JP4648586B2 - Rare earth sintered magnet manufacturing method and rare earth sintered magnet - Google Patents
Rare earth sintered magnet manufacturing method and rare earth sintered magnet Download PDFInfo
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- JP4648586B2 JP4648586B2 JP2001214595A JP2001214595A JP4648586B2 JP 4648586 B2 JP4648586 B2 JP 4648586B2 JP 2001214595 A JP2001214595 A JP 2001214595A JP 2001214595 A JP2001214595 A JP 2001214595A JP 4648586 B2 JP4648586 B2 JP 4648586B2
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- 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
- H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
- H01F1/0557—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together sintered
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Description
【０００１】
【発明の属する技術分野】
本発明は、高保磁力の磁石合金粉末を用いて高配向率の焼結磁石を製造するための粉末冶金法による希土類焼結磁石の製造方法、および保磁力が大きく高配向率の希土類焼結磁石に関する。
【０００２】
【従来の技術】
Ｒ−Ｔ−Ｂ系（但し、ＲはＹを含む希土類元素、Ｔは遷移金属元素）磁石を代表とする希土類元素を主成分とする希土類磁石は、ハードディスク向けボイスコイルモーター（ＶＣＭ）用、医療用磁気共鳴画像装置（ＭＲＩ）用途から、さらにモーター用途の需要が増大し、それに伴い、高保磁力タイプの磁石の需要がさらに伸びつつあるのが現状である。
【０００３】
焼結磁石を製造する工程は、合金を作る工程、合金を粉砕する工程、粉末を磁場配向させて成形する工程、成形体を焼結して焼結体とする工程、さらに加工および表面処理を行う工程に分けられる。
【０００４】
一般的には、希土類磁石合金の粉末の磁場配向は成形時あるいは成形前に行われる。磁場配向の目的は、合金粉末に強力な磁場を加えることにより、強磁性体からなる各粉末粒子の磁化容易軸方向を磁場の方向にそろえることである。この工程により磁石を構成する粉末粒子の結晶粒の磁化容易軸が所望の方向に整列し、特定方位に磁気エネルギー積を集中させることが可能となる。
高性能の焼結磁石を製造するためには、磁場配向工程で如何に粉末の粒子を配向させ、その配向を如何に乱さず圧縮（プレス）成形するかが重要となる。
【０００５】
粉末の成形方法は、一般的に金型を用いる一軸プレスによる金型成形と、静水圧プレス（擬似静水圧プレスを含む）による成形に大別できる。そのうち、従来から焼結磁石の製造には、生産性に優れる金型成形の方が多く使用されてきた。
【０００６】
金型成形は、プレス方向と磁場配向の方向の関係によって、平行磁場プレスと垂直磁場プレスとの２種類に分類できる。
平行磁場プレスではプレス方向と磁場配向方向とが一致しており、加圧の際に磁場配向に整列した粉末の方位が乱されることによって磁石の配向率が低くなる傾向がある。その反面、薄型でなおかつ厚さ方向に配向しているような磁石を作る場合、ニアネットシェイプで作製可能であり、生産性に優れている。
一方、垂直磁場プレスでは、磁場配向方向に垂直にプレスを行うため、成形時の粉末の配列は乱されにくく、平行磁場プレスよりも磁石の配向率は高くなる。しかしながら、厚さ方向に配向した薄型形状とするには、ブロックを配向方向と垂直に薄板状に切り出す必要があり、切りしろのロスが大きいため歩留まりが悪く、加工コストも高い。
【０００７】
一方、静水圧プレスによる成形は、等方的にプレスを行うことで、プレスに伴う配向の乱れを抑制するという方法である。静水圧プレスの具体的な方法として、粉末を柔軟なモールドに充填して全体を等方的に圧縮する冷間静水圧プレス（以下、ＣＩＰ）や、粉末を特殊なゴムモールドに充填して金型内で上下方向から圧縮することで、水平方向からも同じようなプレス圧がかかり、擬似静水圧プレスがなされる方法（以下、ＲＩＰ）などが挙げられる。そのうち、特にＲＩＰは、ＣＩＰの欠点であった生産性の問題を解決し、ＣＩＰ同様の高配向率を得ることができるため、高特性磁石の製造方法として急速に普及してきた。
【０００８】
従来の金型を用いた一軸プレスによる成形法では、成形中に圧力が一方向にかかり粉末の方位が乱れてしまうため、高い配向率を得るためには成形加圧中は常に静磁界をかけ続ける必要があった。しかし、高い配向率を得るには大きな磁界が必要となり、そのための磁場発生装置は極めて大掛りなものとなった。
【０００９】
一方、ＣＩＰあるいはＲＩＰでは成形中の圧力はほぼ等方的にかかるため、プレス成形中の配向の乱れは少ない。そのため、成形前に粉末粒子を磁場配向させておけば、通常プレス成形中に静磁界をかける必要はない。さらに、この成形前の磁場配向にはパルス磁場が利用できる。パルス磁場は、簡単な装置で静磁界では発生出来ないような大きな磁界を容易に発生できるため、配向率を容易に高めることができるという利点がある。
【００１０】
また、静水圧プレス（ＣＩＰあるいはＲＩＰ）で加圧成形中に磁界をかけるためには、非常に大掛かりな装置が必要となる。そのため、生産性やコスト面からみて、静水圧プレスで成形する際はパルス磁場で粉末粒子の磁場配向をし、静磁界をかけずにプレス成形を行うという手段が好ましい。
【００１１】
磁場配向は、強磁性体粒子の磁化容易軸方向が、外部磁場の方向に平行となることによってもたらされ、粒子の形状、粒子間の摩擦のような、粒子の回転を妨げる要素の他に、粒子の磁性によっても左右される。強磁性体は外部磁場で磁化されるが、この磁化が大きいほど、さらには磁気モーメントを磁化容易軸方向に向けようとする力である異方性磁界が大きいほど、外部磁場の方向に回転する力が大きくなる。特に異方性磁界の配向への寄与が大きいことは良く知られている。また、磁場配向の過程で合金粉末の粒子は多少なりとも着磁される。成形体が大きな磁化を有すると、各粒子の磁極間の相互作用により、配向を乱して静磁エネルギーを低くしようとする力が働くようになる。
【００１２】
上述した通り、一般の金型成形では配向に静磁界が用いられ、成形中も静磁界をかけ続けている。静磁界中で成形される方法では、たとえ大きな磁化が残存しても、加圧により高密度の成形体となるまで磁界が加えられるため、外部磁場がなくなっても各粒子はもはや動くことはできない。
【００１３】
一方、ＣＩＰ、ＲＩＰでは、配向にパルス磁場を用いているため、強磁界による配向率の向上が可能である。しかし、配向にパルス磁場を使用すると、強力なパルス磁場によって瞬間的に粒子は配向するが、磁場は短時間しか働かない。ＣＩＰ、ＲＩＰによる成形の場合、磁場配向した後、磁場のない条件下でプレス成形を行っている。そのため、粒子に比較的大きな磁化が残存することにより配向が乱れる可能性がある。
【００１４】
従来、ＣＩＰ、ＲＩＰのような静水圧プレスは、主に高磁化材について行われて来た。ＣＩＰ、ＲＩＰでは、磁場配向の際の充填密度が材料の真密度に対して、２５％程度以上と比較的高く、粒子の回転、再配列を妨げる粒子間の摩擦力が大きいため、プレス成形の際の配向の低下は少なく、従来は配向の乱れは見逃されていた。
【００１５】
しかし、近年、モーター用途への需要が伸びていることから、高磁化材だけでなく、高保磁力材についても同様に静水圧プレスによる成形が行われつつある。しかし、静水圧プレスを高保磁力の磁石合金粉末に用いて磁石を作ると、配向率が金型成形よりも低くなることが判明している。これは、高保磁力材料の希土類磁石合金粉末の粒子の回転、再配列による配向率の低下が原因であると考えられる。
【００１６】
【発明が解決しようとする課題】
近年、希土類系高保磁力磁石、特にＲ-Ｔ-Ｂ系磁石では、強磁性相の異方性磁界を高めることにより保磁力を増加している。例えば最も一般的な希土類元素であるＮｄの一部をＤｙ或いはＴｂと言った重希土類で置換すると、強磁性相のＲ２Ｔ１４Ｂ系磁石合金の異方性磁界が増大し、磁石の保磁力の増加が可能となる。他にもＣｕ、Ａｌ、Ｇａ等の添加元素も有効で、これらは粒界の微細構造の変化に寄与しているが、これらの保磁力増加効果は限界がある。そのため実用上用いられる高保磁力Ｒ−Ｔ−Ｂ系磁石は、Ｄｙ或いはＴｂと言った重希土類を必ず一定量（数質量％）含有し、Ｒ２Ｔ１４Ｂ化合物の異方性磁界が増加している。
【００１７】
Ｒ２Ｔ１４Ｂ系磁石合金の異方性磁界が増加すると磁石だけでなく、原料合金の粉末の保磁力も同様に増大する。粉末の保磁力は磁石と比較すると、大きくても約３００ｋＡ／ｍと極めて小さい。しかし、ＣＩＰ、ＲＩＰのような静水圧プレスを行う前にパルス磁場で配向させる際には、この原料合金粉末の約３００ｋＡ／ｍ程度の保磁力が大きな問題となる。つまり、粉末自体の保磁力が増加することによって、粉末の残留磁化が増大し、粒子の回転、再配列をもたらし、配向率を低下させる。そのため、高保磁力材は、パルス磁場配向を行い、静水圧プレスで成形する希土類焼結磁石の製造方法により製造するのが困難であった。
【００１８】
本発明は、パルス磁場で配向させた後で静水圧プレスにより成形体を得る希土類焼結磁石の製造方法において、高保磁力の希土類磁石合金を用いた場合も配向率を向上させ、高性能の磁石を得ることを目的とする。
【００１９】
【課題を解決するための手段】
すなわち本発明は
（１）水素を吸蔵させて低保磁力化させた希土類磁石合金を粉末化し、該粉末をパルス磁場によって配向させた後静水圧プレスにて成形体とし、さらに該成形体を脱水素処理して、その後成形体の焼結および時効処理を行う希土類焼結磁石の製造方法。
（２）希土類磁石合金が、合金主相がＲ２Ｔ１４Ｂ相（但し、ＲはＹを含む希土類元素、Ｔは遷移金属元素を表わす。）からなり、かつＲ成分中のＲ’（Ｒ’はＤｙ、Ｔｂのうち少なくとも１種以上を表わす。）の質量比率Ｒ’／Ｒが５％以上である希土類磁石合金からなることを特徴とする前記（１）に記載の希土類焼結磁石の製造方法。
（３）合金主相のＲ成分中のＲ’の質量比率Ｒ’／Ｒが１０％以上であることを特徴とする前記（２）に記載の希土類焼結磁石の製造方法。
（４）希土類磁石合金の水素吸蔵量の制御を、希土類磁石合金に水素を飽和量まで吸蔵させ、その後の脱水素工程の加熱温度を２５０℃以下とすることで行うことを特徴とする前記（１）〜（３）に記載の希土類焼結磁石の製造方法。
（５）水素を吸蔵させて低保磁力化させた希土類磁石合金の粉末の保磁力が１６０ｋＡ／ｍ以下であることを特徴とする前記（１）〜（４）に記載の希土類焼結磁石の製造方法。
（６）静水圧プレスを、粉末をゴムモールドに充填して金型内でプレスする擬似静水圧プレス（ＲＩＰ）で行うことを特徴とする前記（１）〜（５）に記載の希土類焼結磁石の製造方法。
（７）成形体の脱水素処理として、成形体を真空中あるいは不活性ガスフロー中で７００〜９００℃の温度で１時間以上保持する加熱処理を、焼結の前に行うことを特徴とする前記（１）〜（６）に記載の希土類焼結磁石の製造方法。
である。
【００２０】
また、本発明は、
（８）前記（１）〜（７）に記載の製造方法によって得られた希土類焼結磁石。
（９）配向率が９０％以上であることを特徴とする前記（８）に記載の希土類焼結磁石。
（１０）保磁力が９５０ｋＡ／ｍ以上であることを特徴とする前記（８）または（９）に記載の希土類焼結磁石。
である。
【００２１】
【発明の実施の形態】
本発明者らは、希土類磁石合金の原料粉末の特性と磁石の配向率の関係を詳細に調査し、焼結磁石の配向率の低下には磁石の原料合金粉末の保磁力の影響が大きいことを見出した。そして、鋭意研究の結果、従来は原料合金粉末の保磁力が高いために、ＣＩＰあるいはＲＩＰのような静水圧プレスにおいて高配向率が得られなかった高保磁力のＲ−Ｔ−Ｂ系合金を用いた磁石に関し、合金組成、組織を全く変えずに、パルス磁場配向とプレス成形の間だけ、原料粉末の保磁力を低下させる方法を見出した。
【００２２】
本発明は静水圧プレスを用いる高配向率を有する希土類焼結磁石の製造方法において、Ｒ−Ｔ−Ｂ系合金の原料粉末の保磁力を合金に水素を吸蔵させることで低下させた後、それの粉末を用いてパルス磁場配向を行い、さらに静水圧プレスにより成形体を形成することにより、得られた磁石の配向率の向上をもたらしたものである。
【００２３】
そして、静水圧プレスにより形成された成形体を焼結することで、保磁力が高く、かつ配向率も高い希土類焼結磁石を製造するものである。
【００２４】
本発明の構成を以下に詳細に記す。
（１）粉末の保磁力
本発明でＣＩＰあるいはＲＩＰなどの静水圧プレスに用いる希土類磁石用合金粉末は、水素を吸蔵させることにより保磁力を好ましくは１６０ｋＡ／ｍ以下に低下させる。さらにパルス磁場配向および静水圧プレスにより成形された後は、脱水素処理を施した後で燒結させて、焼結磁石の保磁力を９５０ｋＡ／ｍ以上とするものである。
【００２５】
先に説明したように、ＣＩＰやＲＩＰのような静水圧プレスの場合、パルス磁場で配向させる際には、原料粉末の保磁力が大きいと磁石の配向率が低下する。これは、粉末の残留磁化の増大による粒子の回転や再配列のためであるものと考えられる。一般に磁石の保磁力が大きいほど、粉末の保磁力も大きくなるが、磁石の保磁力が９５０ｋＡ／ｍ以上で、粉末の保磁力が１６０ｋＡ／ｍ以上と高い場合に配向率の低下が著しい。そこで本発明では、原料粉末の保磁力を好ましくは１６０ｋＡ／ｍ以下に低下させて、パルス磁場による磁場配向と静水圧プレスによる成形体加工を行う。
【００２６】
（２）合金主相と主相中のＤｙ，Ｔｂ濃度
本発明に用いる希土類磁石合金は、合金主相がＲ２Ｔ１４Ｂ相（但し、ＲはＹを含む希土類元素、Ｔは遷移金属元素を表す。）であり、Ｒ成分中のＲ’（Ｒ’はＤｙ、Ｔｂのうち少なくとも１種以上を表す。）の質量比率Ｒ’／Ｒが５％以上であることを特徴とする。強磁性Ｒ２Ｔ１４Ｂ相を主相とすることにより、磁場配向が可能となり、配向率の高い磁石を作製することができる。この際、特にＲ’（Ｄｙ、Ｔｂのうち少なくとも１種以上）の質量比率Ｒ’／Ｒが５％以上であると、磁石の保磁力増加に伴い、合金粉末の保磁力も増加するため、本発明の効果が明確となる。さらにＲ’／Ｒが１０％以上になると、本発明は極めて有効である。
【００２７】
（３）希土類磁石合金中の水素吸蔵量を制御する方法
本発明は、希土類磁石合金の水素吸蔵量の制御を、希土類磁石合金に水素を飽和量まで吸蔵させ、その後の脱水素工程の加熱温度を２５０℃以下とすることで行う。この水素吸蔵量の制御は、例えば希土類磁石合金の水素解砕処理およびそれに引き続く脱水素処理を兼ねて行うことができる。水素解砕処理はＲ−Ｔ−Ｂ系合金の粉砕工程の一部として利用されている。以下に水素解砕処理について説明する。
【００２８】
希土類磁石合金の水素解砕処理においては、まず原料合金を適当に破砕した後、真空引き且つガス加圧のできる炉に挿入して、密閉状態とする。合金をセットしてから、炉内を真空引きした後、炉内に水素ガスを導入する。この際、一般に安全上の理由と効率を考慮し、内部圧を大気圧以上（例えば、０．１４ＭＰａ程度）に加圧する。処理温度は１５０℃以下で行うのが望ましい。１５０℃以上になると、Ｒリッチ相の一部が３水素化物になるまで水素を吸蔵しなくなることから、合金の膨張に伴う割れの発生が遅くなる傾向になる。作業効率の面も考慮すると、約１０〜３５℃程度の室温で行うが好ましい。
【００２９】
合金は、水素ガスを吸蔵して膨張し、自ら割れを生じて解砕していく。この時、炉内の圧力は水素ガスが減少していくため下がっていくので、適宜補充する。合金の水素吸蔵に伴う解砕現象は、炉内圧力の低下が見られなくなったところで終了したものと判断する。この状態で希土類磁石合金に水素を飽和量まで吸蔵させることができたとみなす。
【００３０】
水素を飽和量まで吸蔵させた後、合金を加熱して脱水素を行う。ここで、従来の方法における加熱温度は３００℃以上である。加熱脱水素により、主相から水素が放出される。また、主相中の残存水素は主相の異方性磁界を低下させるため、従来の静磁界による磁場配向方法においては、この脱水素処理の段階で３００℃以上に加熱することによって主相から水素を放出させて残存水素をなくすように処理されていた。
【００３１】
しかし、本発明では、原料粉末の保磁力が回復しない程度の温度に加熱して脱水素を行う。そのため、脱水素温度は２５０℃以下にすることが好ましい。加熱時間は、処理装置の特性によって決まってくるが、Ｒリッチ相がより安定な状態となるために水素原子を放出する反応時間を考慮して、試料全体が加熱されるようになった時点からの経過時間を３０分以上とするのが望ましく、また、作業効率の面から、２時間を超えない方が望ましい。
【００３２】
（４）磁場配向
本発明は、１６０ｋＡ／ｍ以下の保磁力を有する希土類磁石用合金粉末を、パルス磁場を用いて配向させる。先に説明した通り、１６０ｋＡ／ｍ以下の低い保磁力を有する希土類磁石用合金粉末は、パルス磁場を配向工程に使用することによっても、高配向率を有する磁石の作製が可能である。
【００３３】
（５）成形方法
本発明は成形体の成形方法が静水圧プレス（ＣＩＰまたはＲＩＰ）であることを特徴とする。ＣＩＰ、ＲＩＰなどの静水圧プレス又は擬似静水圧プレスでは、成形中のプレス圧による配向の乱れを抑制できる。特にＲＩＰは、ＣＩＰの欠点であった生産性の問題を解決し、ＣＩＰ同様の高配向率を得ることができるためこのましい成形方法である。
【００３４】
（６）脱水素処理方法
成形体の形成後、焼結処理する前に脱水素処理を行う。この脱水素処理は、通常は８００℃付近で長時間、例えば３０分程度加熱すれば完了するが、同様の処理を本発明の原料粉末から作られた成形体に対して行うと、脱水素が不充分な状態で焼結温度近傍まで成形体を加熱することになり、それによって、結晶粒の異常粒成長が起こりやすくなり、且つ、磁石特性を低下させる。これは、本発明の原料粉末から作られた成形体が、従来と異なり主相中にも一定量以上の水素を含有していることによるものである。そこで、本発明では、成形体の脱水素処理として、成形体を真空中あるいは不活性ガスフロー中で７００〜９００℃の温度で１時間以上さらに望ましくは３時間以上保持する加熱処理を行う。
【００３５】
上記の脱水素処理の後は、従来同様、燒結、時効処理を施し、必要に応じて加工、表面処理を経て、焼結磁石の製品とする。
【００３６】
【作用】
本発明によって、従来、パルス磁場で配向させた後でＣＩＰ、ＲＩＰなどの静水圧プレスあるいは擬似静水圧プレスを行うような方法では高配向率が得られなかった高保磁力材料用粉末においても、高配向率が得られるようになった。
【００３７】
【実施例】
（実施例１）
合金組成がＮｄ＝２３．０質量％、Ｄｙ＝７．０質量％、Ｂ＝０．９８質量％、Ａｌ＝０．３質量％、Ｃｕ＝０．０３質量％、残部＝Ｆｅとなるように、原料としてＮｄメタル、Ｄｙメタル、純鉄、フェロボロン、Ａｌ、Ｃｕを配合し、真空雰囲気中あるいは不活性ガス雰囲気中にて溶湯とした。その後、ストリップキャスティング法にて急冷合金とした。
【００３８】
得られた合金について、水素解砕装置にて水素解砕を行った。水素吸蔵の条件としては、実施温度＝３０℃、初期水素圧力＝０．１４ＭＰａとした。その後、装置内を真空引きしながら１７０℃程度に２時間加熱することで脱水素を行った。
【００３９】
水素解砕処理がなされた上記合金について、窒素雰囲気中でブラウンミルにて粗粉砕、さらにジェットミルにて微粉砕を行って粉末を得た。粉末の粒度はフィッシャーサブシーブサイザーで、３．１μｍであった。また、粉末の保磁力をＶＳＭ(振動型磁力計)で測定した結果、１０４ｋＡ／ｍであった。
なお、ステアリン酸亜鉛０．０３質量％をブラウンミル粉砕後に添加、混合した。
【００４０】
上記粉末について、ＲＩＰ法にて成形体を作製した。
粉末をゴムモールドに、約２．８×１０3ｋｇ／ｍ3の密度に充填した後、３Ｔのパルス磁場で配向させ、さらに約１００ＭＰａの圧力で成形体を得た。
【００４１】
上記の成形体について、焼結炉にセット、真空雰囲気中１０３７℃で３時間焼結を行った。
焼結温度に到達する前に、粉末に入っていた水素を除去するために７９０℃で５時間加熱した。得られた焼結体については、さらに７９０℃×１時間、引き続いて５７０℃×１時間の時効処理を施した。
【００４２】
上記の処理によって得られた焼結体を切断、研磨して約７ｍｍ角の立方体に加工し、磁気測定を行った。その結果、得られた磁気特性は、残留磁束密度（以下、Ｂｒ略す）＝１．２３Ｔ、保磁力（以下、ｉＨｃと略す）＝１．８３×１０3ｋＡ／ｍ、磁気エネルギー積（以下、ＢＨｍａｘと略す）＝２９４ｋＪ／ｍ3、配向率＝９５．３％となった。
【００４３】
（比較例１）
実施例１と同様の組成と鋳造条件によって得られた合金について、水素解砕装置にて水素解砕を行った。水素吸蔵の条件は、実施例１と同様とした。その後、装置内を真空引きしながら５００℃程度に２時間加熱することで脱水素を行った。
【００４４】
上記で得られた合金について、実施例１と同様に粉砕を行った。その結果、得られた粉末の粒度は、フィッシャーサブシーブサイザーにて約３．０μｍであった。また、粉末の保磁力をＶＳＭ(振動型磁力計)で測定した結果、２５５ｋＡ／ｍであった。
【００４５】
上記の粉末について、実施例１と同様にＲＩＰ法にて成形体を作製し、焼結体を得た。その結果、得られた磁気特性は、Ｂｒ＝０．７２Ｔ、ｉＨｃ＝１．８５×１０3ｋＡ／ｍ、ＢＨｍａｘ＝９６ｋＪ／ｍ3、配向率＝５８．９％となった。
【００４６】
実施例１と比較例１で得られた磁気特性を図１に示す。縦軸は磁化、横軸は保磁力を表している。両者を比較すると、比較例１では曲線の角型が良好でなく磁石として好ましくないのに対し、実施例１では曲線の角型がより良好であり、磁石として好ましいことが判明した。
【００４７】
（比較例２）
比較例1で得られた粉末を金型モールドに充填して、上パンチがモールドに挿入された時点からプレス方向に垂直な方向に１．２Ｔの静磁界を発生させたまま約７８ＭＰａの圧力でプレスを行い、成形体を作製した。その後、実施例１と同様の加熱処理によって、焼結体を得た。この焼結体を実施例１と同じ形状に加工して、磁気測定をおこなった。その結果、得られた磁気特性は、Ｂｒ＝１．１７Ｔ、ｉＨｃ＝１．７７×１０3ｋＡ／ｍ、ＢＨｍａｘ＝２８０ｋＪ／ｍ3、配向率＝９３．５％となった。
【００４８】
【発明の効果】
従来、高保磁力材ではパルス磁場配向と静水圧プレスによって高い配向率が得られなかったのに対し、本発明によって、高保磁力材において、パルス磁場配向と静水圧プレスから高配向率の成形体が得られるようになった。これによって作製された焼結磁石は、金型プレスによって得られた磁石よりも高い配向率となり、従来では得られなかった高配向の高保磁力型薄型磁石を製造することができるようになった。
【図面の簡単な説明】
【図１】実施例１と比較例１で得られた焼結磁石の磁気特性を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a rare earth sintered magnet by a powder metallurgy method for producing a sintered magnet having a high orientation ratio using a magnet alloy powder having a high coercive force, and a rare earth sintered magnet having a large coercive force and a high orientation ratio. About.
[0002]
[Prior art]
R-T-B system (where R is a rare earth element including Y and T is a transition metal element) Rare earth magnets mainly composed of rare earth elements are used for voice coil motors (VCM) for hard disks, medical From the magnetic resonance imaging apparatus (MRI) application, the demand for the motor application further increases, and accordingly, the demand for the high coercive force type magnet is further increasing.
[0003]
The process of manufacturing a sintered magnet includes a process of making an alloy, a process of pulverizing the alloy, a process of forming powder by magnetic field orientation, a process of sintering the molded body to form a sintered body, and further processing and surface treatment. It is divided into processes to be performed.
[0004]
Generally, the magnetic field orientation of rare earth magnet alloy powder is performed at the time of molding or before molding. The purpose of the magnetic field orientation is to align the easy axis of magnetization of each powder particle made of a ferromagnetic material with the direction of the magnetic field by applying a strong magnetic field to the alloy powder. By this step, the easy magnetization axes of the crystal grains of the powder particles constituting the magnet are aligned in a desired direction, and the magnetic energy product can be concentrated in a specific direction.
In order to manufacture a high-performance sintered magnet, it is important how to orient the powder particles in the magnetic field orientation process and to perform compression (press) molding without disturbing the orientation.
[0005]
Powder forming methods can be broadly classified into die forming by uniaxial press using a die and forming by hydrostatic press (including pseudo isostatic press). Among them, conventionally, die molding having excellent productivity has been used more frequently in the production of sintered magnets.
[0006]
Mold molding can be classified into two types, a parallel magnetic field press and a vertical magnetic field press, depending on the relationship between the press direction and the direction of magnetic field orientation.
In the parallel magnetic field press, the press direction and the magnetic field orientation direction coincide with each other, and the orientation ratio of the powder aligned with the magnetic field orientation is disturbed during pressurization, so that the orientation rate of the magnet tends to be lowered. On the other hand, when making a magnet that is thin and oriented in the thickness direction, it can be manufactured with a near net shape, and is excellent in productivity.
On the other hand, in the vertical magnetic field press, since the press is performed perpendicular to the magnetic field orientation direction, the powder arrangement during molding is not easily disturbed, and the magnet orientation ratio is higher than that in the parallel magnetic field press. However, in order to obtain a thin shape oriented in the thickness direction, it is necessary to cut the block into a thin plate shape perpendicular to the orientation direction, and since the loss of cutting is large, the yield is poor and the processing cost is high.
[0007]
On the other hand, forming by isostatic pressing is a method of suppressing the disorder of orientation accompanying pressing by performing isotropic pressing. Specific methods of isostatic pressing include cold isostatic pressing (hereinafter referred to as CIP) in which powder is filled into a flexible mold and isotropically compressed, or a special rubber mold is filled with gold. A method (hereinafter referred to as “RIP”) in which a similar press pressure is applied from the horizontal direction by performing compression in the mold from the vertical direction, and a pseudo isostatic press is performed. Among them, in particular, RIP has rapidly spread as a method for producing high-performance magnets because it can solve the problem of productivity that has been a drawback of CIP and can obtain a high orientation ratio similar to CIP.
[0008]
In a conventional molding method using a uniaxial press using a mold, pressure is applied in one direction during molding, and the orientation of the powder is disturbed. To obtain a high orientation ratio, a static magnetic field is always applied during molding pressurization. There was a need to continue. However, in order to obtain a high orientation ratio, a large magnetic field is required, and the magnetic field generator for that purpose is extremely large.
[0009]
On the other hand, in CIP or RIP, the pressure during molding is almost isotropic, so there is little orientation disturbance during press molding. Therefore, if the powder particles are magnetically oriented before molding, there is no need to apply a static magnetic field during normal press molding. Further, a pulsed magnetic field can be used for the magnetic field orientation before molding. Since the pulse magnetic field can easily generate a large magnetic field that cannot be generated by a static magnetic field with a simple device, there is an advantage that the orientation ratio can be easily increased.
[0010]
Moreover, in order to apply a magnetic field during press molding by an isostatic press (CIP or RIP), a very large apparatus is required. Therefore, from the viewpoint of productivity and cost, it is preferable to perform a press molding without applying a static magnetic field by orienting powder particles with a pulsed magnetic field when molding by a hydrostatic press.
[0011]
Magnetic field orientation is caused by the fact that the axis of easy magnetization of ferromagnetic particles is parallel to the direction of the external magnetic field, in addition to elements that prevent the rotation of the particles, such as the shape of the particles and the friction between the particles. It depends on the magnetic properties of the particles. Ferromagnetic materials are magnetized by an external magnetic field. The larger the magnetization, and the greater the anisotropic magnetic field, which is the force that directs the magnetic moment in the direction of the easy axis of magnetization, rotates in the direction of the external magnetic field. Strength increases. It is well known that the contribution to the orientation of the anisotropic magnetic field is particularly large. Further, the particles of the alloy powder are magnetized somewhat in the course of magnetic field orientation. When the compact has a large magnetization, a force to disturb the orientation and lower the magnetostatic energy is exerted by the interaction between the magnetic poles of each particle.
[0012]
As described above, a static magnetic field is used for orientation in general mold molding, and the static magnetic field is continuously applied during molding. In the method of molding in a static magnetic field, even if a large magnetization remains, the magnetic field is applied until a compact body is formed by pressing, so that each particle can no longer move even if there is no external magnetic field. .
[0013]
On the other hand, in CIP and RIP, since a pulsed magnetic field is used for orientation, the orientation rate can be improved by a strong magnetic field. However, if a pulsed magnetic field is used for orientation, the particles are instantaneously oriented by a strong pulsed magnetic field, but the magnetic field only works for a short time. In the case of molding by CIP or RIP, press molding is performed under a condition without a magnetic field after the orientation of the magnetic field. Therefore, there is a possibility that the orientation may be disturbed by relatively large magnetization remaining in the particles.
[0014]
Conventionally, hydrostatic presses such as CIP and RIP have been performed mainly for highly magnetized materials. In CIP and RIP, the packing density at the time of magnetic field orientation is relatively high, about 25% or more with respect to the true density of the material, and the frictional force between particles that hinders rotation and rearrangement of particles is large. At the same time, there was little decrease in the orientation, and conventionally, the disorder of the orientation was overlooked.
[0015]
However, in recent years, since the demand for motor applications has increased, not only highly magnetized materials but also high coercive force materials are being similarly molded by a hydrostatic press. However, it has been found that when a magnet is made by using a hydrostatic press for a magnet alloy powder having a high coercive force, the orientation rate is lower than that of mold forming. This is considered to be caused by a decrease in the orientation ratio due to rotation and rearrangement of the particles of the rare earth magnet alloy powder of the high coercive force material.
[0016]
[Problems to be solved by the invention]
In recent years, the coercive force of a rare earth-based high coercive force magnet, particularly an RTB-based magnet, has been increased by increasing the anisotropic magnetic field of the ferromagnetic phase. For example, if a part of Nd, which is the most common rare earth element, is substituted with a heavy rare earth such as Dy or Tb, the anisotropic magnetic field of the R2T14B magnet alloy in the ferromagnetic phase increases and the coercive force of the magnet increases. It becomes possible. In addition, additive elements such as Cu, Al, and Ga are also effective, and these contribute to the change in the fine structure of the grain boundary. However, the effect of increasing the coercive force is limited. Therefore, a practically used high coercive force RTB-based magnet always contains a certain amount (several mass%) of heavy rare earth such as Dy or Tb, and the anisotropic magnetic field of the R2T14B compound is increased.
[0017]
When the anisotropic magnetic field of the R2T14B magnet alloy increases, not only the magnet but also the coercive force of the raw material alloy powder increases. The coercive force of the powder is as small as about 300 kA / m at most compared to the magnet. However, the coercive force of about 300 kA / m of the raw material alloy powder is a big problem when orienting with a pulsed magnetic field before performing isostatic pressing such as CIP and RIP. That is, when the coercive force of the powder itself is increased, the residual magnetization of the powder is increased, causing the rotation and rearrangement of the particles, thereby reducing the orientation rate. For this reason, it has been difficult to produce a high coercive force material by a method for producing a rare earth sintered magnet which is subjected to pulsed magnetic field orientation and molded by an isostatic press.
[0018]
The present invention relates to a method for producing a rare earth sintered magnet, in which a compact is obtained by isostatic pressing after being oriented in a pulsed magnetic field. The purpose is to obtain.
[0019]
[Means for Solving the Problems]
That is, the present invention is (1) pulverizing a rare earth magnet alloy having a low coercive force by occlusion of hydrogen, orienting the powder with a pulsed magnetic field, and then forming the compact with a hydrostatic press, and further dehydrating the compact. A method for producing a rare earth sintered magnet which is subjected to a raw treatment, and thereafter sintering and aging of the molded body.
(2) The rare earth magnet alloy is composed of an R2T14B phase (where R is a rare earth element including Y and T is a transition metal element), and R ′ in the R component (R ′ is Dy, The method for producing a rare earth sintered magnet according to (1) above, wherein the mass ratio R ′ / R of Tb is 5% or more.
(3) The method for producing a rare earth sintered magnet according to (2) above, wherein the mass ratio R ′ / R of R ′ in the R component of the alloy main phase is 10% or more.
(4) The hydrogen storage amount of the rare earth magnet alloy is controlled by allowing the rare earth magnet alloy to store hydrogen up to a saturation amount, and then setting the heating temperature in the subsequent dehydrogenation step to 250 ° C. or less ( The manufacturing method of the rare earth sintered magnet as described in 1)-(3).
(5) The rare earth sintered magnet according to any one of (1) to (4) above, wherein the coercive force of the rare earth magnet alloy powder having a reduced coercive force by occlusion of hydrogen is 160 kA / m or less. Production method.
(6) Rare earth sintering as described in (1) to (5) above, wherein the hydrostatic press is performed by a pseudo isostatic press (RIP) in which a powder is filled in a rubber mold and pressed in a mold. Magnet manufacturing method.
(7) The dehydrogenation treatment of the compact is characterized by performing a heat treatment for holding the compact at 700 to 900 ° C. for 1 hour or longer in a vacuum or in an inert gas flow before sintering. The manufacturing method of the rare earth sintered magnet as described in said (1)-(6).
It is.
[0020]
The present invention also provides:
(8) A rare earth sintered magnet obtained by the production method according to (1) to (7).
(9) The rare earth sintered magnet according to (8), wherein the orientation ratio is 90% or more.
(10) The rare earth sintered magnet according to (8) or (9), wherein the coercive force is 950 kA / m or more.
It is.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have investigated in detail the relationship between the properties of the rare earth magnet alloy raw material powder and the orientation ratio of the magnet, and that the reduction in the orientation ratio of the sintered magnet is greatly influenced by the coercive force of the magnet raw material alloy powder. I found. As a result of diligent research, because of the high coercive force of the raw material alloy powder, a high coercivity R-T-B type alloy such as CIP or RIP in which high orientation ratio could not be obtained was used. The present inventors have found a method for reducing the coercive force of raw material powder only during pulse magnetic field orientation and press molding without changing the alloy composition and structure at all.
[0022]
The present invention relates to a method for producing a rare earth sintered magnet having a high orientation ratio using an isostatic press, after the coercivity of the raw material powder of the R-T-B alloy is reduced by occluding hydrogen in the alloy, The magnetic field orientation of the obtained magnet was performed, and a molded body was formed by isostatic pressing, thereby improving the orientation ratio of the obtained magnet.
[0023]
And the rare earth sintered magnet with a high coercive force and a high orientation rate is manufactured by sintering the molded object formed by the isostatic pressing.
[0024]
The configuration of the present invention will be described in detail below.
(1) Coercive force of powder The alloy powder for rare earth magnets used in the hydrostatic press such as CIP or RIP in the present invention lowers the coercive force to 160 kA / m or less by occluding hydrogen. Further, after being formed by pulse magnetic field orientation and isostatic pressing, it is sintered after being subjected to dehydrogenation treatment so that the coercive force of the sintered magnet is 950 kA / m or more.
[0025]
As described above, in the case of an isostatic press such as CIP or RIP, when the orientation is performed with a pulsed magnetic field, the orientation rate of the magnet decreases when the coercivity of the raw material powder is large. This is considered to be due to the rotation and rearrangement of the particles due to the increase in the residual magnetization of the powder. In general, the larger the coercive force of the magnet, the greater the coercive force of the powder. However, when the coercive force of the magnet is 950 kA / m or more and the coercive force of the powder is as high as 160 kA / m or more, the orientation ratio is significantly reduced. Therefore, in the present invention, the coercive force of the raw material powder is preferably reduced to 160 kA / m or less, and the compact is processed by magnetic field orientation using a pulse magnetic field and isostatic pressing.
[0026]
(2) Alloy main phase and Dy, Tb concentration in main phase In the rare earth magnet alloy used in the present invention, the alloy main phase is R2T14B phase (where R is a rare earth element including Y, and T is a transition metal element). The mass ratio R ′ / R of R ′ (R ′ represents at least one of Dy and Tb) in the R component is 5% or more. By using the ferromagnetic R2T14B phase as the main phase, magnetic field orientation is possible, and a magnet with a high orientation rate can be produced. At this time, particularly when the mass ratio R ′ / R of R ′ (at least one of Dy and Tb) is 5% or more, the coercive force of the alloy powder increases with the increase of the coercive force of the magnet. The effect of the present invention becomes clear. Furthermore, when R ′ / R is 10% or more, the present invention is extremely effective.
[0027]
(3) Method of controlling hydrogen storage amount in rare earth magnet alloy The present invention controls the hydrogen storage amount of rare earth magnet alloy by allowing rare earth magnet alloy to store hydrogen up to the saturation amount, and the heating temperature in the subsequent dehydrogenation step Is performed at 250 ° C. or lower. The control of the hydrogen storage amount can be carried out, for example, in combination with a hydrogen crushing process of a rare earth magnet alloy and a subsequent dehydrogenation process. Hydrogen crushing treatment is used as part of the crushing process of the R-T-B alloy. The hydrogen crushing process will be described below.
[0028]
In the hydrogen crushing treatment of the rare earth magnet alloy, first, the raw material alloy is appropriately crushed and then inserted into a furnace capable of evacuation and gas pressurization to be in a sealed state. After setting the alloy, the furnace is evacuated and then hydrogen gas is introduced into the furnace. At this time, the internal pressure is generally increased to an atmospheric pressure or higher (for example, about 0.14 MPa) in consideration of safety reasons and efficiency. The treatment temperature is desirably 150 ° C. or lower. When the temperature is 150 ° C. or higher, hydrogen does not occlude until a part of the R-rich phase becomes trihydride, so that cracking tends to be delayed as the alloy expands. Considering the work efficiency, it is preferable to carry out at a room temperature of about 10 to 35 ° C.
[0029]
The alloy absorbs hydrogen gas, expands, cracks itself, and breaks up. At this time, the pressure in the furnace decreases as the hydrogen gas decreases, so it is appropriately replenished. It is judged that the crushing phenomenon accompanying hydrogen storage of the alloy ended when the decrease in the furnace pressure was no longer observed. In this state, it is considered that the rare earth magnet alloy was able to occlude hydrogen to a saturation amount.
[0030]
After the hydrogen is occluded to the saturation amount, the alloy is heated to dehydrogenate. Here, the heating temperature in the conventional method is 300 ° C. or higher. Hydrogen is released from the main phase by heat dehydrogenation. In addition, since residual hydrogen in the main phase lowers the anisotropic magnetic field of the main phase, in the conventional magnetic field orientation method using a static magnetic field, heating from the main phase by heating to 300 ° C. or higher at the stage of this dehydrogenation treatment. It was treated to release hydrogen to eliminate residual hydrogen.
[0031]
However, in the present invention, dehydrogenation is performed by heating to a temperature at which the coercive force of the raw material powder does not recover. Therefore, the dehydrogenation temperature is preferably 250 ° C. or lower. The heating time is determined by the characteristics of the processing apparatus. From the time when the entire sample is heated in consideration of the reaction time for releasing hydrogen atoms in order to make the R-rich phase more stable. The elapsed time is preferably 30 minutes or more, and from the viewpoint of work efficiency, it is desirable not to exceed 2 hours.
[0032]
(4) Magnetic Field Orientation In the present invention, a rare earth magnet alloy powder having a coercive force of 160 kA / m or less is oriented using a pulsed magnetic field. As described above, the rare earth magnet alloy powder having a low coercive force of 160 kA / m or less can produce a magnet having a high orientation ratio even when a pulse magnetic field is used in the orientation step.
[0033]
(5) Molding method The present invention is characterized in that the molding method of the compact is an isostatic press (CIP or RIP). In a hydrostatic press such as CIP or RIP or a pseudo isostatic press, it is possible to suppress orientation disturbance due to the press pressure during molding. In particular, RIP is a preferable molding method because it solves the problem of productivity that was a drawback of CIP and can obtain a high orientation ratio similar to CIP.
[0034]
(6) Dehydrogenation treatment method After the formation of the formed body, dehydrogenation treatment is performed before sintering treatment. This dehydrogenation treatment is usually completed by heating at around 800 ° C. for a long time, for example, about 30 minutes. However, when the same treatment is performed on a molded body made from the raw material powder of the present invention, dehydrogenation is performed. The compact is heated to the vicinity of the sintering temperature in an insufficient state, whereby abnormal grain growth is likely to occur, and the magnet characteristics are degraded. This is because the molded body made from the raw material powder of the present invention contains a certain amount or more of hydrogen in the main phase unlike the conventional one. Therefore, in the present invention, as a dehydrogenation treatment of the molded body, a heat treatment is performed in which the molded body is held in a vacuum or an inert gas flow at a temperature of 700 to 900 ° C. for 1 hour or longer, more preferably 3 hours or longer.
[0035]
After the above dehydrogenation treatment, as in the conventional case, sintering and aging treatment are performed, and after processing and surface treatment as necessary, a sintered magnet product is obtained.
[0036]
[Action]
According to the present invention, a high coercivity material powder, which has not been able to obtain a high orientation rate by a method of performing a hydrostatic pressure press such as CIP or RIP or a pseudo isostatic press after orienting in a pulsed magnetic field, has been achieved. An orientation ratio can be obtained.
[0037]
【Example】
Example 1
The alloy composition is Nd = 23.0 mass%, Dy = 7.0 mass%, B = 0.98 mass%, Al = 0.3% mass, Cu = 0.03 mass%, and the balance = Fe. Nd metal, Dy metal, pure iron, ferroboron, Al, and Cu were blended as raw materials, and a molten metal was formed in a vacuum atmosphere or an inert gas atmosphere. Thereafter, a rapidly cooled alloy was obtained by a strip casting method.
[0038]
About the obtained alloy, hydrogen crushing was performed with a hydrogen crushing apparatus. The hydrogen storage conditions were as follows: implementation temperature = 30 ° C. and initial hydrogen pressure = 0.14 MPa. Then, dehydrogenation was performed by heating to about 170 ° C. for 2 hours while evacuating the inside of the apparatus.
[0039]
The above-mentioned alloy that had been subjected to hydrogen crushing treatment was coarsely pulverized by a brown mill in a nitrogen atmosphere and further finely pulverized by a jet mill to obtain a powder. The particle size of the powder was 3.1 μm using a Fischer sub-sieve sizer. Further, the coercive force of the powder was measured with a VSM (vibrating magnetometer), and as a result, it was 104 kA / m.
In addition, 0.03 mass% of zinc stearate was added and mixed after Brown mill grinding.
[0040]
About the said powder, the molded object was produced by RIP method.
The powder was filled in a rubber mold to a density of about 2.8 × 10 3 kg / m 3 , and then oriented with a pulse magnetic field of 3T, and a molded body was obtained at a pressure of about 100 MPa.
[0041]
The above molded body was set in a sintering furnace and sintered in a vacuum atmosphere at 1037 ° C. for 3 hours.
Before reaching the sintering temperature, it was heated at 790 ° C. for 5 hours in order to remove the hydrogen contained in the powder. The obtained sintered body was further subjected to an aging treatment at 790 ° C. × 1 hour and subsequently at 570 ° C. × 1 hour.
[0042]
The sintered body obtained by the above treatment was cut and polished, processed into a cube of about 7 mm square, and subjected to magnetic measurement. As a result, the obtained magnetic properties were as follows: residual magnetic flux density (hereinafter abbreviated as Br) = 1.23 T, coercive force (hereinafter abbreviated as iHc) = 1.83 × 10 3 kA / m, magnetic energy product (hereinafter, BHmax) = 294 kJ / m 3 , orientation rate = 95.3%.
[0043]
(Comparative Example 1)
About the alloy obtained by the composition and casting conditions similar to Example 1, hydrogen crushing was performed with the hydrogen crushing apparatus. The conditions for storing hydrogen were the same as in Example 1. Thereafter, dehydrogenation was performed by heating the apparatus to about 500 ° C. for 2 hours while evacuating the inside of the apparatus.
[0044]
The alloy obtained above was pulverized in the same manner as in Example 1. As a result, the particle size of the obtained powder was about 3.0 μm using a Fischer sub-sieve sizer. Further, the coercive force of the powder was measured by VSM (vibration magnetometer), and as a result, it was 255 kA / m.
[0045]
About said powder, the molded object was produced by the RIP method similarly to Example 1, and the sintered compact was obtained. As a result, the obtained magnetic properties were Br = 0.72T, iHc = 1.85 × 10 3 kA / m, BHmax = 96 kJ / m 3 , and orientation rate = 58.9%.
[0046]
The magnetic characteristics obtained in Example 1 and Comparative Example 1 are shown in FIG. The vertical axis represents magnetization, and the horizontal axis represents coercivity. When both were compared, in Comparative Example 1, the square shape of the curve was not good and not preferred as a magnet, whereas in Example 1, the square shape of the curve was better and preferred as a magnet.
[0047]
(Comparative Example 2)
The powder obtained in Comparative Example 1 is filled in a mold mold, and a 1.2 T static magnetic field is generated in a direction perpendicular to the pressing direction from the time when the upper punch is inserted into the mold at a pressure of about 78 MPa. Pressing was performed to produce a molded body. Then, the sintered compact was obtained by the heat processing similar to Example 1. FIG. This sintered body was processed into the same shape as in Example 1 and magnetic measurement was performed. As a result, the obtained magnetic characteristics were Br = 1.17T, iHc = 1.77 × 10 3 kA / m, BHmax = 280 kJ / m 3 , and orientation rate = 93.5%.
[0048]
【The invention's effect】
Conventionally, a high coercive force material has not been able to obtain a high orientation ratio by pulse magnetic field orientation and hydrostatic pressure press, but according to the present invention, a high coercive force material has a high orientation ratio formed from a pulse magnetic field orientation and hydrostatic pressure press. It came to be obtained. The sintered magnet thus produced has a higher orientation ratio than the magnet obtained by the die press, and a highly oriented high coercive force thin magnet that cannot be obtained conventionally can be produced.
[Brief description of the drawings]
FIG. 1 is a diagram showing magnetic characteristics of sintered magnets obtained in Example 1 and Comparative Example 1. FIG.
Claims (7)
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| JP5059929B2 (en) | 2009-12-04 | 2012-10-31 | 住友電気工業株式会社 | Magnet powder |
| JP5059955B2 (en) | 2010-04-15 | 2012-10-31 | 住友電気工業株式会社 | Magnet powder |
| JP4930813B2 (en) * | 2010-07-01 | 2012-05-16 | 住友電気工業株式会社 | Powder for magnetic member, powder molded body, and magnetic member |
| WO2011145477A1 (en) * | 2010-05-19 | 2011-11-24 | 住友電気工業株式会社 | Powder for magnetic member, powder compact, and magnetic member |
| JP5218869B2 (en) * | 2011-05-24 | 2013-06-26 | 住友電気工業株式会社 | Rare earth-iron-nitrogen alloy material, method for producing rare earth-iron-nitrogen alloy material, rare earth-iron alloy material, and method for producing rare earth-iron alloy material |
| CN102233428B (en) * | 2011-06-23 | 2013-02-20 | 宁波韵升股份有限公司 | Method for preparing bulk sintered Nd-Fe-B permanent magnet material |
| JP6447804B2 (en) * | 2014-05-16 | 2019-01-09 | 住友電気工業株式会社 | Method for manufacturing magnet compact |
| CN110504097B (en) * | 2019-08-29 | 2023-07-28 | 江西开源自动化设备有限公司 | Magnetic field forming method for improving residual magnetism of sintered magnet |
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