JP4702547B2

JP4702547B2 - Functionally graded rare earth permanent magnet

Info

Publication number: JP4702547B2
Application number: JP2006008125A
Authority: JP
Inventors: 中村　　元; 晃一廣田; 正信島尾; 武久美濃輪
Original assignee: Shin Etsu Chemical Co Ltd
Current assignee: Shin Etsu Chemical Co Ltd
Priority date: 2005-03-23
Filing date: 2006-01-17
Publication date: 2011-06-15
Anticipated expiration: 2026-01-17
Also published as: JP2006303434A

Description

本発明は、磁石体表層部のみの電気抵抗を高めた傾斜機能を有し、磁気回路内での渦電流の発生を低減させた高性能希土類永久磁石に関する。 The present invention relates to a high-performance rare earth permanent magnet that has a gradient function that increases the electrical resistance of only the surface layer of a magnet body and that reduces the generation of eddy currents in a magnetic circuit.

Ｎｄ−Ｆｅ−Ｂ系永久磁石は、その優れた磁気特性のために、ますます用途が広がってきている。近年、環境問題への対応から産業機器をはじめ、電気自動車、風力発電などの大型機器へと磁石の応用の幅が広がったことに伴い、Ｎｄ−Ｆｅ−Ｂ系磁石の高性能化とともに、電気抵抗の高い磁石が要求されている。 Nd-Fe-B permanent magnets are increasingly used because of their excellent magnetic properties. In recent years, Nd-Fe-B magnets have been improved in performance with the expansion of the application range of magnets to industrial equipment, electric vehicles, wind power generation, and other large-scale equipment in response to environmental problems. Magnets with high resistance are required.

モータの効率を低下させる原因の１つである渦電流は、主として磁心材に多く発生するが、モータが大型化すると、磁石自信の渦電流も無視できなくなる。特に絶縁膜を挟んで積層した磁心材に穴を開け、そこに永久磁石を擦り込んだ回転子を有するＩＰＭモータでは、磁石が積層板同士の導通を助長してしまい、大きな渦電流が発生してしまう。そこで、絶縁性の樹脂を磁石に被覆する方法が数多く提案されてきたが、磁石を擦り込む際に被覆が剥げ落ちる、あるいは熱膨張を利用して磁石を固定する“焼きばめ”が適応できないという問題があった。 Eddy currents, one of the causes for reducing the efficiency of the motor, are mainly generated in the magnetic core material. However, when the motor is enlarged, the eddy currents of the magnets cannot be ignored. In particular, in an IPM motor having a rotor in which a magnetic core material laminated with an insulating film sandwiched therebetween is perforated and a permanent magnet is rubbed there, the magnet facilitates conduction between the laminated plates, and a large eddy current is generated. End up. Therefore, many methods have been proposed for coating an insulating resin on a magnet, but the coating is peeled off when rubbing the magnet, or "shrink fitting" that fixes the magnet using thermal expansion cannot be applied. There was a problem.

更に、磁石を磁心材と同様に、薄板に加工し、絶縁板を挟んで積層する方法も多く提案されているが、生産性の悪さとコストの上昇という問題から、広く適用されていない。 Furthermore, many methods have been proposed in which a magnet is processed into a thin plate and laminated with an insulating plate sandwiched in the same manner as the magnetic core material, but it has not been widely applied due to the problem of poor productivity and increased cost.

従って、永久磁石その物の電気抵抗を高める方法が有効であり、これまでに数多くの方法が提案されてきた。Ｎｄ−Ｆｅ−Ｂ系永久磁石は金属材料であるため、電気抵抗は比抵抗で１．６×１０^-6Ω・ｍという低い値を示す。従来法では、例えば希土類の酸化物など電気抵抗の高い物質を磁石内に多く分散させて、これらによる電子の散乱を利用して磁石体の抵抗を高めてきた。しかし、これは同時に、磁石の主相であり磁性を担うＮｄ₂Ｆｅ₁₄Ｂ化合物の体積分率を低下させるために、電気抵抗を高めるほど磁気特性の低下が顕著となる問題があった。 Therefore, a method for increasing the electrical resistance of the permanent magnet itself is effective, and many methods have been proposed so far. Since the Nd—Fe—B permanent magnet is a metal material, the electrical resistance has a specific resistance as low as 1.6 × 10 ⁻⁶ Ω · m. In the conventional method, for example, a substance having a high electrical resistance such as a rare earth oxide is dispersed in the magnet, and the resistance of the magnet body is increased by utilizing the scattering of electrons. However, at the same time, in order to reduce the volume fraction of the Nd ₂ Fe ₁₄ B compound, which is the main phase of the magnet and plays a role of magnetism, there is a problem that the decrease in magnetic properties becomes more significant as the electrical resistance is increased.

なお従来、特許第３４７１８７６号公報（特許文献１）には、希土類磁石（希土類元素Ｒのうち少なくとも１種以上含有）をフッ素系ガス雰囲気中又はフッ素系ガスを含有する雰囲気中でフッ素化処理して、該磁石の表層部にその構成相中のＲとのＲＦ₃化合物又はＲＯ_XＦ_Y化合物（Ｘ，Ｙの各々の値が０＜Ｘ＜１．５でかつ２Ｘ＋Ｙ＝３を満足する）あるいはその両化合物の混合物を形成させ、更には２００〜１，２００℃の温度で熱処理を施すことからなる耐食性の優れた希土類磁石が開示されている。 Conventionally, in Japanese Patent No. 3447176 (Patent Document 1), a rare earth magnet (containing at least one rare earth element R) is fluorinated in a fluorine gas atmosphere or a fluorine gas atmosphere. In the surface layer of the magnet, an RF ₃ compound or RO _X F _Y compound with R in the constituent phase (each value of X and Y satisfies 0 <X <1.5 and 2X + Y = 3) Alternatively, a rare earth magnet having excellent corrosion resistance is disclosed, which is formed by forming a mixture of both compounds and further performing heat treatment at a temperature of 200 to 1,200 ° C.

特開２００３−２８２３１２号公報（特許文献２）には、少なくとも、Ｒ−Ｆｅ−（Ｂ，Ｃ）系焼結磁石用合金粉末と、希土類元素のフッ素化合物粉末とを混合し、この混合粉末を磁場配向、圧粉成形して焼結すること、この場合、前記混合粉末の中に３〜２０重量％の希土類元素（好ましくはＤｙ及び／又はＴｂ）のフッ素化合物を含ませることにより、Ｒ−Ｆｅ−（Ｂ，Ｃ）系焼結磁石（但し、Ｒは希土類元素であり、Ｒの５０％以上はＮｄ及び／又はＰｒとする）であって、Ｎｄ₂Ｆｅ₁₄Ｂ型結晶から主として構成される主相の結晶粒界又は粒界三重点に粒状の粒界相が形成され、前記粒界相が希土類元素のフッ素化合物を含み、前記希土類元素のフッ素化合物の焼結磁石全体に対する含有量が３〜２０重量％の範囲にある着磁性が改善されたＲ−Ｆｅ−（Ｂ，Ｃ）系焼結磁石、特にＲ−Ｆｅ−（Ｂ，Ｃ）系焼結磁石（但し、Ｒは希土類元素であり、Ｒの５０％以上はＮｄ及び／又はＰｒとする）であって、Ｎｄ₂Ｆｅ₁₄Ｂ型結晶から主として構成される主相と、希土類元素のフッ素化合物を含む粒界相とを含んで構成され、前記主相中にＤｙ及び／又はＴｂが含まれ、該主相中に、Ｄｙ及び／又はＴｂの濃度が、該主相全体におけるＤｙ及び／又はＴｂの濃度の平均値より低い領域が、形成されているＲ−Ｆｅ−（Ｂ，Ｃ）系焼結磁石が開示されている。 JP-A-2003-28212 (Patent Document 2) includes mixing at least an R—Fe— (B, C) -based sintered magnet alloy powder and a rare earth element fluorine compound powder, Magnetic field orientation, compacting and sintering, in which case the mixed powder contains a fluorine compound of 3 to 20% by weight of a rare earth element (preferably Dy and / or Tb) Fe- (B, C) based sintered magnet (where R is a rare earth element and 50% or more of R is Nd and / or Pr), and is mainly composed of Nd ₂ Fe ₁₄ B type crystals. A grain boundary phase is formed at a crystal grain boundary or grain boundary triple point of the main phase, the grain boundary phase contains a rare earth element fluorine compound, and the content of the rare earth element fluorine compound in the entire sintered magnet is Magnetization in the range of 3-20% by weight is improved Improved R—Fe— (B, C) based sintered magnet, particularly R—Fe— (B, C) based sintered magnet (where R is a rare earth element, 50% or more of R is Nd and / or Or Pr), which is configured to include a main phase mainly composed of Nd ₂ Fe ₁₄ B-type crystals and a grain boundary phase including a fluorine compound of a rare earth element, and Dy and / or In the main phase, a region where the concentration of Dy and / or Tb is lower than the average value of the concentration of Dy and / or Tb in the entire main phase is formed in R-Fe- ( B, C) based sintered magnets are disclosed.

しかし、これらの提案においても、なお、表面電気抵抗の改良の点で十分ではない。 However, these proposals are still not sufficient in terms of improving the surface electrical resistance.

特開２００５−１１９７３号公報（特許文献３）には、磁石を減圧槽内に支持し、該減圧槽内で物理的手法によって蒸気又は微粒子化したＭ元素（但し、Ｍは、Ｐｒ，Ｄｙ，Ｔｂ，Ｈｏから選ばれる希土類元素の１種又は２種以上）又はＭ元素を含む合金を、該磁石の表面の全部又は一部に飛来させて成膜し、かつ該磁石の最表面に露出している結晶粒子の半径に相当する深さ以上に該磁石内部にＭ元素を磁石表面から拡散浸透させることによって、Ｍ元素が富化された結晶粒界層を形成すること、この場合、結晶粒界層のＭ元素の濃度を磁石の表面側ほど高濃度に富化させることにより、磁石表面からのＭ元素（但し、Ｍは、Ｐｒ，Ｄｙ，Ｔｂ，Ｈｏから選ばれる希土類元素の１種又は２種以上）の拡散によりＭ元素が富化した結晶粒界層を有し、保磁力Ｈｃｊと磁石全体に占めるＭ元素含有量が下記の式で表されることを特徴とする、希土類−鉄−ホウ素系磁石が開示されている。
Ｈｃｊ≧１＋０．２×Ｍ（但し、０．０５≦Ｍ≦１０）
但し、Ｈｃｊ：保磁力、単位（ＭＡ／ｍ）、Ｍ：磁石全体に占めるＭ元素含有量（質量％）
しかし、この方法は生産性が極端に悪く、実用的でない。 JP-A-2005-11973 (Patent Document 3) supports a magnet in a decompression tank and vaporizes or atomizes M element by physical means in the decompression tank (where M is Pr, Dy, An alloy containing one or more rare earth elements selected from Tb and Ho) or an alloy containing M element is deposited on all or part of the surface of the magnet, and exposed to the outermost surface of the magnet. Forming a grain boundary layer enriched with the M element by diffusing and penetrating the M element from the magnet surface into the magnet beyond a depth corresponding to the radius of the crystal grain, By enriching the concentration of M element in the boundary layer to a higher concentration on the magnet surface side, M element from the magnet surface (where M is one of rare earth elements selected from Pr, Dy, Tb, Ho or Grain boundary layer enriched with M element by diffusion of 2 or more types) A, wherein the element M content in the whole coercive force Hcj and the magnet is represented by the following formula, the rare earth - iron - boron based magnets is disclosed.
Hcj ≧ 1 + 0.2 × M (where 0.05 ≦ M ≦ 10)
However, Hcj: coercive force, unit (MA / m), M: M element content in the whole magnet (mass%)
However, this method is extremely impractical and impractical.

特許第３４７１８７６号公報Japanese Patent No. 3447176 特開２００３−２８２３１２号公報JP 2003-28212 A 特開２００５−１１９７３号公報Japanese Patent Laid-Open No. 2005-11973

本発明は、上述した従来の問題点に鑑みなされたもので、高い電気抵抗と磁気特性を両立させた傾斜機能を有する希土類永久磁石を提供することを目的とするものである。 The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a rare earth permanent magnet having a gradient function that achieves both high electrical resistance and magnetic characteristics.

本発明者らは、Ｎｄ−Ｆｅ−Ｂ系焼結磁石に代表されるＲ−Ｆｅ−Ｂ系焼結磁石（ＲはＳｃ及びＹを含む希土類元素から選ばれる１種又は２種以上）に対し、Ｒのフッ化物を主成分とする粉末を磁石表面近くの空間内に存在させた状態で焼結温度よりも低い温度で加熱することで粉末に含まれていたＲとフッ素が共に磁石体に高効率で吸収され、磁石体表面層にのみ電気抵抗の高い酸フッ化物粒子を高密度に分散させ、表面層のみの電気抵抗を高めることで、渦電流の発生が低減され、かつ高い磁気特性を維持できることを見出し、この発明を完成したものである。 For the R-Fe-B sintered magnet represented by the Nd-Fe-B sintered magnet (R is one or more selected from rare earth elements including Sc and Y). By heating the powder containing R fluoride as a main component in a space near the magnet surface at a temperature lower than the sintering temperature, both the R and fluorine contained in the powder are transferred to the magnet body. Highly absorbed oxyfluoride particles that are absorbed with high efficiency and only in the surface layer of the magnet body are dispersed at high density, and the electrical resistance of only the surface layer is increased, reducing the generation of eddy currents and high magnetic properties The present invention has been completed.

即ち、本発明は、下記の渦電流損失を低減した傾斜機能性希土類永久磁石を提供する。
（１）ＮｄとＤｙとを含む母合金から得られた焼結磁石体の表面からＮｄ、Ｐｒ、Ｄｙ又はアルカリ土類金属のフッ化物を吸収させることによって得られるか、又はＮｄを含む母合金から得られた焼結磁石体の表面からＰｒのフッ化物を吸収させることによって得られ、下記式（１）又は（２）
Ｒ_aＥ_bＴ_cＡ_dＦ_eＯ_fＭ_g （１）
（Ｒ・Ｅ）_a+bＴ_cＡ_dＦ_eＯ_fＭ_g （２）
（式中、ＲはＳｃ及びＹを含む希土類元素から選ばれる１種又は２種以上、Ｅはアルカリ土類金属元素及び希土類元素から選ばれる１種又は２種以上であるが、ＲとＥとが同一元素を含有していてもよく、ＲとＥとが同一元素を含有していない場合は式（１）で表され、ＲとＥとが同一元素を含有している場合は式（２）で表される。ＴはＦｅ及びＣｏから選ばれる１種又は２種、ＡはＢ及びＣから選ばれる１種又は２種、ＭはＡｌ、Ｃｕ、Ｚｎ、Ｉｎ、Ｓｉ、Ｐ、Ｓ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｎｉ、Ｇａ、Ｇｅ、Ｚｒ、Ｎｂ、Ｍｏ、Ｐｄ、Ａｇ、Ｃｄ、Ｓｎ、Ｓｂ、Ｈｆ、Ｔａ、Ｗの中から選ばれる１種又は２種以上、ａ〜ｇは合金の原子％で、ａ、ｂは式（１）の場合は、１０≦ａ≦１５、０．００５≦ｂ≦２であり、式（２）の場合は１０．００５≦ａ＋ｂ≦１７であり、３≦ｄ≦１５、０．０１≦ｅ≦４、０．０４≦ｆ≦４、０．０１≦ｇ≦１１、残部がｃである。）
で示される組成を有する焼結磁石体であって、その構成元素であるＦが磁石体中心より磁石体表面に向かって平均的に含有濃度が濃くなるように分布し、かつ該焼結磁石中の（Ｒ，Ｅ）₂Ｔ₁₄Ａ正方晶からなる主相結晶粒の周りを取り囲む結晶粒界部において、結晶粒界に含まれるＥ／（Ｒ＋Ｅ）の濃度が主相結晶粒中のＥ／（Ｒ＋Ｅ）濃度より平均的に濃く、更に結晶粒界部の磁石体表面より少なくとも２０μｍの深さ領域にまで、結晶粒界部に（Ｒ，Ｅ）の酸フッ化物が存在し、該領域において円相当径が１μｍ以上の該酸フッ化物粒子が１平方ミリメートル当たり２，０００個以上の割合で分散し、かつ当該酸フッ化物が面積分率で１％以上を占め、磁石体表層部の電気抵抗が内部より高いことを特徴とする渦電流損失を低減した傾斜機能性希土類永久磁石。
（２）ＲがＮｄ及びＤｙからなり、ＥがＭｇ、Ｃａ、Ｐｒ、Ｎｄ、Ｔｂ及びＤｙから選ばれる（１）記載の傾斜機能性希土類永久磁石。
（３）ＲがＮｄ及び／又はＰｒを１０原子％以上含有することを特徴とする（１）又は（２）記載の傾斜機能性希土類永久磁石。
（４）ＴがＦｅを６０原子％以上含有することを特徴とする（１）乃至（３）のいずれかに記載の磁石体表層部の電気抵抗が内部より高い、渦電流損失を低減した傾斜機能性希土類永久磁石。
（５）ＡがＢを８０原子％以上含有することを特徴とする（１）乃至（４）のいずれかに記載の磁石体表層部の電気抵抗が内部より高い、渦電流損失を低減した傾斜機能性希土類永久磁石。
（６）ＮｄとＤｙとを含む母合金から得られた焼結磁石体の表面に、Ｎｄ、Ｐｒ、Ｄｙ又はアルカリ土類金属のフッ化物の粉末を供給するか、又はＮｄを含む母合金から得られた焼結磁石体の表面にＰｒのフッ化物の粉末を供給し、熱処理を行って、下記式（１）又は（２）
Ｒ _a Ｅ _b Ｔ _c Ａ _d Ｆ _e Ｏ _f Ｍ _g （１）
（Ｒ・Ｅ） _a+b Ｔ _c Ａ _d Ｆ _e Ｏ _f Ｍ _g （２）
（式中、ＲはＳｃ及びＹを含む希土類元素から選ばれる１種又は２種以上、Ｅはアルカリ土類金属元素及び希土類元素から選ばれる１種又は２種以上であるが、ＲとＥとが同一元素を含有していてもよく、ＲとＥとが同一元素を含有していない場合は式（１）で表され、ＲとＥとが同一元素を含有している場合は式（２）で表される。ＴはＦｅ及びＣｏから選ばれる１種又は２種、ＡはＢ及びＣから選ばれる１種又は２種、ＭはＡｌ、Ｃｕ、Ｚｎ、Ｉｎ、Ｓｉ、Ｐ、Ｓ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｎｉ、Ｇａ、Ｇｅ、Ｚｒ、Ｎｂ、Ｍｏ、Ｐｄ、Ａｇ、Ｃｄ、Ｓｎ、Ｓｂ、Ｈｆ、Ｔａ、Ｗの中から選ばれる１種又は２種以上、ａ〜ｇは合金の原子％で、ａ、ｂは式（１）の場合は、１０≦ａ≦１５、０．００５≦ｂ≦２であり、式（２）の場合は１０．００５≦ａ＋ｂ≦１７であり、３≦ｄ≦１５、０．０１≦ｅ≦４、０．０４≦ｆ≦４、０．０１≦ｇ≦１１、残部がｃである。）
で示される組成を有する焼結磁石体であって、その構成元素であるＦが磁石体中心より磁石体表面に向かって平均的に含有濃度が濃くなるように分布し、かつ該焼結磁石中の（Ｒ，Ｅ） ₂ Ｔ ₁₄ Ａ正方晶からなる主相結晶粒の周りを取り囲む結晶粒界部において、結晶粒界に含まれるＥ／（Ｒ＋Ｅ）の濃度が主相結晶粒中のＥ／（Ｒ＋Ｅ）濃度より平均的に濃く、更に結晶粒界部の磁石体表面より少なくとも２０μｍの深さ領域にまで、結晶粒界部に（Ｒ，Ｅ）の酸フッ化物が存在し、該領域において円相当径が１μｍ以上の該酸フッ化物粒子が１平方ミリメートル当たり２，０００個以上の割合で分散し、かつ当該酸フッ化物が面積分率で１％以上を占め、磁石体表層部の電気抵抗が内部より高いことを特徴とする渦電流損失を低減した傾斜機能性希土類永久磁石を得ることを特徴とする希土類永久磁石の製造方法。 That is, the present invention provides the following functionally functional rare earth permanent magnet with reduced eddy current loss.
(1) A master alloy obtained by absorbing Nd, Pr, Dy or an alkaline earth metal fluoride from the surface of a sintered magnet body obtained from a master alloy containing Nd and Dy, or containing Nd It is obtained by absorbing Pr fluoride from the surface of the sintered magnet body obtained from the following formula (1) or (2)
_{_{_{_{R a E b T c A d}}}} F e O f M g (1)
_{(R · E) a + b} T c A d F e O f M g (2)
(In the formula, R is one or more selected from rare earth elements including Sc and Y, and E is one or more selected from alkaline earth metal elements and rare earth elements. May contain the same element, and when R and E do not contain the same element, they are represented by the formula (1), and when R and E contain the same element, the formula (2 T is one or two selected from Fe and Co, A is one or two selected from B and C, M is Al, Cu, Zn, In, Si, P, S, One or more selected from Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, W, a to g Is atomic% of the alloy, and a and b are 10 ≦ a ≦ 15 and 0.005 ≦ b ≦ 2 in the case of formula (1), and in the case of formula (2) A 0.005 ≦ a + b ≦ 17, 3 ≦ d ≦ 15,0.01 ≦ e ≦ 4,0.04 ≦ f ≦ 4,0.01 ≦ g ≦ 11, the balance being c.)
And the constituent element F is distributed so that the content concentration is increased from the center of the magnet body toward the surface of the magnet body on the average, and in the sintered magnet In the grain boundary portion surrounding the main phase crystal grains made of (R, E) ₂ T ₁₄ A tetragonal crystal, the concentration of E / (R + E) contained in the crystal grain boundaries is E / in the main phase crystal grains. The (R, E) oxyfluoride is present in the crystal grain boundary portion, which is higher in average than the (R + E) concentration and further to a depth region of at least 20 μm from the magnet body surface in the crystal grain boundary portion. The oxyfluoride particles having an equivalent circle diameter of 1 μm or more are dispersed at a rate of 2,000 or more per square millimeter, and the oxyfluoride occupies 1% or more of the area fraction. Slope with reduced eddy current loss characterized by higher resistance than the inside Potential rare earth permanent magnet.
(2) The functionally functional rare earth permanent magnet according to (1), wherein R is composed of Nd and Dy, and E is selected from Mg, Ca, Pr, Nd, Tb, and Dy.
(3) The functionally functional rare earth permanent magnet according to (1) or (2 ), wherein R contains 10 atomic% or more of Nd and / or Pr.
( 4 ) T contains 60 atomic% or more of Fe, (1) to (3), wherein the magnetic body surface layer has a higher electrical resistance than the inside, and the gradient with reduced eddy current loss Functional rare earth permanent magnet.
( 5 ) A gradient containing 80 atomic% or more of B and having a higher electric resistance of the surface portion of the magnet body according to any one of (1) to ( 4 ) and reducing eddy current loss Functional rare earth permanent magnet.
(6) Nd, Pr, Dy or alkaline earth metal fluoride powder is supplied to the surface of the sintered magnet body obtained from the mother alloy containing Nd and Dy, or from the mother alloy containing Nd. The powder of Pr fluoride is supplied to the surface of the obtained sintered magnet body, and heat treatment is carried out, so that
_{_{_{_{R a E b T c A d}}}} F e O f M g (1)
_{(R · E) a + b} T c A d F e O f M g (2)
(In the formula, R is one or more selected from rare earth elements including Sc and Y, and E is one or more selected from alkaline earth metal elements and rare earth elements. May contain the same element, and when R and E do not contain the same element, they are represented by the formula (1), and when R and E contain the same element, the formula (2 T is one or two selected from Fe and Co, A is one or two selected from B and C, M is Al, Cu, Zn, In, Si, P, S, One or more selected from Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, W, a to g Is atomic% of the alloy, and a and b are 10 ≦ a ≦ 15 and 0.005 ≦ b ≦ 2 in the case of formula (1), and in the case of formula (2) A 0.005 ≦ a + b ≦ 17, 3 ≦ d ≦ 15,0.01 ≦ e ≦ 4,0.04 ≦ f ≦ 4,0.01 ≦ g ≦ 11, the balance being c.)
And the constituent element F is distributed so that the content concentration is increased from the center of the magnet body toward the surface of the magnet body on the average, and in the sintered magnet In the grain boundary portion surrounding the main phase crystal grains made of (R, E) ₂ T ₁₄ A tetragonal crystal, the concentration of E / (R + E) contained in the crystal grain boundaries is E / in the main phase crystal grains. The (R, E) oxyfluoride is present in the crystal grain boundary portion, which is higher in average than the (R + E) concentration and further to a depth region of at least 20 μm from the magnet body surface in the crystal grain boundary portion. The oxyfluoride particles having an equivalent circle diameter of 1 μm or more are dispersed at a rate of 2,000 or more per square millimeter, and the oxyfluoride occupies 1% or more of the area fraction. Slope with reduced eddy current loss characterized by higher resistance than the inside A method for preparing a rare earth permanent magnet, characterized in that to obtain a potential rare earth permanent magnet.

本発明によれば、磁気回路内での渦電流の発生を低減させた傾斜機能性希土類永久磁石を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the functionally functional rare earth permanent magnet which reduced generation | occurrence | production of the eddy current in a magnetic circuit can be provided.

本発明の希土類永久磁石は、Ｒ−Ｆｅ−Ｂ系（ＲはＳｃ及びＹを含む希土類元素）焼結磁石体にその表面からＥ成分（Ｅはアルカリ土類金属元素及び希土類元素から選ばれる１種又は２種以上）及びフッ素原子を吸収させることによって得られるもので、下記式（１）又は（２）で示される組成を有しているものである。
Ｒ_aＥ_bＴ_cＡ_dＦ_eＯ_fＭ_g （１）
（Ｒ・Ｅ）_a+bＴ_cＡ_dＦ_eＯ_fＭ_g （２）
ここで、ＲはＳｃ及びＹを含む希土類元素から選ばれる１種又は２種以上、Ｅはアルカリ土類金属元素及び希土類元素から選ばれる１種又は２種以上、ＴはＦｅ及びＣｏから選ばれる１種又は２種、ＡはＢ及びＣから選ばれる１種又は２種、ＭはＡｌ、Ｃｕ、Ｚｎ、Ｉｎ、Ｓｉ、Ｐ、Ｓ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｎｉ、Ｇａ、Ｇｅ、Ｚｒ、Ｎｂ、Ｍｏ、Ｐｄ、Ａｇ、Ｃｄ、Ｓｎ、Ｓｂ、Ｈｆ、Ｔａ、Ｗの中から選ばれる１種又は２種以上である。この場合、ＲとＥとは重複し得、ＲとＥとが同一元素を含有する場合を許容する。ＲとＥとが同一元素を含有していない場合、希土類永久磁石は式（１）で表され、ＲとＥとが同一元素を含有している場合は式（２）で表される。
また、ａ〜ｇは合金の原子％で、式（１）の場合、１０≦ａ≦１５、０．００５≦ｂ≦２であり、式（２）の場合、１０．００５≦ａ＋ｂ≦１７であり、３≦ｄ≦１５、０．０１≦ｅ≦４、０．０４≦ｆ≦４、０．０１≦ｇ≦１１、残部がｃである。 The rare earth permanent magnet of the present invention is an R-Fe-B-based (R is a rare earth element containing Sc and Y) sintered magnet body, and E component (E is selected from an alkaline earth metal element and a rare earth element) from its surface. Seeds or two or more) and fluorine atoms are absorbed and have a composition represented by the following formula (1) or (2).
_{_{_{_{R a E b T c A d}}}} F e O f M g (1)
_{(R · E) a + b} T c A d F e O f M g (2)
Here, R is one or more selected from rare earth elements including Sc and Y, E is one or more selected from alkaline earth metal elements and rare earth elements, and T is selected from Fe and Co. One or two, A is one or two selected from B and C, M is Al, Cu, Zn, In, Si, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, It is one or more selected from Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, and W. In this case, R and E can overlap, allowing the case where R and E contain the same element. When R and E do not contain the same element, the rare earth permanent magnet is represented by formula (1), and when R and E contain the same element, it is represented by formula (2).
Further, a to g are atomic% of the alloy, and in the case of the formula (1), 10 ≦ a ≦ 15 and 0.005 ≦ b ≦ 2, and in the case of the formula (2), 10.005 ≦ a + b ≦ 17 Yes, 3 ≦ d ≦ 15, 0.01 ≦ e ≦ 4, 0.04 ≦ f ≦ 4, 0.01 ≦ g ≦ 11, and the balance is c.

この場合、Ｒとしては、Ｓｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｙｂ及びＬｕが挙げられ、好ましくはＮｄ、Ｐｒ、Ｄｙを主体とし、Ｒ中Ｎｄ及び／又はＰｒが１０原子％以上、より好ましくは５０原子％以上含有することが好ましい。 In this case, examples of R include Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu, preferably Nd, Pr, and Dy. Nd and / or Pr in R are preferably contained at 10 atomic% or more, more preferably 50 atomic% or more.

一方、Ｅとしては、アルカリ土類金属元素及び希土類元素から選ばれる１種又は２種以上であり、具体的にはＭｇ、Ｃａ、Ｓｒ、Ｂａ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｙｂ及びＬｕ、好ましくはＭｇ、Ｃａ、Ｐｒ、Ｎｄ、Ｔｂ及びＤｙ、更に好ましくはＣａ、Ｐｒ、Ｎｄ及びＤｙが挙げられる。 On the other hand, E is one or more selected from alkaline earth metal elements and rare earth elements, specifically, Mg, Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb and Lu, preferably Mg, Ca, Pr, Nd, Tb and Dy, more preferably Ca, Pr, Nd and Dy are mentioned.

Ｒの含有量ａは１０〜１５原子％、特に１２〜１５原子％である。また、Ｅの含有量ｂは０．００５〜２原子％、より好ましくは０．０１〜２原子％、更に好ましくは０．０２〜１．５原子％である。 The content a of R is 10 to 15 atomic%, particularly 12 to 15 atomic%. The E content b is 0.005 to 2 atomic%, more preferably 0.01 to 2 atomic%, and still more preferably 0.02 to 1.5 atomic%.

更に、ＴはＦｅ及び／又はＣｏであるが、好ましくは６０原子％以上、特に７０原子％以上であり、この場合、Ｃｏは０原子％であってもよいが、残留磁束密度の温度安定性を向上させるなどの点で１原子％以上、より好ましくは３原子％以上、特に５原子％以上含有してもよい。 Further, T is Fe and / or Co, preferably 60 atomic% or more, particularly 70 atomic% or more, and in this case, Co may be 0 atomic%, but the temperature stability of the residual magnetic flux density. 1 atom% or more, more preferably 3 atom% or more, and particularly 5 atom% or more may be contained.

Ａは、上述した通り、Ｂ及び／又はＣであるが、ＡはＢを８０原子％以上、特に８５原子％以上含有していることが好ましい。Ａの量ｄは３〜１５原子％であるが、好ましくは４〜１２原子％、より好ましくは５〜８原子％である。 As described above, A is B and / or C, but it is preferable that A contains B at 80 atomic% or more, particularly 85 atomic% or more. The amount d of A is 3 to 15 atomic%, preferably 4 to 12 atomic%, more preferably 5 to 8 atomic%.

Ｆ（フッ素）の含有量ｅは、０．０１〜４原子％であるが、好ましくは０．０２〜３．５原子％、特に０．０５〜３．５原子％であり、フッ素含有量が少なすぎると、保磁力増大の効果が認められなくなり、多すぎると、粒界相が変質し、保磁力が減少する。 The content e of F (fluorine) is 0.01 to 4 atomic%, preferably 0.02 to 3.5 atomic%, particularly 0.05 to 3.5 atomic%, and the fluorine content is If the amount is too small, the effect of increasing the coercive force is not recognized. If the amount is too large, the grain boundary phase is altered and the coercive force is decreased.

Ｏ（酸素）の含有量ｆは０．０４〜４原子％であるが、好ましくは０．０４〜３．５原子％、特に０．０４〜３原子％である。 The content f of O (oxygen) is 0.04 to 4 atomic%, preferably 0.04 to 3.5 atomic%, particularly 0.04 to 3 atomic%.

更に、他金属元素Ｍの含有量ｇは、上述した通り０．０１〜１１原子％であるが、好ましくは０．０１〜８原子％、特に０．０２〜５原子％であり、０．０５原子％以上、特に０．１原子％以上含まれていてもよい。 Further, the content g of the other metal element M is 0.01 to 11 atomic% as described above, preferably 0.01 to 8 atomic%, particularly 0.02 to 5 atomic%, 0.05 It may be contained in atomic percent or more, particularly 0.1 atomic percent or more.

この場合、本発明の希土類永久磁石は、その焼結磁石体のＦ（フッ素）が、当該磁石体の中心より磁石体表面に向かって平均的にＦの含有濃度が濃くなるように分布している。つまり、磁石体の表面部においてＦの濃度が最も高く、中心に向かってその濃度が漸次低下していくものである。なお、該磁石体の中心部において、Ｆは存在しなくてもよく、結晶粒界部の磁石体表面から少なくとも２０μｍの深さまでの領域において、その結晶粒界部にＲ及びＥの酸フッ化物、典型的には（Ｒ_1-xＥ_x）ＯＦ［ｘは０〜１の数］が存在していればよい。また、該焼結磁石中のいわゆる（Ｒ，Ｅ）₂Ｔ₁₄Ａ正方晶からなる主相結晶粒の周りを取り囲む結晶粒界部において、結晶粒界に含まれるＥ／（Ｒ＋Ｅ）の濃度が主相結晶粒中のＥ／（Ｒ＋Ｅ）濃度より平均的に濃くなっているものである。 In this case, in the rare earth permanent magnet of the present invention, F (fluorine) of the sintered magnet body is distributed so that the average concentration of F increases from the center of the magnet body toward the surface of the magnet body. Yes. That is, the concentration of F is the highest at the surface portion of the magnet body, and the concentration gradually decreases toward the center. In the central part of the magnet body, F may not be present, and R and E oxyfluorides are present at the crystal grain boundary in the region from the surface of the magnet body at the crystal grain boundary to a depth of at least 20 μm. Typically, (R _1−x E _x ) OF [x is a number from 0 to 1] may be present. In addition, the concentration of E / (R + E) contained in the crystal grain boundary in the crystal grain boundary part surrounding the main phase crystal grain composed of the so-called (R, E) ₂ T ₁₄ A tetragonal crystal in the sintered magnet is It is higher in average than the E / (R + E) concentration in the main phase crystal grains.

ここで、本発明の永久磁石においては、上述したように、結晶粒界部の磁石体表面より少なくとも２０μｍの深さ領域にまで、結晶粒界部に（Ｒ，Ｅ）の酸フッ化物が存在しているものであるが、この場合該領域において円相当径が１μｍ以上の該酸フッ化物粒子が１平方ミリメートル当たり２，０００個以上、好ましくは３，０００個以上、更に好ましくは４，０００〜２０，０００個の割合で分散し、かつ当該酸フッ化物が面積分率で１％以上、好ましくは２％以上、更に好ましくは２．５〜１０％を占めるものである。なお、粒子の個数及び面積分率の測定は、ＥＰＭＡの組成像を画像処理することで円相当径が１μｍ以上の酸フッ化物を検出し、測定した。 Here, in the permanent magnet of the present invention, as described above, the (R, E) oxyfluoride is present at the crystal grain boundary part to a depth region of at least 20 μm from the surface of the magnet body at the crystal grain boundary part. In this case, the oxyfluoride particles having an equivalent circle diameter of 1 μm or more in the region are 2,000 or more, preferably 3,000 or more, more preferably 4,000 per square millimeter. It is dispersed at a rate of ˜20,000, and the oxyfluoride occupies 1% or more, preferably 2% or more, more preferably 2.5 to 10% by area fraction. The number of particles and the area fraction were measured by detecting an oxyfluoride having an equivalent circle diameter of 1 μm or more by subjecting an EPMA composition image to image processing.

本発明の希土類永久磁石は、特にＲ−Ｆｅ−Ｂ系焼結磁石体表面にＥ及びＦ（フッ素）を含有する粉末を供給し、熱処理することによって得ることができる。 The rare earth permanent magnet of the present invention can be obtained by supplying a powder containing E and F (fluorine) to the surface of the R—Fe—B based sintered magnet body and performing a heat treatment.

ここで、上記Ｒ−Ｆｅ−Ｂ系焼結磁石体は、常法に従い、母合金を粗粉砕、微粉砕、成形、焼結させることにより得ることができる。 Here, the R—Fe—B based sintered magnet body can be obtained by roughly pulverizing, finely pulverizing, forming and sintering the mother alloy according to a conventional method.

この場合、母合金は、Ｒ、Ｔ、Ａ、Ｍを含有する。ＲはＳｃ及びＹを含む希土類元素から選ばれる１種又は２種以上で、具体的にはＳｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｙｂ及びＬｕが挙げられ、好ましくはＮｄ、Ｐｒ、Ｄｙを主体とする。これらＳｃ及びＹを含む希土類元素は合金全体の１０〜１５原子％、特に１２〜１５原子％であることが好ましく、更に好ましくはＲ中にＮｄとＰｒあるいはそのいずれか１種を全Ｒに対して１０原子％以上、特に５０原子％以上含有することが好適である。ＴはＦｅ及びＣｏから選ばれる１種又は２種で、Ｆｅは合金全体の５０原子％以上、特に６５原子％以上含有することが好ましい。ＡはＢ及びＣから選ばれる１種又は２種で、Ｂは合金全体の２〜１５原子％、特に３〜８原子％含有することが好ましい。ＭはＡｌ、Ｃｕ、Ｚｎ、Ｉｎ、Ｓｉ、Ｐ、Ｓ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｎｉ、Ｇａ、Ｇｅ、Ｚｒ、Ｎｂ、Ｍｏ、Ｐｄ、Ａｇ、Ｃｄ、Ｓｎ、Ｓｂ、Ｈｆ、Ｔａ、Ｗの中から選ばれる１種又は２種以上を０．０１〜１１原子％、特に０．１〜５原子％含有してもよい。残部はＮ、Ｏ等の不可避的な不純物である。 In this case, the master alloy contains R, T, A, and M. R is one or more selected from rare earth elements including Sc and Y, specifically, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb and Lu are mentioned, preferably Nd, Pr and Dy. These rare earth elements including Sc and Y are preferably 10 to 15 atomic%, particularly 12 to 15 atomic% of the whole alloy, and more preferably Nd and Pr or any one of them in R is based on the total R. It is preferable to contain 10 atomic% or more, especially 50 atomic% or more. T is one or two selected from Fe and Co, and Fe is preferably contained in an amount of 50 atomic% or more, particularly 65 atomic% or more of the whole alloy. A is one or two selected from B and C, and B is preferably contained in an amount of 2 to 15 atomic%, particularly 3 to 8 atomic% of the whole alloy. M is Al, Cu, Zn, In, Si, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, You may contain 0.01-11 atomic%, especially 0.1-5 atomic% of 1 type, or 2 or more types chosen from W. The balance is inevitable impurities such as N and O.

母合金は原料金属あるいは合金を真空あるいは不活性ガス、好ましくはＡｒ雰囲気中で溶解したのち、平型やブックモールドに鋳込む、あるいはストリップキャストにより鋳造することで得られる。また、本系合金の主相であるＲ₂Ｆｅ₁₄Ｂ化合物組成に近い合金と焼結温度で液相助剤となるＲリッチな合金とを別々に作製し、粗粉砕後に秤量混合する、いわゆる２合金法も本発明には適用可能である。但し、主相組成に近い合金に対して、鋳造時の冷却速度や合金組成に依存してα−Ｆｅが残存しやすく、Ｒ₂Ｆｅ₁₄Ｂ化合物相の量を増やす目的で必要に応じて均質化処理を施す。その条件は真空あるいはＡｒ雰囲気中にて７００〜１，２００℃で１時間以上熱処理する。液相助剤となるＲリッチな合金については上記鋳造法のほかに、いわゆる液体急冷法やストリップキャスト法も適用できる。 The mother alloy can be obtained by melting a raw metal or alloy in a vacuum or an inert gas, preferably in an Ar atmosphere, and then casting it in a flat mold or a book mold, or by strip casting. Also, an alloy close to the R ₂ Fe ₁₄ B compound composition that is the main phase of this alloy and an R-rich alloy that becomes a liquid phase aid at the sintering temperature are separately prepared, and are weighed and mixed after coarse pulverization. A two alloy method is also applicable to the present invention. However, for alloys close to the main phase composition, α-Fe is likely to remain depending on the cooling rate during casting and the alloy composition, and it is homogeneous as necessary for the purpose of increasing the amount of R ₂ Fe ₁₄ B compound phase. The process is applied. The conditions are heat treatment at 700 to 1,200 ° C. for 1 hour or more in a vacuum or Ar atmosphere. In addition to the above casting method, a so-called liquid quenching method or strip casting method can be applied to the R-rich alloy serving as the liquid phase aid.

上記合金は、通常０．０５〜３ｍｍ、特に０．０５〜１．５ｍｍに粗粉砕される。粗粉砕工程にはブラウンミルあるいは水素粉砕が用いられ、ストリップキャストにより作製された合金の場合は水素粉砕が好ましい。粗粉は、例えば高圧窒素を用いたジェットミルにより通常０．２〜３０μｍ、特に０．５〜２０μｍに微粉砕される。この時、高圧窒素に微量の酸素を混合することで、焼結体の酸素量が制御される。インゴット作製時に混入する酸素と微粉から焼結体に到るまでに吸収した酸素とを合わせて、最終的な焼結体に含まれる酸素量は０．０４〜４原子％、特に０．０４〜３．５原子％であることが好ましい。 The alloy is generally coarsely pulverized to 0.05 to 3 mm, particularly 0.05 to 1.5 mm. Brown mill or hydrogen pulverization is used for the coarse pulverization process, and hydrogen pulverization is preferable in the case of an alloy produced by strip casting. The coarse powder is usually finely pulverized to 0.2 to 30 μm, particularly 0.5 to 20 μm, for example, by a jet mill using high-pressure nitrogen. At this time, the amount of oxygen in the sintered body is controlled by mixing a small amount of oxygen with high-pressure nitrogen. The oxygen amount contained in the final sintered body is 0.04 to 4 atomic%, particularly 0.04 to 4% by combining the oxygen mixed during the preparation of the ingot and the oxygen absorbed from the fine powder to the sintered body. It is preferably 3.5 atomic%.

微粉末は磁界中圧縮成形機で成形され、焼結炉に投入される。焼結は真空あるいは不活性ガス雰囲気中、通常９００〜１，２５０℃、特に１，０００〜１，１００℃で行われる。得られた焼結磁石は、正方晶Ｒ₂Ｆｅ₁₄Ｂ化合物を主相として６０〜９９体積％、特に好ましくは８０〜９８体積％含有し、残部は０．５〜２０体積％のＲに富む相、０〜１０体積％のＢに富む相、０．１〜１０体積％のＲの酸化物及び不可避的不純物により生成した炭化物、窒化物、水酸化物のうち少なくとも１種あるいはこれらの混合物又は複合物からなる。 The fine powder is formed by a compression molding machine in a magnetic field and put into a sintering furnace. Sintering is usually performed at 900 to 1,250 ° C, particularly 1,000 to 1,100 ° C in a vacuum or an inert gas atmosphere. The obtained sintered magnet contains a tetragonal R ₂ Fe ₁₄ B compound as a main phase in an amount of 60 to 99% by volume, particularly preferably 80 to 98% by volume, and the remainder is rich in R of 0.5 to 20% by volume. At least one of a phase, 0 to 10% by volume of a B-rich phase, 0.1 to 10% by volume of an oxide of R and unavoidable impurities, nitride, hydroxide, or a mixture thereof; Composed of a composite.

得られた焼結ブロックは所定形状に研削される。この後、本発明の特徴である磁石体表層部の電気抵抗が内部よりも高い物理的構造を付与するために、Ｅ及びフッ素原子を磁石体表面から吸収させる。 The obtained sintered block is ground into a predetermined shape. Thereafter, E and fluorine atoms are absorbed from the surface of the magnet body in order to provide a physical structure in which the electrical resistance of the surface layer portion of the magnet body, which is a feature of the present invention, is higher than the inside.

処理法の一例として、Ｅ及びフッ素原子を含む粉末を上記焼結磁石体表面に存在させ、磁石と粉末は真空あるいはＡｒ、Ｈｅ等の不活性ガス雰囲気中で焼結温度（Ｔ_sと称する）以下の温度、好ましくは２００〜（Ｔ_s−５）℃、特に２５０〜（Ｔ_s−１０）℃で、０．５〜１００時間、特に１〜５０時間熱処理する。この処理によりＥ及びフッ素は、磁石表面から磁石内に吸収され、磁石内に存在していたＲの酸化物はＦと反応して酸フッ化物へと化学変化する。 As an example of the processing method, a powder containing E and fluorine atoms is present on the surface of the sintered magnet body, and the magnet and the powder are sintered in vacuum or in an inert gas atmosphere such as Ar or He (referred to as T _s ). Heat treatment is performed at the following temperature, preferably 200 to (T _s −5) ° C., particularly 250 to (T _s −10) ° C., for 0.5 to 100 hours, particularly 1 to 50 hours. By this treatment, E and fluorine are absorbed from the magnet surface into the magnet, and the oxide of R present in the magnet reacts with F and chemically changes to oxyfluoride.

なお、磁石内に存在するＲの酸フッ化物とは、好ましくはＲＯＦであるが、これ以外のＲＯ_mＦ_n（ｍ、ｎは任意の正数）や、金属元素によりＲの一部を置換したあるいは安定化されたもの等、本発明の効果を達成することができるＲと酸素とフッ素を含む酸フッ化物を指す。 The oxyfluoride of R present in the magnet is preferably ROF, but a part of R is replaced by other RO _m F _n (m and n are arbitrary positive numbers) or metal elements. It refers to an oxyfluoride containing R, oxygen, and fluorine that can achieve the effects of the present invention, such as those that have been made or stabilized.

この時、磁石体内に吸収されるＦ量は、用いる粉末の組成、粒度、処理時に磁石表面を囲む空間内に存在させる割合、磁石の比表面積、処理温度・時間によって変化するが、０．０１〜４原子％であることが好ましいが、特に磁石体の結晶粒界部に存在する円相当径が１μｍ以上の該酸フッ化物粒子の存在比率を１ｍｍ²当たり２，０００個以上、特に３，０００個以上とする点から０．０２〜３．５原子％であることがより好ましく、更に好ましくは０．０５〜３．５原子％であり、このため磁石体表面にＦを０．０３〜３０ｍｇ／ｃｍ²、特に０．１５〜１５ｍｇ／ｃｍ²供給、吸収させることが好ましい。 At this time, the amount of F absorbed in the magnet body varies depending on the composition of the powder used, the particle size, the ratio of the powder to be present in the space surrounding the magnet surface during processing, the specific surface area of the magnet, and the processing temperature / time. Although it is preferably ˜4 atomic%, the ratio of the oxyfluoride particles having an equivalent circle diameter of 1 μm or more present in the crystal grain boundary portion of the magnet body is 2,000 or more per 1 mm ² , especially 3, From the point which makes it 000 or more, it is more preferable that it is 0.02-3.5 atomic%, More preferably, it is 0.05-3.5 atomic%, Therefore F is 0.03-0.03 on the magnet body surface. 30 mg / cm ^2, particularly 0.15~15mg / cm ² supply, it is preferable to absorb.

なお、上述した通り、磁石体表面から少なくとも２０μｍ以上の領域において、結晶粒界部に存在する円相当径が１μｍ以上の酸フッ化物の存在比率は、１平方ミリメートル当たり２，０００個以上であるが、酸フッ化物が存在する領域の磁石体表面からの深さは磁石含有酸素濃度により制御することができる。かかる点から、磁石含有酸素濃度は０．０４〜４原子％、より好ましくは０．０４〜３．５原子％、更に好ましくは０．０４〜３原子％とすることが推奨される。酸フッ化物が存在する領域の磁石体表面からの深さ、酸フッ化物の粒径及び酸フッ化物の存在比率が上記範囲外であると効果的に比電気抵抗を増大できないため好ましくない。 Note that, as described above, in the region of at least 20 μm or more from the surface of the magnet body, the abundance ratio of the oxyfluoride having an equivalent circle diameter of 1 μm or more present in the crystal grain boundary is 2,000 or more per square millimeter. However, the depth from the surface of the magnet body in the region where the oxyfluoride is present can be controlled by the magnet-containing oxygen concentration. From this point, it is recommended that the magnet-containing oxygen concentration be 0.04 to 4 atomic%, more preferably 0.04 to 3.5 atomic%, and still more preferably 0.04 to 3 atomic%. If the depth of the region where the oxyfluoride exists from the surface of the magnet body, the particle size of the oxyfluoride, and the abundance ratio of the oxyfluoride are outside the above ranges, the specific electrical resistance cannot be effectively increased, which is not preferable.

また、上記処理によりＥ成分も粒界近傍に濃化されるが、この場合、磁石体内に吸収されるＥ成分の合計量は、０．００５〜２原子％、より好ましくは０．０１〜２原子％、更に好ましくは０．０２〜１．５原子％であり、磁石体表面にＥ成分を合計で０．０７〜７０ｍｇ／ｃｍ²、特に０．３５〜３５ｍｇ／ｃｍ²供給、吸収させることが好ましい。 Further, the E component is also concentrated in the vicinity of the grain boundary by the above treatment. In this case, the total amount of the E component absorbed in the magnet body is 0.005 to 2 atomic%, more preferably 0.01 to 2. atomic%, more preferably from 0.02 to 1.5 atomic%, 0.07~70mg / cm ² in total component E the magnet body surface, in particular 0.35~35mg / cm ² supplied, are absorbed Is preferred.

磁石体表面に酸フッ化物が上記範囲内で存在する領域を含んだ比電気抵抗の値は５．０×１０^-6Ωｍ以上、好ましくは１．０×１０^-5Ωｍ以上である。この場合、磁石体中心部の比電気抵抗は２×１０^-6Ωｍ程度で、表面部の比電気抵抗が中心部の２．５倍以上、特に５倍以上であることが好ましい。比電気抵抗が上記範囲外であると、渦電流を効果的に低減できず磁石体の発熱を抑えられない。 The value of the specific electric resistance including the region where the oxyfluoride is present in the above range on the surface of the magnet body is 5.0 × 10 ⁻⁶ Ωm or more, preferably 1.0 × 10 ⁻⁵ Ωm or more. In this case, it is preferable that the specific electric resistance at the center of the magnet body is about 2 × 10 ⁻⁶ Ωm, and the specific electric resistance at the surface is 2.5 times or more, particularly 5 times or more than that of the center. If the specific electric resistance is outside the above range, the eddy current cannot be effectively reduced and the heat generation of the magnet body cannot be suppressed.

なお、本発明の永久磁石において、表面部の渦電流損失は、従来の磁石と比べて約２分の１以下に低減される。 In the permanent magnet of the present invention, the eddy current loss on the surface portion is reduced to about half or less than that of the conventional magnet.

以上のようにして得られたＲの酸フッ化物を含む永久磁石材料は、表面から内部に向かって電気抵抗値が変化する傾斜機能を有し、磁気回路内での渦電流の発生を低減させた高性能希土類永久磁石として用いることができ、特にＩＰＭモータ等の磁石として、好適に用いられる。 The permanent magnet material containing the oxyfluoride of R obtained as described above has a gradient function in which the electric resistance value changes from the surface to the inside, reducing the generation of eddy currents in the magnetic circuit. It can be used as a high performance rare earth permanent magnet, and is particularly preferably used as a magnet for an IPM motor or the like.

以下、本発明の具体的態様について実施例及び比較例をもって詳述するが、本発明の内容はこれに限定されるものではない。 Hereinafter, although the specific aspect of this invention is explained in full detail with an Example and a comparative example, the content of this invention is not limited to this.

［実施例１、比較例１］
純度９９質量％以上のＮｄ、Ｃｏ、Ａｌ、Ｆｅメタルとフェロボロンを所定量秤量してＡｒ雰囲気中で高周波溶解し、この合金溶湯をＡｒ雰囲気中で銅製単ロールに注湯するストリップキャスト法により薄板状の合金とした。得られた合金の組成はＮｄが１２．８原子％、Ｃｏが１．０原子％、Ａｌが０．５原子％、Ｂが５．８原子％、Ｆｅが残部であり、これを合金Ａと称する。合金Ａに水素を吸蔵させた後、真空排気を行いながら５００℃まで加熱して部分的に水素を放出させる、いわゆる水素粉砕により３０メッシュ以下の粗粉とした。更に純度９９質量％以上のＮｄ、Ｄｙ、Ｆｅ、Ｃｏ、Ａｌ、Ｃｕメタルとフェロボロンを所定量秤量し、Ａｒ雰囲気中で高周波溶解した後、鋳造した。得られた合金の組成はＮｄが２０原子％、Ｄｙが１０原子％、Ｆｅが２４原子％、Ｂが６原子％、Ａｌが１原子％、Ｃｕが２原子％、Ｃｏが残部であり、これを合金Ｂと称する。合金Ｂは窒素雰囲気中、ブラウンミルを用いて３０メッシュ以下に粗粉砕された。 [Example 1, Comparative Example 1]
Nd, Co, Al, Fe metal with a purity of 99% by mass or more and ferroboron are weighed in predetermined amounts and melted by high frequency in an Ar atmosphere, and the molten alloy is poured into a copper single roll in an Ar atmosphere by a strip cast method. A shaped alloy was obtained. The composition of the resulting alloy is 12.8 atomic% Nd, 1.0 atomic% Co, 0.5 atomic% Al, 5.8 atomic% B, and the balance Fe. Called. The alloy A was occluded with hydrogen and then heated to 500 ° C. while being evacuated to partially release hydrogen, so that a coarse powder of 30 mesh or less was obtained by so-called hydrogen pulverization. Further, Nd, Dy, Fe, Co, Al, Cu metal having a purity of 99% by mass or more and ferroboron were weighed in predetermined amounts, melted by high frequency in an Ar atmosphere, and then cast. The composition of the resulting alloy is Nd 20 atom%, Dy 10 atom%, Fe 24 atom%, B 6 atom%, Al 1 atom%, Cu 2 atom%, and Co remaining. Is referred to as Alloy B. Alloy B was coarsely pulverized to 30 mesh or less using a brown mill in a nitrogen atmosphere.

続いて、合金Ａ粉末を９３質量％、合金Ｂ粉末を７質量％秤量して、窒素置換したＶブレンダー中で３０分間混合した。この混合粉末は高圧窒素ガスを用いたジェットミルにて、粉末の質量中位粒径４μｍに微粉砕された。得られた混合微粉末を窒素雰囲気下１５ｋＯｅの磁界中で配向させながら、約１ｔｏｎ／ｃｍ²の圧力で成形した。次いで、この成形体はＡｒ雰囲気の焼結炉内に投入され、１，０６０℃で２時間焼結して磁石ブロックを作製した。ここまでの工程は低酸素雰囲気下で行い、得られた磁石体の酸素濃度は０．８１原子％であった。磁石ブロックはダイヤモンドカッターにより５０×５０×５ｍｍに全面研削加工された。 Subsequently, 93% by mass of the alloy A powder and 7% by mass of the alloy B powder were weighed and mixed for 30 minutes in a nitrogen-substituted V blender. This mixed powder was finely pulverized to a mass median particle size of 4 μm by a jet mill using high-pressure nitrogen gas. The obtained mixed fine powder was molded at a pressure of about 1 ton / cm ² while being oriented in a magnetic field of 15 kOe under a nitrogen atmosphere. Next, this compact was put into a sintering furnace in an Ar atmosphere and sintered at 1,060 ° C. for 2 hours to produce a magnet block. The steps so far were performed in a low oxygen atmosphere, and the oxygen concentration of the obtained magnet body was 0.81 atomic%. The magnet block was ground to 50 × 50 × 5 mm with a diamond cutter.

研削加工された磁石体をアルカリ溶液で洗浄した後、酸洗浄して乾燥させた。各洗浄の前後には純水による洗浄工程が含まれている。 The ground magnet body was washed with an alkaline solution, and then washed with an acid and dried. A cleaning process with pure water is included before and after each cleaning.

次に、平均粉末粒径が１０μｍのフッ化ネオジムを質量分率５０％でエタノールと混合し、これに超音波を印加しながら磁石体を１分間浸した。引き上げた磁石は直ちに熱風により乾燥させた。この時のフッ化ネオジムの供給量は０．８ｍｇ／ｃｍ²であった。これにＡｒ雰囲気中８００℃で１０時間という条件で吸収処理を施し、更に５００℃で１時間時効処理して急冷することで、磁石体を得た。これを磁石体Ｍ１と称する。比較のためにフッ化ネオジムを付着させずに熱処理を施した磁石体も作製した。これをＰ１と称する。 Next, neodymium fluoride having an average powder particle size of 10 μm was mixed with ethanol at a mass fraction of 50%, and the magnet body was immersed for 1 minute while applying ultrasonic waves thereto. The magnet pulled up was immediately dried with hot air. The supply amount of neodymium fluoride at this time was 0.8 mg / cm ² . This was subjected to an absorption treatment at 800 ° C. for 10 hours in an Ar atmosphere, and further subjected to an aging treatment at 500 ° C. for 1 hour, followed by rapid cooling to obtain a magnet body. This is referred to as a magnet body M1. For comparison, a magnet body that was heat-treated without attaching neodymium fluoride was also produced. This is referred to as P1.

磁石体Ｍ１、Ｐ１の磁気特性を表１に示した。また、磁石組成を表２に示した。フッ化ネオジムの吸収処理を施していない磁石（Ｐ１）の磁気特性に対して本発明による磁石はほぼ同等な磁気特性が得られている。続いて、Ｍ１、Ｐ１を着磁した後、断熱材により密封し、これをソレノイドコイル内に設置して、コイルに１０００ｋＨｚで１２ｋＡ／ｍの交番磁界を発生させ、磁石体の温度の時間変化を測定することで、渦電流損失を算出した。この結果も表１に併記してある。本発明のＭ１はＰ１に対して、半分以下の損失となっている。図１にＥＰＭＡによる磁石体Ｍ１の表面層におけるＮｄ（図１（ａ））、Ｏ（図１（ｂ））、Ｆ（図１（ｃ））の組成像を示す。表面層には多数のＮｄＯＦ粒子が存在しており、この領域における円相当径が１μｍ以上のＮｄＯＦ粒子の分散頻度は４，５００個／ｍｍ²、面積分率は３．８％であった。更に、磁石体Ｍ１、Ｐ１を１×１×１０ｍｍに研削加工した。このとき、加工前の磁石表面の１つは加工後にも残るように他の５面を研削加工した。続いて、Ｍ１の非研削面（１×１０ｍｍの面）を１８０番の紙やすりで湿式研磨した後、１０００〜４０００番の紙やすりで鏡面に研磨し、その面に対して比抵抗を測定した。図２に、比抵抗と研磨により削られた表面層の厚さの関係を示した。磁石体表面から深さ２００μｍ以上では、従来と同じ低い比抵抗となっている。従って、Ｍ１において、表面層に近いほど比抵抗が高められたことが分かり、これにより低い損失が得られた。以上のことから、酸フッ化物を表層部のみに分散させることで、渦電流損失の低減した永久磁石となることが可能となった。 Table 1 shows the magnetic characteristics of the magnet bodies M1 and P1. The magnet composition is shown in Table 2. The magnet according to the present invention has almost the same magnetic characteristics as the magnetic characteristics of the magnet (P1) not subjected to the neodymium fluoride absorption treatment. Subsequently, after magnetizing M1 and P1, it is sealed with a heat insulating material, and this is installed in a solenoid coil to generate an alternating magnetic field of 12 kA / m at 1000 kHz in the coil, and the time change of the temperature of the magnet body The eddy current loss was calculated by measuring. The results are also shown in Table 1. M1 of the present invention is less than half the loss with respect to P1. FIG. 1 shows composition images of Nd (FIG. 1 (a)), O (FIG. 1 (b)), and F (FIG. 1 (c)) on the surface layer of the magnet body M1 by EPMA. A large number of NdOF particles were present in the surface layer. The dispersion frequency of NdOF particles having an equivalent circle diameter of 1 μm or more in this region was 4,500 particles / mm ² and the area fraction was 3.8%. Further, the magnet bodies M1 and P1 were ground to 1 × 1 × 10 mm. At this time, the other five surfaces were ground so that one of the magnet surfaces before processing remained after processing. Subsequently, the non-ground surface (1 × 10 mm surface) of M1 was wet-polished with No. 180 sandpaper, then polished to a mirror surface with No. 1000-4000 sandpaper, and the specific resistance was measured with respect to that surface. . FIG. 2 shows the relationship between the specific resistance and the thickness of the surface layer shaved by polishing. At a depth of 200 μm or more from the surface of the magnet body, the specific resistance is as low as the conventional one. Therefore, in M1, it was found that the specific resistance was increased closer to the surface layer, and thereby a low loss was obtained. From the above, it becomes possible to obtain a permanent magnet with reduced eddy current loss by dispersing oxyfluoride only in the surface layer portion.

［実施例２、比較例２］
純度９９質量％以上のＮｄ、Ｃｏ、Ａｌ、Ｆｅメタルとフェロボロンを所定量秤量してＡｒ雰囲気中で高周波溶解し、この合金溶湯をＡｒ雰囲気中で銅製単ロールに注湯するストリップキャスト法により薄板状の合金とした。得られた合金の組成はＮｄが１２．８原子％、Ｃｏが１．０原子％、Ａｌが０．５原子％、Ｂが５．８原子％、Ｆｅが残部であり、これを合金Ａと称する。合金Ａに水素を吸蔵させた後、真空排気を行いながら５００℃まで加熱して部分的に水素を放出させる、いわゆる水素粉砕により３０メッシュ以下の粗粉とした。更に純度９９質量％以上のＮｄ、Ｄｙ、Ｆｅ、Ｃｏ、Ａｌ、Ｃｕメタルとフェロボロンを所定量秤量し、Ａｒ雰囲気中で高周波溶解した後、鋳造した。得られた合金の組成はＮｄが２０原子％、Ｄｙが１０原子％、Ｆｅが２４原子％、Ｂが６原子％、Ａｌが１原子％、Ｃｕが２原子％、Ｃｏが残部であり、これを合金Ｂと称する。合金Ｂは窒素雰囲気中、ブラウンミルを用いて３０メッシュ以下に粗粉砕された。 [Example 2, Comparative Example 2]
Nd, Co, Al, Fe metal with a purity of 99% by mass or more and ferroboron are weighed in predetermined amounts and melted by high frequency in an Ar atmosphere, and the molten alloy is poured into a copper single roll in an Ar atmosphere by a strip cast method. A shaped alloy was obtained. The composition of the resulting alloy is 12.8 atomic% Nd, 1.0 atomic% Co, 0.5 atomic% Al, 5.8 atomic% B, and the balance Fe. Called. The alloy A was occluded with hydrogen and then heated to 500 ° C. while being evacuated to partially release hydrogen, so that a coarse powder of 30 mesh or less was obtained by so-called hydrogen pulverization. Further, Nd, Dy, Fe, Co, Al, Cu metal having a purity of 99% by mass or more and ferroboron were weighed in predetermined amounts, melted by high frequency in an Ar atmosphere, and then cast. The composition of the resulting alloy is Nd 20 atom%, Dy 10 atom%, Fe 24 atom%, B 6 atom%, Al 1 atom%, Cu 2 atom%, and Co remaining. Is referred to as Alloy B. Alloy B was coarsely pulverized to 30 mesh or less using a brown mill in a nitrogen atmosphere.

続いて、合金Ａ粉末を９３質量％、合金Ｂ粉末を７質量％秤量して、窒素置換したＶブレンダー中で３０分間混合した。この混合粉末は高圧窒素ガスを用いたジェットミルにて、粉末の質量中位粒径４μｍに微粉砕された。得られた混合微粉末を窒素雰囲気下１５ｋＯｅの磁界中で配向させながら、約１ｔｏｎ／ｃｍ²の圧力で成形した。次いで、この成形体はＡｒ雰囲気の焼結炉内に投入され、１，０６０℃で２時間焼結して磁石ブロックを作製した。ここまでの工程は低酸素雰囲気下で行い、得られた磁石体の酸素濃度は０．７３原子％であった。磁石ブロックはダイヤモンドカッターにより５０×５０×５ｍｍに全面研削加工された。 Subsequently, 93% by mass of the alloy A powder and 7% by mass of the alloy B powder were weighed and mixed for 30 minutes in a nitrogen-substituted V blender. This mixed powder was finely pulverized to a mass median particle size of 4 μm by a jet mill using high-pressure nitrogen gas. The obtained mixed fine powder was molded at a pressure of about 1 ton / cm ² while being oriented in a magnetic field of 15 kOe under a nitrogen atmosphere. Next, this compact was put into a sintering furnace in an Ar atmosphere and sintered at 1,060 ° C. for 2 hours to produce a magnet block. The process so far was performed in a low oxygen atmosphere, and the oxygen concentration of the obtained magnet body was 0.73 atomic%. The magnet block was ground to 50 × 50 × 5 mm with a diamond cutter.

次に、平均粉末粒径が５μｍのフッ化ディスプロシウムを質量分率５０％でエタノールと混合し、これに超音波を印加しながら磁石体を１分間浸した。引き上げた磁石は直ちに熱風により乾燥させた。この時のフッ化ディスプロシウムの供給量は１．１ｍｇ／ｃｍ²であった。これにＡｒ雰囲気中９００℃で１時間という条件で吸収処理を施し、更に５００℃で１時間時効処理して急冷することで、磁石体を得た。これを磁石体Ｍ２と称する。比較のためにフッ化ディスプロシウムを付着させずに熱処理を施した磁石体も作製した。これをＰ２と称する。 Next, dysprosium fluoride having an average powder particle size of 5 μm was mixed with ethanol at a mass fraction of 50%, and the magnet body was immersed for 1 minute while applying ultrasonic waves thereto. The magnet pulled up was immediately dried with hot air. The supply amount of dysprosium fluoride at this time was 1.1 mg / cm ² . This was subjected to an absorption treatment at 900 ° C. for 1 hour in an Ar atmosphere, and further subjected to an aging treatment at 500 ° C. for 1 hour, followed by rapid cooling to obtain a magnet body. This is referred to as a magnet body M2. For comparison, a magnet body that was heat-treated without adhering dysprosium fluoride was also produced. This is referred to as P2.

磁石体Ｍ２、Ｐ２の磁気特性を表１に示した。また、磁石組成を表２に示した。フッ化ディスプロシウムの吸収処理を施していない磁石（Ｐ２）の磁気特性と比較して、本発明による磁石はほぼ同等な残留磁束密度と、より高い保磁力が得られている。続いて、実施例１と同じ方法で、渦電流損失を測定した。この結果も表１に併記してある。本発明のＭ２はＰ２の６．８６Ｗと比較して半分以下である２．４１Ｗという低い値を示している。ＥＰＭＡにより磁石体Ｍ２の表面層における各元素の濃度分布を測定した結果、実施例１と同様な形態で多数のＲＯＦ粒子が存在していた。 Table 1 shows the magnetic properties of the magnet bodies M2 and P2. The magnet composition is shown in Table 2. Compared with the magnetic characteristics of the magnet (P2) not subjected to the dysprosium fluoride absorption treatment, the magnet according to the present invention has substantially the same residual magnetic flux density and higher coercive force. Subsequently, eddy current loss was measured by the same method as in Example 1. The results are also shown in Table 1. M2 of the present invention shows a low value of 2.41 W, which is less than half compared with 6.86 W of P2. As a result of measuring the concentration distribution of each element in the surface layer of the magnet body M2 by EPMA, a large number of ROF particles were present in the same form as in Example 1.

［実施例３、比較例３］
純度９９質量％以上のＮｄ、Ｃｏ、Ａｌ、Ｆｅメタルとフェロボロンを所定量秤量してＡｒ雰囲気中で高周波溶解し、この合金溶湯をＡｒ雰囲気中で銅製単ロールに注湯するストリップキャスト法により薄板状の合金とした。得られた合金の組成はＮｄが１３．５原子％、Ｃｏが１．０原子％、Ａｌが０．５原子％、Ｂが５．８原子％、Ｆｅが残部であった。この合金に水素を吸蔵させた後、真空排気を行いながら５００℃まで加熱して部分的に水素を放出させる、いわゆる水素粉砕により３０メッシュ以下の粗粉とした。 [Example 3, Comparative Example 3]
Nd, Co, Al, Fe metal with a purity of 99% by mass or more and ferroboron are weighed in predetermined amounts and melted by high frequency in an Ar atmosphere, and the molten alloy is poured into a copper single roll in an Ar atmosphere by a strip cast method. A shaped alloy was obtained. The composition of the obtained alloy was such that Nd was 13.5 atomic%, Co was 1.0 atomic%, Al was 0.5 atomic%, B was 5.8 atomic%, and Fe was the balance. After this alloy was occluded with hydrogen, it was heated to 500 ° C. while being evacuated to partially release hydrogen, so that a coarse powder of 30 mesh or less was obtained by so-called hydrogen pulverization.

続いて、粗粉は高圧窒素ガスを用いたジェットミルにて、粉末の質量中位粒径４μｍに微粉砕された。得られた混合微粉末を窒素雰囲気下１５ｋＯｅの磁界中で配向させながら、約１ｔｏｎ／ｃｍ²の圧力で成形した。次いで、この成形体はＡｒ雰囲気の焼結炉内に投入され、１，０６０℃で２時間焼結し磁石ブロックを作製した。ここまでの工程は低酸素雰囲気下で行い、得られた磁石体の酸素濃度は０．８９原子％であった。磁石ブロックはダイヤモンドカッターにより５０×５０×５ｍｍ寸法に全面研削加工された。 Subsequently, the coarse powder was finely pulverized to a mass median particle diameter of 4 μm by a jet mill using high-pressure nitrogen gas. The obtained mixed fine powder was molded at a pressure of about 1 ton / cm ² while being oriented in a magnetic field of 15 kOe under a nitrogen atmosphere. Next, this compact was put into a sintering furnace in an Ar atmosphere and sintered at 1,060 ° C. for 2 hours to produce a magnet block. The steps so far were performed in a low oxygen atmosphere, and the oxygen concentration of the obtained magnet body was 0.89 atomic%. The magnet block was ground to 50 × 50 × 5 mm with a diamond cutter.

次に、平均粉末粒径が５μｍのフッ化プラセオジムを質量分率５０％でエタノールと混合し、これに超音波を印加しながら磁石体を１分間浸した。引き上げた磁石は直ちに熱風により乾燥させた。この時のフッ化プラセオジムの供給量は０．９ｍｇ／ｃｍ²であった。これにＡｒ雰囲気中９００℃で５時間という条件で吸収処理を施し、更に５００℃で１時間時効処理して急冷することで、磁石体を得た。これを磁石体Ｍ３と称する。比較のためにフッ化プラセオジムを付着させずに熱処理を施した磁石体も作製した。これをＰ３と称する。 Next, praseodymium fluoride having an average powder particle size of 5 μm was mixed with ethanol at a mass fraction of 50%, and the magnet body was immersed for 1 minute while applying ultrasonic waves thereto. The magnet pulled up was immediately dried with hot air. The supply amount of praseodymium fluoride at this time was 0.9 mg / cm ² . This was subjected to an absorption treatment at 900 ° C. for 5 hours in an Ar atmosphere, and further subjected to an aging treatment at 500 ° C. for 1 hour, followed by rapid cooling to obtain a magnet body. This is referred to as a magnet body M3. For comparison, a magnet body that was heat-treated without adhering praseodymium fluoride was also produced. This is referred to as P3.

磁石体Ｍ３、Ｐ３の磁気特性を表１に示した。また、磁石組成を表２に示した。フッ化プラセオジムの吸収処理を施していない磁石（Ｐ３）の磁気特性と比較して、本発明による磁石はほぼ同等な残留磁束密度と、より高い保磁力が得られている。続いて、実施例１と同じ方法で、渦電流損失を測定した。この結果も表１に併記してある。本発明のＭ３はＰ３と比較して半分以下の低い値を示している。ＥＰＭＡにより磁石体Ｍ３の表面層における各元素の濃度分布を測定した結果、実施例１と同様な形態で多数のＲＯＦ粒子が存在していた。 Table 1 shows the magnetic properties of the magnet bodies M3 and P3. The magnet composition is shown in Table 2. Compared with the magnetic characteristics of the magnet (P3) not subjected to the absorption treatment of praseodymium fluoride, the magnet according to the present invention has substantially the same residual magnetic flux density and higher coercive force. Subsequently, eddy current loss was measured by the same method as in Example 1. The results are also shown in Table 1. M3 of the present invention shows a low value of less than half compared with P3. As a result of measuring the concentration distribution of each element in the surface layer of the magnet body M3 by EPMA, a large number of ROF particles were present in the same form as in Example 1.

［実施例４、比較例４］
純度９９質量％以上のＮｄ、Ｃｏ、Ａｌ、Ｆｅメタルとフェロボロンを所定量秤量してＡｒ雰囲気中で高周波溶解し、この合金溶湯をＡｒ雰囲気中で銅製単ロールに注湯するストリップキャスト法により薄板状の合金とした。得られた合金の組成はＮｄが１２．８原子％、Ｃｏが１．０原子％、Ａｌが０．５原子％、Ｂが５．８原子％、Ｆｅが残部であり、これを合金Ａと称する。合金Ａに水素を吸蔵させた後、真空排気を行いながら５００℃まで加熱して部分的に水素を放出させる、いわゆる水素粉砕により３０メッシュ以下の粗粉とした。更に純度９９質量％以上のＮｄ、Ｄｙ、Ｆｅ、Ｃｏ、Ａｌ、Ｃｕメタルとフェロボロンを所定量秤量し、Ａｒ雰囲気中で高周波溶解した後、鋳造した。得られた合金の組成はＮｄが２０原子％、Ｄｙが１０原子％、Ｆｅが２４原子％、Ｂが６原子％、Ａｌが１原子％、Ｃｕが２原子％、Ｃｏが残部であり、これを合金Ｂと称する。合金Ｂは窒素雰囲気中、ブラウンミルを用いて３０メッシュ以下に粗粉砕された。 [Example 4, Comparative Example 4]
Nd, Co, Al, Fe metal with a purity of 99% by mass or more and ferroboron are weighed in predetermined amounts and melted by high frequency in an Ar atmosphere, and the molten alloy is poured into a copper single roll in an Ar atmosphere by a strip cast method. A shaped alloy was obtained. The composition of the resulting alloy is 12.8 atomic% Nd, 1.0 atomic% Co, 0.5 atomic% Al, 5.8 atomic% B, and the balance Fe. Called. The alloy A was occluded with hydrogen and then heated to 500 ° C. while being evacuated to partially release hydrogen, so that a coarse powder of 30 mesh or less was obtained by so-called hydrogen pulverization. Further, Nd, Dy, Fe, Co, Al, Cu metal having a purity of 99% by mass or more and ferroboron were weighed in predetermined amounts, melted by high frequency in an Ar atmosphere, and then cast. The composition of the resulting alloy is Nd 20 atom%, Dy 10 atom%, Fe 24 atom%, B 6 atom%, Al 1 atom%, Cu 2 atom%, and Co remaining. Is referred to as Alloy B. Alloy B was coarsely pulverized to 30 mesh or less using a brown mill in a nitrogen atmosphere.

続いて、合金Ａ粉末を８８質量％、合金Ｂ粉末を１２質量％秤量して、窒素置換したＶブレンダー中で３０分間混合した。この混合粉末は高圧窒素ガスを用いたジェットミルにて、粉末の質量中位粒径５．５μｍに微粉砕された。得られた混合微粉末を窒素雰囲気下１５ｋＯｅの磁界中で配向させながら、約１ｔｏｎ／ｃｍ²の圧力で成形した。次いで、この成形体はＡｒ雰囲気の焼結炉内に投入され、１，０６０℃で２時間焼結して磁石ブロックを作製した。ここまでの工程は酸素濃度２１％雰囲気下で行い、得られた磁石体の酸素濃度は２．４原子％であった。磁石ブロックはダイヤモンドカッターにより５０×５０×５ｍｍに全面研削加工された。 Subsequently, 88% by mass of alloy A powder and 12% by mass of alloy B powder were weighed and mixed for 30 minutes in a V-blender purged with nitrogen. The mixed powder was finely pulverized to a mass median particle size of 5.5 μm by a jet mill using high-pressure nitrogen gas. The obtained mixed fine powder was molded at a pressure of about 1 ton / cm ² while being oriented in a magnetic field of 15 kOe under a nitrogen atmosphere. Next, this compact was put into a sintering furnace in an Ar atmosphere and sintered at 1,060 ° C. for 2 hours to produce a magnet block. The steps so far were performed in an atmosphere with an oxygen concentration of 21%, and the oxygen concentration of the obtained magnet body was 2.4 atomic%. The magnet block was ground to 50 × 50 × 5 mm with a diamond cutter.

次に、平均粉末粒径が５μｍのフッ化ディスプロシウムを質量分率５０％でエタノールと混合し、これに超音波を印加しながら磁石体を１分間浸した。引き上げた磁石は直ちに熱風により乾燥させた。この時のフッ化ディスプロシウムの供給量は１．４ｍｇ／ｃｍ²であった。これにＡｒ雰囲気中９００℃で１時間という条件で吸収処理を施し、更に５００℃で１時間時効処理して急冷することで、磁石体を得た。これを磁石体Ｍ４と称する。比較のためにフッ化ディスプロシウムを付着させずに熱処理を施した磁石体も作製した。これをＰ４と称する。 Next, dysprosium fluoride having an average powder particle size of 5 μm was mixed with ethanol at a mass fraction of 50%, and the magnet body was immersed for 1 minute while applying ultrasonic waves thereto. The magnet pulled up was immediately dried with hot air. At this time, the supply amount of dysprosium fluoride was 1.4 mg / cm ² . This was subjected to an absorption treatment at 900 ° C. for 1 hour in an Ar atmosphere, and further subjected to an aging treatment at 500 ° C. for 1 hour, followed by rapid cooling to obtain a magnet body. This is referred to as a magnet body M4. For comparison, a magnet body that was heat-treated without adhering dysprosium fluoride was also produced. This is referred to as P4.

磁石体Ｍ４、Ｐ４の磁気特性を表１に示した。また、磁石組成を表２に示した。フッ化ディスプロシウムの吸収処理を施していない磁石（Ｐ４）の磁気特性と比較して、本発明による磁石はほぼ同等な残留磁束密度と、より高い保磁力が得られている。続いて、実施例１と同じ方法で、渦電流損失を測定した。この結果も表１に併記してある。本発明のＭ４はＰ４の５．５３Ｗと比較して半分以下である２．２５Ｗという低い値を示している。図３にＥＰＭＡによる磁石体Ｍ４の表面層におけるＮｄ（図３（ｄ））、Ｏ（図３（ｅ））、Ｆ（図３（ｆ））の組成像を示す。表面層には多数のＮｄＯＦ粒子が存在しており、この領域における分散頻度は３，２００個／ｍｍ²、面積率は８．５％であった。更に、実施例１と同様の方法で比抵抗を測定した。図４に、比抵抗と研磨により削られた表面層の厚さの関係を示した。磁石体表面から深さ１７０μｍ以上では、従来と同じ低い比抵抗となっている。 Table 1 shows the magnetic properties of the magnet bodies M4 and P4. The magnet composition is shown in Table 2. Compared with the magnetic characteristics of the magnet (P4) not subjected to the dysprosium fluoride absorption treatment, the magnet according to the present invention has a substantially equivalent residual magnetic flux density and higher coercive force. Subsequently, eddy current loss was measured by the same method as in Example 1. The results are also shown in Table 1. M4 of the present invention shows a low value of 2.25 W, which is less than half compared with 5.53 W of P4. FIG. 3 shows composition images of Nd (FIG. 3 (d)), O (FIG. 3 (e)), and F (FIG. 3 (f)) on the surface layer of the magnet body M4 by EPMA. A large number of NdOF particles were present in the surface layer, the dispersion frequency in this region was 3,200 particles / mm ² , and the area ratio was 8.5%. Furthermore, the specific resistance was measured in the same manner as in Example 1. FIG. 4 shows the relationship between the specific resistance and the thickness of the surface layer shaved by polishing. At a depth of 170 μm or more from the surface of the magnet body, the specific resistance is as low as before.

［実施例５、比較例５］
純度９９質量％以上のＮｄ、Ｃｏ、Ａｌ、Ｆｅメタルとフェロボロンを所定量秤量してＡｒ雰囲気中で高周波溶解し、この合金溶湯をＡｒ雰囲気中で銅製単ロールに注湯するストリップキャスト法により薄板状の合金とした。得られた合金の組成はＮｄが１２．８原子％、Ｃｏが１．０原子％、Ａｌが０．５原子％、Ｂが５．８原子％、Ｆｅが残部であり、これを合金Ａと称する。合金Ａに水素を吸蔵させた後、真空排気を行いながら５００℃まで加熱して部分的に水素を放出させる、いわゆる水素粉砕により３０メッシュ以下の粗粉とした。更に純度９９質量％以上のＮｄ、Ｄｙ、Ｆｅ、Ｃｏ、Ａｌ、Ｃｕメタルとフェロボロンを所定量秤量し、Ａｒ雰囲気中で高周波溶解した後、鋳造した。得られた合金の組成はＮｄが２０原子％、Ｄｙが１０原子％、Ｆｅが２４原子％、Ｂが６原子％、Ａｌが１原子％、Ｃｕが２原子％、Ｃｏが残部であり、これを合金Ｂと称する。合金Ｂは窒素雰囲気中、ブラウンミルを用いて３０メッシュ以下に粗粉砕された。 [Example 5, Comparative Example 5]
Nd, Co, Al, Fe metal with a purity of 99% by mass or more and ferroboron are weighed in predetermined amounts and melted by high frequency in an Ar atmosphere, and the molten alloy is poured into a copper single roll in an Ar atmosphere by a strip cast method. A shaped alloy was obtained. The composition of the resulting alloy is 12.8 atomic% Nd, 1.0 atomic% Co, 0.5 atomic% Al, 5.8 atomic% B, and the balance Fe. Called. The alloy A was occluded with hydrogen and then heated to 500 ° C. while being evacuated to partially release hydrogen, so that a coarse powder of 30 mesh or less was obtained by so-called hydrogen pulverization. Further, Nd, Dy, Fe, Co, Al, Cu metal having a purity of 99% by mass or more and ferroboron were weighed in predetermined amounts, melted by high frequency in an Ar atmosphere, and then cast. The composition of the resulting alloy is Nd 20 atom%, Dy 10 atom%, Fe 24 atom%, B 6 atom%, Al 1 atom%, Cu 2 atom%, and Co remaining. Is referred to as Alloy B. Alloy B was coarsely pulverized to 30 mesh or less using a brown mill in a nitrogen atmosphere.

次に、平均粉末粒径が１０μｍのフッ化カルシウムを質量分率５０％でエタノールと混合し、これに超音波を印加しながら磁石体を１分間浸した。引き上げた磁石は直ちに熱風により乾燥させた。この時のフッ化カルシウムの供給量は０．７ｍｇ／ｃｍ²であった。これにＡｒ雰囲気中９００℃で１時間という条件で吸収処理を施し、更に５００℃で１時間時効処理して急冷することで、磁石体を得た。これを磁石体Ｍ５と称する。比較のためにフッ化カルシウムを付着させずに熱処理を施した磁石体も作製した。これをＰ５と称する。 Next, calcium fluoride having an average powder particle size of 10 μm was mixed with ethanol at a mass fraction of 50%, and the magnet body was immersed for 1 minute while applying ultrasonic waves thereto. The magnet pulled up was immediately dried with hot air. At this time, the supply amount of calcium fluoride was 0.7 mg / cm ² . This was subjected to an absorption treatment at 900 ° C. for 1 hour in an Ar atmosphere, and further subjected to an aging treatment at 500 ° C. for 1 hour, followed by rapid cooling to obtain a magnet body. This is referred to as a magnet body M5. For comparison, a magnet body that was heat-treated without attaching calcium fluoride was also produced. This is referred to as P5.

磁石体Ｍ５、Ｐ５の磁気特性を表１に示した。また、磁石組成を表２に示した。フッ化カルシウムの吸収処理を施していない磁石（Ｐ５）の磁気特性と比較して、本発明による磁石はほぼ同等な残留磁束密度と保磁力が得られている。続いて、実施例１と同じ方法で、渦電流損失を測定した。この結果も表１に併記してある。本発明のＭ５はＰ５の６．９５Ｗと比較して半分以下である２．４４Ｗという低い値を示している。ＥＰＭＡにより磁石体Ｍ５の表面層における各元素の濃度分布を測定した結果、実施例１と同様な形態で多数のＲＯＦ粒子が存在していた。 Table 1 shows the magnetic properties of the magnet bodies M5 and P5. The magnet composition is shown in Table 2. Compared with the magnetic characteristics of the magnet (P5) not subjected to the calcium fluoride absorption treatment, the magnet according to the present invention has substantially the same residual magnetic flux density and coercive force. Subsequently, eddy current loss was measured by the same method as in Example 1. The results are also shown in Table 1. M5 of the present invention shows a low value of 2.44 W, which is less than half compared with 6.95 W of P5. As a result of measuring the concentration distribution of each element in the surface layer of the magnet body M5 by EPMA, a large number of ROF particles were present in the same form as in Example 1.

注１：磁石素材のＲ及びＥに含まれている共通元素の合計量
注２：式（１）又は（２）中のＭに相当する元素の合計量 Note 1: Total amount of common elements contained in R and E of magnet material Note 2: Total amount of elements corresponding to M in formula (1) or (2)

分析値は、希土類元素・アルカリ土類金属元素については、実施例、比較例と同等の試料を王水によって全量溶かし、ＩＣＰ法により求めた。酸素については不活性ガス融解赤外吸収測定法で、フッ素については水蒸気蒸留−アルフッソン比色法で求めた。 Analytical values were determined by the ICP method for rare earth elements and alkaline earth metal elements by dissolving all the samples equivalent to those in Examples and Comparative Examples with aqua regia. Oxygen was determined by an inert gas melting infrared absorption measurement method, and fluorine was determined by a steam distillation-Alfusson colorimetric method.

実施例１において作製された磁石体Ｍ１のＮｄ組成像（ａ）、Ｏ組成像（ｂ）、及びＦ組成像（ｃ）を示した図である。It is the figure which showed the Nd composition image (a), O composition image (b), and F composition image (c) of the magnet body M1 produced in Example 1. FIG. 実施例１において作製された磁石体Ｍ１における比抵抗と磁石表面からの深さの関係を示す図である。It is a figure which shows the relationship between the specific resistance in the magnet body M1 produced in Example 1, and the depth from the magnet surface. 実施例４において作製された磁石体Ｍ４のＮｄ組成像（ｄ）、Ｏ組成像（ｅ）、及びＦ組成像（ｆ）を示した図である。It is the figure which showed the Nd composition image (d), O composition image (e), and F composition image (f) of the magnet body M4 produced in Example 4. FIG. 実施例４において作製された磁石体Ｍ４における比抵抗と磁石表面からの深さの関係を示す図である。It is a figure which shows the relationship between the specific resistance in the magnet body M4 produced in Example 4, and the depth from the magnet surface.

Claims

Obtained by absorbing fluoride of Nd, Pr, Dy or alkaline earth metal from the surface of a sintered magnet body obtained from a master alloy containing Nd and Dy, or obtained from a master alloy containing Nd Obtained by absorbing Pr fluoride from the surface of the sintered magnet body, and the following formula (1) or (2)
_{_{_{_{R a E b T c A d}}}} F e O f M g (1)
_{(R · E) a + b} T c A d F e O f M g (2)
(In the formula, R is one or more selected from rare earth elements including Sc and Y, and E is one or more selected from alkaline earth metal elements and rare earth elements. May contain the same element, and when R and E do not contain the same element, they are represented by the formula (1), and when R and E contain the same element, the formula (2 T is one or two selected from Fe and Co, A is one or two selected from B and C, M is Al, Cu, Zn, In, Si, P, S, One or more selected from Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, W, a to g Is atomic% of the alloy, and a and b are 10 ≦ a ≦ 15 and 0.005 ≦ b ≦ 2 in the case of formula (1), and in the case of formula (2) A 0.005 ≦ a + b ≦ 17, 3 ≦ d ≦ 15,0.01 ≦ e ≦ 4,0.04 ≦ f ≦ 4,0.01 ≦ g ≦ 11, the balance being c.)
And the constituent element F is distributed so that the content concentration is increased from the center of the magnet body toward the surface of the magnet body on the average, and in the sintered magnet In the grain boundary portion surrounding the main phase crystal grains made of (R, E) ₂ T ₁₄ A tetragonal crystal, the concentration of E / (R + E) contained in the crystal grain boundaries is E / in the main phase crystal grains. The (R, E) oxyfluoride is present in the crystal grain boundary portion, which is higher in average than the (R + E) concentration and further to a depth region of at least 20 μm from the magnet body surface in the crystal grain boundary portion. The oxyfluoride particles having an equivalent circle diameter of 1 μm or more are dispersed at a rate of 2,000 or more per square millimeter, and the oxyfluoride occupies 1% or more of the area fraction. Slope with reduced eddy current loss characterized by higher resistance than the inside Potential rare earth permanent magnet.

The functionally functional rare earth permanent magnet according to claim 1, wherein R is composed of Nd and Dy, and E is selected from Mg, Ca, Pr, Nd, Tb, and Dy.

The functionally functional rare earth permanent magnet according to claim 1 or 2, wherein R contains Nd and / or Pr in an amount of 10 atomic% or more.

The functionally functional rare earth element according to any one of claims 1 to 3, wherein T contains 60 atomic% or more of Fe, and has a higher electrical resistance than the inside in the surface layer of the magnet body and reduced eddy current loss. permanent magnet.

A is the electrical resistance of the magnet body surface portion according to any one of claims 1 to 4, characterized in that it contains 80 atomic% or more B is higher than the internal, functionally graded rare earth with reduced eddy current loss permanent magnet.

Nd, Pr, Dy or alkaline earth metal fluoride powder is supplied to the surface of a sintered magnet body obtained from a master alloy containing Nd and Dy, or obtained from a master alloy containing Nd. The powder of Pr fluoride is supplied to the surface of the sintered magnet body, and heat treatment is performed to obtain the following formula (1) or (2)
R _aa E _bb T _cc A _dd F _ee O _ff M _gg (1)
(R / E) _{a+ba + b} T _cc A _dd F _ee O _ff M _gg (2)
(In the formula, R is one or more selected from rare earth elements including Sc and Y, and E is one or more selected from alkaline earth metal elements and rare earth elements. May contain the same element, and when R and E do not contain the same element, they are represented by the formula (1), and when R and E contain the same element, the formula (2 T is one or two selected from Fe and Co, A is one or two selected from B and C, M is Al, Cu, Zn, In, Si, P, S, One or more selected from Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, W, a to g Is atomic% of the alloy, and a and b are 10 ≦ a ≦ 15 and 0.005 ≦ b ≦ 2 in the case of formula (1), and in the case of formula (2) A 0.005 ≦ a + b ≦ 17, 3 ≦ d ≦ 15,0.01 ≦ e ≦ 4,0.04 ≦ f ≦ 4,0.01 ≦ g ≦ 11, the balance being c.)
And the constituent element F is distributed so that the content concentration is increased from the center of the magnet body toward the surface of the magnet body on the average, and in the sintered magnet (R, E) ₂₂ T ₁₄₁₄ In the grain boundary part surrounding the main phase crystal grains composed of A tetragonal crystals, the concentration of E / (R + E) contained in the crystal grain boundaries is higher on average than the E / (R + E) concentration in the main phase crystal grains. Further, (R, E) oxyfluoride is present in the crystal grain boundary part to a depth region of at least 20 μm from the surface of the magnet body in the crystal grain boundary part, and the acid having an equivalent circle diameter of 1 μm or more in the region. Fluoride particles are dispersed at a rate of 2,000 or more per square millimeter, the oxyfluoride occupies 1% or more in area fraction, and the electrical resistance of the magnet surface layer is higher than the inside. A method for producing a rare earth permanent magnet comprising obtaining a functionally functional rare earth permanent magnet with reduced eddy current loss.