JP3695964B2 - Rare earth magnetic powder for bonded magnet and method for producing the same - Google Patents
Rare earth magnetic powder for bonded magnet and method for producing the same Download PDFInfo
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- JP3695964B2 JP3695964B2 JP31466598A JP31466598A JP3695964B2 JP 3695964 B2 JP3695964 B2 JP 3695964B2 JP 31466598 A JP31466598 A JP 31466598A JP 31466598 A JP31466598 A JP 31466598A JP 3695964 B2 JP3695964 B2 JP 3695964B2
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims description 64
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- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 66
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 63
- 239000013078 crystal Substances 0.000 claims description 56
- 239000000843 powder Substances 0.000 claims description 56
- 239000002245 particle Substances 0.000 claims description 38
- 229910052751 metal Inorganic materials 0.000 claims description 34
- 239000002184 metal Substances 0.000 claims description 33
- 239000000203 mixture Substances 0.000 claims description 20
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- 238000010899 nucleation Methods 0.000 claims description 17
- 150000001768 cations Chemical class 0.000 claims description 15
- 230000008018 melting Effects 0.000 claims description 15
- 238000002844 melting Methods 0.000 claims description 15
- 150000002500 ions Chemical class 0.000 claims description 13
- 229910052723 transition metal Inorganic materials 0.000 claims description 13
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- 229910052788 barium Inorganic materials 0.000 claims description 6
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- 238000005324 grain boundary diffusion Methods 0.000 claims 2
- 238000001947 vapour-phase growth Methods 0.000 claims 1
- 238000000034 method Methods 0.000 description 35
- 230000005291 magnetic effect Effects 0.000 description 19
- 238000010438 heat treatment Methods 0.000 description 10
- 239000002994 raw material Substances 0.000 description 10
- 238000001816 cooling Methods 0.000 description 8
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- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 230000005294 ferromagnetic effect Effects 0.000 description 5
- 238000005470 impregnation Methods 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 230000005381 magnetic domain Effects 0.000 description 5
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- 229910052752 metalloid Inorganic materials 0.000 description 3
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- 239000001301 oxygen Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000006356 dehydrogenation reaction Methods 0.000 description 2
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- 239000001257 hydrogen Substances 0.000 description 2
- 238000001746 injection moulding Methods 0.000 description 2
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- 238000004544 sputter deposition Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
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- 241001669696 Butis Species 0.000 description 1
- -1 Ca metal Chemical class 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
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- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910000941 alkaline earth metal alloy Inorganic materials 0.000 description 1
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- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
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- 238000007740 vapor deposition Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
- H01F1/0573—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes obtained by reduction or by hydrogen decrepitation or embrittlement
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- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Hard Magnetic Materials (AREA)
- Compounds Of Iron (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Powder Metallurgy (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、核生成型の保磁力発生機構を有するボンド磁石用希土類磁性粉末及びその製造方法に関する。
【０００２】
【従来の技術】
保磁力の発生機構がピンニング型の希土類磁性粉末（例：Ｓｍ2Ｃｏ17）は、所定組成の溶解インゴットを粉砕するだけでボンド磁石用のＳｍ2Ｃｏ17磁性粉末を得ることができる。一方、ニュークレーション型の希土類磁性粉末（例：Ｎｄ2Ｆｅ14Ｂ）は、基本的に粉末粒子中の結晶粒径を単磁区粒子径以下にしなければ、実用的な保磁力が発生しない。そのため、粉末粒子中のＮｄ2Ｆｅ14Ｂ結晶粒径が単磁区粒子径以下となるような製法として、超急冷法やＨＤＤＲ（Hydrogenation(水素化)−Decomposition(相分解)−Dehydrogenation(脱水素化)−Recombination(再結合)）法が採用されている。
【０００３】
【発明が解決しようとする課題】
しかしながら、超急冷法やＨＤＤＲ法は、製造設備に係る投資費用が重く、また製造条件が厳しくコストが高いという短所がある。
【０００４】
本発明の目的は、磁気特性が高く、安価に製造されるボンド磁石用の希土類磁性粉末及びその製造方法を提供することである。
【０００５】
【課題を解決するための手段】
本発明による核生成型の保磁力発生機構を有するボンド磁石用希土類磁性粉末は、第１の視点において、複数のＲ2ＴＭ14Ｂ（Ｒ：Ｙを含む希土類元素、ＴＭ：遷移金属元素）相を含む多結晶粒子の結晶粒界に、Ｃａ，Ｓｒ，Ｂａのうち少なくとも一種からなるアルカリ土類金属が金属又は合金状態で粒界拡散して該Ｒ 2 ＴＭ 14 Ｂ相に隣接する界面に結晶を形成してなるボンド磁石用希土類磁性粉末であって、前記アルカリ土類金属が、前記界面に形成された前記結晶において陽イオンとして存在し、前記陽イオンは、前記Ｒ 2 ＴＭ 14 Ｂ相の最外殻に位置する前記希土類元素イオンに隣接し、且つ該希土類元素イオンの 4f 電子雲が伸びている方向に位置する、ことを特徴とする。
本発明による核生成型の保磁力発生機構を有するボンド磁石用ボンド磁石用希土類磁性粉末は、第２の視点において、前記界面において、前記アルカリ土類金属の結晶が、格子定数ａ＝０．４７〜０．５７ｎｍ（４．７〜５．７オングストローム）の範囲で存在することを特徴とする。
本発明による核生成型の保磁力発生機構を有するボンド磁石用ボンド磁石用希土類磁性粉末は、第３の視点において、前記複数のＲ 2 ＴＭ 14 Ｂ相を含む多結晶粒子１００重量部当たり、前記アルカリ土類金属０．５〜７重量部を含むことを特徴とする。
本発明による核生成型の保磁力発生機構を有するボンド磁石用ボンド磁石用希土類磁性粉末は、第４の視点において、複数のＲ 2 ＴＭ 14 Ｂ（Ｒ：Ｙを含む希土類元素、ＴＭ：遷移金属元素）相を含有する多結晶粒子である磁性粉末にＣａ，Ｓｒ，Ｂａのうち少なくとも一種からなるアルカリ土類金属を添加し、混合して該アルカリ土類金属を付着させ、該アルカリ土類金属が付着した前記粉末を前記Ｒ 2 ＴＭ 14 Ｂ相の融点以下かつ該アルカリ土類金属の融点以下の温度で熱処理して、前記アルカリ土類金属を前記多結晶粒子の結晶粒界に金属又は合金状態で粒界拡散させて前記Ｒ 2 ＴＭ 14 Ｂ相に隣接する界面に結晶を析出させ、前記アルカリ土類金属が、前記界面に形成された前記結晶において陽イオンとして存在し、前記陽イオンは、前記Ｒ 2 ＴＭ 14 Ｂ相の最外殻に位置する前記希土類元素イオンに隣接し、且つ該希土類元素イオンの 4f 電子雲が伸びている方向に位置する、ことを特徴とする。
本発明による核生成型の保磁力発生機構を有するボンド磁石用ボンド磁石用希土類磁性粉末は、第５の視点において、前記アルカリ土類金属を添加する前の前記磁性粉末の平均粒度が３〜４００μｍの範囲であり、前記アルカリ土類金属の平均粒度が０．５〜３ｍｍの範囲であることを特徴とする。
本発明による核生成型の保磁力発生機構を有するボンド磁石用ボンド磁石用希土類磁性粉末は、第６の視点において、複数のＲ 2 ＴＭ 14 Ｂ（Ｒ：Ｙを含む希土類元素、ＴＭ：遷移金属元素）相を含有する多結晶粒子である磁性粉末に、気相成膜法を用いて、該粉末表面にＣａ，Ｓｒ，Ｂａのうち少なくとも一種からなるアルカリ土類金属を付着させる工程と、前記付着後、前記アルカリ土類金属が付着した前記粉末を前記Ｒ 2 ＴＭ 14 Ｂ相の融点以下かつ該アルカリ土類金属の融点以下の温度で熱処理して、前記アルカリ土類金属を前記多結晶粒子の結晶粒界に金属又は合金状態で粒界拡散させて前記Ｒ 2 ＴＭ 14 Ｂ相に隣接する界面に結晶を析出させ、前記アルカリ土類金属が、前記界面に形成された前記結晶において陽イオンとして存在し、前記陽イオンは、前記Ｒ 2 ＴＭ 14 Ｂ相の最外殻に位置する前記希土類元素イオンに隣接し、且つ該希土類元素イオンの 4f 電子雲が伸びている方向に位置する、ことを特徴とする。
【０００６】
本発明による希土類磁性粉末の製造方法は、Ｒ2ＴＭ14Ｂ（Ｒ：Ｙを含む希土類元素、ＴＭ：遷移金属元素）相を含有する磁性粒子から主としてなる粉末にアルカリ土類金属を含浸する工程を有する。
【０００７】
なお、本明細書において、「アルカリ土類金属が存在している」とは、特段のことわり書きがなく且つその記載の趣旨に反しない限り、アルカリ土類金属が単体として存在している場合だけでなく、合金又はこれらの混合形態で存在している場合も含んでいる。
【０００８】
本発明者らは、Ｎｄ2+xＦｅ14Ｂ合金（但し、０＜ｘ≦０．３）を溶解した後、そのインゴットを所定の粒度になるように粉砕して希土類粉末を作製し、その粉砕粉末にＣａ金属を粒子表面から含浸させた場合、Ｎｄ金属を含浸させた場合よりも保磁力が大幅に向上することを知見し、さらに研究を進めた結果、本発明を完成するに至ったものである。
【０００９】
本発明によれば、従来の技術のようにニュークレーション型（核生成型）の希土類磁性粉末を無理やり結晶粒径を小さくしたピンニング型の希土類磁性粉末にせずに、ニュークレーション型の特徴をそのまま生かした高保磁力のＲ2ＴＭ14Ｂ系希土類磁性粉末を提供することができる。加えて、本発明によれば、Ｒ2ＴＭ14Ｂ系希土類磁性粉末の製造工程が簡素化されているため、製造コストが低減され、品質も安定化される。
【００１０】
［整合の成立による結晶磁気異方性の向上］
ここで、図１、図２（Ａ）及び図２（Ｂ）を参照して、Ｒ2ＴＭ14Ｂからなる主相（強磁性相）と粒界相（Ｃａ金属）がその界面で整合している場合と、整合していない場合とで、界面近傍における結晶磁気異方性の分布の相違を説明する。図１又は図２（Ａ）及び図２（Ｂ）において、横軸の「最外殻」とは主相の最も外側の原子層の位置を示し、「第２層」、「第３層」とはそれぞれ最外殻位置から内部に向かって数えて２番目、３番目の原子層の位置を示す。第ｎ層とは最外殻からの距離が遠く、界面からの影響が無視できる位置を示す。図１のグラフ中、縦軸は主相の一軸異方性定数Ｋ1（結晶磁気異方性の強さを示す）の大きさを示し、Ｋ1の値が大きいほど主相の自発磁化の向きは磁化容易軸（ｃ軸）の方向で安定化する。また、図１中、実施例（本発明）は図２（Ａ）に示すように主相と粒界相が界面で整合している条件でのＫ1の計算値を示し、比較例は図２（Ｂ）に示すように粒界相の欠落などによって界面の不整合などがある場合のＫ1の計算値を示している。
【００１１】
図１を参照して、比較例においては、界面からの距離によって異方性定数Ｋ1の大きさが大きく変化し、最外殻におけるＫ1の値が内部に比べて著しく低下している。一方、実施例においては、界面からの距離によってＫ1の大きさがあまり変化せず、むしろ最外殻相においてＫ1が上昇している。従って、比較例によれば、最外殻において逆磁区の核生成に要するエネルギーが局所的に低下して核生成と磁化反転が容易になるため、磁石の保磁力が低下する。一方、実施例によれば、最外殻におけるＫ1がむしろ内部より高いため、界面における逆磁区の核生成が抑制され、その結果磁石の保磁力が増加する。
【００１２】
【発明の実施の形態】
以下、本発明の好ましい実施の形態を説明する。
【００１３】
本発明による核生成型の保磁力発生機構を有するボンド磁石用希土類磁性粉末は、複数のＲ2ＴＭ14Ｂ相を含む多結晶粒子の粒界にＣａ，Ｓｒ，Ｂａのうち少なくとも一種からなるアルカリ土類金属が拡散して、Ｒ2ＴＭ14Ｂ（Ｒ：Ｙを含む希土類元素、ＴＭ：遷移金属元素）相との界面に、Ｃａ金属などのアルカリ土類金属がＲ2ＴＭ14Ｂ結晶相と整合して存在している。ここで、上記アルカリ土類金属がＣａである場合について、粉末の保磁力が発現ないし向上する理由を説明する。
【００１４】
Ｒ2ＴＭ14Ｂ結晶粒界にＣａ金属を拡散させたＲ2ＴＭ14Ｂ系磁性粒子においては、Ｒ2ＴＭ14Ｂ結晶粒子に最隣接する粒界中のＣａが、Ｒ2ＴＭ14Ｂ結晶粒子の最外接ＴＭ位置にｃ軸方向の結晶場を作るようにイオン化して配置されていると考えられる。このような特定配置によって、Ｒ2ＴＭ14Ｂ結晶粒子の最外接ＴＭはｃ軸方向の結晶場を感じ、この結果、このＴＭサイトからの逆磁区の発生が防止され、保磁力が発現する。
【００１５】
上記Ｒとして代表的にはＮｄである。ところで、Ｎｄ2ＴＭ14Ｂ系焼結磁石において、Ｎｄ2ＴＭ14Ｂ結晶粒子の周りに存在するＮｄは、ｆｃｃ（面心立方構造）構造をとり、その格子定数は５．２Ａ（オングストローム）である。本発明において、含浸する金属は、このＮｄの結晶構造と近い結晶構造を有し、このＮｄの格子定数に近い格子定数をもったものが好ましい。このような好ましい金属として、上記のＣａ（ｆｃｃ、ａ＝５．５８２Ａ）等の金属、あるいは、アルカリ土類金属同士、または他属の金属を混合した合金（Ｃａ−Ａｌ等）がある。例えば、Ｓｒ（ａ＝６．０８５Ａ）と、Ｂａ（ａ＝５．０２５Ａ）を所定比率で合金化して、好ましい結晶構造及び格子定数を得ることができる。アルカリ土類金属としては、上記のＣａ、…等のメタル、Ｓｒ−Ｂａ等の合金が用いられる。
【００１６】
このように、Ｒ2ＴＭ14Ｂ相との界面においてＲ2ＴＭ14Ｂ相と整合する相が立方晶系の構造をとり、特に格子定数ａ＝４．７〜５．７Ａ（オングストローム）の範囲で存在することが好ましい。バルク化されたＲ2ＴＭ14Ｂ系のボンド磁石又は焼結磁石などにおいても同様である。
【００１７】
本発明によるボンド磁石用希土類磁性粉末の好ましい実施の形態においては、アルカリ土類金属がＲ2ＴＭ14Ｂ相との界面において立方晶系の構造をとり格子定数ａ＝４．７〜５．７Ａ（オングストローム）の範囲で存在する。上記アルカリ土類金属は、上記粉末中に好ましくは単体、アルカリ土類金属同士又はそれ以外との合金又はこれらが混合した形態で存在する。
【００１８】
界面の整合性の効果を得るには、Ｒ2ＴＭ14Ｂ相（以下、これを「主相」という）の界面近傍のたかだか数原子層の範囲でＣａ金属などのアルカリ土類金属（以下、これを「粒界相」という）結晶構造が立方晶系構造になっていればよい。立方晶系構造としては、面心立方構造、ホタル石型構造、ＮａＣｌ型構造等があげられ、特に、Ｎｄの結晶構造と同様の面心立方構造は好ましい。また、主相は一般に粒界相よりも早く形成されており、主相を構成する結晶粒は単結晶になっているため、主相と粒界相が整合していることにより、結晶粒内部から外殻に至るまで結晶粒内の結晶磁気異方性が高くなり、高保磁力が得られる。
【００１９】
上記の主相と粒界相の界面における原子同士の位置関係をさらに理想的に制御するには、主相と粒界相の結晶学的方位関係を特定すればよい。ここで、記号[hkl]はミラー指数がh、k、lで表される結晶面に垂直な法線の方向を表す。また、記号[hkl]の添字「主相」又は「粒界相」とは、それぞれの方向が主相、または粒界相のものであることを示す。例えば、記号[001]主相は主相であるＲ2ＴＭ14Ｂ相のｃ軸の方向を表している。一組の方向の間に記された記号「//」は、これらの方向が互いに平行であることを示す。
【００２０】
次に、記号(hkl)はミラー指数がh、k、lで表される結晶面を表し、添字で記された「主相」、「粒界相」と、記号「//」の意味するところは方向の場合と同じである。ここで、同一の相についての方向と結晶面の表記においては、用いられるミラー指数は一般化された指数ではなく、特定の結晶方向、ないし結晶面を示している。
【００２１】
例えば、下記に示すミラー指数は粒界相の固定されたx、y、z座標に基づいた指数であり、いいかえれば(221)面と(212)面は厳密に区別される。このような表記方法によって、主相と粒界相の空間的な方位関係は厳密に規定される。
【００２２】
【化１】
界面における特定の結晶方位関係が磁石の磁気特性を向上させる理由は以下の通りである。すなわち、主相の界面近傍では、主相の結晶磁気異方性を決めているＲ原子の周囲の結晶場が、隣接する粒界相の原子配列の影響を受けて変化する。粒界相の結晶方位が主相に対して、下記の(A)〜(E)の関係を有する場合、粒界相のＣａ金属と、主相中のＲ原子とが上記の結晶場の異方性を強める位置関係にあるため、主相の界面近傍での結晶磁気異方性が高まる。その結果、粒界近傍での逆磁区発生が困難となり、容易に磁化反転することができないため保磁力が向上すると考えられる。
【００２４】
【化２】
上記の説明において、主相中のＲ原子の結晶場に影響を与える粒界相の原子は、主相に隣接する界面の近傍の原子に限られる。したがって、本発明において、粒界相の結晶構造（上記の主相）と粒界相の方位関係は両相の界面の近傍のたかだか数原子層の範囲で成立していればよい。
【００２６】
この際に、主相と粒界相の成分元素、あるいは組成の違いによって両相の格子定数の比率が異なるために、結晶方位が若干ずれることもある。しかし、このずれの角度はたかだか５°以内であるため、たとえずれたとしても主相中のＲ原子の結晶場に与える影響は少なく、所期の効果を発現することができる。
【００２７】
本発明において、Ｃａなどのアルカリ土類金属以外に、粒界相として好ましい金属、合金は、室温よりも高く、かつ、主相の融点、または分解速度よりも低い融点、または分解温度を有し、熱処理によって主相の周りに拡散させることが容易なものである。また、粒界相を構成する原子は主相の最外殻原子に対して陽イオンとしてふるまい、主相の結晶磁気異方性を高めるものが好ましい。特に、少なくとも強磁性粒子に隣接する粒界相部分に陽イオン源を含む結晶を析出し、強磁性相に隣接する粒界相の結晶構造において、強磁性粒子の最外殻に位置する希土類元素イオンの4f電子雲が伸びている方向に陽イオンを位置させることが好ましい。
【００２８】
［微量添加元素の範囲］
本発明において、主相と粒界相との整合性を高めるためないし磁気特性を高めるために、主として金属元素又は半金属元素を微量に添加することは好ましい実施形態である。上記の微量添加元素は、粒界相に濃縮偏在して界面の濡れ性を高めたり、あるいは界面の不整合な位置に拡散して粒界相の格子定数を調整して界面エネルギーを下げ、界面の整合性を高める効果があり、その結果として磁石の保磁力が向上する。
【００２９】
上記の働きをする微量添加元素としては、粒界相中に固溶しうる元素が好ましく、例えば、Ｃ、Ｎ、Ａｌ、Ｓｉ、Ｐ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｇａ、Ｚｒ、Ｎｂ、Ｍｏ、これら以外の上述の金属元素などがあるが、以上に挙げた例は本発明の適用範囲を限定するものではない。上記の目的で添加する元素の添加量は、磁石全体に対する割合で１．０wt%以下で良好な磁石の残留磁束密度が得られ、０．０５wt%以上で所定の効果が得られるので、添加量の範囲は０．０５〜１．０wt%が好ましい。より好ましい範囲は０．１〜０．５wt%である。微量添加元素の添加方法は、母合金に初めから含有させる、粉末冶金的手法で後から添加するなど、磁石の製造方法に応じて適宜選択できる。また、上記微量元素などが主相（強磁性相）に侵入し又は主相を構成する元素を置換してもよい。
【００３０】
本発明によるボンド磁石用希土類磁性粉末は、その好ましい実施形態において、１つのＲ2ＴＭ14Ｂ結晶を含む粒子にＣａを含浸させ、このＲ2ＴＭ14Ｂ結晶の周囲の少なくとも一部、好ましくは全周がＣａを含む粒界相で覆われたものである。
【００３１】
あるいは、複数のＲ2ＴＭ14Ｂ結晶を含む粒子（Ｒ2ＴＭ14Ｂ多結晶粒子）にＣａを含浸させることにより、多結晶の粒界にＣａを拡散させ、各Ｒ2ＴＭ14Ｂ結晶の周囲の少なくとも一部、好ましくは全周がＣａを含む粒界相で覆われたものである。図３は、多結晶粉末（後者）の場合の結晶組織を説明するための図である。
【００３２】
Ｒ2ＴＭ14Ｂ結晶の界面が十分に覆われ、保磁力が向上された粉末を、Ｒ2ＴＭ14Ｂ（Ｒ：Ｙを含む希土類元素、ＴＭ：遷移金属元素）相を含有する磁性粒子１００重量部当たり、好ましくは０．５〜７重量部の前記アルカリ土類金属を含浸することにより得ることができる。さらに好ましくは、１〜７重量部の前記アルカリ土類金属を含浸する。
【００３３】
本発明によれば、Ｒ2ＴＭ14Ｂ（Ｒ：Ｙを含む希土類元素、ＴＭ：遷移金属元素）相を含有する磁性粒子から主としてなる粉末に、アルカリ土類金属を含浸することにより、１７ｋＯｅ以上、さらには２０ｋＯｅ以上の保磁力（iHc）を有するボンド用希土類磁性粉末を得ることができる。
【００３４】
本発明によるボンド磁石用希土類磁性粉末においては、Ｒ2ＴＭ14Ｂ（Ｒ：Ｙを含む希土類元素、ＴＭ：遷移金属元素）相の他に、Ｂ−ｒｉｃｈ相、Ｒ−ｒｉｃｈ相が含まれていてもよい。また、Ｒ−ＴＭ−Ｏ相、Ｒ3ＴＭ相が共存していてもよい。特に、Ｒ−ＴＭ−Ｏ相がＲ2Ｆｅ14Ｂ相に整合して共存していることが好ましい。Ｒ−（Ｆｅ，Ｃｏ）−Ｂ相が存在する場合、Ｒ3ＴＭ相がＲ−（Ｆｅ，Ｃｏ）−Ｂ相に整合して共存していることが好ましい。
【００３５】
本発明によるボンド磁石用希土類磁性粉末の製造方法は、その好ましい実施形態において、下記の工程を含む。
【００３６】
（１） 所定成分の原料からインゴットを溶製する。
（２） インゴットを粉砕して、原料粉末（含浸前粉末）を得る。
（３） 上記（２）の粉末に、Ｃａなどのアルカリ土類金属を含浸し、Ｒ2ＴＭ14Ｂ相とアルカリ土類金属が整合した粉末を得る。
【００３７】
さらに、上記（３）の粉末を用いて、下記の工程からボンド磁石を製造することができる。
【００３８】
（４） 上記（３）の粉末に、ボンド、助剤を添加し、混練する。
（５） 混練物をプレス成形する。
（６） 成形体を加熱硬化する。
（７） 硬化体の表面をコーティングをする。
【００３９】
本発明によれば、原料粉末（含浸前粉末）として、低コストの鋳造法によって得られるインゴットを粉砕したもの（鋳造インゴット粉砕粉末）を用いても、高保磁力の磁性粉末（含浸粉末）を得ることができる。他に、原料粉末（含浸前粉末）として、溶湯急冷法による薄板粉砕粉末、超急冷法、直接還元拡散法、HDDR法（水素含有崩壊法）、アトマイズ法などの公知の方法によって得られた粉末の一種又は二種以上を選択して用いることができる。
【００４０】
次に、好ましい出発原料（原料粉末又はその母合金、或いは母合金の原料組成）の組成を説明する。
【００４１】
Ｒ中、ＮｄとＰｒの合計を５０at%以上とすることにより、得られる磁石の保磁力と残留磁化が向上するので好ましい。また、保磁力を向上させるためにＮｄの一部をＤｙやＴｂで置換することも好ましい。ＴＭは、特にＦｅ又はＣｏが好ましい。ＴＭ中のＦｅが５０at%以上で保磁力と残留磁化が向上するので好ましい。この他、さまざまな目的で上記以外の添加元素を添加することも可能である。
【００４２】
Ｒ2ＴＭ14Ｂ相を構成するＲ、ＴＭ及びＢに係る好ましい組成について説明する。好ましくは、組成範囲をＲ:８〜３０at%、Ｂ:２〜４０at%、残部主としてＴＭとする。また、好ましくは、組成範囲をＲ:８〜３０at%、Ｂ:２〜４０at%、Ｆｅ:４０〜９０at%、Ｃｏ:50at%以下とする。さらに、好ましくは組成範囲をＲ:１１〜５０at%、Ｂ:５〜４０at%、残部主としてＴＭとする。より好ましくは、組成範囲をＲ:１２〜１６at%、Ｂ:６．５〜９at%、残部主としてＴＭとする。一層好ましくは、組成範囲をＲ:１２〜１４at%、Ｂ:７〜８at%、残部主としてＴＭとする。また、用いる原料は必ずしも単一の所要組成からなる必要はなく、異なる組成の合金を粉砕した後、混合し所要組成に調整して用いることもできる。
【００４３】
また、主相において、Ｂの一部ないし大部分がＣ，Ｓｉ，Ｐなどのいわゆる半金族元素で置換されるように、これらの半金属元素を添加してもよい。例えば、ＢをＣで置換する場合、Ｂ1-xＣx；但し好ましくはｘは少なくとも０．８まで可である。
【００４４】
次に、原料粉末（含浸前粉末）に対する、Ｃａ金属などのアルカリ土類金属の好ましい含浸量（添加量）を説明する。好ましくは、Ｒ−ＴＭ−Ｂ（Ｒ：Ｙを含む希土類元素、但し０＜ｘ≦０．３、ＴＭ：遷移金属元素）１００重量部当たり、アルカリ土類金属０．５〜７（さらに好ましくは１〜５）重量部を含浸する。この実施の形態によれば、安価なアルカリ土類金属の添加によって、高価な希土類の使用量を制限しても、高い保磁力を得ることができる。
【００４５】
Ｃａ金属などのアルカリ土類金属の含浸方法として、好ましくは、Ｒ2ＴＭ14Ｂ（Ｒ：Ｙを含む希土類元素、ＴＭ：遷移金属元素）相を含有する磁性粒子から主としてなる粉末にアルカリ土類金属粉末を添加し、混合し、Ｒ2ＴＭ14Ｂの融点以下の温度で熱処理してアルカリ土類金属をＲ2ＴＭ14Ｂ相の界面に沿って拡散させる。
【００４６】
上記実施の形態において、磁性粒子から主としてなる粉末の平均粒度が３〜４００μｍの範囲、一方アルカリ土類金属粉末の平均粒度が０．５〜３ｍｍ、さらには１〜３ｍｍの範囲とすることが好ましい。これによって、Ｒ2ＴＭ14Ｂ相の界面が十分な面積でアルカリ土類金属と整合する。
【００４７】
また別に、希土類磁性粉末にＣａ等のアルカリ土類金属を粒子表面から含浸させる方法としては、真空蒸着法、スパッターリング法、イオンプレーティング法、ＣＶＤ法、ＰＶＤ法などの気相成膜法によって、磁性粒粒子表面にＣａなどアルカリ土類金属を付着させた後、不活性ガス雰囲気中もしくは真空中で熱処理することにより磁性粉末内部まで上記Ｃａなどが粒界に沿って拡散浸透すると同時に、粒子表面上でも磁性原子と整合する（完全に結合する）。
【００４８】
上記熱処理の温度は、Ｒ2Ｆｅ14Ｂ相が溶けない温度（Ｒ＝Ｎｄの場合は＜１２００℃）で、しかもＣａ金属が十分に拡散する温度が好ましい。すなわちＣａ金属の融点は８５１℃であるため、熱処理温度としては、６００〜８００℃が好ましい。
【００４９】
Ｃａ金属がＲ2Ｆｅ14Ｂ相の界面において、面心立方構造をとるためには、熱処理後の冷却速度を１０〜２００℃/minの範囲内とすることが好ましい。このように冷却に十分時間をかけることにより、Ｃａ金属を含む液相状の粒界相が過冷却にならずに、冷却時に規則正しい結晶構造をとることが可能になる。粒界相が非晶質ではなく面心立方構造をとることにより、主相と粒界相の界面における原子同士の位置関係が規則正しくなり、両者の整合性が保たれる結果、界面が逆磁区発生の起点となる可能性が減少し、高保磁力が実現する。より好ましい焼結後の冷却速度の範囲は２０〜１００℃/minである。
【００５０】
またＣａ等のアルカリ土類金属は、非常に酸化しやすいために該金属を磁性粉末粒子に付着、含浸させた後は樹脂コーティングあるいはメッキコーティングさらにＴｉＮコーティングを行い、防錆処理を施すことが好ましい。
【００５１】
Ｃａ等のアルカリ土類金属は比較的融点（８５１℃）が低いため、Ｃａ等が含浸されている本発明による希土類磁性粉末をバルク化するには、ボンドを用いることが好ましい。
【００５２】
ボンド磁石の成形工程としては、圧縮成形、押出成形、射出成形、圧延成形など、公知の工程を用いることができる。また、ボンドしては、例えば、エポキシ樹脂、ナイロン樹脂、ゴムなどの種々の材料を用いることができる。
【００５３】
得られたボンド磁石を、必要に応じて、洗浄、面取り、電解メッキ、無電解メッキ、電着塗装、樹脂塗装などの表面処理を施し、着磁をして永久磁石として用いることができる。
【００５４】
また、本発明による希土類磁性粉末を金型中に給粉し、磁界中で配向しながら圧縮成形してもよい。この際に、例えば特開平8-20801号公報に開示されているように、合金粉末の流動性を高めて給粉を容易にする目的で合金粉末にバインダーを添加してスプレー造粒を行うことも好ましい。あるいは、特開平6-77028号公報に開示されているように、合金粉末にバインダーを加えて金属射出成形法によって複雑形状品の成形を行うことも可能である。
【００５５】
本発明によるＲ2ＴＭ14Ｂ系磁性粒子から主としてなる粉末へＣａ金属等を含浸する技術は、Ｒ2ＴＭ14Ｂ系の薄膜磁石の保磁力向上の手段としても利用できる。例えば、真空蒸着法やスパッターリング法によって作製したＮｄ2Ｆｅ14Ｂ系の薄膜磁石の上にＣａなどのアルカリ土類金属を付着させて磁気特性を一段と向上させることもできる。
【００５６】
なお、本明細書において、数値範囲に関する記載は、その上下限値のみならず、その数値範囲に含まれる任意の中間値を含むものとする。
【００５７】
【実施例】
以上説明した本発明の実施の形態をさらに明確化するために、本発明の一実施例を説明する。
【００５８】
［実施例１］
表１に示す成分からなる原料をＡｒガス雰囲気中で高周波溶解してインゴットを作製した。このインゴットを粗粉砕、さらにジェットミル粉砕して表２に示す平均粒径まで粉砕した。各粒度の磁性粉末１００重量部に顆粒状（〜１ｍｍ）のＣａ金属を４重量部添加して混合した後、真空中で表４に示す温度で２時間熱処理した。
【００５９】
得られた磁性粉末の残留酸素量と磁気特性を表３に示す。比較のため、下記の超急冷法によって得られた粉末（商品名「ＭＱＰ」、米ＭＱＩ社製）と、下記のＨＤＤＲ法によって得られた粉末の組成を表３に、製造条件と、得られた粉末の残留酸素量及び磁気特性を合わせて表４に示す。
【００６０】
［比較例：超急冷法］
下記の表３に示す組成のインゴットを石英管ノズル内においてＡｒガス中で高周波溶解した後、Ｃｕ製の回転ロール上に溶湯を噴射して超急冷リボンを得、得られたリボンを平均粒径２５０μｍに粉砕した後、Ａｒガス中で６５０℃、１５分の熱処理をした。
【００６１】
［比較例：ＨＤＤＲ法］
下記の表３に示す組成のインゴットを水素中で８００℃、２時間、水素化処理した後、続いて真空中で８００℃、１時間、脱水素処理し、得られた磁石粉末を平均粒径４００μｍに粉砕した。
【００６２】
【表１】
インゴットの原料組成
【表２】
磁性粉末の平均粒径
【表３】
超急冷法、ＨＤＤＲ法による粉末の組成（ｗｔ％）
【表４】
製造条件と磁気特性
表４に示したように、実施例１に係る方法によれば、比較例である超急冷法、ＨＤＤＲ法によって得られる粉末と比較しても、同等以上の粉末が得られた。実施例１に係る方法は、超急冷法及びＨＤＤＲ法と比べて、工数が少なく低コストであるから、実施例１の方法によって得られた粉末は工業上きわめて有用である。また、実施例１においては、平均粒度が小さい方が、高い磁気特性が得られた。サンプルＮｏ．９のように、結晶粒径（平均粒度）が４００μｍを超える場合には、Ｃａが結晶粒界に沿って含浸していくことが困難となり、保磁力が比較的小さくなると考えられる。
【００６７】
［実施例２］
実施例１の各平均粒径の磁性粉末にＣａ金属を５μｍの膜厚になるように真空蒸着した後、真空中で表５に示す温度で２時間熱処理した。製造条件と得られた磁性粉末の残留酸素量及び磁気特性を表５に示す。
【００６８】
【表５】
製造条件と磁気特性
表５に示したように、真空蒸着法のような気相成膜法によっても、高保磁力の粉末が得られた。
【００７０】
［実施例３：実施例３中、サンプル１及び３〜６は参考例である。］
実施例１の平均粒径が４．１μｍのインゴットＮｏ．２の粉砕粉１００重量部に、表６に示す含浸物質を４重量部添加して混合した後、真空中で表６に示す温度で２時間熱処理した。得られた磁性粉末の磁気特性を表６に示す。表６に示したように、実施例３に係る方法によればアルカリ土類金属として合金を用いた場合においてもすぐれた磁気特性を有する磁性粉末が得られた。
【００７１】
【表６】
【００７２】
【発明の効果】
本発明によって得られるボンド磁石用希土類磁性粉末は、従来の超急冷法、ＨＤＤＲ法によって得られる粉末と比較しても、磁気特性にすぐれ、かつ、比較的簡単な製造方法で製造できる。このため、本発明の粉末を用いることにより、希土類ボンド磁石の製造コストを低減でき、安価で磁気特性の高い希土類ボンド磁石を提供することが可能である。本発明の粉末は、特に高保磁力材用の磁性粉末として有用となるものである。また、今後磁石寸法の小型化が一層要求される中で、本発明は、超小型のＮｄ2Ｆｅ14Ｂ系磁石の保磁力向上にも大いに役立つ技術を提供するものである。
【図面の簡単な説明】
【図１】界面からの距離と結晶磁気異方性の関係を説明するための図であって、白丸が実施例の一軸異方性定数Ｋ1、黒丸が比較例の一軸異方性定数Ｋ1を示す。
【図２】（Ａ）は主相と粒界相が整合している様子を示すモデル図、（Ｂ）は主相と粒界相の界面が整合していない様子を示すモデル図である。
【図３】本発明の一実施形態に係るボンド磁石用希土類磁性粉末（Ｒ2ＴＭ14Ｂ多結晶粉末）の結晶組織を説明するための図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rare earth magnetic powder for a bond magnet having a nucleation type coercive force generation mechanism and a method for producing the same.
[0002]
[Prior art]
Coercivity generation mechanism is pinning type rare earth magnetic powder (eg Sm2Co17) Sm for bonded magnets just by crushing a melted ingot of a predetermined composition2Co17Magnetic powder can be obtained. On the other hand, nucleation type rare earth magnetic powder (eg, Nd2Fe14In B), practical coercive force is not generated unless the crystal grain size in the powder particles is basically equal to or smaller than the single domain particle diameter. Therefore, Nd in the powder particles2Fe14As a manufacturing method in which the B crystal grain size is equal to or less than the single magnetic domain particle size, there are ultra-quenching method and HDDR (Hydrogenation (dehydrogenation) -Decomposition (dehydrogenation) -Recombination (recombination)) method. It has been adopted.
[0003]
[Problems to be solved by the invention]
However, the ultra-quenching method and the HDDR method have the disadvantages that the investment cost for manufacturing equipment is heavy, the manufacturing conditions are severe, and the cost is high.
[0004]
An object of the present invention is to provide a rare earth magnetic powder for a bonded magnet that has high magnetic properties and is manufactured at low cost, and a method for manufacturing the same.
[0005]
[Means for Solving the Problems]
According to the inventionFor bonded magnets with nucleation type coercive force generation mechanismRare earth magnetic powderIn the first perspective,Multiple R2TM14Of polycrystalline particles containing a B (R: Y rare earth element, TM: transition metal element) phasecrystalAlkaline earth metal composed of at least one of Ca, Sr, and Ba is present at the grain boundary.Grain boundary in metal or alloy stateDiffuseR 2 TM 14 A rare earth magnetic powder for a bond magnet formed by forming a crystal at an interface adjacent to the B phase, wherein the alkaline earth metal is present as a cation in the crystal formed at the interface, and the cation is: R 2 TM 14 Adjacent to the rare earth element ion located in the outermost shell of the B phase and of the rare earth element ion 4f Located in the direction where the electron cloud extends,It is characterized by that.
In a second aspect, the rare earth magnetic powder for a bonded magnet having a nucleation type coercive force generation mechanism according to the present invention is such that the alkaline earth metal crystal has a lattice constant a = 0.47 at the interface. It exists in the range of -0.57nm (4.7-5.7angstrom), It is characterized by the above-mentioned.
In a third aspect, the rare earth magnetic powder for a bond magnet having a nucleation type coercive force generation mechanism according to the present invention is a plurality of R 2 TM 14 The alkaline earth metal is contained in an amount of 0.5 to 7 parts by weight per 100 parts by weight of the polycrystalline particles containing the B phase.
According to the fourth aspect of the present invention, there is provided a rare earth magnetic powder for a bond magnet having a nucleation type coercive force generation mechanism. 2 TM 14 An alkaline earth metal composed of at least one of Ca, Sr, and Ba is added to and mixed with magnetic powder that is polycrystalline particles containing a B (R: R rare earth element, TM: transition metal element) phase. The alkaline earth metal is adhered, and the powder to which the alkaline earth metal is adhered is the R 2 TM 14 Heat treatment is performed at a temperature not higher than the melting point of the B phase and not higher than the melting point of the alkaline earth metal, and the alkaline earth metal is diffused into the crystal grain boundaries of the polycrystalline particles in a metal or alloy state to cause the R 2 TM 14 Crystals are precipitated at the interface adjacent to the B phase, and the alkaline earth metal is present as a cation in the crystal formed at the interface, and the cation is the R 2 TM 14 Adjacent to the rare earth element ion located in the outermost shell of the B phase and of the rare earth element ion 4f The electron cloud is located in the extending direction.
According to the fifth aspect of the rare earth magnetic powder for a bonded magnet having a nucleation type coercive force generation mechanism according to the present invention, the average particle size of the magnetic powder before adding the alkaline earth metal is 3 to 400 μm. The average particle size of the alkaline earth metal is in the range of 0.5 to 3 mm.
According to the sixth aspect of the present invention, there is provided a rare earth magnetic powder for a bond magnet having a nucleation type coercive force generation mechanism. 2 TM 14 A magnetic powder, which is a polycrystalline particle containing a B (R: Y rare earth element, TM: transition metal element) phase, is formed on the powder surface using at least one of Ca, Sr, and Ba using a vapor phase film forming method. A step of adhering a kind of alkaline earth metal, and after the adhesion, the powder to which the alkaline earth metal is adhered is the R 2 TM 14 Heat treatment is performed at a temperature not higher than the melting point of the B phase and not higher than the melting point of the alkaline earth metal, and the alkaline earth metal is diffused into the crystal grain boundaries of the polycrystalline particles in a metal or alloy state to cause the R 2 TM 14 Crystals are precipitated at the interface adjacent to the B phase, and the alkaline earth metal is present as a cation in the crystal formed at the interface, and the cation is the R 2 TM 14 Adjacent to the rare earth element ion located in the outermost shell of the B phase and of the rare earth element ion 4f The electron cloud is located in the extending direction.
[0006]
The method for producing a rare earth magnetic powder according to the present invention comprises R2TM14A step of impregnating an alkaline earth metal into a powder mainly composed of magnetic particles containing a B (R: R rare earth element, TM: transition metal element) phase.
[0007]
In the present specification, “alkaline earth metal is present” means that the alkaline earth metal exists as a simple substance unless otherwise specified and contrary to the purpose of the description. Not an alloyOrThe case where it exists in these mixed forms is also included.
[0008]
We have Nd2 + xFe14Balloy(However, 0 <x ≦ 0.3), The ingot is pulverized to a predetermined particle size to produce a rare earth powder. When the pulverized powder is impregnated with Ca metal from the particle surface, the ingot is retained more than when impregnated with Nd metal. As a result of finding out that the magnetic force is greatly improved and further researching it, the present invention has been completed.
[0009]
According to the present invention, the nucleation type rare earth magnetic powder is not changed into a pinning type rare earth magnetic powder with a reduced crystal grain size as in the prior art, but the characteristics of the nucleation type are utilized as they are. High coercivity R2TM14B-based rare earth magnetic powder can be provided. In addition, according to the present invention, R2TM14Since the manufacturing process of the B-based rare earth magnetic powder is simplified, the manufacturing cost is reduced and the quality is stabilized.
[0010]
[Improvement of magnetocrystalline anisotropy by the formation of matching]
Here, referring to FIG. 1, FIG. 2 (A) and FIG. 2 (B), R2TM14The difference in the distribution of magnetocrystalline anisotropy in the vicinity of the interface between the case where the main phase (ferromagnetic phase) composed of B and the grain boundary phase (Ca metal) are matched at the interface and the case where they are not matched. explain. In FIG. 1 or FIG. 2 (A) and FIG. 2 (B), the “outermost shell” on the horizontal axis indicates the position of the outermost atomic layer of the main phase, and “second layer”, “third layer” And respectively indicate the positions of the second and third atomic layers counted from the outermost shell position toward the inside. The n-th layer indicates a position where the distance from the outermost shell is long and the influence from the interface can be ignored. In the graph of FIG. 1, the vertical axis represents the uniaxial anisotropy constant K of the main phase.1Indicates the magnitude of the magnetocrystalline anisotropy, and K1The larger the value of is, the more stable the direction of spontaneous magnetization of the main phase is in the direction of the easy axis (c-axis). Further, in FIG. 1, the example (the present invention) shows K under the condition that the main phase and the grain boundary phase are aligned at the interface as shown in FIG.1In the comparative example, as shown in FIG. 2B, K in the case where there is an interface mismatch due to a lack of a grain boundary phase or the like.1The calculated value is shown.
[0011]
Referring to FIG. 1, in the comparative example, the anisotropy constant K depends on the distance from the interface.1Greatly changes in size, and K in the outermost shell1The value of is significantly lower than the inside. On the other hand, in the embodiment, K is determined by the distance from the interface.1Does not change much, rather it is K in the outermost shell phase.1Is rising. Therefore, according to the comparative example, the energy required for nucleation of the reverse magnetic domain in the outermost shell is locally reduced to facilitate nucleation and magnetization reversal, so that the coercive force of the magnet is reduced. On the other hand, according to the embodiment, K in the outermost shell1However, since it is higher than the inside, nucleation of reverse magnetic domains at the interface is suppressed, and as a result, the coercive force of the magnet increases.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described.
[0013]
The rare earth magnetic powder for bonded magnets having a nucleation type coercive force generation mechanism according to the present invention comprises a plurality of R2TM14An alkaline earth metal consisting of at least one of Ca, Sr, and Ba diffuses into the grain boundaries of the polycrystalline particles containing the B phase, and R2TM14Alkaline earth metal such as Ca metal is R at the interface with the B (rare earth element including R: Y, TM: transition metal element) phase.2TM14It is consistent with the B crystal phase. Here, the reason why the coercive force of the powder is expressed or improved when the alkaline earth metal is Ca will be described.
[0014]
R2TM14R in which Ca metal is diffused in the B grain boundary2TM14For B-based magnetic particles, R2TM14Ca in the grain boundary nearest to the B crystal grain is R2TM14It is considered that the B crystal grains are ionized so as to form a crystal field in the c-axis direction at the outermost TM position of the B crystal grains. With such a specific arrangement, R2TM14The outermost TM of the B crystal particles feels a crystal field in the c-axis direction. As a result, the generation of reverse magnetic domains from this TM site is prevented, and coercive force is expressed.
[0015]
R is typically Nd. By the way, Nd2TM14For B-based sintered magnets, Nd2TM14Nd present around the B crystal grains has an fcc (face-centered cubic structure) structure, and its lattice constant is 5.2 A (angstrom). In the present invention, the impregnated metal preferably has a crystal structure close to the crystal structure of Nd and has a lattice constant close to that of Nd. As such a preferable metal, a metal such as the above-mentioned Ca (fcc, a = 5.582A), an alkaline earth metal, or an alloy mixed with a metal of another genus (Ca-Al, etc.)Butis there. For example, Sr (a = 6.085A) and Ba (a = 5.025A) can be alloyed at a predetermined ratio to obtain a preferable crystal structure and lattice constant. Examples of alkaline earth metals include the above metals such as Ca,..., And alloys such as Sr—Ba.ButUsed.
[0016]
Thus, R2TM14R at the interface with B phase2TM14It is preferable that the phase matching with the B phase has a cubic structure, and particularly exists in the range of the lattice constant a = 4.7 to 5.7 A (angstrom). Bulkized R2TM14The same applies to B-type bonded magnets or sintered magnets.
[0017]
In a preferred embodiment of the rare earth magnetic powder for bonded magnets according to the present invention, the alkaline earth metal is R.2TM14It has a cubic structure at the interface with the B phase and exists in the range of the lattice constant a = 4.7 to 5.7 A (angstrom). The alkaline earth metal is preferably a simple substance in the powder, an alloy with alkaline earth metals or the other.OrThese exist in a mixed form.
[0018]
To obtain the effect of interface consistency, R2TM14Alkaline earth metal such as Ca metal (hereinafter referred to as “grain boundary phase”) crystal structure is cubic in the range of at most several atomic layers in the vicinity of the interface of the B phase (hereinafter referred to as “main phase”) It only needs to be structured. Examples of the cubic structure include a face-centered cubic structure, a fluorite-type structure, an NaCl-type structure, and the like. Particularly, a face-centered cubic structure similar to the crystal structure of Nd is preferable. In addition, the main phase is generally formed earlier than the grain boundary phase, and the crystal grains constituting the main phase are single crystals. The crystal magnetic anisotropy in the crystal grains increases from the core to the outer shell, and a high coercive force is obtained.
[0019]
In order to more ideally control the positional relationship between atoms at the interface between the main phase and the grain boundary phase, the crystallographic orientation relationship between the main phase and the grain boundary phase may be specified. Here, the symbol [hkl] represents the direction of the normal line perpendicular to the crystal plane whose Miller index is represented by h, k, and l. The subscript “main phase” or “grain boundary phase” of the symbol [hkl] indicates that the respective directions are those of the main phase or the grain boundary phase. For example, the symbol [001] main phase is the main phase R2TM14The direction of the c-axis of the B phase is shown. The symbol “//” between a set of directions indicates that these directions are parallel to each other.
[0020]
Next, the symbol (hkl) represents the crystal plane whose Miller index is represented by h, k, l, and means “main phase”, “grain boundary phase” indicated by subscripts, and the symbol “//”. However, it is the same as the direction. Here, in the notation of the direction and crystal plane for the same phase, the Miller index used is not a generalized index, but indicates a specific crystal direction or crystal plane.
[0021]
For example, the Miller index shown below is an index based on x, y, and z coordinates with fixed grain boundary phases. In other words, the (221) plane and the (212) plane are strictly distinguished. By such a notation method, the spatial orientation relationship between the main phase and the grain boundary phase is strictly defined.
[0022]
[Chemical 1]
The reason why the specific crystal orientation relationship at the interface improves the magnetic properties of the magnet is as follows. That is, in the vicinity of the interface of the main phase, the crystal field around the R atom that determines the magnetocrystalline anisotropy of the main phase changes under the influence of the atomic arrangement of the adjacent grain boundary phase. When the crystal orientation of the grain boundary phase has the following relationships (A) to (E) with respect to the main phase, the Ca metal in the grain boundary phase and the R atom in the main phase differ from each other in the above crystal field. Due to the positional relationship that enhances the directivity, the magnetocrystalline anisotropy near the interface of the main phase increases. As a result, it is considered difficult to generate a reverse magnetic domain in the vicinity of the grain boundary, and the magnetization cannot be easily reversed, so that the coercive force is improved.
[0024]
[Chemical 2]
In the above description, the atoms in the grain boundary phase that affect the crystal field of R atoms in the main phase are limited to those in the vicinity of the interface adjacent to the main phase. Therefore, in the present invention, the crystal structure of the grain boundary phase (the main phase) and the orientation relation between the grain boundary phases may be established within the range of several atomic layers in the vicinity of the interface between the two phases.
[0026]
At this time, since the ratio of the lattice constants of both phases differs depending on the component elements of the main phase and the grain boundary phase, or the composition, the crystal orientation may be slightly shifted. However, since the angle of this shift is at most 5 °, even if it is shifted, there is little influence on the crystal field of R atoms in the main phase, and the desired effect can be expressed.
[0027]
In the present invention, in addition to alkaline earth metals such as Ca, preferred metals and alloys as grain boundary phasesIsIt has a melting point higher than room temperature and a melting point or decomposition temperature lower than the melting point or decomposition rate of the main phase, and can be easily diffused around the main phase by heat treatment. Further, it is preferable that the atoms constituting the grain boundary phase behave as cations with respect to the outermost shell atoms of the main phase, and increase the magnetocrystalline anisotropy of the main phase. In particular, a crystal including a cation source is precipitated at least in the grain boundary phase portion adjacent to the ferromagnetic particle, and the rare earth element located in the outermost shell of the ferromagnetic particle in the crystal structure of the grain boundary phase adjacent to the ferromagnetic phase. It is preferable to place the cation in the direction in which the 4f electron cloud of the ion extends.
[0028]
[Range of trace added elements]
In the present invention, in order to enhance the consistency between the main phase and the grain boundary phase or to enhance the magnetic properties, it is a preferred embodiment that a metal element or a metalloid element is mainly added in a trace amount. The above trace additive elements are concentrated and unevenly distributed in the grain boundary phase to increase the wettability of the interface, or diffuse to an inconsistent position of the interface to adjust the lattice constant of the grain boundary phase, thereby lowering the interface energy. As a result, the coercive force of the magnet is improved.
[0029]
As the trace additive element having the above function, an element that can be dissolved in the grain boundary phase is preferable. For example, C, N, Al, Si, P, Ti, V, Cr, Mn, Fe, Co, Ni, There are Cu, Zn, Ga, Zr, Nb, Mo, the above-described metal elements other than these, and the examples given above do not limit the scope of application of the present invention. The additive amount of the element added for the above purpose is 1.0 wt% or less in proportion to the whole magnet, and a good residual magnetic flux density of the magnet is obtained, and a predetermined effect is obtained when 0.05 wt% or more. The range of 0.05 to 1.0 wt% is preferable. A more preferable range is 0.1 to 0.5 wt%. The addition method of the trace additive element can be appropriately selected according to the method of manufacturing the magnet, such as adding it to the mother alloy from the beginning or adding it later by a powder metallurgy technique. Further, the trace element or the like may enter the main phase (ferromagnetic phase) or replace an element constituting the main phase.
[0030]
In a preferred embodiment, the rare earth magnetic powder for bonded magnets according to the present invention has one R2TM14The particles containing B crystals are impregnated with Ca, and this R2TM14At least a part of the periphery of the B crystal, preferably the entire circumference, is covered with a grain boundary phase containing Ca.
[0031]
Alternatively, multiple R2TM14Particles containing B crystals (R2TM14B polycrystal particles) are impregnated with Ca to diffuse Ca into the polycrystalline grain boundary, and each R2TM14At least a part of the periphery of the B crystal, preferably the entire circumference, is covered with a grain boundary phase containing Ca. FIG. 3 is a diagram for explaining the crystal structure in the case of polycrystalline powder (the latter).
[0032]
R2TM14A powder in which the interface of the B crystal is sufficiently covered and the coercive force is improved is R2TM14It is preferably obtained by impregnating 0.5 to 7 parts by weight of the alkaline earth metal per 100 parts by weight of magnetic particles containing a B (R: Y rare earth element, TM: transition metal element) phase. it can. More preferably, 1 to 7 parts by weight of the alkaline earth metal is impregnated.
[0033]
According to the present invention, R2TM14By impregnating a powder mainly composed of magnetic particles containing a B (R: R rare earth element, TM: transition metal element) phase with an alkaline earth metal, a coercive force (iHc) of 17 kOe or more, further 20 kOe or more. Can be obtained.
[0034]
In the rare earth magnetic powder for bonded magnets according to the present invention, R2TM14In addition to the B (rare earth element including R: Y, TM: transition metal element) phase, a B-rich phase and an R-rich phase may be included. R-TM-O phase, RThreeThe TM phase may coexist. In particular, the R-TM-O phase is R2Fe14It is preferable that they coexist with the B phase. When R- (Fe, Co) -B phase is present, RThreeIt is preferable that the TM phase coexists with the R- (Fe, Co) -B phase.
[0035]
In a preferred embodiment, the method for producing a rare earth magnetic powder for a bonded magnet according to the present invention includes the following steps.
[0036]
(1) Ingot is melted from raw materials of predetermined components.
(2) The ingot is pulverized to obtain a raw material powder (pre-impregnation powder).
(3) The powder of (2) is impregnated with an alkaline earth metal such as Ca, and R2TM14A powder in which the B phase and the alkaline earth metal are matched is obtained.
[0037]
Furthermore, a bonded magnet can be manufactured from the following process using the powder of said (3).
[0038]
(4) A bond and an auxiliary agent are added to the powder of (3) and kneaded.
(5) Press molding the kneaded product.
(6) The molded body is cured by heating.
(7) The surface of the cured body is coated.
[0039]
According to the present invention, a magnetic powder (impregnated powder) having a high coercive force is obtained even when a material obtained by pulverizing an ingot obtained by a low-cost casting method (cast ingot pulverized powder) is used as the raw material powder (pre-impregnated powder). be able to. In addition, as raw material powder (pre-impregnation powder), powder obtained by a known method such as thin plate pulverized powder by molten metal quenching method, super quenching method, direct reduction diffusion method, HDDR method (hydrogen-containing decay method), atomization method, etc. One type or two or more types can be selected and used.
[0040]
Next, the composition of a preferable starting material (raw material powder or a mother alloy thereof, or a raw material composition of the mother alloy) will be described.
[0041]
It is preferable that the total of Nd and Pr is 50 at% or more in R, because the coercive force and residual magnetization of the magnet obtained are improved. It is also preferable to substitute part of Nd with Dy or Tb in order to improve the coercive force. TM is particularly preferably Fe or Co. It is preferable because the coercive force and the residual magnetization are improved when Fe in TM is 50 at% or more. In addition, it is possible to add additional elements other than the above for various purposes.
[0042]
R2TM14A preferred composition relating to R, TM and B constituting the B phase will be described. Preferably, the composition ranges are R: 8 to 30 at%, B: 2 to 40 at%, and the balance mainly TM. Preferably, the composition range is R: 8 to 30 at%, B: 2 to 40 at%, Fe: 40 to 90 at%, and Co: 50 at% or less. Further, the composition range is preferably R: 11 to 50 at%, B: 5 to 40 at%, and the balance mainly TM. More preferably, the composition range is R: 12 to 16 at%, B: 6.5 to 9 at%, and the balance is mainly TM. More preferably, the composition range is R: 12 to 14 at%, B: 7 to 8 at%, and the balance is mainly TM. Moreover, the raw material to be used does not necessarily have to have a single required composition, and an alloy having a different composition can be pulverized and then mixed and adjusted to the required composition.
[0043]
Further, in the main phase, these metalloid elements may be added so that a part or most of B is replaced by a so-called metalloid element such as C, Si, or P. For example, when replacing B with C, B1-xCxBut preferably x can be up to at least 0.8.
[0044]
Next, a preferable impregnation amount (addition amount) of an alkaline earth metal such as Ca metal with respect to the raw material powder (pre-impregnation powder) will be described. Preferably, alkaline earth metal 0.5 to 7 (more preferably) per 100 parts by weight of R-TM-B (R: rare earth element including Y, where 0 <x ≦ 0.3, TM: transition metal element) 1-5) Impregnating parts by weight. According to this embodiment, a high coercive force can be obtained by adding an inexpensive alkaline earth metal even if the amount of expensive rare earth used is limited.
[0045]
As an impregnation method for alkaline earth metal such as Ca metal, preferably R2TM14An alkaline earth metal powder is added to a powder mainly composed of magnetic particles containing a B (R: rare earth element including Y, TM: transition metal element) phase, and mixed.2TM14Heat the alkaline earth metal at a temperature below the melting point of B to convert the alkaline earth metal to R2TM14Diffusion along the interface of the B phase.
[0046]
In the above embodiment, the average particle size of the powder mainly composed of magnetic particles is preferably in the range of 3 to 400 μm, while the average particle size of the alkaline earth metal powder is preferably in the range of 0.5 to 3 mm, more preferably 1 to 3 mm. . As a result, R2TM14The interface of the B phase matches with the alkaline earth metal with a sufficient area.
[0047]
In addition, as a method of impregnating rare earth magnetic powder with alkaline earth metal such as Ca from the particle surface, vapor deposition methods such as vacuum deposition, sputtering, ion plating, CVD, and PVD are used. After the alkaline earth metal such as Ca is attached to the surface of the magnetic grain particles, the Ca is diffused and penetrated along the grain boundary to the inside of the magnetic powder by heat treatment in an inert gas atmosphere or in vacuum. Matches with magnetic atoms on the surface (completely bonded).
[0048]
The temperature of the heat treatment is R2Fe14At a temperature at which the B phase does not melt (when R = Nd, <1200 ° C), and the Ca metal diffuses sufficientlyDoTemperature is preferred. That is, since the melting point of Ca metal is 851 ° C., the heat treatment temperature is preferably 600 to 800 ° C.
[0049]
Ca metal is R2Fe14In order to have a face-centered cubic structure at the interface of the B phase, it is preferable to set the cooling rate after the heat treatment within a range of 10 to 200 ° C./min. Thus, by taking sufficient time for cooling, the liquid phase grain boundary phase containing Ca metal is not overcooled, and can take a regular crystal structure during cooling. By adopting a face-centered cubic structure instead of an amorphous grain boundary phase, the positional relationship between atoms at the interface between the main phase and the grain boundary phase becomes regular, and the consistency between the two is maintained. The possibility of starting is reduced and high coercivity is achieved. A more preferable range of the cooling rate after sintering is 20 to 100 ° C./min.
[0050]
Further, since alkaline earth metals such as Ca are very easy to oxidize, it is preferable to apply a rust preventive treatment by applying resin coating or plating coating and further TiN coating after the metal is adhered to and impregnated with magnetic powder particles. .
[0051]
Since alkaline earth metals such as Ca have a relatively low melting point (851 ° C.), it is preferable to use bonds to bulk the rare earth magnetic powder according to the present invention impregnated with Ca or the like.
[0052]
As a process for forming the bonded magnet, known processes such as compression molding, extrusion molding, injection molding, and rolling molding can be used. For bonding, various materials such as epoxy resin, nylon resin, and rubber can be used.
[0053]
The obtained bonded magnet can be subjected to surface treatment such as cleaning, chamfering, electrolytic plating, electroless plating, electrodeposition coating, resin coating, and the like, and can be used as a permanent magnet.
[0054]
Alternatively, the rare earth magnetic powder according to the present invention may be fed into a mold and compression molded while being oriented in a magnetic field. At this time, for example, as disclosed in JP-A-8-20801, spray granulation is performed by adding a binder to the alloy powder for the purpose of enhancing the fluidity of the alloy powder and facilitating powder feeding. Is also preferable. Alternatively, as disclosed in Japanese Patent Laid-Open No. 6-77028, it is possible to add a binder to the alloy powder and form a complex shape product by a metal injection molding method.
[0055]
R according to the invention2TM14The technique of impregnating Ca metal or the like into powder mainly composed of B-based magnetic particles is R2TM14It can also be used as a means for improving the coercive force of a B-based thin film magnet. For example, Nd produced by vacuum deposition or sputtering2Fe14Magnetic characteristics can be further improved by attaching an alkaline earth metal such as Ca on the B-based thin film magnet.
[0056]
In addition, in this specification, the description regarding a numerical range shall include not only the upper and lower limit values but also any intermediate value included in the numerical range.
[0057]
【Example】
In order to further clarify the embodiment of the present invention described above, an example of the present invention will be described.
[0058]
[Example 1]
Ingots were prepared by high-frequency melting raw materials comprising the components shown in Table 1 in an Ar gas atmosphere. This ingot was coarsely pulverized and further jet mill pulverized to an average particle size shown in Table 2. After adding 4 parts by weight of granular (˜1 mm) Ca metal to 100 parts by weight of magnetic powder of each particle size and mixing, heat treatment was performed at a temperature shown in Table 4 for 2 hours in a vacuum.
[0059]
Table 3 shows the amount of residual oxygen and the magnetic properties of the obtained magnetic powder. For comparison, Table 3 shows the composition of the powder obtained by the following rapid quenching method (trade name “MQP”, manufactured by US MQI) and the powder obtained by the HDDR method below. The residual oxygen amount and magnetic properties of the powders are shown in Table 4.
[0060]
[Comparative example: Super rapid cooling method]
An ingot having the composition shown in Table 3 below is melted at high frequency in an Ar gas in a quartz tube nozzle, and then a molten metal is sprayed onto a Cu rotating roll to obtain a super-quenched ribbon. After pulverizing to 250 μm, heat treatment was performed in Ar gas at 650 ° C. for 15 minutes.
[0061]
[Comparative example: HDDR method]
The ingot having the composition shown in Table 3 below was hydrogenated in hydrogen at 800 ° C. for 2 hours, and then dehydrogenated in vacuum at 800 ° C. for 1 hour. It grind | pulverized to 400 micrometers.
[0062]
[Table 1]
Ingot raw material composition
[Table 2]
Average particle size of magnetic powder
[Table 3]
Composition of powder by ultra rapid cooling method and HDDR method (wt%)
[Table 4]
Manufacturing conditions and magnetic properties
As shown in Table 4, according to the method according to Example 1, an equivalent or better powder was obtained even when compared with the powder obtained by the ultra rapid cooling method and HDDR method as comparative examples. Since the method according to Example 1 has fewer man-hours and is lower in cost than the ultra rapid cooling method and the HDDR method, the powder obtained by the method of Example 1 is extremely useful industrially. Further, in Example 1, a higher magnetic property was obtained when the average particle size was smaller. Sample No. As in 9, when the crystal grain size (average grain size) exceeds 400 μm, it is difficult for Ca to impregnate along the crystal grain boundary, and the coercive force is considered to be relatively small.
[0067]
[Example 2]
Ca metal was vacuum-deposited on the magnetic powder having the average particle diameter of Example 1 so as to have a film thickness of 5 μm, and then heat-treated at a temperature shown in Table 5 for 2 hours in a vacuum. Table 5 shows the production conditions, the amount of residual oxygen and the magnetic properties of the obtained magnetic powder.
[0068]
[Table 5]
Manufacturing conditions and magnetic properties
As shown in Table 5, a high coercive force powder was also obtained by a vapor phase film forming method such as a vacuum evaporation method.
[0070]
Example 3: In Example 3, Samples 1 and 3 to 6 are reference examples.]
Ingot No. 1 having an average particle diameter of 4.1 μm in Example 1 was used. After adding 4 parts by weight of the impregnated material shown in Table 6 to 100 parts by weight of the pulverized powder of No. 2, the mixture was heat treated in vacuum at the temperature shown in Table 6 for 2 hours. Table 6 shows the magnetic properties of the obtained magnetic powder. As shown in Table 6, according to the method according to Example 3, as an alkaline earth metalalloyA magnetic powder having excellent magnetic properties was obtained even when using.
[0071]
[Table 6]
[0072]
【The invention's effect】
The rare earth magnetic powder for bonded magnets obtained by the present invention is excellent in magnetic properties and can be produced by a relatively simple production method as compared with powders obtained by the conventional ultra-quenching method and HDDR method. Therefore, by using the powder of the present invention, it is possible to reduce the manufacturing cost of the rare earth bonded magnet, and to provide an inexpensive rare earth bonded magnet with high magnetic properties. The powder of the present invention is particularly useful as a magnetic powder for a high coercive force material. Further, in the future, with further demand for smaller magnet dimensions, the present invention provides ultra-small Nd.2Fe14The present invention provides a technology that is greatly useful for improving the coercive force of a B-based magnet.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the relationship between a distance from an interface and magnetocrystalline anisotropy, and a white circle indicates a uniaxial anisotropy constant K of an example.1, Black circle is the uniaxial anisotropy constant K of the comparative example1Indicates.
FIG. 2A is a model diagram showing a state in which a main phase and a grain boundary phase are matched, and FIG. 2B is a model diagram showing a state in which an interface between the main phase and a grain boundary phase is not matched.
FIG. 3 shows a rare earth magnetic powder for bonded magnets (R) according to an embodiment of the present invention.2TM14It is a figure for demonstrating the crystal structure of (B polycrystal powder).
Claims (6)
前記アルカリ土類金属が、前記界面に形成された前記結晶において陽イオンとして存在し、
前記陽イオンは、前記Ｒ 2 ＴＭ 14 Ｂ相の最外殻に位置する前記希土類元素イオンに隣接し、且つ該希土類元素イオンの 4f 電子雲が伸びている方向に位置する、ことを特徴とする核生成型の保磁力発生機構を有するボンド磁石用希土類磁性粉末。A plurality of R 2 TM 14 B (R: rare earth element including Y, TM: transition metal element) in the grain boundary of the polycrystalline particles containing phase, Ca, Sr, alkaline earth metal comprising at least one of Ba is A rare earth magnetic powder for a bond magnet, in which a grain boundary is diffused in a metal or alloy state to form a crystal at an interface adjacent to the R 2 TM 14 B phase,
The alkaline earth metal is present as a cation in the crystal formed at the interface;
The cation is adjacent to the rare earth element ion located in the outermost shell of the R 2 TM 14 B phase, and is located in a direction in which a 4f electron cloud of the rare earth element ion extends. A rare earth magnetic powder for bonded magnets having a nucleation type coercive force generation mechanism.
前記アルカリ土類金属が、前記界面に形成された前記結晶において陽イオンとして存在し、
前記陽イオンは、前記Ｒ 2 ＴＭ 14 Ｂ相の最外殻に位置する前記希土類元素イオンに隣接し、且つ該希土類元素イオンの 4f 電子雲が伸びている方向に位置する、ことを特徴とする核生成型の保磁力発生機構を有するボンド磁石用希土類磁性粉末の製造方法。 An alkaline earth metal composed of at least one of Ca, Sr, and Ba is added to a magnetic powder that is a polycrystalline particle containing a plurality of R 2 TM 14 B (R: Y-containing rare earth element, TM: transition metal element) phases. Add and mix to adhere the alkaline earth metal, and heat-treat the powder to which the alkaline earth metal is adhered at a temperature below the melting point of the R 2 TM 14 B phase and below the melting point of the alkaline earth metal. Te, to precipitate crystals at the interface adjacent the alkaline earth metals by grain boundary diffusion of a metal or an alloy state in the grain boundary of the polycrystalline particles in said R 2 TM 14 B phase,
The alkaline earth metal is present as a cation in the crystal formed at the interface;
The cation is adjacent to the rare earth element ion located in the outermost shell of the R 2 TM 14 B phase, and is located in a direction in which a 4f electron cloud of the rare earth element ion extends. A method for producing a rare earth magnetic powder for a bonded magnet having a nucleation type coercivity generating mechanism.
前記アルカリ土類金属が、前記界面に形成された前記結晶において陽イオンとして存在し、
前記陽イオンは、前記Ｒ 2 ＴＭ 14 Ｂ相の最外殻に位置する前記希土類元素イオンに隣接し、且つ該希土類元素イオンの 4f 電子雲が伸びている方向に位置する、ことを特徴とする核生成型の保磁力発生機構を有するボンド磁石用希土類磁性粉末の製造方法。 A plurality of R 2 TM 14 B (R: rare earth element including Y, TM: transition metal element) in the magnetic powder is polycrystalline grains containing phase, by using a vapor phase deposition method, Ca in the powder surface, A step of attaching an alkaline earth metal composed of at least one of Sr and Ba; and after the attachment, the powder to which the alkaline earth metal has adhered is equal to or lower than the melting point of the R 2 TM 14 B phase and the alkaline earth metal. heat-treated at a temperature below the melting point of the precipitated crystals of the alkaline-earth metal at the interface adjacent to the grain boundaries in the metal or alloy state by grain boundary diffusion the R 2 TM 14 B phase of the polycrystalline grains Let
The alkaline earth metal is present as a cation in the crystal formed at the interface;
The cation is adjacent to the rare earth element ion located in the outermost shell of the R 2 TM 14 B phase, and is located in a direction in which a 4f electron cloud of the rare earth element ion extends. A method for producing a rare earth magnetic powder for a bonded magnet having a nucleation type coercivity generating mechanism.
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| JP31466598A JP3695964B2 (en) | 1998-11-05 | 1998-11-05 | Rare earth magnetic powder for bonded magnet and method for producing the same |
| US09/265,669 US6511552B1 (en) | 1998-03-23 | 1999-03-10 | Permanent magnets and R-TM-B based permanent magnets |
| EP99105857A EP0945878A1 (en) | 1998-03-23 | 1999-03-23 | Permanent magnets and methods for their production |
| CNB991073118A CN1242426C (en) | 1998-03-23 | 1999-03-23 | Permanent magnet and R-TM-B series permanent magnet |
| CNB031016642A CN1242424C (en) | 1998-03-23 | 1999-03-23 | Permanent magnet and R-TM-B series permanent magnet |
| EP06006902A EP1737001A3 (en) | 1998-03-23 | 1999-03-23 | Permanent magnets and methods for their production |
| KR1019990009794A KR100606156B1 (en) | 1998-03-23 | 1999-03-23 | Permanent magnets and R-TM-B based permanent magnet |
| US10/256,193 US6821357B2 (en) | 1998-03-23 | 2002-09-27 | Permanent magnets and R-TM-B based permanent magnets |
| US10/256,166 US7025837B2 (en) | 1998-03-23 | 2002-09-27 | Permanent magnets and R-TM-B based permanent magnets |
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| JP4788690B2 (en) * | 2007-08-27 | 2011-10-05 | 日立金属株式会社 | R-Fe-B rare earth sintered magnet and method for producing the same |
| JP5381435B2 (en) * | 2009-07-14 | 2014-01-08 | 富士電機株式会社 | Method for producing magnet powder for permanent magnet, permanent magnet powder and permanent magnet |
| KR101341344B1 (en) | 2012-02-08 | 2013-12-13 | 한양대학교 산학협력단 | R-Fe-B Sintered magnet with enhanced coercivity and fabrication method thereof |
| JP6600693B2 (en) * | 2015-11-02 | 2019-10-30 | 日産自動車株式会社 | Grain boundary modification method for Nd-Fe-B magnet, and grain boundary reformer treated by the method |
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