JPH04268051A - R-fe-co-b-c permanent magnet alloy reduced in irreversible demagnetization and excellent in heat stability - Google Patents
R-fe-co-b-c permanent magnet alloy reduced in irreversible demagnetization and excellent in heat stabilityInfo
- Publication number
- JPH04268051A JPH04268051A JP3048757A JP4875791A JPH04268051A JP H04268051 A JPH04268051 A JP H04268051A JP 3048757 A JP3048757 A JP 3048757A JP 4875791 A JP4875791 A JP 4875791A JP H04268051 A JPH04268051 A JP H04268051A
- Authority
- JP
- Japan
- Prior art keywords
- less
- magnetic
- irreversible demagnetization
- grain boundary
- magnet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005347 demagnetization Effects 0.000 title claims abstract description 70
- 230000002427 irreversible effect Effects 0.000 title claims abstract description 69
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 45
- 239000000956 alloy Substances 0.000 title claims abstract description 45
- 230000002829 reductive effect Effects 0.000 title abstract description 8
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 13
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 10
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 9
- 229910052802 copper Inorganic materials 0.000 claims abstract description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 8
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 7
- 229910052787 antimony Inorganic materials 0.000 claims abstract description 7
- 229910052797 bismuth Inorganic materials 0.000 claims abstract description 7
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 7
- 229910052733 gallium Inorganic materials 0.000 claims abstract description 7
- 229910052735 hafnium Inorganic materials 0.000 claims abstract description 7
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 7
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 7
- 229910052718 tin Inorganic materials 0.000 claims abstract description 7
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 7
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 7
- 229910052692 Dysprosium Inorganic materials 0.000 claims abstract description 6
- 229910052691 Erbium Inorganic materials 0.000 claims abstract description 6
- 229910052779 Neodymium Inorganic materials 0.000 claims abstract description 6
- 229910052771 Terbium Inorganic materials 0.000 claims abstract description 6
- 229910052775 Thulium Inorganic materials 0.000 claims abstract description 6
- 229910052769 Ytterbium Inorganic materials 0.000 claims abstract description 6
- 229910052732 germanium Inorganic materials 0.000 claims abstract description 6
- 229910052737 gold Inorganic materials 0.000 claims abstract description 6
- 229910052738 indium Inorganic materials 0.000 claims abstract description 6
- 229910052745 lead Inorganic materials 0.000 claims abstract description 6
- 229910052709 silver Inorganic materials 0.000 claims abstract description 6
- 229910052715 tantalum Inorganic materials 0.000 claims abstract description 6
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 6
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 6
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 5
- 229910052688 Gadolinium Inorganic materials 0.000 claims abstract description 5
- 229910052689 Holmium Inorganic materials 0.000 claims abstract description 5
- 229910052746 lanthanum Inorganic materials 0.000 claims abstract description 5
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 5
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 5
- 229910052777 Praseodymium Inorganic materials 0.000 claims abstract description 4
- 229910052772 Samarium Inorganic materials 0.000 claims abstract description 4
- 229910001339 C alloy Inorganic materials 0.000 claims abstract description 3
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 3
- 239000013078 crystal Substances 0.000 claims description 36
- 239000000203 mixture Substances 0.000 claims description 28
- 239000012535 impurity Substances 0.000 claims description 17
- 229910052796 boron Inorganic materials 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910001004 magnetic alloy Inorganic materials 0.000 claims description 3
- 230000004907 flux Effects 0.000 abstract description 11
- 229910052761 rare earth metal Inorganic materials 0.000 abstract description 7
- 229910052697 platinum Inorganic materials 0.000 abstract description 5
- 230000000052 comparative effect Effects 0.000 description 26
- 238000000034 method Methods 0.000 description 23
- 239000000463 material Substances 0.000 description 17
- 230000007423 decrease Effects 0.000 description 16
- 230000000694 effects Effects 0.000 description 16
- 230000003647 oxidation Effects 0.000 description 16
- 238000007254 oxidation reaction Methods 0.000 description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 12
- 239000010955 niobium Substances 0.000 description 12
- 239000002994 raw material Substances 0.000 description 11
- 229910052799 carbon Inorganic materials 0.000 description 10
- 230000006872 improvement Effects 0.000 description 10
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 9
- 230000006866 deterioration Effects 0.000 description 9
- 230000005381 magnetic domain Effects 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 8
- 239000011572 manganese Substances 0.000 description 8
- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- 230000002441 reversible effect Effects 0.000 description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 239000006229 carbon black Substances 0.000 description 6
- 239000010949 copper Substances 0.000 description 6
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 6
- 230000007613 environmental effect Effects 0.000 description 6
- 239000011253 protective coating Substances 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 239000000654 additive Substances 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 230000005415 magnetization Effects 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 229910020674 Co—B Inorganic materials 0.000 description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 4
- 230000000996 additive effect Effects 0.000 description 4
- 238000005275 alloying Methods 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910017061 Fe Co Inorganic materials 0.000 description 3
- 229910052786 argon Inorganic materials 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- 239000010941 cobalt Substances 0.000 description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000000265 homogenisation Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- -1 T a Inorganic materials 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000004453 electron probe microanalysis Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 230000005389 magnetism Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- 229910000531 Co alloy Inorganic materials 0.000 description 1
- 229910017112 Fe—C Inorganic materials 0.000 description 1
- 229910001047 Hard ferrite Inorganic materials 0.000 description 1
- 229910001122 Mischmetal Inorganic materials 0.000 description 1
- 229910000583 Nd alloy Inorganic materials 0.000 description 1
- 235000014676 Phragmites communis Nutrition 0.000 description 1
- 241000872198 Serjania polyphylla Species 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 229910001068 laves phase Inorganic materials 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000006148 magnetic separator Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
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
- H01F1/058—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IVa elements, e.g. Gd2Fe14C
Abstract
Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】本発明は，不可逆減磁の小さい熱
安定性の優れたＲ（希土類元素）−Ｆｅ−Ｃｏ−Ｂ−Ｃ
系の永久磁石合金に関する。
【０００２】
【従来の技術】近年， Ｓｍ−Ｃｏ系磁石の磁力を凌ぐ
次世代の永久磁石としてＲ−Ｆｅ−Ｂ系磁石が佐川等に
よって発表されて以来， 当該磁石について多くの報告
がなされてきた。しかしながら，該磁石はＳｍ−Ｃｏ系
磁石に比べて磁力は優れるものの， その磁気特性の熱
安定性及び耐酸化性が著しく劣るという欠点を有する。
特に耐酸化性に係わる欠点は，重要な改善課題であり，
上述報告の多くはその改善方法を開示している。
【０００３】他方，従来のＲ−Ｆｅ−Ｂ又はＲ−Ｆｅ−
Ｃｏ−Ｂ系磁石は環境温度が上昇すると残留磁束密度
（Ｂｒ）および保磁力（ｉＨｃ）がＳｍ−Ｃｏ系磁石に
比較して著しく低下するという性質がある。すなわち熱
安定性に劣るという欠点がある。このような状況下，環
境温度の変化に対して磁気特性の安定化を図る手段とし
ては，一般に残留磁束密度の温度依存係数を小さくする
こと及び室温における保磁力を十分に高くすることが提
案されている。前者の改善法としては，磁石のキューリ
ー温度を高める方法が一般的であり， 例えば特開昭５
９−６４７３３号公報では，Ｆｅの一部をＣｏで置換す
ることによりキューリー温度を高め， 残留磁束密度の
温度依存係数を小さくすることを提案している。他方，
環境温度の上昇に伴って， 保磁力が急激に低下する
ことは既に述べたところだが， この保磁力の低下がも
たらす重大な欠点は， 大きな不可逆減磁を招くという
ことである。
【０００４】不可逆減磁とは，高温時低下したＢｒが室
温に戻した時に元に回復しない現象であり，一般に磁石
形状の薄型化に伴ってその劣化が顕著になる。この不可
逆減磁の劣化は， たとえＦｅの一部をＣｏで置換して
残留磁束密度の温度依存係数を小さくしても， 抜本的
な改善には至らない。このため，実使用に際しては環境
温度及び形状が厳しく制限され， 例えば自動車関係，
高速機器等の過酷な用途への適用は困難となる。この
不可逆減磁の改善法としては専ら室温におけるｉＨｃを
高める方法に頼っているのが実状である。つまり，高温
時のｉＨｃの低下を見込んで，室温でのｉＨｃを十分に
高くすることによって不可逆減磁を小さくする方法であ
るが， 例えば特開昭５９−８９４０１号公報は，Ｔｉ
，Ｎｉ，Ｂｉ，Ｖ，Ｎｂ，Ｃｒ，Ｍｏ等を添加すること
により， 室温におけるｉＨｃを高め， 不可逆減磁率
を小さくすることを教示し，又，特開昭６０−３２３０
６号公報は，希土類元素成分として，軽希土類元素に加
え， Ｄｙ，Ｔｂ，Ｈｏ，Ｇｄ，Ｅｒ，Ｔｍ，Ｙｂの重
希土類元素の添加を特定し，これによりｉＨｃを高め，
不可逆減磁率を改善することを教示している。
【０００５】しかし，このようにしてｉＨｃを十分高め
れば確かに不可逆減磁は改善されるものの， 従来法で
は例えば１６０℃の高温にもなると， たとえ室温時の
ｉＨｃが１５〜２０ｋＯｅと十分高くても急激に劣化す
ると言う問題点が残る。この場合， 更にｉＨｃを高く
することになる。一方，このようにｉＨｃが高くなると
，着磁の問題が新たに発生する。即ち， 磁石の磁力を
最大に引き出すためにはその磁力が飽和するまで十分大
きな磁界で着磁する必要があり，着磁率が低いと磁気特
性の不安定を招くが，通常，該着磁界の大きさとしては
磁石が有するｉＨｃの３〜４倍の磁界が必要とされるこ
とから，従来法のように極端なｉＨｃの増加は，着・脱
磁の操作を困難にし，又， 設備の大型化を招くことに
なる。したがって，従来においては上記高温時の不可逆
減磁の劣化と共にこれらの問題を避けることはできなか
った。
【０００６】
【発明が解決しようとする課題】このように， 従来の
Ｒ−Ｆｅ−Ｃｏ−Ｂ系磁石では，高い環境温度での不可
逆減磁に対して， 十分な改善効果を得るに至っておら
ず，Ｓｍ−Ｃｏ系に比べて優れた磁力を有するにも拘ら
ず， 特に高温時の熱安定性及び実用レベルでの高ｉＨ
ｃ化に伴う着磁の問題が， 依然として存在し，上記メ
リットが大きく損なわれているのが実状である。
【０００７】一般に， Ｒ−Ｆｅ−Ｂ （またはＲ−Ｆ
ｅ−Ｃｏ−Ｂ） 系磁石は， Ｒ２Ｆｅ１４Ｂ〔または
Ｒ２（Ｆｅ，Ｃｏ）１４Ｂ〕型の正方晶と，ＲＦｅ４Ｂ
４〔Ｒ（Ｆｅ，Ｃｏ）４Ｂ４〕型のＢリッチ相， Ｒリ
ッチ相及びＢ２Ｏ３相を含む非磁性相とから構成され
（尚， Ｒ−Ｆｅ−Ｃｏ−Ｂ系磁石ではＲ（Ｆｅ，Ｃｏ
）２で代表されるラーベス相も存在するとされている）
，その保磁力発生の原理は，逆磁区核発生機構によると
されている。つまり， この逆磁区の存在が保磁力を決
定し，その成長に伴いｉＨｃが低下することから，核発
生型磁石の保磁力は構造敏感型となり正方晶と粒界相，
Ｒリッチ相， Ｂリッチ相及びその他不純物相に支配
されることになる。
【０００８】ところで，該逆磁区核の芽， 即ち逆磁区
核は正方晶及び粒界相の欠陥， 軟質な磁性相， その
他不純物相において発生し，これらの欠陥， 異物の存
在により容易に成長する。このように， 磁石の組織が
不均質であったり不純物及び種々の欠陥を含むと， ｉ
Ｈｃは容易に低下し，これに伴い実用レベルで重要とな
る残留磁気の不可逆減磁は大きくなる。
【０００９】以上のことから，不可逆減磁率を小さくす
る基本的な対策としては，磁石組織の観点から次のこと
が言える。（１） 正方晶の均質化，（２） 粒界相の
均質・均一化， （３） 軟質な磁性相の除去， （４
） その他不純物相の除去，である。これらの改善がな
された後に，ｉＨｃを適正化することにより抜本的な不
可逆減磁の改善に至ると考えられる。
【００１０】なお，従来の不可逆減磁の改善法として例
えば前出の特開昭５９−８９４０１号公報及び特開昭６
０−３２３０６号公報は，室温におけるｉＨｃを十分高
めることにより改善する方法を開示していることを既に
述べたが，これらの方法では磁石の組織に対しては何ら
改善がなされておらず， 単に添加物により異方性磁界
を大きくすることによって， 室温におけるｉＨｃを極
めて高くし，その結果， 不可逆減磁を改善するという
， 高温時のｉＨｃの低下を犠牲にした消極的な改善方
法である。このため，より高温時の改善効果は少なく，
又着磁等の問題が残ることは，既に既述した。
【００１１】一方， 永久磁石合金の組成を均質にし，
ｉＨｃを向上させる方法も数多く報告されており，
一般には磁石合金を熱処理することが提案されている。
例えば特開昭５９−２１７３０４号公報では，焼結後３
５０℃以上の温度で熱処理することにより， ｉＨｃが
改善されることを教示している。該法によれば， 熱処
理することにより磁石組成の均質化は改善されるものの
， 依然としてＢリッチ相やＢ２Ｏ３相等の不純物相が
存在していることから， 組織の構造上は何ら変化がな
く逆磁区核の発生点及びその成長に対しては，抜本的に
解決されていない。このため該法によりｉＨｃを高めて
も高温時の不可逆減磁の改善効果は小さいと判断される
。
【００１２】このように従来技術による不可逆減磁の改
善は磁石合金組織の構造に何ら対策手段を講じていない
のが実状である。
【００１３】また，不純物を除去することにより逆磁区
核の発生及びその成長を抑制する方法としては， 例え
ば酸化物相並びにＢリッチ相等の生成を抑制することが
考えられ，酸化物については磁石中の酸素を低減するこ
とにより抑制することが可能である。また，Ｂリッチ相
については従来材では多く存在し，その大きさは正方晶
と同程度にもなることから，不純物相としての欠陥だけ
でなく， 場合によっては大きな磁気的空間となり減磁
界形成の要因にもなる。しかしながら， 従来より実用
レベルの高い磁気特性を得るためにはＢの含有量を高く
せざるを得ないのが実状であり，例えば特開昭５９−４
６００８号公報及び前摘の特開昭５９−６４７３３号公
報では， １ｋＯｅ以上のｉＨｃを確保するためには，
Ｂ含有量を２〜２８原子％に特定しており，ｉＨｃを３
ｋＯｅにするためには，Ｂ含有量は少なくとも４原子％
必要であるとし，更に実用レベルの高いｉＨｃを得るた
めには，Ｂの含有量をさらに高くすることを教示してい
る。
【００１４】即ち，従来技術では，Ｂ含有量を少なくす
るとα−Ｆｅが析出しやすくなりこれに伴いｉＨｃは急
激に低下するので，ｉＨｃを高めるためにＢ含有量を多
くするという考え方に立っていることから，Ｂリッチ相
の生成を抑制することはできなかった。従ってこのよう
にＢを多く含み，不純物相として多くのＢリッチ相を含
有する従来材を実用化するためには，高温時の不可逆減
磁対策として， 前述のごとく極めて高いｉＨｃが必要
となる。
【００１５】本発明の目的はこのようなＲ−Ｆｅ−Ｃｏ
−Ｂ系永久磁石の問題， とりわけ， 不可逆減磁の問
題点を解決することにあり， 従来材のように， ｉＨ
ｃを極めて高くすることなく比較的低いｉＨｃでも不可
逆減磁が小さく熱安定性に優れた永久磁石合金を提供す
ることにある。
【００１６】
【課題を解決するための手段】本発明者等は，これらの
問題点を解決するための手段として， 磁石合金の組織
構造による抜本的な不可逆減磁の改善を鋭意検討した結
果， 正方晶構造を有する磁性結晶粒及びＲリッチ粒界
相を均質にし， 且つ磁性結晶粒の各々を該粒界相で被
覆することにより， 従来材に比べて著しく不可逆減磁
が改善されることを見い出し， 更には， これらの効
果を一層高めるために，Ｂリッチ相を除去するという従
来技術では，予想すら困難であった新規技術を見出すに
至り， 従来材より低いｉＨｃでも高温に於ける不可逆
減磁が極めて小さく， 且つ同等以上の最大エネルギー
積を有する新規な永久磁石合金の提供を可能とした。即
ち， 従来技術ではもはや高い磁気特性が得られず実用
範囲外とされていたＢ含有量２原子％未満領域でも実用
に耐え得る良好な磁気特性を付与し得る新規な技術を見
出したことにより，画期的な不可逆減磁の改善に至った
のである。
【００１７】すなわち本発明によれば，Ｒ−Ｆｅ−Ｃｏ
−Ｍ−Ｂ−Ｃ系合金磁石 （但し， ＲはＮｄ，Ｐｒ，
Ｃｅ，Ｌａ，Ｙ，Ｓｍ，Ｔｂ，Ｄｙ，Ｇｄ，Ｈｏ，Ｅｒ
，Ｔｍ，Ｙｂより選ばれる少なくとも１種， ＭはＴｉ
，Ｖ，Ｃｒ，Ｍｎ，Ｎｉ，Ｚｒ，Ｎｂ，Ｍｏ，Ｈｆ，Ｔ
ａ，Ｗ，Ｐｄ，Ａｇ，Ｐｔ，Ａｕ，Ａｌ，Ｃｕ，Ｇａ，
Ｉｎ，Ｓｎ，Ｓｂ，Ｐｂ，Ｂｉ，Ｚｎ，Ｐ，Ｓｉ，Ｇｅ
，Ｓより選ばれる少なくとも１種）において， 該合金
中，磁性結晶粒の各々が粒界相で覆われており，この粒
界相は１６重量％以下 （０重量％を含まず）のＣを含
むことを特徴とする不可逆減磁率の小さい熱安定性に優
れたＲ−Ｆｅ−Ｃｏ−Ｍ−Ｂ−Ｃ系永久磁石合金を提供
する。
【００１８】ここで該磁性結晶粒は，粒径が好ましくは
０．３〜１５０μｍの範囲にあり， この粒径の各結晶
粒を覆っている粒界相の厚みは０．００１〜３０μｍの
範囲である。
【００１９】本発明磁石の好ましい組成（磁性結晶粒と
粒界相の全体の組成）は， 原子百分比で，Ｒ （Ｒは
Ｎｄ，Ｐｒ，Ｃｅ，Ｌａ，Ｙ，Ｓｍ，Ｔｂ，Ｄｙ，Ｇｄ
，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂより選ばれる少なくとも１種
） ：１０〜３０％， Ｂ：７％以下好ましくは２％未
満（０原子％を含まず）， Ｃ：０．１〜２０％， Ｃ
ｏ：４０％以下 （０原子％を含まず），Ｍ：下記所定
％の金属元素Ｍの少なくとも１種 （但し，２種以上含
む場合のＭ含有合計量は当該元素のうち最も大きいＭの
値以下），残部がＦｅおよび製造上不可避的な不純物か
らなる。ここで， Ｍ元素の含有量（但し，０原子％を
含まず）は，Ｔｉ：６％以下，Ｖ：１０％以下， Ｃｒ
：９％以下，Ｍｎ：６％以下，Ｎｉ：６．５％以下，
Ｚｒ：６．５％以下， Ｎｂ：１３％以下， Ｍｏ：１
０．５％以下， Ｈｆ：６％以下， Ｔａ：１１％以下
， Ｗ：１０％以下， Ｐｄ：６％以下，Ａｇ：３％以
下，Ｐｔ：４％以下，Ａｕ：４％以下，Ａｌ：１０％以
下， Ｃｕ：４．５％以下， Ｇａ：７．５％以下，
Ｉｎ：６％以下，Ｓｎ：４％以下，Ｓｂ：３％以下，Ｐ
ｂ：０．８％以下，Ｂｉ：５．５％以下， Ｚｎ：０．
３％以下， Ｐ：４．１％以下， Ｓｉ：８．５％以下
，Ｇｅ：７％以下， Ｓ：２．５％以下である。
【００２０】〔作用〕本発明合金において不可逆減磁を
小さくする効果はＢが２％以上でも十分発揮されるもの
ではあるが，特にＢが２％未満と少ない場合には，不可
逆減磁が顕著に良好となり，しかも磁気特性は従来材と
同等以上である。
【００２１】更にＭが無添加であっても， 従来材に比
べて不可逆減磁は小さくなるが，Ｍを前記記載の所定原
子％ （但し， ０原子％を含まず）含有せしめること
により，一層効果的に小さくできる。
【００２２】本発明による永久磁石の特徴は，従来のよ
うに磁石のｉＨｃを極めて高くしなくても高温時の不可
逆減磁が小さいことであり， 例えばパーミアンス係数
（ＰＣ）が３，ｉＨｃが１１．６ｋＯｅの磁石を環境
温度１６０℃で３０分放置した後， 室温に戻した時，
その不可逆減磁率は−８．０％である。他方，同じく
ＰＣ３でｉＨｃ １１．５ｋＯｅの従来材を上記と同一
の方法で測定した不可逆減磁率が−２８．１％であり，
ｉＨｃが同等にも拘らず大きな劣化を示す。従ってこの
ような高温の環境下でも本発明磁石の不可逆減磁特性は
，従来材に比べて十分低いｉＨｃでも極めて良好であり
， この点でまったく新規な永久磁石であるといえる。
【００２３】一方，本発明磁石の磁気特性については等
方性焼結磁石では，Ｂｒ≧４０００（Ｇ），ｉＨｃ≧４
０００（Ｏｅ）， （ＢＨ）ｍａｘ≧４（ＭＧＯｅ），
異方性焼結磁石では， Ｂｒ≧７０００（Ｇ），ｉＨ
ｃ≧４０００（Ｏｅ）， （ＢＨ）ｍａｘ≧１０（ＭＧ
Ｏｅ）であり， 従来のＲ−Ｆｅ−Ｂ系永久磁石と同等
以上の値を有する。
【００２４】このような新規な不可逆減磁特性は，本発
明磁石を構成している各磁性結晶粒の周囲を適切なＣ含
有量をもつ非磁性相で覆ったことによって得られたもの
である。即ち， 本発明者等は非磁性相である粒界相に
Ｃ （炭素） の所定量を含有せしめることにより，
つまり該相の１６重量％以下がＣとなるように， 好ま
しくは０．０５〜１６重量％の範囲になるように含有さ
せることにより， この非磁性相をより均質にし， 不
可逆減磁特性を改善できることを見い出した。更には磁
石中に，Ｍを前記記載の所定原子％ （但し０原子％含
まず）含有させることにより，一層効果的となることを
見出した。Ｍの含有は磁性結晶粒相及び粒界相における
原子拡散を促進し，こらの相を均質化すると共に不純物
相の生成を抑制していると推定される。つまり， この
ようなＣ含有非磁性相で各磁性結晶粒を被覆すれば，従
来材と同等のＢ含有量でも不可逆減磁を改善することが
できること，更にはＢを２原子％未満に低減することに
より，磁気特性は従来の同等レベル以上でありながら不
可逆減磁が画期的に改善され， 更に，前記Ｍを含有さ
せるとその効果は一層良好となることが明らかとなった
。
【００２５】〔発明の詳述〕
本発明磁石はＣ （炭素） の利用の仕方に大きな特徴
があるので先ずこの点から説明する。
【００２６】従来より， この種の磁石において一般に
Ｃは不可避的に混入する不純物元素とされており， 特
別のことがない限り積極的に添加する合金元素とは扱わ
れていなかった。例えば前出特開昭５９−４６００８号
公報では，ＣでＢの一部を置換することを開示するが，
これは磁石中のＢの含有量を２〜２８原子％と規定し２
原子％未満のＢ量では保磁力ｉＨｃが１ｋＯｅ未満にな
るので２原子％以上のＢ量を必要とするが，Ｂの多量の
含有ではコストが高くなるのでコストダウンのメリット
から，この場合にはＢの一部をＣで置換することが可能
であると述べられているに過ぎない。更に特開昭５９−
１６３８０３号公報にはＲ−Ｆｅ−Ｃｏ−Ｂ−Ｃ系磁石
が開示され，磁石中のＢの含有量を２〜２８原子％，
Ｃの含有量を４原子％以下と規定し，ＢとＣの具体的な
併用を開示しているが，Ｃの併用にも拘らずＢの含有量
を２原子％以上を必須とし，２原子％未満のＢ量では，
上記特開昭５９−４６００８号公報と同様にｉＨｃが１
ｋＯｅ未満となると説明されている。すなわち，該公報
が指摘するように，Ｃは磁気特性を低下させる不純物で
あると把握されており， 例えば粉末の成形時に用いる
滑剤等からのＣの混入は不可避であり， また，これを
完全に取り除く操作はコストアップを招くという理由か
らハードフエライト磁石相当のＢｒ ４０００Ｇまでな
ら，Ｃの含有量として４原子％以下を許容できると提案
するものであり，Ｃは磁気特性については消極的な作用
をもつものであり必ずしもＣを必須とはしていない。ま
たＣ含有の粒界相（非磁性相）の形成についてはこれら
の公報では全く示唆されていない。
【００２７】さらに特開昭６２−１３３０４号公報では
Ｒ−Ｆｅ−Ｃｏ−Ｂ−Ｃ系磁石において，耐酸化性を改
善するためにはＣ量が多いと良くないと教示し，Ｃの含
有量を０．０５重量％（原子百分比で約０．３％） 以
下に抑制することを提案し，更に他の出願人による特開
昭６３−７７１０３号公報でも同じ目的からＣを１００
０ｐｐｍ以下にすることを提案している。このように従
来においてＣは磁気特性および耐酸化性について消極的
元素とされており， 必須の添加元素とはされていなか
った。
【００２８】本発明者等は，ＣをＢの単なる置換元素と
して含有させるのではなく，磁性結晶粒を包囲する非磁
性相 （粒界） 中にＣを積極的に含有させるという添
加の仕方をするならば，従来の常識に反してＣは磁石の
不可逆減磁の改善に大きく寄与できることを見い出した
ものであり，更にはＣと共にＭを磁石中に含有させるこ
とによって一層これらの効果が有利に発現することを見
出した。即ち， このような非磁性相へのＣの含有によ
って，Ｂの含有量が公知の通常範囲であっても従来に比
べて低いｉＨｃで不可逆減磁が改善されるのであるが，
特に２原子％未満のＢ量の場合にはその効果が更に著し
いものになることがわかった。尚，従来ではＢの含有量
が２原子％未満ではｉＨｃが１ｋＯｅ以下になるとされ
ていたのであるが，本発明では２原子％未満のＢ量であ
ってもｉＨｃは４ｋＯｅ以上となる。このような本発明
による新規な効果は磁性結晶粒の各々を包囲するＣ含有
粒界相の形成並びにＣ含有粒界相及び磁石中へのＭの含
有によってもたらされ，このことから， これまでの磁
気特性の低下及び耐酸化の劣化をもたらしていたＣを消
極元素とする従来磁石とは全く異なり， Ｃを必須成分
とする新規な磁石の発明を完成することができた。
【００２９】この場合， 磁性結晶粒の各々を包囲する
Ｃ含有粒界相は，Ｃ以外に磁石を構成している合金元素
の少なくとも１種以上を含むものである。このような不
可逆減磁の改善をもたらす理由については以下のように
推察する。
【００３０】Ｃ含有粒界相が上記磁性結晶粒を構成して
いる合金元素の少なくとも１種以上を含むことは既に述
べたが，このうちＦｅ又はＣｏの遷移金属元素はα−Ｆ
ｅやＲ（Ｆｅ，Ｃｏ）２等の軟質な磁性相の生成を招き
やすく，これらの相が僅かに生成しても逆磁区核の発生
及びその成長を促進し，不可逆減磁の劣化をもたらす。
これに対して， 本発明による永久磁石合金の粒界相で
は，不定比なＲ−Ｆｅ−Ｃｏ−Ｍ−Ｃ系の金属間化合物
が生成していると推定され，これにより上記不純物の生
成が抑制されていると考えられる。このことは，該粒界
相が均質な非磁性相であるということであり， これに
より逆磁区核の発生が抑制されると推定される。又，Ｍ
は，磁性結晶粒内の原子拡散を促進することにより，均
質な結晶粒としｉＨｃを向上させると推定され， これ
により不可逆減磁率は改善される。
【００３１】一方，Ｂを２原子％未満としても不可逆減
磁は著しく改善されるが，これは従来材では必ず存在す
るＢリッチ相が抑制されたことによると推定される。つ
まりこの場合も上記同様Ｂリッチ相が逆磁区発生点とな
っていたと考えられる。尚，従来においてはＢを２％未
満にすると，α−Ｆｅの生成が容易となり磁気特性の著
しい劣化が生じると報告されているが，本発明による永
久磁石合金では，Ｃ含有粒界相によりα−Ｆｅの生成が
抑制され，従来材と同等以上の特性レベルが可能となる
。
【００３２】このように，本発明者等は個々の磁性結晶
粒をＣ含有粒界相で被覆し，更に磁石中にＭを含有せし
めることにより， 従来材に比べて低いｉＨｃでも不可
逆減磁を著しく改善せしめ，特に高温での改善効果が大
きく更にＢ含有量の低減により一層その効果が著しくな
ることを見出し， 公知の技術では困難であった熱安定
性の良好な永久磁石を発明するに至った。
【００３３】このＣ含有粒界相は，前記のようにＣ以外
に， 磁石を構成している合金元素の少なくとも１種以
上を含んでいるが， そのＣ含有量は粒界相組成におい
て１６重量％以下 （０重量％を含まず） であること
が必要である。すなわち，粒界相中のＣは該粒界相を均
質な非磁性相とするだけでなく，Ｂの減少に伴うｉＨｃ
の低下を抑制する効果をもたらすことから，その含有量
は粒界相の組成において好ましくは０．０５〜１６重量
％， 更に好ましくは， ０．１〜１６重量％を必要と
する。Ｃの含有量が０．０５重量％未満では粒界相を均
質な非磁性相にすることが不十分でｉＨｃが４ＫＯｅ未
満となることもある。一方， 粒界相中のＣ量が１６重
量％を超えると磁石のＢｒの低下が著しくもはや実用が
困難となる。
【００３４】この粒界相については個々の磁性結晶粒を
均一に被覆することが重要であるが，その厚みは０．０
０１μｍ未満ではｉＨｃの低下が著しく， 又３０μｍ
を超えるとＢｒがもはや本発明で意図する値を満足しな
くなるので０．００１μｍ〜３０μｍの範囲， 好まし
くは０．００５μｍ〜１５μｍの範囲とするのがよい。
なおこの厚みは粒界三重点も含むものである。この厚み
はＴＥＭを用いて測定することができる （後記の実施
例でもこの測定によった）。
【００３５】一方，この粒界相で囲われる各磁性結晶自
身は周知のＲ−Ｆｅ−Ｃｏ−Ｂ−（Ｃ） 系永久磁石と
同様の組成であってもよい。しかしＢが低量であっても
本発明磁石の場合には良好な磁気特性を発現できる。本
発明の合金磁石の組成 （磁性結晶粒と粒界相とを併せ
た全体の組成） は，好ましくは原子百分比でＲ：１０
〜３０％， Ｂ：７％以下望ましくは２％未満（０原子
％を含まず），Ｃｏ：４０％以下（０原子％を含まず）
，Ｍ：下記所定％の金属元素Ｍの少なくとも１種以上
（但し２種以上含む場合のＭの含有合計量は当該元素の
うち最も大きいＭの値以下， 但し０原子％を含まず。
）， Ｃ：０．１ 〜２０％， 残部がＦｅおよび製造
上不可避的な不純物からなる。Ｍ元素の含有量（０原子
％は含まず）は，Ｔｉ：６％以下，Ｖ：１０％以下，
Ｃｒ：９％以下，Ｍｎ：６％以下，Ｎｉ：６．５％以下
， Ｚｒ：６．５％以下， Ｎｂ：１３％以下， Ｍｏ
：１０．５％以下， Ｈｆ：６％以下， Ｔａ：１１％
以下， Ｗ：１０％以下， Ｐｄ：６％以下，Ａｇ：３
％以下，Ｐｔ：４％以下，Ａｕ：４％以下，Ａｌ：１０
％以下， Ｃｕ：４．５％以下， Ｇａ：７．５％以下
， Ｉｎ：６％以下，Ｓｎ：４％以下，Ｓｂ：３％以下
，Ｐｂ：０．８％以下，Ｂｉ：５．５％以下， Ｚｎ：
０．３％以下， Ｐ：４．１％以下， Ｓｉ：８．５％
以下，Ｇｅ：７％以下， Ｓ：２．５％以下である。
【００３６】本発明において，磁石中の総Ｃ含有量は好
ましくは０．１〜２０原子％である。磁石中の総Ｃ含有
量が２０原子％を超えるとＢｒの低下が著しく， 本発
明で目的とする等方性焼結磁石としてのＢｒ≧４ＫＧ，
並びに異方性焼結磁石としてのＢｒ≧７ＫＧの値を満
足しなくなる。一方， ０．１原子％未満ではもはや不
可逆減磁を改善することが困難となる。このように磁石
中の総Ｃ含有量としては好ましくは０．１〜２０原子％
とするが，前述の粒界相中のＣは不可逆減磁を改善する
だけでなく， Ｂの減少に伴うｉＨｃの低下を抑制する
効果をもたらすことから，その含有量は粒界相の組成に
おいて１６重量％以下 （０重量％は含まず），好まし
くは０．０５〜１６重量％， 更に好ましくは０．１〜
１６重量％を必須とする。Ｃの原料としては，カーボン
ブラック， 高純度カーボン又はＮｄ−Ｃ， Ｆｅ−Ｃ
等の合金を用いることができる。
【００３７】Ｒは， Ｙ，Ｌａ，Ｃｅ，Ｎｄ，Ｐｒ，Ｓ
ｍ，Ｔｂ，Ｄｙ，Ｇｄ，Ｈｏ，Ｅｒ，Ｔｍ，及びＹｂの
うち１種又は２種以上が用いられる。なお２種以上の混
合物であるミッシュメタル，ジジム等も用いることがで
きる。ここでＲを好ましくは，１０〜３０原子％とする
のは， この範囲内ではＢｒが実用上非常に優れるため
である。
【００３８】Ｂとしては，純ボロン又はフエロボロンを
用いることができ，その含有量は公知の範囲である２原
子％以上でも従来材に比べて不可逆減磁は改善され，
例えば７％程度までＢを含有させても本発明の前記目的
は達成されるのであるが，前述のように好ましくはＢは
２原子％未満，更に好ましくは１．８原子％以下におい
てより一層の効果がある。他方， Ｂ無添加ではｉＨｃ
が極端に低下し本発明の目的を達成できなくなる。フエ
ロボロンとしてはＡｌ，Ｓｉ等の不純物を含有するもの
でも用いることができる。
【００３９】Ｃｏとしては，電解コバルト若しくはＮｄ
−Ｃｏ，Ｆｅ−Ｃｏ， Ｃｏ−Ｃ等の合金を用いること
ができ，磁石中に含有する総Ｃｏ量 （粒界相と磁性結
晶粒のＣｏ量を合計した値） は４０原子％以下 （０
原子％を含まず）とする。このようにＣｏ量を限定する
理由は，Ｃｏを含有せしめることにより，キューリー点
を高め，残留磁束密度の温度係数を小さくする効果があ
り，一方総Ｃｏ量が４０原子％を超えると， Ｂｒやｉ
Ｈｃの磁気特性の減少が著しくなって本発明の意図する
永久磁石とはならないからである。
【００４０】ＭはＴｉ，Ｖ，Ｃｒ，Ｍｎ，Ｎｉ，Ｚｒ，
Ｎｂ，Ｍｏ，Ｈｆ，Ｔａ，Ｗ，Ｐｄ，Ａｇ，Ｐｔ，Ａｕ
，Ａｌ，Ｃｕ，Ｇａ，Ｉｎ，Ｓｎ，Ｓｂ，Ｐｂ，Ｂｉ，
Ｚｎ，Ｐ，Ｓｉ，Ｇｅ，Ｓのうち１種又は２種以上が用
いられる。磁石中のＭが０原子％でも不可逆減磁率は従
来品よりも改善されるが，Ｍを前記所定量を含有せしめ
ることにより，一層効果的に改善することができる。
一方Ｍ含有量が前記所定含有量を超えると，Ｂｒ，ｉＨ
ｃの減少が著しくなって，もはや本発明磁石の特性を満
足しなくなる。
【００４１】本発明の永久磁石合金は，前述のように厚
みが０．００１〜３０μｍ， 好ましくは０．００１〜
１５μｍの範囲のＣ含有粒界相で各々の磁性結晶粒が覆
われているものであるが， その磁性結晶粒の粒径は０
．３〜１５０μｍ，好ましくは０．５〜５０μｍの範囲
にある。磁性結晶粒の粒径が０．３μｍ未満になるとｉ
Ｈｃが４ＫＯｅ未満となり， また１５０μｍを超える
とｉＨｃの低下が著しくなり， 本発明磁石の特徴が損
なわれる。なおこの結晶粒の粒径の測定はＳＥＭによっ
て， また組成分析はＥＰＭＡを用いて正確に行うこと
ができる （後記実施例でもこれらの測定を行った）。
【００４２】本発明の永久磁石を製造するには，該永久
磁石合金が焼結体の場合には，溶解・鋳造・粉砕・成形
・焼結， 若しくは溶解・鋳造・粉砕・成形・焼結・熱
処理の一連の工程からなる従来同様の方法でも作製可能
であるが，好ましくは上記製造プロセスにおいて， 鋳
造後に該鋳造合金を熱処理する工程を導入するか，また
は粉砕時若しくは粉砕後にＣ原料の一部若しくは全量を
二次添加する工程を導入すること，さらにはこの二つの
工程を組合わせて導入することによって，有利に製造す
ることができる。またＭについてもその一部若しくは全
量を二次添加してもよい。他方， 該永久磁石合金が鋳
造合金である場合には，熱間塑性加工法を用いることに
よって，前述の効果を発揮する良好な本発明の永久磁石
合金を作製することができる。
【００４３】このような本発明の永久磁石合金は熱安定
性に優れたものであるが， 一方において耐酸化性につ
いても従来材に比べて画期的に改善されていることから
， 従来のように磁石の最外表面を耐酸化性の保護被覆
で被覆しなくても， 磁石自身が極めて優れた耐酸化性
を有するので， 場合によっては前記保護被覆の形成は
不要となる。本発明による永久磁石合金から調整された
合金粉末は，従来材に比べて熱安定性および耐酸化性の
良好なボンド磁石を提供することができる。
【００４４】このように本発明による永久磁石合金は，
従来のものに比べて熱安定性及び耐酸化性が著しく優れ
， 又，良好な磁気特性を有することから種々の磁石応
用製品に好適に用いられる。磁石応用製品としては，例
えば次の製品が挙げられる。ＤＣブラシレスモーター，
サーボモーター等の各種モーター；駆動用アクチュエ
ーター， 光学ビックアップ用Ｆ／Ｔアクチュエーター
等の各種アクチュエーター；スピーカー， ヘッドホン
， イヤホン等の各種音響機器；回転センサー， 磁気
センサー等の各種センサー；ＭＲＩ等の電磁石代替製品
；リードリレー， 有極リレー等の各種リレー；ブレー
キ， クラッチ等の各種磁気カップリング；ブザー，
チャイム等の各種振動発振機；マグネットセパレーター
， マグネットチャック等の各種吸着用機器；電磁開閉
器， マイクロスイッチ， ロッドレスエアーシリンダ
ー等の各種開閉制御機器；光アイソレーター， クライ
ストロン， マグネトロン等の各種マイクロ波機器；マ
グネット発電器；健康器具， 玩具等である。なお，こ
のような磁石応用製品は一例であり，これらに限定され
るものではない。
【００４５】また，本発明による永久磁石合金の特徴は
熱安定性に優れ，錆にくいことであり高い環境温度で使
用しても， 従来材よりも特性の劣化は少なく， 又従
来材のように磁石品の最外露出表面に耐酸化性保護被膜
を形成しなくても高い磁気特性を保持しながら該磁石自
身に優れた耐酸化性が付与されていることから， 保護
被膜が不要となることはもとより， 特殊な環境用とし
て保護被膜の必要が生じた場合でも， 磁石内部からの
錆の発生がないので， 保護被膜を形成するさいの接着
性が良好であると共に， 被膜の剥離や被膜厚みの変動
による寸法精度の問題等が解消される。この面からも熱
安定性及び耐酸化性を必要とする用途には最適な永久磁
石を提供できる。 以下に実施例を挙げて本発明磁石
の特性を明らかにする。
【００４６】
【実施例１】原料として純度９９．９％の電解鉄， 純
度９９．５％の電解コバルト， ボロン含有量が１９．
３２％のフエロボロン合金， 添加元素Ｍ金属として純
度９９％のニオブ，さらにＲ元素として純度９８．５％
（不純物として， 他の希土類元素を含有する） の
ネオジウム金属を使用し，組成比 （原子比） として
１８Ｎｄ−５６Ｆｅ−１５Ｃｏ−１Ｂ−３Ｎｂとなるよ
うに計量・配合し，真空中， 高周波誘導炉で溶解した
後， 水冷銅鋳型中に鋳込み， 合金塊を得た。このよ
うにして得られた合金塊をジョークラッシャーで破砕後
，アルゴンガス中でスタンプミルを用いて−１００ｍｅ
ｓｈまで粗砕した後， 組成比（原子比） が１８Ｎｄ
−５６Ｆｅ−１５Ｃｏ−１Ｂ−７Ｃ−３Ｎｂとなるよう
に，更に純度９９．５％のカーボンブラックを該粗砕粉
に添加し， 次いで， 振動ミルを用いて平均粒子径５
μｍまで粉砕した。このようにして得られた合金粉末を
１０ ＫＯｅの磁界中で１ｔｏｎ／ｃｍ２の圧力で成形
した後， アルゴンガス中１１２０℃で１時間保持した
後，急冷し， 焼結体を得た。
【００４７】なお，比較例１として， 原料のニオブを
除き，組成比が１８Ｎｄ−５９Ｆｅ−１５Ｃｏ−１Ｂ−
７Ｃとした以外は，実施例１と同一の操作で焼結体を得
た。また比較例２として，原料はカーボンブラックを除
いて実施例１と同一とし，組成比が１８Ｎｄ−５８Ｆｅ
−１５Ｃｏ−６Ｂ−３Ｎｂとなるように計量・配合し，
実施例１と同様に（但しカーボンブラックは無添加）溶
解後，粗砕，微粉砕，磁場成形し，次いで焼結，急冷し
て焼結体を得た。
【００４８】このようにして得られた焼結体の不可逆減
磁率をフラックスメーターを用いて次の手順で測定した
。
【００４９】（１） パーミアンス係数（Ｐｃ）が３に
なるように形状調整した上記焼結体試料を５０ＫＯｅで
着磁後， 室温（２５℃） でフラックスを測定する。
この時のフラックス値をＡ０とする。
（２） ついで上記試料を１６０℃で１２０分間加熱処
理した後， 室温まで冷却し，再びフラックスを測定す
る。この時のフラックス値をＡｔとする。
（３） 不可逆減磁率の値を次の式で算出する。
上記測定法に基づく焼結体の不可逆減磁率の評価を後記
の表１に示した。表１において「比１」は比較例１の略
である（以下，同じ）。
【００５０】表１から明らかのように，実施例１の焼結
体の不可逆減磁率は，−８．０％であるのに対して比較
例１のものでは−１３．５％と本発明の実施例１に比べ
て劣っている。更には，本発明による実施例１の焼結体
（Ｃ含有粒界相で各磁性結晶粒を被覆してなる焼結体）
では，比較例２（Ｃ含有の粒界相を持たない焼結体）に
比較して室温（２５℃） における保磁力（ｉＨｃ）
がほぼ同等であるが不可逆減磁率は比較例２の−２８．
１に比べて著しく小さくなっている。尚，本発明のＣ含
有の粒界相を持った比較例１はＣ含有の粒界相を持たな
い比較例２に比べてｉＨｃが０．８ ＫＯｅ低いにも拘
わらず不可逆減磁率は大幅に小さくなっている。
【００５１】また，実施例１の焼結体の粒界相における
Ｃ含有量をＥＰＭＡを用いて測定した結果は ４．５重
量％であった。更に磁性結晶粒の粒径を焼結組織のＳＥ
Ｍによる観察から１００個を測定したところ，その範囲
は０．９〜３３μｍであった。一方，ＴＥＭにより測定
した粒界相の厚みは０．０１３ 〜６．２μｍであった
。これらの値を表１に示した。又室温（２５℃）におけ
る磁気特性としてＶＳＭを用いて測定したＢｒ， ｉＨ
ｃ及び（ＢＨ）ｍａｘの値も表１に示した。このように
，本発明による永久磁石合金は比較例１及び２のものに
比べて熱安定性に優れていることが明らかである。
【００５２】なお，上記焼結体の耐酸化性の評価（耐候
性試験）として，温度６０℃， 湿度９０％の恒温・恒
湿下で６ケ月間（５０４０時間） 放置した時のＢｒ，
ｉＨｃの減少率を測定したところ， Ｂｒ：−０．２
３％， ｉＨｃ：−０．１２と極めて小さく， また外
観観察では錆がほとんど認められず， 耐酸化性が著し
く向上していることが明らかになった。これに対して比
較例２の焼結体ではわずか１ケ月（７２０時間） 後の
減少率がＢｒ：−８．１％， ｉＨｃ：−２．２％とな
り，これ以上の放置時間では， 原形を留めないほど錆
が激しく測定不能であった。このように本発明による永
久磁石合金は比較例２のものに比べて耐酸化性にも優れ
ていることがわかる。
【００５３】
【実施例２〜５】カーボン量が，表１に示す組成比にな
るように，カーボンブラックを微粉砕時に追添した以外
は，実施例１と同様の操作を行い焼結体を得た。更に，
比較例３として， １８Ｎｄ−６３Ｆｅ１５Ｃｏ−１Ｂ
−３Ｎｂとなるように計量・配合した後， 比較例２と
同様な操作を行って焼結体を得た。また比較例４〜７と
して， 原料のニオブを除いたうえ， 更にはカーボン
量が表１の組成となるようにした以外は，上記実施例と
同様の操作を行って焼結体を得た。このようにして得ら
れた焼結体の１６０℃における不可逆減磁率， 粒界相
におけるＣ量， 磁性結晶粒径， 粒界相の厚み及び磁
気特性を実施例１と同一の方法で評価し，その結果を表
１に示した。表１から明らかなように，ニオブを添加し
た本発明に従う焼結体はいずれも各比較例４〜７のニオ
ブ無添加のものに比べて不可逆減磁率が小さいことがわ
かる。なお，比較例３では粒界相中にＣが含有されてお
らず，磁気特性は低い値となった。
【００５４】
【表１】
【００５５】
【実施例６〜１０】原料の溶解時に，表２に示すボロン
（Ｂ）量及びシリコン（Ｓｉ）量になるように計量・配
合した以外は， 全て実施例１と同様の操作を行って実
施例６〜１０の焼結体を得た。また比較例８〜１１とし
て， 原料のシリコンを除き， またボロン量が表２の
組成になるように計量・配合し同様の操作を行って焼結
体を得た。比較例１２はボロン （Ｂ） 量を０原子％
とした例であり，ボロンを配合しなかった以外は上記実
施例と同様な操作を行い焼結体を得たものである。
【００５６】このようにして得られた焼結体の１６０℃
における不可逆減磁率， 粒界相におけるＣ量，磁性結
晶粒径，磁界相の厚み及び磁気特性を実施例１と同一の
方法で評価し，その結果を表２に示した。
【００５７】表２から明らかなようにシリコンを添加し
た実施例６〜１０の焼結体は，いずれも対応する各比較
例８〜１１のシリコン無添加のものに比べて不可逆減磁
率が小さいことがわかる。又Ｂ含有量が２原子％未満の
実施例８は，Ｂ含有量が２原子％以上の実施例９に比べ
て，ｉＨｃが０．４ＫＯｅ低いにも拘わらず， 不可逆
減磁率は小さくなっている。更にＢ含有量が２原子％以
上の実施例１０についても， 実施例４に比較すると同
様なことが言え，Ｂ含有量が２原子％未満の実施例４で
は， ｉＨｃが０．４ＫＯｅ低いにも拘わらず， 不可
逆減磁率は実施例１０より小さくなっており， 特にＢ
含有量が２原子％未満ではＢ≧２原子％よりも不可逆減
磁率は小さい。尚，比較例１２のボロン無添加では （
ＢＨ）ｍａｘは０であった。
【００５８】
【表２】
【００５９】
【実施例１１〜３５】原料の溶解時に， 表３に示す各
添加元素（Ｍ）を， 表示の量となるように計量・配合
した以外は，全て実施例１と同様の操作を行って実施例
１１〜３５の焼結体を得た。このようにして得られた焼
結体の１６０℃における不可逆減磁率， 粒界相におけ
るＣ量， 磁性結晶粒径， 粒界相の厚み及び磁気特性
を実施例１と同一の方法で評価し，その結果を表３に示
した。表３から明らかなように，添加元素（Ｍ）を添加
した実施例１１〜３５の焼結体は， 表１のＭ元素無添
加の比較例１のものに比べて不可逆減磁率が小さくなっ
ており，Ｍ元素添加の効果が認められる。
【００６０】
【表３】
【００６１】
【実施例３６〜４３】原料として純度９９．９％の電解
鉄， 純度９９．５％の電解コバルト， ボロン含有量
が１９．３２％のフエロボロン合金， 純度９９．５％
のカーボンブラック，添加元素Ｍ金属として純度９９％
のマンガン， 及び表４に示す希土類元素を，表４に示
す組成比となるように計量・配合し，真空中， 高周波
誘導炉で溶解した後， 水冷銅鋳型中に鋳込み合金塊を
得た。このようにして得られた合金塊を６８０℃で１５
時間加熱後， 炉内放冷した。次いで該合金塊をジョー
クラッシャーで破砕した後， アルゴンガス中でスタン
プミルを用いて−１００ｍｅｓｈまで粗砕し， 次いで
， 振動ミルを用いて平均粒子径５μｍまで粉砕した。
このようにして得られた合金粉末を実施例１と同様の操
作を行って実施例３６〜４３の焼結体を得た。また比較
例１３〜２０として，原料のマンガンを除いたうえ，
表４の組成になるように計量・配合した以外は，上記実
施例と同様の操作を行って焼結体を得た。このようにし
て得られた焼結体の１６０℃における不可逆減磁率，
粒界相におけるＣ量， 磁性結晶粒径， 粒界相の厚み
及び磁気特性を実施例１と同一の方法で評価し，その結
果を表４に示した。表４から明らかなようにマンガンを
添加した実施例３６〜４３の焼結体はいずれも対応する
比較例１３〜２０のマンガン無添加のもの比べて不可逆
減磁率が小さいことがわかる。
【００６２】
【表４】
【００６３】
【実施例４４】実施例１と同組成の合金微粉末を無磁場
中で成形した以外は，全て実施例１と同様の操作を行っ
て実施例１と同組成の焼結体を得た。比較例２１として
，合金微粉末を無磁場中で成形した以外は，比較例１と
同様の操作を行って比較例１と同組成の焼結体を得た。
このようにして得られた焼結体の１６０℃における不可
逆減磁率， 粒界相におけるＣ量， 磁性結晶粒径，
粒界相の厚み及び磁気特性を実施例１と同一の方法で評
価し，その結果を表５に示した。表５から明らかなよう
に，ニオブを添加した焼結体は比較例２１の無添加のも
のに比べて不可逆減磁率が小さいことが分かる。
【００６４】
【表５】Detailed Description of the Invention [0001] [Industrial Application Field] The present invention is directed to R (rare earth element)-Fe-Co-B-C, which has low irreversible demagnetization and excellent thermal stability.
Permanent magnetic alloys. [0002] In recent years, since R-Fe-B magnets were announced by Sagawa et al. as next-generation permanent magnets that surpass the magnetic force of Sm-Co magnets, many reports have been made regarding these magnets. Ta. However, although this magnet has superior magnetic force compared to Sm--Co magnets, it has the disadvantage that its magnetic properties are significantly inferior in thermal stability and oxidation resistance. In particular, deficiencies related to oxidation resistance are important issues to improve.
Many of the above reports disclose methods of improvement. On the other hand, conventional R-Fe-B or R-Fe-
The residual magnetic flux density of Co-B magnets decreases as the environmental temperature rises.
(Br) and coercive force (iHc) are significantly lower than those of Sm--Co magnets. In other words, it has the disadvantage of poor thermal stability. Under these circumstances, as a means of stabilizing the magnetic properties against changes in environmental temperature, it has generally been proposed to reduce the temperature dependence coefficient of the residual magnetic flux density and to sufficiently increase the coercive force at room temperature. ing. A common method for improving the former is to increase the Curie temperature of the magnet, for example,
Publication No. 9-64733 proposes replacing part of Fe with Co to increase the Curie temperature and reduce the temperature dependence coefficient of residual magnetic flux density. On the other hand,
As already mentioned, the coercive force decreases rapidly as the environmental temperature rises, but a serious drawback of this decrease in coercive force is that it causes large irreversible demagnetization. [0004] Irreversible demagnetization is a phenomenon in which Br, which has decreased at high temperatures, does not recover to its original state when the temperature returns to room temperature, and generally, as the magnet shape becomes thinner, its deterioration becomes more noticeable. This irreversible demagnetization deterioration cannot be fundamentally improved even if some of the Fe is replaced with Co to reduce the temperature dependence coefficient of the residual magnetic flux density. For this reason, the environmental temperature and shape are severely restricted in actual use. For example, in automobiles,
Application to harsh applications such as high-speed equipment will be difficult. The current situation is that methods for improving this irreversible demagnetization rely exclusively on methods of increasing iHc at room temperature. In other words, this is a method of reducing irreversible demagnetization by sufficiently increasing iHc at room temperature in anticipation of a decrease in iHc at high temperatures.
, Ni, Bi, V, Nb, Cr, Mo, etc., the iHc at room temperature is increased and the irreversible demagnetization rate is reduced.
Publication No. 6 specifies the addition of heavy rare earth elements such as Dy, Tb, Ho, Gd, Er, Tm, and Yb in addition to light rare earth elements as rare earth element components, thereby increasing iHc and
It teaches improving the irreversible demagnetization rate. [0005] However, although irreversible demagnetization can certainly be improved by sufficiently increasing iHc in this way, in the conventional method, when the temperature reaches a high temperature of, for example, 160°C, even if the iHc at room temperature is sufficiently high as 15 to 20 kOe, However, there remains the problem of rapid deterioration. In this case, iHc will be further increased. On the other hand, when iHc increases in this way, a new problem of magnetization occurs. In other words, in order to maximize the magnetic force of a magnet, it is necessary to magnetize it with a sufficiently large magnetic field until the magnetic force is saturated, and a low magnetization rate will lead to instability of the magnetic properties. Since a magnetic field that is 3 to 4 times stronger than the iHc of the magnet is required for magnetization, an extreme increase in iHc as in the conventional method makes it difficult to attach and demagnetize the magnet, and also increases the size of the equipment. will be invited. Therefore, in the past, it has not been possible to avoid these problems as well as the deterioration of irreversible demagnetization at high temperatures. [Problems to be Solved by the Invention] As described above, conventional R-Fe-Co-B magnets have not been able to sufficiently improve irreversible demagnetization at high environmental temperatures. Although it has superior magnetic force compared to the Sm-Co system, it has poor thermal stability especially at high temperatures and high iH at a practical level.
The reality is that the problem of magnetization associated with C conversion still exists, and the above merits are greatly diminished. Generally, R-Fe-B (or R-F
e-Co-B) system magnets are R2Fe14B [or R2(Fe,Co)14B] type tetragonal and RFe4B
4[R(Fe,Co)4B4] type B-rich phase, R-rich phase and non-magnetic phase containing B2O3 phase.
(In addition, in R-Fe-Co-B magnets, R(Fe, Co
) It is said that there is also a Laves phase represented by 2)
The principle of coercive force generation is said to be based on a reverse magnetic domain nucleation mechanism. In other words, the existence of this reverse magnetic domain determines the coercive force, and as iHc decreases as it grows, the coercive force of the nucleation type magnet becomes structure-sensitive, and the coercive force of the tetragonal and grain boundary phases
It is dominated by the R-rich phase, B-rich phase, and other impurity phases. By the way, the sprouts of the reverse magnetic domain nuclei, that is, the reverse magnetic domain nuclei, are generated in defects in the tetragonal and grain boundary phases, soft magnetic phases, and other impurity phases, and easily grow due to the presence of these defects and foreign substances. . In this way, if the structure of the magnet is inhomogeneous or contains impurities and various defects, i
Hc easily decreases, and as a result, irreversible demagnetization of residual magnetism, which is important at a practical level, increases. From the above, the following basic measures can be taken to reduce the irreversible demagnetization rate from the viewpoint of the magnet structure. (1) Homogenization of tetragonal crystals, (2) Homogenization and uniformity of grain boundary phase, (3) Removal of soft magnetic phase, (4
) Removal of other impurity phases. After these improvements have been made, it is thought that by optimizing iHc, a drastic improvement in irreversible demagnetization can be achieved. [0010] As a conventional method for improving irreversible demagnetization, for example, the above-mentioned Japanese Patent Application Laid-Open No. 59-89401 and Japanese Patent Application Laid-Open No. 6
It has already been mentioned that Publication No. 0-32306 discloses a method of improving iHc at room temperature by sufficiently increasing it, but these methods do not make any improvement to the structure of the magnet, and are simply This is a passive improvement method in which the iHc at room temperature is made extremely high by increasing the anisotropic magnetic field using additives, thereby improving irreversible demagnetization at the expense of lowering the iHc at high temperatures. Therefore, the improvement effect at higher temperatures is small;
As already mentioned, problems such as magnetization remain. On the other hand, by making the composition of the permanent magnet alloy homogeneous,
Many methods have been reported to improve iHc.
It has generally been proposed to heat treat magnet alloys. For example, in Japanese Patent Application Laid-open No. 59-217304, after sintering,
It is taught that iHc can be improved by heat treatment at a temperature of 50°C or higher. According to this method, although the homogenization of the magnet composition is improved by heat treatment, there are still impurity phases such as B-rich phase and B2O3 phase, so there is no change in the structure of the structure and the reverse magnetic domain remains. The origin of the nucleus and its growth have not been fundamentally resolved. Therefore, even if iHc is increased by this method, it is judged that the effect of improving irreversible demagnetization at high temperatures is small. [0012] As described above, in order to improve irreversible demagnetization according to the prior art, the actual situation is that no countermeasures are taken for the structure of the magnet alloy structure. [0013] Furthermore, as a method of suppressing the generation and growth of reverse magnetic domain nuclei by removing impurities, it is possible to suppress the generation of oxide phases and B-rich phases, for example. This can be suppressed by reducing the amount of oxygen. In addition, many B-rich phases exist in conventional materials, and their size is comparable to that of tetragonal crystals, so they not only cause defects as an impurity phase, but also become large magnetic spaces in some cases, causing demagnetization field formation. It can also be a factor. However, the reality is that in order to obtain higher magnetic properties at a practical level than before, it is necessary to increase the B content; for example, in JP-A-59-4
In Publication No. 6008 and Japanese Unexamined Patent Publication No. 1987-64733, in order to secure an iHc of 1 kOe or more,
The B content is specified to be 2 to 28 at%, and the iHc is 3 to 28 at%.
To achieve kOe, the B content must be at least 4 at%
In order to obtain iHc at a higher practical level, it is taught that the content of B should be further increased. That is, in the prior art, if the B content is reduced, α-Fe tends to precipitate, and iHc accordingly decreases rapidly. Therefore, it was not possible to suppress the formation of the B-rich phase. Therefore, in order to put into practical use conventional materials that contain a large amount of B and a large amount of B-rich phase as an impurity phase, an extremely high iHc is required as described above as a countermeasure against irreversible demagnetization at high temperatures. [0015] The object of the present invention is to obtain such R-Fe-Co
-The aim is to solve the problems of B-based permanent magnets, especially the problem of irreversible demagnetization, and unlike conventional materials, iH
The object of the present invention is to provide a permanent magnet alloy that exhibits small irreversible demagnetization and excellent thermal stability even at a relatively low iHc without making c extremely high. [Means for Solving the Problems] As a means to solve these problems, the inventors of the present invention have intensively studied the drastic improvement of irreversible demagnetization through the structure of the magnetic alloy. By making the magnetic crystal grains with a tetragonal structure and the R-rich grain boundary phase homogeneous, and by covering each magnetic crystal grain with the grain boundary phase, irreversible demagnetization is significantly improved compared to conventional materials. Moreover, in order to further enhance these effects, we have discovered a new technology that was difficult to even predict using the conventional technology of removing the B-rich phase. We have made it possible to provide a new permanent magnet alloy that has extremely small magnetism and a maximum energy product equal to or greater than that of the new permanent magnet alloy. In other words, we have discovered a new technology that can provide good magnetic properties that can withstand practical use even in the B content range of less than 2 at %, which was considered to be out of the practical range because high magnetic properties could no longer be obtained with conventional technology. This led to a revolutionary improvement in irreversible demagnetization. That is, according to the present invention, R-Fe-Co
-M-B-C alloy magnet (However, R is Nd, Pr,
Ce, La, Y, Sm, Tb, Dy, Gd, Ho, Er
, Tm, Yb, M is Ti
, V, Cr, Mn, Ni, Zr, Nb, Mo, Hf, T
a, W, Pd, Ag, Pt, Au, Al, Cu, Ga,
In, Sn, Sb, Pb, Bi, Zn, P, Si, Ge
, S), each of the magnetic crystal grains in the alloy is covered with a grain boundary phase, and this grain boundary phase contains 16% by weight or less (not including 0% by weight) of C. Provided is an R-Fe-Co-M-B-C permanent magnet alloy having a small irreversible demagnetization rate and excellent thermal stability. [0018] The magnetic crystal grains preferably have a grain size in the range of 0.3 to 150 μm, and the thickness of the grain boundary phase covering each crystal grain of this grain size is in the range of 0.001 to 30 μm. It is. The preferred composition (total composition of magnetic crystal grains and grain boundary phase) of the magnet of the present invention is R (R is Nd, Pr, Ce, La, Y, Sm, Tb, Dy, Gd) in atomic percentage.
, Ho, Er, Tm, Yb): 10 to 30%, B: 7% or less, preferably less than 2% (not including 0 atomic %), C: 0.1 to 20%, C
o: 40% or less (not including 0 atomic %), M: at least one of the following specified percentages of metal elements M (however, if two or more types are included, the total amount of M content is the largest value of M among the elements) (below), the remainder consists of Fe and impurities unavoidable during manufacturing. Here, the content of M element (excluding 0 atomic %) is Ti: 6% or less, V: 10% or less, Cr
: 9% or less, Mn: 6% or less, Ni: 6.5% or less,
Zr: 6.5% or less, Nb: 13% or less, Mo: 1
0.5% or less, Hf: 6% or less, Ta: 11% or less, W: 10% or less, Pd: 6% or less, Ag: 3% or less, Pt: 4% or less, Au: 4% or less, Al: 10% or less, Cu: 4.5% or less, Ga: 7.5% or less,
In: 6% or less, Sn: 4% or less, Sb: 3% or less, P
b: 0.8% or less, Bi: 5.5% or less, Zn: 0.
3% or less, P: 4.1% or less, Si: 8.5% or less, Ge: 7% or less, and S: 2.5% or less. [Operation] Although the effect of reducing irreversible demagnetization in the alloy of the present invention is sufficiently exhibited even when the B content is 2% or more, irreversible demagnetization is particularly noticeable when the B content is as low as less than 2%. Furthermore, the magnetic properties are equivalent to or better than conventional materials. Furthermore, even if no M is added, irreversible demagnetization is smaller than that of conventional materials, but by containing M at the predetermined atomic % (excluding 0 atomic %) as described above, it becomes even more Can be effectively made smaller. A feature of the permanent magnet according to the present invention is that irreversible demagnetization at high temperatures is small even if the iHc of the magnet is not extremely high as in the conventional case. For example, if the permeance coefficient (PC) is 3 and the iHc is 11, .When a 6kOe magnet was left at an ambient temperature of 160℃ for 30 minutes and then returned to room temperature,
Its irreversible demagnetization rate is -8.0%. On the other hand, the irreversible demagnetization rate of the conventional material with iHc 11.5 kOe measured using PC3 using the same method as above was -28.1%.
Although the iHc is the same, it shows a large deterioration. Therefore, even in such a high-temperature environment, the irreversible demagnetization characteristics of the magnet of the present invention are extremely good even at iHc, which is sufficiently lower than that of conventional materials, and in this respect it can be said that it is a completely new permanent magnet. On the other hand, regarding the magnetic properties of the magnet of the present invention, in an isotropic sintered magnet, Br≧4000 (G), iHc≧4
000(Oe), (BH)max≧4(MGOe),
For anisotropic sintered magnets, Br≧7000(G), iH
c≧4000 (Oe), (BH)max≧10 (MG
Oe), which is equal to or higher than that of conventional R-Fe-B permanent magnets. [0024] Such novel irreversible demagnetization characteristics were obtained by covering each magnetic crystal grain constituting the magnet of the present invention with a non-magnetic phase having an appropriate C content. . That is, the present inventors incorporated a predetermined amount of C (carbon) into the grain boundary phase, which is a non-magnetic phase.
In other words, by including C in the phase so that 16% by weight or less, preferably in the range of 0.05 to 16% by weight, this nonmagnetic phase becomes more homogeneous and the irreversible demagnetization characteristics are improved. I found out what I can do. Furthermore, it has been found that by containing M in the above-described predetermined atomic % (excluding 0 atomic %) in the magnet, it becomes even more effective. It is presumed that the inclusion of M promotes atomic diffusion in the magnetic crystal grain phase and the grain boundary phase, homogenizes these phases, and suppresses the formation of impurity phases. In other words, if each magnetic crystal grain is coated with such a C-containing nonmagnetic phase, irreversible demagnetization can be improved even with the same B content as in conventional materials, and furthermore, B can be reduced to less than 2 atomic percent. As a result, irreversible demagnetization has been dramatically improved while the magnetic properties are at or above the same level as conventional ones, and it has also become clear that the effect becomes even better when the above-mentioned M is included. [Detailed Description of the Invention] Since the magnet of the present invention has a major feature in the way C (carbon) is utilized, this point will be explained first. [0026] Conventionally, carbon has generally been regarded as an impurity element that is unavoidably mixed in this type of magnet, and has not been treated as an alloying element that is actively added unless there is a special case. For example, the aforementioned Japanese Unexamined Patent Publication No. 59-46008 discloses replacing a part of B with C, but
This defines the content of B in the magnet as 2 to 28 atomic%, and 2
If the amount of B is less than atomic %, the coercive force iHc will be less than 1 kOe, so a B amount of 2 atomic % or more is required. It is merely stated that it is possible to replace part of B with C. Furthermore, JP-A-59-
Publication No. 163803 discloses an R-Fe-Co-B-C magnet, in which the B content in the magnet is set to 2 to 28 at%,
The content of C is specified as 4 at% or less, and a specific combination of B and C is disclosed, but despite the combination of C, the content of B is required to be at least 2 at%, and If the amount of B is less than %,
Similar to the above Japanese Patent Application Laid-open No. 59-46008, iHc is 1.
It is explained that it is less than kOe. In other words, as the publication points out, C is understood to be an impurity that degrades magnetic properties. For example, C contamination from lubricants used during powder molding is unavoidable, and it is impossible to completely eliminate this. Because removing it would increase costs, we proposed that up to 4000G of Br, which is equivalent to a hard ferrite magnet, would allow a C content of 4 atomic percent or less, and C has a negative effect on magnetic properties. However, C is not necessarily required. Further, these publications do not suggest at all the formation of a C-containing grain boundary phase (non-magnetic phase). Furthermore, JP-A-62-13304 teaches that in order to improve oxidation resistance in R-Fe-Co-B-C magnets, it is not good to have a large amount of C; proposed to suppress C to below 0.05% by weight (approximately 0.3% in terms of atomic percentage), and furthermore, in JP-A-63-77103 published by another applicant, for the same purpose, C was suppressed to 100% by weight.
It is proposed to reduce the amount to 0 ppm or less. Thus, in the past, C was considered to be a negative element in terms of magnetic properties and oxidation resistance, and was not considered an essential additive element. The present inventors have developed a method of addition in which C is actively included in the non-magnetic phase (grain boundaries) surrounding magnetic crystal grains, rather than simply containing C as a replacement element for B. Therefore, contrary to conventional wisdom, we have found that C can greatly contribute to improving the irreversible demagnetization of magnets, and furthermore, by incorporating M together with C into the magnet, these effects can be made even more advantageous. We have found that this occurs. That is, by including C in such a non-magnetic phase, irreversible demagnetization is improved at a lower iHc than before even if the B content is within the known normal range.
In particular, it has been found that the effect becomes even more remarkable when the amount of B is less than 2 at %. In the past, it was thought that if the B content was less than 2 at %, the iHc would be 1 kOe or less, but in the present invention, even if the B content is less than 2 at %, the iHc is 4 kOe or more. Such novel effects of the present invention are brought about by the formation of a C-containing grain boundary phase surrounding each magnetic crystal grain and the inclusion of M in the C-containing grain boundary phase and the magnet. We were able to complete the invention of a new magnet that uses C as an essential component, which is completely different from conventional magnets that use C as a negative element, which causes deterioration of magnetic properties and deterioration of oxidation resistance. In this case, the C-containing grain boundary phase surrounding each of the magnetic crystal grains contains, in addition to C, at least one of the alloying elements constituting the magnet. The reason for this improvement in irreversible demagnetization is surmised as follows. It has already been mentioned that the C-containing grain boundary phase contains at least one of the alloying elements constituting the magnetic crystal grains, among which the transition metal elements Fe or Co are α-F.
It tends to lead to the formation of soft magnetic phases such as e and R (Fe, Co)2, and even a small amount of these phases will promote the generation and growth of reversed magnetic domain nuclei, leading to irreversible demagnetization deterioration. . On the other hand, it is estimated that a non-stoichiometric R-Fe-Co-M-C intermetallic compound is generated in the grain boundary phase of the permanent magnet alloy according to the present invention, which prevents the formation of the above impurities. considered to be suppressed. This means that the grain boundary phase is a homogeneous non-magnetic phase, which is presumed to suppress the generation of reverse magnetic domain nuclei. Also, M
It is estimated that by promoting atomic diffusion within the magnetic crystal grains, the crystal grains become homogeneous and the iHc is improved, thereby improving the irreversible demagnetization rate. On the other hand, irreversible demagnetization is significantly improved even when the B content is less than 2 atomic %, but this is presumed to be due to the suppression of the B-rich phase that always exists in conventional materials. In other words, it is considered that in this case as well, the B-rich phase was the point of generation of the reversed magnetic domain. In the past, it has been reported that when B is less than 2%, α-Fe is easily generated and magnetic properties are significantly deteriorated, but in the permanent magnet alloy according to the present invention, α-Fe is easily generated due to the C-containing grain boundary phase. -The generation of Fe is suppressed, making it possible to achieve a level of properties equal to or higher than that of conventional materials. [0032] As described above, the present inventors coated individual magnetic crystal grains with a C-containing grain boundary phase and further contained M in the magnet, thereby achieving irreversible demagnetization even at a lower iHc than conventional materials. They found that the improvement effect was particularly large at high temperatures, and that the effect became even more significant as the B content was reduced, leading to the invention of a permanent magnet with good thermal stability, which had been difficult to achieve with known technology. Ta. As mentioned above, this C-containing grain boundary phase contains, in addition to C, at least one kind of alloying element constituting the magnet, and the C content is 16% by weight in the grain boundary phase composition. % (excluding 0% by weight). In other words, C in the grain boundary phase not only makes the grain boundary phase a homogeneous nonmagnetic phase, but also reduces iHc as B decreases.
Since it has the effect of suppressing a decrease in , its content is preferably 0.05 to 16% by weight, more preferably 0.1 to 16% by weight in the composition of the grain boundary phase. If the C content is less than 0.05% by weight, it is insufficient to make the grain boundary phase a homogeneous nonmagnetic phase, and iHc may be less than 4 KOe. On the other hand, if the amount of C in the grain boundary phase exceeds 16% by weight, the Br content of the magnet decreases significantly, making it difficult to put it into practical use. Regarding this grain boundary phase, it is important to uniformly cover each magnetic crystal grain, but the thickness is 0.0
Below 01μm, iHc decreases significantly, and below 30μm
If it exceeds Br, it no longer satisfies the value intended in the present invention, so it is preferably in the range of 0.001 .mu.m to 30 .mu.m, preferably in the range of 0.005 .mu.m to 15 .mu.m. Note that this thickness also includes grain boundary triple points. This thickness can be measured using a TEM (this measurement was also used in the Examples described later). On the other hand, each magnetic crystal itself surrounded by this grain boundary phase may have the same composition as the well-known R-Fe-Co-B-(C) permanent magnet. However, even if the amount of B is low, the magnet of the present invention can exhibit good magnetic properties. The composition of the alloy magnet of the present invention (total composition including magnetic crystal grains and grain boundary phase) is preferably R:10 in atomic percentage.
~30%, B: 7% or less, preferably less than 2% (not including 0 atomic %), Co: 40% or less (not including 0 atomic %)
, M: at least one metal element M in the following specified percentage
(However, when two or more types of M are included, the total content of M must be less than or equal to the largest value of M among the elements, but does not include 0 atomic %.), C: 0.1 to 20%, the balance being Fe and manufacturing Consists of unavoidable impurities. The content of M element (not including 0 atomic %) is Ti: 6% or less, V: 10% or less,
Cr: 9% or less, Mn: 6% or less, Ni: 6.5% or less, Zr: 6.5% or less, Nb: 13% or less, Mo
: 10.5% or less, Hf: 6% or less, Ta: 11%
Below, W: 10% or less, Pd: 6% or less, Ag: 3
% or less, Pt: 4% or less, Au: 4% or less, Al: 10
% or less, Cu: 4.5% or less, Ga: 7.5% or less, In: 6% or less, Sn: 4% or less, Sb: 3% or less, Pb: 0.8% or less, Bi: 5.5 % or less, Zn:
0.3% or less, P: 4.1% or less, Si: 8.5%
Hereinafter, Ge: 7% or less, S: 2.5% or less. In the present invention, the total C content in the magnet is preferably 0.1 to 20 atomic %. When the total C content in the magnet exceeds 20 at%, the Br decreases significantly, and Br≧4KG, which is the purpose of the present invention as an isotropic sintered magnet.
In addition, the value of Br≧7KG as an anisotropic sintered magnet is no longer satisfied. On the other hand, if it is less than 0.1 atomic %, it becomes difficult to improve irreversible demagnetization. In this way, the total C content in the magnet is preferably 0.1 to 20 at%.
However, as mentioned above, C in the grain boundary phase not only improves irreversible demagnetization but also has the effect of suppressing the decrease in iHc due to the decrease in B, so its content is determined by the composition of the grain boundary phase. 16% by weight or less (not including 0% by weight), preferably 0.05 to 16% by weight, more preferably 0.1 to 16% by weight
16% by weight is required. Raw materials for C include carbon black, high purity carbon, Nd-C, Fe-C
Alloys such as the following can be used. [0037] R is Y, La, Ce, Nd, Pr, S
One or more of m, Tb, Dy, Gd, Ho, Er, Tm, and Yb are used. Note that a mixture of two or more types of mischmetal, didyme, etc. can also be used. The reason why R is preferably set to 10 to 30 atomic % here is because Br is practically excellent within this range. [0038] As B, pure boron or ferroboron can be used, and even if its content is within the known range of 2 atomic % or more, irreversible demagnetization is improved compared to conventional materials.
For example, the object of the present invention can be achieved even if B is contained up to about 7%, but as mentioned above, B is preferably less than 2 atomic %, more preferably 1.8 atomic % or less. effective. On the other hand, without B addition, iHc
is extremely reduced, making it impossible to achieve the object of the present invention. Ferroboron containing impurities such as Al and Si can also be used. [0039] As Co, electrolytic cobalt or Nd
Alloys such as -Co, Fe-Co, and Co-C can be used, and the total amount of Co contained in the magnet (the sum of the amount of Co in the grain boundary phase and magnetic crystal grains) is 40 at% or less (0
(excluding atomic percent). The reason for limiting the amount of Co in this way is that containing Co has the effect of raising the Curie point and reducing the temperature coefficient of residual magnetic flux density.On the other hand, if the total amount of Co exceeds 40 at%, Br and i
This is because the magnetic properties of Hc are significantly reduced and the permanent magnet as intended by the present invention cannot be obtained. M is Ti, V, Cr, Mn, Ni, Zr,
Nb, Mo, Hf, Ta, W, Pd, Ag, Pt, Au
, Al, Cu, Ga, In, Sn, Sb, Pb, Bi,
One or more of Zn, P, Si, Ge, and S may be used. Although the irreversible demagnetization rate is improved compared to conventional products even when M in the magnet is 0 atomic %, it can be improved even more effectively by containing M in the predetermined amount. On the other hand, when the M content exceeds the predetermined content, Br, iH
The decrease in c becomes significant, and the characteristics of the magnet of the present invention are no longer satisfied. As mentioned above, the permanent magnet alloy of the present invention has a thickness of 0.001 to 30 μm, preferably 0.001 to 30 μm.
Each magnetic crystal grain is covered with a C-containing grain boundary phase in the range of 15 μm, but the grain size of the magnetic crystal grain is 0.
．． It is in the range of 3 to 150 μm, preferably 0.5 to 50 μm. When the grain size of magnetic crystal grains is less than 0.3 μm, i
When Hc is less than 4 KOe and exceeds 150 μm, iHc decreases significantly and the characteristics of the magnet of the present invention are impaired. Note that the grain size of the crystal grains can be accurately measured using SEM, and the composition analysis can be performed accurately using EPMA (these measurements were also performed in the examples described later). [0042] In order to manufacture the permanent magnet of the present invention, when the permanent magnet alloy is a sintered body, melting, casting, crushing, shaping, sintering, or melting, casting, crushing, shaping, sintering, Although it can be produced by a conventional method consisting of a series of heat treatment steps, it is preferable to introduce a step of heat treating the cast alloy after casting in the above manufacturing process, or to add a part of the C raw material during or after crushing. Alternatively, it can be advantageously produced by introducing a step of secondary addition of the entire amount, or by introducing a combination of these two steps. Further, part or all of M may be added secondarily. On the other hand, when the permanent magnet alloy is a cast alloy, a good permanent magnet alloy of the present invention that exhibits the above-mentioned effects can be manufactured by using a hot plastic working method. Although the permanent magnet alloy of the present invention has excellent thermal stability, it also has dramatically improved oxidation resistance compared to conventional materials. Even if the outermost surface of the magnet is not coated with an oxidation-resistant protective coating, the magnet itself has extremely excellent oxidation resistance, so the formation of the protective coating may be unnecessary in some cases. The alloy powder prepared from the permanent magnet alloy according to the present invention can provide a bonded magnet with better thermal stability and oxidation resistance than conventional materials. [0044] As described above, the permanent magnet alloy according to the present invention is
It has significantly better thermal stability and oxidation resistance than conventional products, and also has good magnetic properties, making it suitable for use in a variety of magnet-applied products. Examples of magnet application products include the following products. DC brushless motor,
Various motors such as servo motors; various actuators such as drive actuators and F/T actuators for optical pickup; various audio equipment such as speakers, headphones, and earphones; various sensors such as rotation sensors and magnetic sensors; electromagnet substitutes for MRI, etc. Products: Various relays such as reed relays and polarized relays; Various magnetic couplings such as brakes and clutches; Buzzers,
Various vibration oscillators such as chimes; various adsorption devices such as magnetic separators and magnetic chucks; various opening/closing control devices such as electromagnetic switches, microswitches, and rodless air cylinders; various microwave devices such as optical isolators, klystrons, and magnetrons. ; magnetic generator; health equipment, toys, etc. Note that such magnet-applied products are merely examples, and the present invention is not limited to these. [0045] Furthermore, the permanent magnet alloy according to the present invention has excellent thermal stability and is resistant to rust, and even when used at high environmental temperatures, there is less deterioration in properties than conventional materials, and it does not deteriorate like conventional materials. Since the magnet itself has excellent oxidation resistance while maintaining high magnetic properties without forming an oxidation-resistant protective coating on the outermost exposed surface of the magnet, no protective coating is required. In addition, even if a protective coating is required for use in a special environment, there is no rust from inside the magnet, so the adhesion when forming the protective coating is good, and there is no problem with peeling of the coating or thinning of the coating. This solves problems such as dimensional accuracy due to fluctuations in . From this point of view as well, it is possible to provide a permanent magnet that is optimal for applications that require thermal stability and oxidation resistance. Examples are given below to clarify the characteristics of the magnet of the present invention. [Example 1] The raw materials were electrolytic iron with a purity of 99.9%, electrolytic cobalt with a purity of 99.5%, and boron content of 19.9%.
32% ferroboron alloy, 99% pure niobium as additional element M metal, and 98.5% pure as R element.
Neodymium metal (containing other rare earth elements as impurities) was weighed and mixed to have a composition ratio (atomic ratio) of 18Nd-56Fe-15Co-1B-3Nb, and then heated in a high-frequency induction furnace in a vacuum. After melting, the alloy was poured into a water-cooled copper mold to obtain an alloy ingot. After crushing the alloy ingot thus obtained with a jaw crusher, it was crushed for -100 m using a stamp mill in argon gas.
After coarsely crushing to sh, the composition ratio (atomic ratio) is 18Nd
-56Fe-15Co-1B-7C-3Nb, carbon black with a purity of 99.5% was further added to the crushed powder, and then the average particle size was 5 using a vibration mill.
It was ground to μm. The alloy powder thus obtained was compacted at a pressure of 1 ton/cm2 in a magnetic field of 10 KOe, held at 1120°C for 1 hour in argon gas, and then rapidly cooled to obtain a sintered body. [0047] As Comparative Example 1, except for the raw material niobium, the composition ratio was 18Nd-59Fe-15Co-1B-
A sintered body was obtained in the same manner as in Example 1 except that 7C was used. In addition, as Comparative Example 2, the raw materials were the same as in Example 1 except for carbon black, and the composition ratio was 18Nd-58Fe.
-15Co-6B-3Nb was measured and mixed,
After melting in the same manner as in Example 1 (however, no carbon black was added), the mixture was coarsely crushed, finely pulverized, and formed in a magnetic field, and then sintered and rapidly cooled to obtain a sintered body. The irreversible demagnetization rate of the sintered body thus obtained was measured using a flux meter according to the following procedure. (1) After magnetizing the above sintered body sample whose shape has been adjusted so that the permeance coefficient (Pc) is 3 at 50 KOe, the flux is measured at room temperature (25° C.). Let the flux value at this time be A0. (2) Next, heat-treat the sample at 160°C for 120 minutes, cool it to room temperature, and measure the flux again. Let the flux value at this time be At. (3) Calculate the value of irreversible demagnetization rate using the following formula. Evaluation of the irreversible demagnetization rate of the sintered body based on the above measurement method is shown in Table 1 below. In Table 1, "Ratio 1" is an abbreviation for Comparative Example 1 (the same applies hereinafter). As is clear from Table 1, the irreversible demagnetization rate of the sintered body of Example 1 was -8.0%, while that of Comparative Example 1 was -13.5%, which is the same as that of the present invention. This is inferior to Example 1. Furthermore, the sintered body of Example 1 according to the present invention (sintered body in which each magnetic crystal grain is coated with a C-containing grain boundary phase)
Now, the coercive force (iHc) at room temperature (25°C) is compared with Comparative Example 2 (sintered body without C-containing grain boundary phase).
are almost the same, but the irreversible demagnetization rate is -28.
It is significantly smaller than 1. In addition, although Comparative Example 1 which has a C-containing grain boundary phase of the present invention has an iHc lower by 0.8 KOe than Comparative Example 2 which does not have a C-containing grain boundary phase, the irreversible demagnetization rate is significantly lower. It's getting smaller. Further, the C content in the grain boundary phase of the sintered body of Example 1 was measured using EPMA and was found to be 4.5% by weight. Furthermore, the grain size of the magnetic crystal grains is determined by the SE of the sintered structure.
When 100 pieces were measured through observation by M, the range was 0.9 to 33 μm. On the other hand, the thickness of the grain boundary phase measured by TEM was 0.013 to 6.2 μm. These values are shown in Table 1. In addition, as magnetic properties at room temperature (25°C), Br, iH measured using VSM
The values of c and (BH)max are also shown in Table 1. Thus, it is clear that the permanent magnet alloy according to the present invention has superior thermal stability compared to Comparative Examples 1 and 2. [0052] As an evaluation of the oxidation resistance (weather resistance test) of the above-mentioned sintered body, the Br,
When the reduction rate of iHc was measured, Br: -0.2
3%, iHc: -0.12, which is extremely small, and almost no rust was observed upon external observation, indicating that the oxidation resistance was significantly improved. On the other hand, in the case of the sintered compact of Comparative Example 2, the reduction rate after only one month (720 hours) was -8.1% for Br and -2.2% for iHc, and if left for longer than this, it would lose its original shape. It was so rusted that it was impossible to measure it. Thus, it can be seen that the permanent magnet alloy according to the present invention is also superior in oxidation resistance compared to that of Comparative Example 2. [Examples 2 to 5] A sintered body was produced in the same manner as in Example 1, except that carbon black was added during pulverization so that the amount of carbon became the composition ratio shown in Table 1. Obtained. Furthermore,
As comparative example 3, 18Nd-63Fe15Co-1B
After measuring and blending to give -3Nb, the same operation as in Comparative Example 2 was performed to obtain a sintered body. Further, as Comparative Examples 4 to 7, sintered bodies were obtained by carrying out the same operations as in the above examples, except that niobium as a raw material was omitted and the amount of carbon was adjusted to the composition shown in Table 1. The irreversible demagnetization rate at 160°C, the amount of C in the grain boundary phase, the magnetic crystal grain size, the thickness of the grain boundary phase, and the magnetic properties of the sintered body thus obtained were evaluated using the same method as in Example 1. The results are shown in Table 1. As is clear from Table 1, the irreversible demagnetization rate of the sintered bodies according to the present invention to which niobium is added is lower than that of Comparative Examples 4 to 7, which do not contain niobium. In addition, in Comparative Example 3, C was not contained in the grain boundary phase, and the magnetic properties were low values. [Table 1] [Examples 6 to 10] All procedures were carried out except that when melting the raw materials, the amounts of boron (B) and silicon (Si) were measured and mixed so that the amounts of boron (B) and silicon (Si) were as shown in Table 2. The same operation as in Example 1 was performed to obtain sintered bodies of Examples 6 to 10. In addition, as Comparative Examples 8 to 11, sintered bodies were obtained by removing the raw material silicon, measuring and blending the boron content so that it became the composition shown in Table 2, and performing the same operation. In Comparative Example 12, the amount of boron (B) was 0 atomic%.
This is an example in which a sintered body was obtained by performing the same operations as in the above example except that boron was not blended. [0056] The temperature of the sintered body thus obtained is 160°C.
The irreversible demagnetization rate, C content in the grain boundary phase, magnetic crystal grain size, thickness of the magnetic field phase, and magnetic properties were evaluated using the same method as in Example 1, and the results are shown in Table 2. As is clear from Table 2, the sintered bodies of Examples 6 to 10 to which silicon was added had a smaller irreversible demagnetization rate than the corresponding Comparative Examples 8 to 11, which did not contain silicon. I understand. In addition, in Example 8 where the B content is less than 2 at %, the irreversible demagnetization rate is smaller even though the iHc is 0.4 KOe lower than in Example 9 where the B content is 2 at % or more. . Furthermore, the same can be said about Example 10 where the B content is 2 atomic % or more when compared with Example 4, and in Example 4 where the B content is less than 2 atomic %, even though the iHc is 0.4 KOe lower, Regardless, the irreversible demagnetization rate is smaller than that of Example 10, especially for B.
When the content is less than 2 at %, the irreversible demagnetization rate is smaller than when B≧2 at %. In addition, in Comparative Example 12 without boron addition (
BH) max was 0. [Table 2] [Examples 11 to 35] All additive elements (M) shown in Table 3 were measured and mixed to the indicated amounts when melting the raw materials. The same operation as in Example 1 was performed to obtain sintered bodies of Examples 11 to 35. The irreversible demagnetization rate at 160°C, the amount of C in the grain boundary phase, the magnetic crystal grain size, the thickness of the grain boundary phase, and the magnetic properties of the sintered body thus obtained were evaluated using the same method as in Example 1. The results are shown in Table 3. As is clear from Table 3, the sintered bodies of Examples 11 to 35 to which the additive element (M) was added had smaller irreversible demagnetization rates than those of Comparative Example 1 in Table 1, in which the M element was not added. The effect of adding M element is recognized. [Table 3] [Examples 36 to 43] As raw materials, electrolytic iron with a purity of 99.9%, electrolytic cobalt with a purity of 99.5%, feroboron alloy with a boron content of 19.32%, purity 99.5%
Carbon black, purity 99% as additive element M metal
Manganese and the rare earth elements shown in Table 4 were weighed and mixed to give the composition ratio shown in Table 4, and after melting in a high-frequency induction furnace in a vacuum, an alloy ingot was cast into a water-cooled copper mold. The alloy ingot thus obtained was heated to 680°C for 15
After heating for an hour, it was allowed to cool in the furnace. Next, the alloy ingot was crushed with a jaw crusher, then coarsely crushed to -100 mesh using a stamp mill in argon gas, and then crushed to an average particle size of 5 μm using a vibration mill. The alloy powder thus obtained was subjected to the same operation as in Example 1 to obtain sintered bodies of Examples 36 to 43. In addition, as Comparative Examples 13 to 20, in addition to excluding manganese as a raw material,
A sintered body was obtained by performing the same operations as in the above example except that the compositions were measured and blended so as to have the composition shown in Table 4. The irreversible demagnetization rate of the sintered body thus obtained at 160°C,
The amount of C in the grain boundary phase, the magnetic crystal grain size, the thickness of the grain boundary phase, and the magnetic properties were evaluated using the same method as in Example 1, and the results are shown in Table 4. As is clear from Table 4, the irreversible demagnetization rates of the sintered bodies of Examples 36 to 43 in which manganese was added are lower than those of the corresponding Comparative Examples 13 to 20 in which no manganese was added. [Table 4] [Example 44] The same procedure as in Example 1 was carried out except that the fine alloy powder having the same composition as in Example 1 was molded in the absence of a magnetic field. A sintered body with the same composition was obtained. As Comparative Example 21, a sintered body having the same composition as Comparative Example 1 was obtained by performing the same operation as Comparative Example 1 except that the alloy fine powder was molded in the absence of a magnetic field. The irreversible demagnetization rate at 160℃ of the sintered body thus obtained, the amount of C in the grain boundary phase, the magnetic crystal grain size,
The thickness of the grain boundary phase and magnetic properties were evaluated using the same method as in Example 1, and the results are shown in Table 5. As is clear from Table 5, the sintered body to which niobium is added has a smaller irreversible demagnetization rate than the sintered body of Comparative Example 21 without the addition of niobium. [Table 5]
Claims (5)
石（但し， ＲはＮｄ，Ｐｒ，Ｃｅ，Ｌａ，Ｙ，Ｓｍ，
Ｔｂ，Ｄｙ，Ｇｄ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂより選ばれ
る少なくとも１種， ＭはＴｉ，Ｖ，Ｃｒ，Ｍｎ，Ｎｉ
，Ｚｒ，Ｎｂ，Ｍｏ，Ｈｆ，Ｔａ，Ｗ，Ｐｄ，Ａｇ，Ｐ
ｔ，Ａｕ，Ａｌ，Ｃｕ，Ｇａ，Ｉｎ，Ｓｎ，Ｓｂ，Ｐｂ
，Ｂｉ，Ｚｎ，Ｐ，Ｓｉ，Ｇｅ，Ｓより選ばれる少なく
とも１種） において， 該合金の磁性結晶粒の各々が
， １６重量％以下 （０重量％を含まず）のＣを含む
粒界相で覆われていることを特徴とする不可逆減磁の小
さい熱安定性に優れた永久磁石合金。[Claim 1] R-Fe-Co-M-B-C alloy magnet (where R is Nd, Pr, Ce, La, Y, Sm,
At least one selected from Tb, Dy, Gd, Ho, Er, Tm, Yb, M is Ti, V, Cr, Mn, Ni
, Zr, Nb, Mo, Hf, Ta, W, Pd, Ag, P
t, Au, Al, Cu, Ga, In, Sn, Sb, Pb
, Bi, Zn, P, Si, Ge, and S), each of the magnetic crystal grains of the alloy has a grain boundary phase containing 16% by weight or less (excluding 0% by weight) of C. A permanent magnet alloy with excellent thermal stability and low irreversible demagnetization.
μｍの範囲にあり， 粒界相の厚みが０．００１〜３０
μｍの範囲にある請求項１に記載の永久磁石合金。[Claim 2] The magnetic crystal grains have a grain size of 0.3 to 150
The thickness of the grain boundary phase is in the range of 0.001 to 30 μm.
Permanent magnet alloy according to claim 1, in the μm range.
Ｃである請求項１または２に記載の永久磁石合金。[Claim 3] 0.05 to 16% by weight of the grain boundary phase is
The permanent magnet alloy according to claim 1 or 2, which is C.
相とを併せた全体の組成）が，原子百分比でＲ：１０〜
３０％， Ｂ：７％以下（０原子％を含まず），Ｃ：０
．１〜２０％， Ｃｏ：４０％以下 （０原子％を含ま
ず），Ｍ：下記所定％の元素Ｍの少なくとも１種以上
（但し，２種以上含む場合のＭの合計量は当該元素のう
ち最も大きいＭの値以下），残部がＦｅおよび製造上不
可避的不純物からなる請求項１，２または３に記載の永
久磁石合金，Ｍ元素の含有量（但し，０原子％を含まず
）は，Ｔｉ：６％以下，Ｖ：１０％以下， Ｃｒ：９％
以下，Ｍｎ：６％以下，Ｎｉ：６．５％以下， Ｚｒ：
６．５％以下， Ｎｂ：１３％以下， Ｍｏ：１０．５
％以下， Ｈｆ：６％以下， Ｔａ：１１％以下， Ｗ
：１０％以下， Ｐｄ：６％以下，Ａｇ：３％以下，Ｐ
ｔ：４％以下，Ａｕ：４％以下，Ａｌ：１０％以下，
Ｃｕ：４．５％以下， Ｇａ：７．５％以下， Ｉｎ：
６％以下，Ｓｎ：４％以下，Ｓｂ：３％以下，Ｐｂ：０
．８％以下，Ｂｉ：５．５％以下， Ｚｎ：０．３％以
下， Ｐ：４．１％以下， Ｓｉ：８．５％以下，Ｇｅ
：７％以下， Ｓ：２．５％以下である。4. The composition of the magnetic alloy (total composition including magnetic crystal grains and grain boundary phase) is R: 10 to 10 in atomic percentage.
30%, B: 7% or less (not including 0 atom%), C: 0
．． 1 to 20%, Co: 40% or less (not including 0 atomic %), M: at least one of the following specified % of elements M
(However, when two or more types of M are included, the total amount of M is less than or equal to the largest value of M among the elements), and the remainder is Fe and impurities inevitable in manufacturing. , M element content (excluding 0 atomic %): Ti: 6% or less, V: 10% or less, Cr: 9%
Below, Mn: 6% or less, Ni: 6.5% or less, Zr:
6.5% or less, Nb: 13% or less, Mo: 10.5
% or less, Hf: 6% or less, Ta: 11% or less, W
: 10% or less, Pd: 6% or less, Ag: 3% or less, P
T: 4% or less, Au: 4% or less, Al: 10% or less,
Cu: 4.5% or less, Ga: 7.5% or less, In:
6% or less, Sn: 4% or less, Sb: 3% or less, Pb: 0
．． 8% or less, Bi: 5.5% or less, Zn: 0.3% or less, P: 4.1% or less, Si: 8.5% or less, Ge
: 7% or less, S: 2.5% or less.
ある請求項４に記載の永久磁石合金。5. The permanent magnet alloy according to claim 4, wherein B is less than 2% (not including 0 atomic %).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3048757A JP2794496B2 (en) | 1991-02-22 | 1991-02-22 | R-Fe-Co-BC permanent magnet alloy with small irreversible demagnetization and excellent thermal stability |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3048757A JP2794496B2 (en) | 1991-02-22 | 1991-02-22 | R-Fe-Co-BC permanent magnet alloy with small irreversible demagnetization and excellent thermal stability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04268051A true JPH04268051A (en) | 1992-09-24 |
| JP2794496B2 JP2794496B2 (en) | 1998-09-03 |
Family
ID=12812155
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|---|---|---|---|
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Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2794496B2 (en) |
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| CN113674944A (en) * | 2021-07-29 | 2021-11-19 | 福建省长汀金龙稀土有限公司 | Neodymium-iron-boron magnet material and preparation method and application thereof |
| CN113674944B (en) * | 2021-07-29 | 2023-10-20 | 福建省长汀金龙稀土有限公司 | Neodymium-iron-boron magnet material and preparation method and application thereof |
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