白い部分（Ｄｙ濃度が高い部分）が取り囲んでいるものと、逆に、白い粒子状の部分（Ｄｙ濃度が高い部分）をドーナツ状に黒い部分（Ｄｙ濃度が低い部分）が取り囲んでいるものとが混在している。これを図２（ａ）と照らし合わせると、ドーナツ状の部分（黒い粒子状の部分を含む）が一つの主相結晶粒に相当することが分かる。すなわち、図２（ａ）に示すとおり、比較例の焼結磁石においては、主相結晶粒の外殻部にＤｙを濃縮した組織と、全く逆の組織が存在する。   On the other hand, in FIG. 2 (b), a black particle portion (a portion having a low Dy concentration) is surrounded by a white portion (portion having a high Dy concentration) in a donut shape, and conversely, a white particle portion ( A portion where the Dy concentration is high) is mixed with a black portion (portion where the Dy concentration is low) surrounded by a donut shape. When this is compared with FIG. 2A, it can be seen that a donut-shaped portion (including a black particle-shaped portion) corresponds to one main phase crystal grain. That is, as shown in FIG. 2A, in the sintered magnet of the comparative example, there is a structure that is completely opposite to the structure in which Dy is concentrated in the outer shell portion of the main phase crystal grains.

これは、比較例の永久磁石においては、第一合金粉末と第二合金粉末のＣｏ含有量が同じであるため、焼結時に第一合金粉末と第二合金粉末とからほぼ同様に液相化し、第一合金粉末の外殻部を第二合金粉末で取り囲むように粒成長するものもあれば、第二合金粉末の外殻部を第一合金粉末で取り囲むように粒成長しているものもあると考えられる。このような粒成長により焼結された焼結磁石は、表１の磁気特性の結果からも明らかなようにＨｃＪは向上しない。 This is because, in the comparative permanent magnet, the Co content of the first alloy powder and the second alloy powder is the same, so that the liquid phase of the first alloy powder and the second alloy powder is substantially the same during sintering. Some grains grow so that the outer shell part of the first alloy powder is surrounded by the second alloy powder, and some grains grow so as to surround the outer shell part of the second alloy powder with the first alloy powder. It is believed that there is. The sintered magnets sintered by such grain growth do not improve HcJ, as is apparent from the results of the magnetic properties shown in Table 1.

以上のように、本発明の製造方法によれば、主相結晶粒の外殻部に重希土類元素ＲＨを濃縮した組織を実現することができ、Ｂｒを低下させずにＨｃＪを向上させたＲ−Ｔ−Ｂ系焼結磁石を得ることができる。 As described above, according to the manufacturing method of the present invention, main phase crystal grains was concentrated heavy rare-earth element RH to the outer shell structure can realize, improve H cJ without lowering the B r R-T-B sintered magnets can be obtained.

実施例２
表２に示す第一合金粉末と第二合金粉末の組成になるように各原料粉末を配合することと、表２に示す質量比にて混合する以外は実施例１と同様な方法によりＲ−Ｔ−Ｂ系焼結磁石を作製した。得られた焼結磁石の組成分析及び酸素分析の結果、並びに磁気特性の測定結果を表２に示す。 Example 2
R- by the same method as in Example 1 except that each raw material powder is blended so as to have the composition of the first alloy powder and the second alloy powder shown in Table 2, and mixed at a mass ratio shown in Table 2. A TB sintered magnet was produced. Table 2 shows the results of composition analysis and oxygen analysis of the obtained sintered magnet and the measurement results of magnetic properties.

本実施例は、質量比を９５：５から５０：５０に変化させ、同じ組成の焼結磁石を作製したものである。表２に示すように、第二合金粉末の質量比が大きくなるにつれＨｃＪが低下する傾向があり、質量比が６０：４０（試料Ｎｏ．１２）になると、ＨｃＪが大きく低下する。好ましい質量比は９０：１０である。 In this example, the mass ratio was changed from 95: 5 to 50:50 to produce a sintered magnet having the same composition. As shown in Table 2, HcJ tends to decrease as the mass ratio of the second alloy powder increases, and when the mass ratio becomes 60:40 (sample No. 12), HcJ decreases greatly. A preferred mass ratio is 90:10.

実施例３
表３に示す第一合金粉末と第二合金粉末の組成になるように各原料粉末を配合する以外は実施例１と同様な方法によりＲ−Ｔ−Ｂ系焼結磁石を作製した。得られた焼結磁石の組成分析および酸素分析の結果、並びに磁気特性の測定結果を表３に示す。 Example 3
An RTB-based sintered magnet was produced in the same manner as in Example 1 except that each raw material powder was blended so as to have the composition of the first alloy powder and the second alloy powder shown in Table 3. Table 3 shows the results of composition analysis and oxygen analysis of the obtained sintered magnet, and the measurement results of magnetic properties.

本実施例は、第二合金粉末のＤｙ含有量を変化させ、同じ組成の焼結磁石を作製したものである。表３に示すように、第二合金粉末のＤｙ含有量が１０質量％（試料Ｎｏ．１５）および２５質量％（試料Ｎｏ．１６）でＨｃＪが大きく向上している。このように、第二合金粉末におけるＤｙ含有量は、１０質量％〜２５質量％の範囲が好ましい。 In this example, the Dy content of the second alloy powder was changed to produce a sintered magnet having the same composition. As shown in Table 3, HcJ is greatly improved when the Dy content of the second alloy powder is 10 mass% (sample No. 15) and 25 mass% (sample No. 16). Thus, the Dy content in the second alloy powder is preferably in the range of 10% by mass to 25% by mass.

実施例４
表４に示す第一合金粉末と第二合金粉末の組成になるように各原料粉末を配合する以外は実施例１と同様な方法によりＲ−Ｔ−Ｂ系焼結磁石を作製した。得られた焼結磁石の組成分析及び酸素分析の結果、並びに磁気特性の測定結果を表４に示す。 Example 4
An RTB-based sintered magnet was produced in the same manner as in Example 1 except that each raw material powder was blended so as to have the composition of the first alloy powder and the second alloy powder shown in Table 4. Table 4 shows the results of composition analysis and oxygen analysis of the obtained sintered magnet, and the measurement results of magnetic properties.

本実施例は、第二合金粉末のＣｏ含有量、Ｃｕ含有量、Ｇａ含有量を変化させたものである。表４の試料Ｎｏ．１８〜２２に示すように、第二合金粉末のＣｏ含有量が５質量％（試料Ｎｏ．１９）、１０質量％（試料Ｎｏ．２０）、２０質量％（試料Ｎｏ．２１）で高いＨｃＪが得られている。一方、Ｃｏ含有量が３質量％（試料Ｎｏ．１８）ではＨｃＪが低下し、３０質量％（試料Ｎｏ．２２）になるとＢｒが低下する。このように、第二合金粉末におけるＣｏ含有量は、５質量％〜２０質量％の範囲が好ましい。 In this example, the Co content, Cu content, and Ga content of the second alloy powder are changed. Sample No. in Table 4 As shown in 18 to 22, the Co content of the second alloy powder is 5 mass% (sample No. 19), 10 mass% (sample No. 20), and 20 mass% (sample No. 21), and high H cJ Is obtained. On the other hand, Co content is 3% by mass decreases (sample No.18) In H cJ, B r decreases becomes 30 wt% (Sample No.22). Thus, the Co content in the second alloy powder is preferably in the range of 5% by mass to 20% by mass.

表４の試料Ｎｏ．２３〜２６は、第二合金粉末にＤｙ、ＣｏおよびＣｕを多く含有するものである。試料Ｎｏ．１９と２３、２０と２４、２１と２５の対比から明らかなように、第二合金粉末にＤｙ、Ｃｏを多く含有するとともにＣｕを含有することにより、ＨｃＪが向上している。但し、試料Ｎｏ．２５と２６の対比から明らかなように、Ｃｕ含有量が３質量％になるとＢｒが低下する。このように、第二合金粉末におけるＣｕ含有量は、２質量％以下が好ましい。 Sample No. in Table 4 Nos. 23 to 26 contain a large amount of Dy, Co and Cu in the second alloy powder. Sample No. As is clear from the comparison between 19 and 23, 20 and 24, and 21 and 25, the HcJ is improved by containing a large amount of Dy and Co and Cu in the second alloy powder. However, sample No. As evident from comparison of 25 and 26, B r decreases when Cu content is 3 wt%. Thus, the Cu content in the second alloy powder is preferably 2% by mass or less.

表４の試料Ｎｏ．２７〜３０は、第二合金粉末にＤｙ、Ｃｏ、ＣｕおよびＧａを多く含有するものである。試料Ｎｏ．２３と２７、２４と２８、２５と２９の対比から明らかなように、第二合金粉末にＤｙ、Ｃｏ、Ｃｕを多く含有するとともにＧａを含有することにより、ＨｃＪが向上している。但し、試料Ｎｏ．２９と３０の対比から明らかなように、Ｇａ含有量が３質量％になると、Ｂｒが低下する。このように、第二合金粉末におけるＧａ含有量は、２質量％以下が好ましい。 Sample No. in Table 4 27 to 30 contain a large amount of Dy, Co, Cu and Ga in the second alloy powder. Sample No. As is clear from the comparison between 23 and 27, 24 and 28, and 25 and 29, the HcJ is improved by containing a large amount of Dy, Co, Cu and Ga in the second alloy powder. However, sample No. 29 As is apparent from the comparison 30, the Ga content is 3 mass%, B r is decreased. Thus, the Ga content in the second alloy powder is preferably 2% by mass or less.

実施例５
表５の試料Ｎｏ．３１に示す第一合金粉末と第二合金粉末の組成になるように各原料を配合し、それぞれを溶解し、ストリップキャスト法によって厚さ０．２ｍｍ〜０．４ｍｍの板状合金を得た。前記板状合金を水素加圧雰囲気で水素脆化させた後、６００℃まで真空中で加熱後、冷却し粗粉砕粉末を得た。得られた第一合金粉末の粗粉砕粉末と第二合金粉末の粗粉砕粉末を９０：１０の質量比でＶ型混合機に投入して混合し、混合粉末を得た。前記混合粉末を、実質的に酸素を含有しない不活性ガス中でジェットミルにより微粉砕し、平均粒径３．０μｍの微粉砕粉末を得た。 Example 5
Sample No. in Table 5 Each raw material was mix | blended so that it might become the composition of the 1st alloy powder and the 2nd alloy powder which are shown in 31, each was melt | dissolved, and the plate-shaped alloy of thickness 0.2mm-0.4mm was obtained by the strip cast method. The plate-like alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere, heated to 600 ° C. in a vacuum, and then cooled to obtain a coarsely pulverized powder. The coarsely pulverized powder of the obtained first alloy powder and the coarsely pulverized powder of the second alloy powder were put into a V-type mixer at a mass ratio of 90:10 and mixed to obtain a mixed powder. The mixed powder was finely pulverized by a jet mill in an inert gas containing substantially no oxygen to obtain a finely pulverized powder having an average particle size of 3.0 μm.

ジェットミルの微粉砕粉末の取出口に油が入った容器を設置し、微粉砕粉末をジェットミルから直接油中へ回収した。得られた油と微粉砕粉末からなるスラリーを磁界中で湿式成形し、成形体を得た。前記成形体を真空中において２００℃で１時間加熱する脱油処理を行い、引き続き真空中において１０５０℃で２時間焼結し、室温まで冷却してＲ−Ｔ−Ｂ系焼結磁石を得た。得られた焼結磁石の組成分析及び酸素分析の結果、並びに磁気特性の測定結果を表５に示す。   A container containing oil was placed at the outlet of the finely pulverized powder of the jet mill, and the finely pulverized powder was directly collected into the oil from the jet mill. The resulting slurry of oil and finely pulverized powder was wet-molded in a magnetic field to obtain a molded body. The molded body was deoiled by heating at 200 ° C. for 1 hour in vacuum, then sintered in vacuum at 1050 ° C. for 2 hours, and cooled to room temperature to obtain an RTB-based sintered magnet. . Table 5 shows the results of composition analysis and oxygen analysis of the obtained sintered magnet, and the measurement results of magnetic properties.

また、表５の試料Ｎｏ．３２に示す第一合金粉末と第二合金粉末の組成になるように各原料を配合する以外は実施例と同様な方法（大気中で乾式成形）によりＲ−Ｔ−Ｂ系焼結磁石を作製した。得られた焼結磁石の組成分析および酸素分析の結果、並びに磁気特性の測定結果を表５に示す。   In addition, Sample No. An RTB-based sintered magnet was prepared by the same method (dry molding in the atmosphere) as in the examples except that the respective raw materials were blended so as to have the composition of the first alloy powder and the second alloy powder shown in FIG. did. Table 5 shows the results of composition analysis and oxygen analysis of the obtained sintered magnet, and the measurement results of magnetic properties.

表５に示す通り、湿式成形した焼結磁石（試料Ｎｏ．３１）の含有酸素量は０．１質量％（１０００ｐｐｍ）であり、大気中で乾式成形した焼結磁石（試料Ｎｏ．３２）の含有酸素量の０．３９質量％（３９００ｐｐｍ）に比べ、大幅に低減されている。すなわち、微粉砕粉末を油中に浸漬してスラリー状となし、そのスラリーを磁場中で湿式成形することにより、微粉砕粉末の酸化が防止されている。これによって、大気中で乾式成形した焼結磁石に比べ、Ｂｒ、ＨｃＪが大きく向上している。 As shown in Table 5, the oxygen content of the wet-molded sintered magnet (sample No. 31) is 0.1% by mass (1000 ppm), and the sintered magnet (sample No. 32) dry-molded in the atmosphere (sample No. 32). Compared to 0.39 mass% (3900 ppm) of the oxygen content, it is greatly reduced. That is, the finely pulverized powder is immersed in oil to form a slurry, and the slurry is wet-molded in a magnetic field to prevent oxidation of the finely pulverized powder. As a result, B r and H cJ are greatly improved as compared with a sintered magnet dry-formed in the atmosphere.

実施例６
表６に示す第一合金粉末と第二合金粉末の組成になるように各原料を配合する以外は実施例１と同様な方法によりＲ−Ｔ−Ｂ系焼結磁石を作製した。得られた焼結磁石の組成分析及び酸素分析の結果、並びに磁気特性の測定結果を表６に示す。 Example 6
An RTB-based sintered magnet was produced by the same method as in Example 1 except that the respective raw materials were blended so as to have the composition of the first alloy powder and the second alloy powder shown in Table 6. Table 6 shows the results of composition analysis and oxygen analysis of the obtained sintered magnet, and the measurement results of magnetic properties.

本実施例は、第二合金粉末のみにＰｒを含有する組成（試料Ｎｏ．３３）と第一合金粉末と第二合金粉末の両方に同量のＰｒを含有する組成（試料Ｎｏ．３４）と、第一合金粉末および第二合金粉末ともにＰｒを含有しない組成（試料Ｎｏ．３５）で焼結磁石を製作したものである。なお、試料Ｎｏ．３３及び試料Ｎｏ．３５の第一合金粉末に含有されているＰｒ（０．１質量％）は不可避的不純物として混入したものである。   In this example, the composition containing only Pr in the second alloy powder (sample No. 33) and the composition containing the same amount of Pr in both the first alloy powder and the second alloy powder (sample No. 34) A sintered magnet was manufactured with a composition containing no Pr (sample No. 35) for both the first alloy powder and the second alloy powder. Sample No. 33 and Sample No. Pr (0.1 mass%) contained in 35 first alloy powder is mixed as an inevitable impurity.

表６に示すように、第二合金粉末のみにＰｒを含有する試料Ｎｏ．３３の焼結磁石は、第一合金粉末と第二合金粉末の両方に同量のＰｒを含有する試料Ｎｏ．３４ならびに第一合金粉末および第二合金粉末ともにＰｒを含有しない試料Ｎｏ．３５の焼結磁石よりもＨｃＪが向上している。すなわち、第二合金粉末のみにＰｒを含有させることにより、Ｂｒを低下させずにＨｃＪをさらに向上させることができる。 As shown in Table 6, sample No. 1 containing Pr only in the second alloy powder. The sintered magnet No. 33 has a sample No. 3 containing the same amount of Pr in both the first alloy powder and the second alloy powder. Sample No. 34 containing no Pr and any of the first alloy powder and the second alloy powder. HcJ is improved over 35 sintered magnets. That is, by containing Pr only the second alloy powder, it is possible to further improve the H cJ without lowering the B r.

表６の試料Ｎｏ．３３の焼結磁石の断面ＥＰＭＡ分析結果を示す写真を図３に示す。図３において、（ａ）が反射電子線像の写真、（ｂ）がＤｙの分布を示すマッピング写真、（ｃ）がＰｒの分布を示すマッピング写真であり、それぞれ倍率は２０００倍である。図３（ａ）において、灰色の部分及び黒みがかった灰色の部分が主相結晶粒であり、白色の部分が粒界相である。また、図３（ｂ）において、灰色の部分がＤｙの濃度が高い部分、黒色の部分がＤｙの濃度が低い部分であり、図３（ｃ）において、黒みがかった灰色の部分がＰｒの濃度が高い部分、黒い部分がＰｒの濃度が低い部分であり、灰色（黒みがかった灰色よりも白い）の部分は粒界相である。   Sample No. in Table 6 The photograph which shows the cross-sectional EPMA analysis result of 33 sintered magnets is shown in FIG. In FIG. 3, (a) is a photograph of a reflected electron beam image, (b) is a mapping photograph showing the distribution of Dy, and (c) is a mapping photograph showing the distribution of Pr, and each magnification is 2000 times. In FIG. 3A, the gray portion and the blackish gray portion are main phase crystal grains, and the white portion is a grain boundary phase. In FIG. 3B, the gray portion is a portion having a high Dy concentration, the black portion is a portion having a low Dy concentration, and in FIG. 3C, the blackish gray portion is a concentration of Pr. The part where the density is high, the black part is the part where the concentration of Pr is low, and the gray part (whiter than the dark gray) is the grain boundary phase.

図３（ｂ）、（ｃ）では、多数の黒い粒子状の部分（ＤｙまたはＰｒ濃度が低い部分）が存在し、図３（ｂ）においては灰色の部分（Ｄｙ濃度が高い部分）が、図３（ｃ）においては黒みがかった灰色の部分（Ｐｒ濃度が高い部分）が、黒い粒子状の部分の周りをドーナツ状に取り囲んでいる。これを図３（ａ）と照らしあわせると、ドーナツ状の部分（黒い粒子状の部分を含む）が一つの主相結晶粒に相当することがわかる。すなわち、第二合金粉末のみにＰｒを含有することにより、主相結晶粒の外殻部にＤｙおよびＰｒを濃縮した組織となっていることがわかる。   3 (b) and 3 (c), there are a large number of black particulate portions (portions where the Dy or Pr concentration is low), and in FIG. 3 (b), gray portions (portions where the Dy concentration is high) In FIG. 3C, a blackish gray portion (a portion having a high Pr concentration) surrounds the black particle-like portion in a donut shape. When this is compared with FIG. 3A, it can be seen that a donut-shaped portion (including a black particle-shaped portion) corresponds to one main phase crystal grain. That is, it can be seen that the inclusion of Pr only in the second alloy powder results in a structure in which Dy and Pr are concentrated in the outer shell of the main phase crystal grains.

表７は、前記表６の試料Ｎｏ．３３と試料Ｎｏ．３４の焼結磁石における主相結晶粒の中心部と外殻部を下記に記載する方法により分析し、Ｒ（Ｎｄ、Ｐｒ、Ｄｙ）の組成（質量％）を求めたものである。なお、試料Ｎｏ．３３については８ヵ所を分析した。分析方法は以下の通りである、例えばＰｒを分析する場合、まず、試料表面を平滑に研磨後、ＥＰＭＡにより各元素の特性Ｘ線のラインプロファイルのカウント数（以下、Ｘ線カウント数と記載する。）を５００μｍの範囲で測定する。次に、焼結磁石全体のＰｒのＩＣＰ分析値と、同じ焼結磁石におけるＰｒのＸ線カウント数の５００μｍの範囲での平均値を、Ｐｒ組成の異なる複数の焼結磁石において求める。そして、これらのデータを元に一次関数(検量線)を作成する。この検量線を用いて、ＰｒのＸ線カウント数からＰｒの組成を分析することができる。   Table 7 shows the sample No. in Table 6 above. 33 and Sample No. The center part and outer shell part of the main phase crystal grains in 34 sintered magnets were analyzed by the method described below to determine the composition (mass%) of R (Nd, Pr, Dy). Sample No. For 33, 8 sites were analyzed. The analysis method is as follows, for example, when analyzing Pr, first, after the sample surface is polished smoothly, the count number of the characteristic X-ray line profile of each element by EPMA (hereinafter referred to as X-ray count number) .) In the range of 500 μm. Next, the Pr ICP analysis value of the entire sintered magnet and the average value of the Pr X-ray counts in the same sintered magnet in the range of 500 μm are obtained for a plurality of sintered magnets having different Pr compositions. Then, a linear function (calibration curve) is created based on these data. Using this calibration curve, the composition of Pr can be analyzed from the X-ray count of Pr.

表７に示すように、試料Ｎｏ．３３および試料Ｎｏ．３４は、いずれも焼結磁石におけるＤｙ含有量（２．３質量％）、Ｐｒ含有量（１．０質量％）は同じであるが、試料Ｎｏ．３３は、ＤｙおよびＰｒの濃度が主相結晶粒における中心部よりも外殻部の方が高く、主相結晶粒の外殻部にＤｙおよびＰｒが濃縮されている。これに対し、試料Ｎｏ．３４は、Ｄｙは主相結晶粒の外殻部に濃縮されているが、Ｐｒは主相結晶粒における中心部と外殻部とで濃度差がほとんどなく、主相結晶粒の外殻部にＰｒが濃縮されていないことが分かる。   As shown in Table 7, sample no. 33 and Sample No. No. 34 has the same Dy content (2.3% by mass) and Pr content (1.0% by mass) in the sintered magnet. In No. 33, the concentration of Dy and Pr is higher in the outer shell than in the central portion of the main phase crystal grains, and Dy and Pr are concentrated in the outer shell of the main phase crystal grains. In contrast, sample no. 34, Dy is concentrated in the outer shell portion of the main phase crystal grains, but Pr has almost no difference in concentration between the central portion and the outer shell portion of the main phase crystal grains, and in the outer shell portion of the main phase crystal grains. It can be seen that Pr is not concentrated.

また、表７に示すように、試料Ｎｏ．３３は、Ｒ−Ｔ−Ｂ系焼結磁石のＰｒの含有量をｘ質量％としたとき、主相結晶粒の外殻部におけるＰｒの含有量は０．７ｘ質量％以上となり、また、主相結晶粒の中心部におけるＰｒの含有量は０．４ｘ質量％以下となる。以上の通り、第二合金粉末のみにＰｒを含有させることにより、主相結晶粒の外殻部にＰｒを濃縮させることができＢｒを低下させずにＨｃＪをさらに向上させることができる。 In addition, as shown in Table 7, sample No. No. 33, when the Pr content of the RTB-based sintered magnet is x mass%, the Pr content in the outer shell portion of the main phase crystal grains is 0.7 x mass% or more. The Pr content in the center of the phase crystal grains is 0.4 ×% by mass or less. As described above, by containing Pr only the second alloy powder, it is possible to further improve the H cJ without reducing can be B r be concentrated Pr on the outer shell of the main phase crystal grains.

実施例７
表８に示す第一合金粉末と第二合金粉末の組成になるように各原料粉末を配合すること以外は実施例１と同様な方法によりＲ−Ｔ−Ｂ系焼結磁石を作製した。得られた焼結磁石の組成分析及び酸素分析の結果、並びに１４０℃におけるＨｃＪの測定結果を表８に示す。 Example 7
An RTB-based sintered magnet was produced in the same manner as in Example 1 except that the raw material powders were blended so as to have the composition of the first alloy powder and the second alloy powder shown in Table 8. Table 8 shows the results of composition analysis and oxygen analysis of the obtained sintered magnet, and the measurement results of HcJ at 140 ° C.

Ｒ−Ｔ−Ｂ系焼結磁石にＰｒを多量に含有させると温度特性が悪化し、高温においてＨｃＪが大きく低下してしまう。本実施例は、焼結磁石におけるＰｒの含有量を変化させ、得られた焼結磁石を１４０℃の高温に加熱し、１４０℃におけるＨｃＪを測定したものである。表８に示すように、Ｐｒの含有量が、焼結磁石においては０．６質量％から２質量％の範囲で、第二合金粉末においては６質量％以上１９質量％の範囲で、ＨｃＪが大きく向上している。このように、Ｐｒの含有量が焼結磁石において０．６質量％未満（第二合金粉末において６質量％未満）であると、添加量が少なすぎる為、所望のＨｃＪ向上効果が得られないので好ましくない。また、Ｐｒの含有量が焼結磁石において２．０質量％を超えると（第二合金粉末において１９質量％を超えると）焼結磁石の温度特性が悪化し、高温においてＨｃＪが低下してしまうため好ましくない。 When a large amount of Pr is contained in the RTB -based sintered magnet, the temperature characteristics are deteriorated, and HcJ is greatly reduced at high temperatures. In this example, the Pr content in the sintered magnet was changed, the obtained sintered magnet was heated to a high temperature of 140 ° C., and HcJ at 140 ° C. was measured. As shown in Table 8, the content of Pr is in the range of 2 wt% to 0.6 wt% in the sintered magnet in the range of more than 6 wt% 19 wt% in the second alloy powder, H cJ Has greatly improved. Thus, when the Pr content is less than 0.6% by mass in the sintered magnet (less than 6% by mass in the second alloy powder), the amount of addition is too small, so that the desired effect of improving HcJ is obtained. It is not preferable because it is not. Moreover, when the content of Pr exceeds 2.0 mass% in the sintered magnet (when it exceeds 19 mass% in the second alloy powder), the temperature characteristics of the sintered magnet deteriorate, and H cJ decreases at high temperatures. Therefore, it is not preferable.

実施例８
前記実施例６の試料Ｎｏ．３３の焼結磁石断面のＦＥ−ＳＥＭによる反射電子線像の写真を図４に示す。図４からわかるように、個々の主相結晶粒において、外殻部と中心部とで濃淡が異なっている。すなわち、ドーナツ状の黒みがかった灰色の部分が外殻部であり、黒い粒子状の部分が中心部である。前記実施例６の表７に示す通り、主相結晶粒の外殻部におけるＰｒの含有量は０．７ｘ質量％以上、主相結晶粒の中心部におけるＰｒの含有量は０．４ｘ質量％以上となっている。この主相結晶粒のＲ−Ｔ−Ｂ系焼結磁石中における存在量（体積比率）を求めた。体積比率は、図４を用いて点算法により前記主相結晶粒の面積比率を求め、それを前記主相結晶粒の体積比率とした。その結果、前記主相結晶粒の存在量は体積比率で９０％であった。また、前記実施例７の試料Ｎｏ．３７、３８、３９の焼結磁石断面のＦＥ−ＳＥＭによる反射電子線像を複数個所観察し、前記と同様に前記主相結晶粒の存在量を点算法により求めた。その結果、前記主相結晶粒の存在量は体積比率で６０％〜９５％の範囲にあった。 Example 8
Sample No. 6 in Example 6 was used. FIG. 4 shows a photograph of a reflection electron beam image obtained by FE-SEM of a cross section of 33 sintered magnets. As can be seen from FIG. 4, in each main phase crystal grain, the density differs between the outer shell portion and the central portion. That is, the blackish gray portion of the donut shape is the outer shell portion, and the black particle-like portion is the central portion. As shown in Table 7 of Example 6, the Pr content in the outer shell portion of the main phase crystal grains is 0.7 x mass% or more, and the Pr content in the central portion of the main phase crystal grains is 0.4 x mass%. That's it. The abundance (volume ratio) of the main phase crystal grains in the RTB-based sintered magnet was determined. As for the volume ratio, the area ratio of the main phase crystal grains was obtained by a point calculation method using FIG. 4, and this was used as the volume ratio of the main phase crystal grains. As a result, the abundance of the main phase crystal grains was 90% by volume ratio. In addition, the sample no. A plurality of backscattered electron beam images of the 37, 38, and 39 sintered magnet cross-sections were observed by FE-SEM, and the abundance of the main phase crystal grains was determined by a point calculation method as described above. As a result, the abundance of the main phase crystal grains was in the range of 60% to 95% by volume ratio.

実施例９
表９に示す第一合金粉末と第二合金粉末の組成になるように各原料粉末を配合すること以外は実施例１と同様な方法によりＲ−Ｔ−Ｂ系焼結磁石を作製した。得られた焼結磁石の組成分析及び酸素分析の結果、並びに磁気特性の測定結果を表９に示す。 Example 9
An RTB-based sintered magnet was produced in the same manner as in Example 1 except that the raw material powders were blended so as to have the composition of the first alloy powder and the second alloy powder shown in Table 9. Table 9 shows the results of composition analysis and oxygen analysis of the obtained sintered magnet, and the measurement results of magnetic properties.

本実施例は、第二合金粉末のみにＰｒを含有する組成（試料Ｎｏ．３３）と第一合金粉末および第二合金粉末ともにＰｒを含有しない組成（試料Ｎｏ．４１）とでＨｃＪの値が同じになるように、Ｄｙ量を調整して焼結磁石を製作したものである。 In this example, the value of H cJ is a composition containing Pr only in the second alloy powder (Sample No. 33) and a composition containing no Pr in both the first alloy powder and the second alloy powder (Sample No. 41). The sintered magnets are manufactured by adjusting the amount of Dy so that the two are the same.

表９に示すように、試料Ｎｏ．３３および試料Ｎｏ．４１は、いずれもＨｃＪの値は同じ（１４９０ｋＡ／ｍ）であるが、試料Ｎｏ．３３のＤｙの含有量は２．３質量％であるのに対し、試料Ｎｏ．４１のＤｙの含有量は２．８質量％であり、試料Ｎｏ．３３に比べてＤｙの含有量が０．５質量％多い。すなわち、第二合金粉末のみにＰｒを含有する組成（試料Ｎｏ．３３）にすることで、第一合金粉末および第二合金粉末ともにＰｒを含有しない組成（試料Ｎｏ．４１）と比べてＤｙの使用量を０．５質量％削減させることができる。 As shown in Table 9, sample no. 33 and Sample No. No. 41 has the same H cJ value (1490 kA / m). The Dy content of 33 is 2.3% by mass, whereas the sample No. The content of Dy of 41 is 2.8% by mass. Compared to 33, the Dy content is 0.5 mass% higher. That is, by making the composition containing Pr only in the second alloy powder (sample No. 33), both the first alloy powder and the second alloy powder do not contain Pr (sample No. 41). The amount used can be reduced by 0.5 mass%.

Claims (2)

Ｒ２８質量％以上３３質量％以下（Ｒは軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ０．５質量％以上５質量％以下、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ０．５質量％以上２．５質量％以下、
Ｃｕ０．０５質量％以上０．２質量％以下、
Ｇａ０．０５質量％以上０．２質量％以下、
残部Ｆｅおよび不可避的不純物からなるＲ−Ｔ−Ｂ系焼結磁石の製造方法において、
Ｒ１２８質量％以上３３質量％以下（Ｒ１は軽希土類元素ＲＬまたは軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ４．４質量％以下（０質量％を含む）、
Ｂ０．５質量％以上２質量％以下、
Ｃｏ２質量％以下（０質量％を含む）、
Ｃｕ０．２質量％以下（０質量％を含む）、
Ｇａ０．２質量％以下（０質量％を含む）、
残部Ｆｅおよび不可避的不純物からなる第一合金粉末を準備する工程と、
Ｒ２２８質量％以上３３質量％以下（Ｒ２は軽希土類元素ＲＬと重希土類元素ＲＨからなり、ＲＬはＮｄおよび／またはＰｒ、ＲＨはＤｙ）、
ＲＨ１０質量％以上２５質量％以下、
Ｂ０．５質量以上２質量％以下、
Ｃｏ５質量％以上２０質量％以下、
Ｃｕ０．５質量％以上２質量％以下、
Ｇａ０．５質量％以上２質量％以下、
残部Ｆｅおよび不可避的不純物からなる第二合金粉末を準備する工程と、
前記第一合金粉末と前記第二合金粉末を質量比７０：３０〜９７：３で混合し、平均粒径が３〜５μｍの混合粉末を準備する工程と、
前記混合粉末を成形し、成形体を準備する工程と、
前記成形体を焼結する工程と、
を含み、第一合金粉末に含まれる前記Ｒ１の含有量（質量％）と第二合金粉末に含まれる前記Ｒ２の含有量（質量％）との値の差が１以内である、Ｒ−Ｔ−Ｂ系焼結磁石の製造方法。 R28 mass% or more and 33 mass% or less (R consists of light rare earth elements RL and heavy rare earth elements RH, RL is Nd and / or Pr, RH is Dy),
RH 0.5 mass% or more and 5 mass% or less,
B 0.5 mass% or more and 2 mass% or less,
Co 0.5 mass% or more and 2.5 mass% or less,
Cu 0.05 mass% or more and 0.2 mass% or less,
Ga 0.05% by mass or more and 0.2% by mass or less,
In the method for producing an RTB-based sintered magnet composed of the remaining Fe and inevitable impurities,
R 1 28 mass% or more and 33 mass% or less (R 1 is composed of light rare earth element RL or light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 4.4% by mass or less (including 0% by mass),
B 0.5 mass% or more and 2 mass% or less,
Co2 mass% or less (including 0 mass%),
Cu 0.2 mass% or less (including 0 mass%),
Ga 0.2 mass% or less (including 0 mass%),
Preparing a first alloy powder composed of the remaining Fe and inevitable impurities;
R 2 28 mass% or more and 33 mass% or less (R 2 is composed of light rare earth element RL and heavy rare earth element RH, RL is Nd and / or Pr, RH is Dy),
RH 10 mass% or more and 25 mass% or less,
B 0.5 mass to 2 mass%,
Co 5 mass% or more and 20 mass% or less,
Cu 0.5 mass% or more and 2 mass% or less,
Ga 0.5 mass% or more and 2 mass% or less,
Preparing a second alloy powder comprising the balance Fe and inevitable impurities;
Mixing the first alloy powder and the second alloy powder in a mass ratio of 70:30 to 97: 3 to prepare a mixed powder having an average particle size of 3 to 5 μm ;
Forming the mixed powder and preparing a molded body;
Sintering the molded body;
The difference in value between the content (mass%) of the R 1 contained in the first alloy powder and the content (mass%) of the R 2 contained in the second alloy powder is within 1; -Manufacturing method of TB sintered magnet. 請求項１に記載のＲ−Ｔ−Ｂ系焼結磁石の製造方法において、
前記Ｒ−Ｔ−Ｂ系焼結磁石におけるＲＬがＮｄおよびＰｒであるとともに、
Ｐｒの含有量が０．６質量％以上２質量％以下であり、
前記第一合金粉末におけるＲＬがＮｄであり、
前記第二合金粉末におけるＲＬがＮｄおよびＰｒであるとともに、
Ｐｒの含有量が６質量％以上１９質量％以下である、
Ｒ−Ｔ−Ｂ系焼結磁石の製造方法。 In the manufacturing method of the RTB system sintered magnet according to claim 1 ,
RL in the RTB-based sintered magnet is Nd and Pr,
The Pr content is 0.6 mass% or more and 2 mass% or less,
RL in the first alloy powder is Nd,
RL in the second alloy powder is Nd and Pr,
The Pr content is 6 mass% or more and 19 mass% or less,
Manufacturing method of RTB-based sintered magnet.
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