JP2700643B2

JP2700643B2 - Manufacturing method of rare earth permanent magnet with excellent oxidation resistance

Info

Publication number: JP2700643B2
Application number: JP62087917A
Authority: JP
Inventors: 努大塚
Original assignee: Tokin Corp
Current assignee: Tokin Corp
Priority date: 1987-04-11
Filing date: 1987-04-11
Publication date: 1998-01-21
Anticipated expiration: 2013-01-21
Also published as: JPS63254703A

Description

【発明の詳細な説明】〔産業上の利用分野〕本発明はNd₂Fe₁₄B系磁石で代表される希土類（Ｒ）と
遷移金属（Ｔ）とＢとからなるR₂T₁₄B系金属間化合物磁
石の中で，特にＲ−Fe−Ｂを主成分とする永久磁石に係
わり，その耐酸化性及び磁石特性を改善したＲ−Fe−Ｂ
系磁石に関するものである。〔従来の技術〕 Nd−Fe−Ｂ系磁石で代表されるＲ−Fe−Ｂ系磁石は，
従来より普及しているSm−Co系合金永久磁石に比べ，高
い磁石を有するため，その用途が拡大しつつある。しかしながら,R−Fe−Ｂ系磁石合金はその金属組織中
に，大気中において極めて酸化し易いＲ−Fe固溶体相を
含有しているため，磁気回路等の装置に組込だ場合に,S
m−Co系磁石に比べ磁石の酸化による特性劣化及びバラ
ツキが大きく，また磁石より発生した酸化物の飛散によ
る周辺部品への汚染を引き起こすという欠点を有する。これら耐食性の改善に関する文献として，特開昭60−
54406号（J.P.A）や特開昭60−63903号等が挙げられ
る。これら文献では，磁石体表面にメッキ，化成皮膜等
の耐酸化性皮膜を形成し，その耐食性向上を図ることを
目的としている。しかし，これらの耐酸化性皮膜は，その工程中におい
て多量の水及び水溶液を使用するため，処理工程中に，
磁石のＲ−Fe固溶体相が酸化することにより，皮膜形成
後，内部より酸化が進行しふくれ又は皮膜の剥離等を生
じてしまうため，耐食性の改善としては適していない。
また，水を使用しない方法として，エポキシ等の耐酸化
性樹脂コーティングまたは，最近，普及してきたスパッ
タ，蒸着，イオンプレーティング等の方法によるAl,Ni
等の金属皮膜を形成させ，耐食性改善を図る乾式メッキ
等の方法もある。しかしながら，これら水を未使用のク
ーリング（cooling）においても，長期使用による皮膜
の劣化，使用中又は製品検査および装置への組み込みな
どの取扱い時に，微小なカケ等により磁石表面が大気と
接した場合，この部分より磁石組織中のＲ−Fe固溶体が
時間と共に著しく酸化し，磁石内部全体に広がっていく
ため，耐食性改善の方策としては適していない。〔発明が解決しようとする問題点〕以上述べたように，いずれの従来の耐食性改善方法に
おいても，磁石中に極度に酸化し易いＲ−Fe固溶体が存
在するため上記した各方策が有する本来の耐食性を本系
磁石に付寄することは極めて困難であった。すなわち，本系磁石においてはこのＲ−Fe固溶体相の
耐食性を根本的に改善しなければ，充分な耐食性を得る
ことは不可能である。この方策として，本系磁石合金にNi,Cu,Sm,Pb等を添
加することにより，本系磁石合金の耐食性を向上させた
先に述べた各種耐食性皮膜を本系磁石にクーリング（co
oling）することにより上記欠点を解決することも可能
であるが，従来の方法では磁石合金インゴット作製時
に，これら元素を添加して溶解したインゴットを使用す
るため,R−Fe固溶体のみならず，本系磁石の磁性相であ
るNd₂Fe₁₄B相へも，これら元素が一様に拡散してしまい
磁石特性を著しく劣化させてしまうため，対策としては
適していない。そこで，本発明はこれらの問題点を解決するものであ
り,R−Fe−M,R−Fe−Ｍ−Ｂ（ＭはNi,Cu,Pb,Smの一種以
上）液体急冷合金粉末及び薄帯（アモルファス及び微結
晶）より得られる合金粉末と，従来より製造されている
主にNd₂Fe₁₄B固相成分相より成るingot粉末を混合，成
形した圧粉体を従来通りの方法で焼結することにより著
しく耐食性が向上し磁石特性の劣化の度合が，極めて小
さい磁石を得ることができるものである。〔問題点を解決するための手段〕そこで，本発明によれば,R,Fe,Bを主成分とするR₂T₁₄
B系合金磁石（ここで,RはＹを含む希土類元素,Tは遷移
金属を示す。）を粉末冶金法にて製造する方法におい
て,R₂T₁₄B相結晶質合金粉末にＲ−Fe−Ｍ又はＲ−Fe−
Ｍ−Ｂ（ＭはNi,Cu,Pb,Snの一種以上）液体急冷合金粉
末又は薄帯（アモルファス及び微結晶）より得られる合
金粉末を10〜30vol％含有する粉末成形体を焼結するこ
とを特徴とする希土類永久磁石の製造方法が得られる。尚、好ましくはＭ（Ni,Cu,Pb,Sm）より一種を選択す
る場合は,Ni,Cu:10〜40wt％,Pb:10〜25wt％,Sn:10〜15w
t％とする。またＭ（Ni,Cu,Pb,Sm）より二種以上の元素を選択す
る場合は，これら元素の総含有量が10〜55wt％とする。ここで本発明は，１）焼結時に液相の核となり，また，液相の主成分と
なるＲ−Fe−Ｂ粉末のみにNi,Cu,Pb等の元素を添加した
Ｒ−Fe−Ｍ又はＲ−Fe−Ｍ−Ｂ（Ｍ＝Ni,Cu,Pb,Smの１
種以上）を用いることにより，焼結体中のＲ−Fe固溶体
相を耐食性の向上したＲ−Fe−Ｍ固溶体にさせる。ま
た，更にメッキ，化成被膜等の持つ本来の耐食性を本系
磁石に付与する。２）上記Ｒ−Fe−Ｍ又はＲ−Fe−Ｍ−Ｂ（Ｍ＝Ni,Cu,
Pb,Snの一種以上）を用いることにより，焼結体の磁性
相（R₂Fe₁₄B相）の界面付近のみにCu,Pb,Ni,Snを分布さ
せ，磁性相のBrの低下を極力押えるの２点を目的として
いる。すなわち，本発明によれば，焼結時に液相の核とな
り，液相の主成分となる粉末にＲ−Fe−Ｂよりも耐食性
の向上したＲ−Fe−M,R−Fe−Ｍ−Ｂ（Ｍ＝Ni,Cu,Pb,Sn
の一種以上）粉末を用いているため焼結後得られた焼結
体組織中のＲ−Fe固溶体は,R−（Fe−Ｍ）固溶体となっ
ており，耐食性が向上しているために，本発明の目的の
第一項が達成される。又，焼結時に液相の核となり，液相の主成分となる粉
末のみにNi,Cu等を添加しており，焼結時に主に固相と
なる粉末には，これら元素を添加していないため，両粉
末を混合，成形した圧粉体を焼結することにより，得ら
れた焼結体の金属組織において，磁性相（R₂Fe₁₄B相）
の界面付近及びＲ−Fe固溶体相のみに,Cu,Ni,Pb,Sn等の
Brを低下せしめる元素を濃縮させることが可能となる。
すなわち,R₂Fe₁₄B相の持つ高い飽和磁化の低減を極力押
えた焼結体組織が得られるため本発明の目的の第２項が
達成される。本発明において，焼結時液相の核となり，主成分とな
るＲ−Fe−M,R−Fe−Ｍ−Ｂ（Ｍ＝Ni,Cu,Pb,Snの一種以
上）粉末を，液体急冷合金粉末又は，薄帯（アモルファ
ス及び微結晶）より得られる合金粉末としたのは,R−Fe
−M,R−Fe−Ｍ−Ｂインゴットは被粉砕性に劣るため，
粉砕した粉末の粒度分布が広くなったり，焼結時に，液
相の核となるＲ−Fe−Ｍ固溶体相粉末と固相であるR₂Fe
₁₄B相粉末との均一混合ができないため，焼結体組織が
不均一となり磁石特性の劣化をもたらすため本発明の目
的の第２項の効果を低減させてしまう。それ故,R−Fe−M,R−Fe−Ｍ−Ｂ粉末は，被粉砕性の
高い液体急冷合金粉末，又は薄帯（アモルファス及び微
結晶）より得られる合金粉末とする必要がある。本発明において，液体急冷合金粉末又は薄帯（アモル
ファス及び微結晶）より成るＲ−Fe−Ｍ又はＲ−Fe−Ｍ
−Ｂ粉末のＭ（Ni,Cu,Sn,Pb）値を10wt％以上としたの
は，これよりも低いＭ値では，本発明の特徴とするＲ−
Fe固溶体相の耐食性向上が不充分であるためである。又
ni,Cu≦40wt％,Pb≦25wt％,Sn≦15wt％及びこれら元素
の複合添加においてその上限を55wt％としたのは，これ
よりも多いＭ値では，磁性結晶粒内に存在するCu,Pb,Sn
値が多くなり過ぎたり，また,Niにおいては焼結体内に
磁石の_IHcを劣化させるラーフェス（Laves）相の量が多
くなり過ぎることによる磁石特性の劣化を生ずるためで
ある。又，これら液体急冷合金粉末及び薄帯（アモルフ
ァス及び微結晶）より成る粉末の添加量を10〜30vol％
としたのは10vol％より少ない領域では耐食性向上が得
られず,30vol％を越えた領域では上記同様磁石特性の劣
化が著しく本発明の目的にそわないためである。本発明によれば，従来法で得られるインゴットを粉砕
して得られたR₂Fe₁₄B相を主相とし焼結時に主に固相と
なる粉末に焼結時主に液相となるＲ−Fe−Ｍ又はＲ−Fe
−Ｍ−Ｂ（Ｍ＝Ni,Cu,Pb,Snの一種以上）原料粉末を液
体急冷合金粉末又は薄帯（アモルファス及び微結晶）よ
り得た後，これら粉末を混合・成形した圧粉体を従来と
同様の方法で焼結することにより，従来よりも耐食性に
優れた，しかも，磁石特性の優れた結晶体が得られ実用
上非常に有益である。＜実施例−１＞純度99wt％以上のNd−Fe−Ｂを用いアルゴン雰囲気中
にて高周波加熱により26.7Nd−1.0B−Febal（wt％）の
組成を有するR₂Fe₁₄B相ingotを得てさらにディスクミル
を用いて，粗粉砕した。そしてこの粉末をＩ材とした。次に上記同等のNd,Fe,B,Ni,Cu,Sn,Pbを用いて,60Nd−
1.0B−10Ni,57Nd−1.0B−18Ni,50Nd−1.0B−40Ni,60Nd
−1.0B−10Cu,60Nd−1.0B−21Cu,45Nd−1.0B−39Cu,60N
d−1.0B−10Pb,60Nd−1.0B−17Pb,60Nd−1.0B−25Pb,60
Nd−1.0B−10Sn,60Nd−1.0B−15Sn,（いずれもwt％,Fe
はbalance）の組成を有する15種類のアモルファスリボ
ン細片を単ロール法にて得た。そしてこれらアモルファ
スリボン細片を粗粉砕して得られた15種類の粗粉末をII
材とした。そして，この15種類のII材に対してＩ材をお
のおの加え30Nd−1.0B−（Fe−Ｍ）bal（Ｍ＝Ni,Cu,Sn,
Pb）の秤量組成を有する15種類の粗粉末を得た。これら
15種の粗粉末をボールミルを用いて平均粒径３〜５μｍ
に微粉砕した。次に得られた微粉末を20kOeの磁場中,1.
0ton/cm²の圧力で成形し圧粉体を得た。これら圧粉体を
1000〜1200℃で０〜2hr Ar中焼結した。その後,400〜80
0℃で0.5〜10hr加熱した後急冷した。又比較材として30
Nd−1.0B−febal（wt％）の組成を有するインゴットを
上記と同様にして得た。その後上記と同様粗粉砕，微粉
砕磁場中成形，焼結，熱処理を行い焼結体を得た。そし
てこれら焼結体を10mm×10mm×8mmに加工した後,Cu下皿
メッキとした電解Niメッキ及びフロメート処理を施こし
た。そしてこれらの膜厚を測定したところ３〜20μｍで
あったこれら試験片の磁石特性及び60℃×90％湿度試験
を300hr施こし耐食性試験を行った結果を第一表に示
す。第一表より本発明による試験片はいずれも比較例の試
験片に比べ耐食性を示し，又磁石特性の面でも永久磁石
として優れた磁石特性を示すことがわかる。＜実施例−２＞実施例−１と同等の純度のNd,Fe,B,Ni,Cu,Pb,Snを用
いて60Nd−1.0B−5Sn−5Pb,50Nd−1.0B−20Cu−10Pb,50
Nd−1.0B−10Cu−20Ni,50Nd−1.0B−20Ni−5Sn,50Nd−
1.0B−15Ni−10Pb,60Nd−1.0B−10Cu−5Sn−5Pb,50Nd−
1.0B−15Ni−6Cu−3Pb（いずれもFe−bal,wt％）の組成
を有するアモルファスリボン細片をAr中単ロール法にて
得た。そしてこれらアモルファスリボン細片を粗粉砕し
得られた粗粉末をIII材とした。次にこれら10種類のIII
材おのおのに実施例−１で得られたＩ材のingot粉末を
加え30Nd−1.0B−（Fe−Ｍ）bal（Ｍ＝Ni,Cu,Sn,Pbの一
種以上）wt％の組成を有する10種類の粗粉末を得た。さ
らにこれら10種類の粗粉末を実施例−１と同様にして微
粉砕，磁場中成形，焼結，熱処理，加工を耐食性メッキ
及び化成処理を行い試験片（10×10×８）を得た。次に
これら試験片に実施例１と同様60℃×90％極温恒湿試験
を行った。第２表にこれら試験片の磁石特性及び恒温恒
湿試験結果実施例−１の比較材の結果を示す。第２表より本発明による磁石試験片は，いずれも比較
材の試験片に比べ耐食性に優れ，又磁石特性の面でも永
久磁石として優れた磁石特性を示している。＜実施例−３＞実施例−１で得られた焼結体のうち,60Nd−1.0B−21C
u−Febal,60Nd−1.0B−17Pb−Febal（wt％）及び実施例
２で得られた焼結体のうち60Nd−1.0B−10Cu−20Ni−Fe
bal（wt％）を加えて得られた焼結体について,E.D.Xを
用いて各元素の濃度分布を調査するためNd₂Fe₁₄B相界面
付近より粒子内へ２μｍ間隔にてスポット分析を行っ
た。その結果をおのおの第３表〜第５表に示す。第３〜第５表よりCu,Ni,Pb,Snの元素がNd₂Fe₁₄B粒子
界面付近に濃縮していることがわかる。ここで，表を簡単に説明する。第１表は実施例１におけるアモルファスNd−Fe−Ｂ−
Ｍ（Ｍ＝Ni,Cu,Pb,Snの一種）を混合して得られた焼結
体の磁石特性及びこれら焼結体に電解Niメッキ及び亜鉛
クロメート処理を施した試料の60℃×90％湿度試験（30
0hr）結果を示したものである。第２表は実施例２におれるアモルファスNd−Fe−Ｂ−
Ｍ（Ｍ＝Ni,Cu,Pb,Snの二種以上）を混合して得られた
焼結体の磁石特性及びこれら焼結体に電解Niメッキ，亜
鉛クロメート処理を施した試料の60℃×90％湿度試験
（300hr）結果を示したものである。第３表は実施例３における60Nd−1.0B−21Cu−Febal
（wt％）のアモルファス粉末を混合して得られた焼結体
のE.D.Xスポット分析結果である。第４表，第５表はおのおの実施例３における60Nd−1.
0B−17Pb−Febal,60Nd−1.0B−10Cu−20Ni−Febalアモ
ルファス粉末をおのおの加えて得られた焼結体のE.D.X
スポット分析結果である。〔発明の効果〕以上の実施例で示される如く,Nd−Fe−Ｂ系磁石を粉
末冶金法により製造する場合において，従来の製法で得
られる結晶性Nd₂Fe₁₄B相を主相とするインゴット粉末に
焼結時に主に液相となる原料粉末であるＲ−Fe−Ｍ又は
Ｆ−Fe−Ｂ−Ｍ粉末を非晶質合金又は微結晶合金より得
た後，これら粉末を混合成形した圧粉体を焼結すること
により従来よりも耐酸化性を向上させることができ,Ni
等の耐酸化性メッキ，化成被膜等の持つ本来の耐食性を
付与することが可能となる。また，特に液相成分と固相
成分とを混合した成形体を焼結しているため,Nd₂Fe₁₄B
相界面付近にのみ，耐食性を向上させ磁石特性を劣化さ
せるNi,Cu,Pb,Sn等の元素を濃縮させた金属組織を有す
る焼結体が得られ，磁石特性の劣化が小さく，しかも耐
酸化性に優れた焼結体磁石を得ることができる。以上Nd−Fe−Ｂについてのみ述べたが,Yを含めた希土
類元素（Ｒ）−Fe−Ｂ系合金についても同様の効果が期
待できることは容易に推察できるところである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an R ₂ T ₁₄ B-based metal composed of a rare earth (R), a transition metal (T), and B represented by an Nd ₂ Fe ₁₄ B-based magnet. R-Fe-B with improved oxidation resistance and magnet properties, particularly to permanent magnets containing R-Fe-B as a main component among inter-compound magnets
It relates to a system magnet. [Prior art] R-Fe-B magnets represented by Nd-Fe-B magnets are:
Compared to Sm-Co alloy permanent magnets that have been widely used, they have higher magnets, and their applications are expanding. However, since the R-Fe-B based magnetic alloy contains an R-Fe solid solution phase which is extremely oxidizable in the atmosphere in its metal structure, when it is incorporated in a device such as a magnetic circuit, the R-Fe-B magnet alloy has
Compared to m-Co magnets, the magnets have the disadvantages that the properties are deteriorated and scattered due to the oxidation of the magnets, and that the oxides generated from the magnets scatter and contaminate peripheral parts. For a reference on the improvement of corrosion resistance, see Japanese Unexamined Patent Publication No.
54406 (JPA) and JP-A-60-63903. In these documents, an object is to form an oxidation-resistant film such as plating and a chemical conversion film on the surface of a magnet body and to improve the corrosion resistance. However, these oxidation resistant coatings use a large amount of water and aqueous solution during the process,
Oxidation of the R-Fe solid solution phase of the magnet causes oxidation to proceed from the inside after the film is formed, causing blistering or peeling of the film. Therefore, it is not suitable for improving corrosion resistance.
As a method not using water, an oxidation-resistant resin coating such as epoxy or Al, Ni by a method such as sputtering, vapor deposition, or ion plating, which has recently become popular, is used.
There is also a method such as dry plating for improving the corrosion resistance by forming a metal film such as However, even when these waters are unused, even if the magnet surface comes into contact with the atmosphere due to minute chipping, etc., during handling such as deterioration of the coating due to long-term use, or during use or product inspection and incorporation into equipment. From this part, the R-Fe solid solution in the magnetic structure is remarkably oxidized with time and spreads throughout the magnet, so that it is not suitable as a measure for improving corrosion resistance. [Problems to be Solved by the Invention] As described above, in any of the conventional methods for improving corrosion resistance, since the R-Fe solid solution which is extremely easily oxidized is present in the magnet, the above-mentioned respective methods have the original It was extremely difficult to contribute corrosion resistance to this magnet. That is, in the present magnet, it is impossible to obtain sufficient corrosion resistance unless the corrosion resistance of the R-Fe solid solution phase is fundamentally improved. As a measure, the addition of Ni, Cu, Sm, Pb, etc. to the present magnet alloy improves the corrosion resistance of the present magnet alloy.
oling) can solve the above drawbacks. However, in the conventional method, an ingot in which these elements are added and melted is used at the time of manufacturing a magnet alloy ingot. These elements diffuse evenly into the Nd ₂ Fe ₁₄ B phase, which is the magnetic phase of the system magnet, and significantly degrade the magnet properties, so it is not suitable as a countermeasure. Accordingly, the present invention has been made to solve these problems, and it has been proposed that R-Fe-M, R-Fe-MB (M is at least one of Ni, Cu, Pb, and Sm) liquid quenched alloy powder and ribbon. (Amorphous and microcrystalline) alloy powder and conventionally produced ingot powder consisting mainly of Nd ₂ Fe ₁₄ B solid phase component phase are mixed and compacted by conventional method. By doing so, it is possible to obtain a magnet in which the corrosion resistance is significantly improved and the degree of deterioration of the magnet characteristics is extremely small. [Means for Solving the Problems] Therefore, according to the present invention, R ₂ T ₁₄ containing R, Fe, and B as main components is used.
In a method of manufacturing a B-based alloy magnet (where R represents a rare earth element containing Y and T represents a transition metal) by a powder metallurgy method, R ₂ T ₁₄ B phase crystalline alloy powder is mixed with R-Fe- M or R-Fe-
Sintering a powder compact containing 10 to 30 vol% of MB (M is at least one of Ni, Cu, Pb, Sn) liquid quenched alloy powder or alloy powder obtained from thin ribbon (amorphous and microcrystalline) Thus, a method for producing a rare earth permanent magnet is obtained. Preferably, when one kind is selected from M (Ni, Cu, Pb, Sm), Ni, Cu: 10 to 40 wt%, Pb: 10 to 25 wt%, Sn: 10 to 15 w
t%. When two or more elements are selected from M (Ni, Cu, Pb, Sm), the total content of these elements is 10 to 55 wt%. Here, the present invention provides: 1) R-Fe-M in which elements such as Ni, Cu, Pb and the like are added to only R-Fe-B powder which is a nucleus of a liquid phase during sintering and is a main component of the liquid phase. Or R-Fe-MB (M = Ni, Cu, Pb, Sm 1
), The R-Fe solid solution phase in the sintered body is converted into an R-Fe-M solid solution having improved corrosion resistance. In addition, the original corrosion resistance of plating, chemical conversion coating, etc. is imparted to the present magnet. 2) R-Fe-M or R-Fe-MB (M = Ni, Cu,
Pb, Sn) is used to distribute Cu, Pb, Ni, and Sn only near the interface of the magnetic phase (R ₂ Fe ₁₄ B phase) of the sintered body, and to reduce the Br of the magnetic phase as much as possible. The aim is to hold down two points. That is, according to the present invention, R-Fe-M, R-Fe-M-B, which becomes a nucleus of a liquid phase during sintering and has a higher corrosion resistance than R-Fe-B, is used as a main component of the liquid phase. (M = Ni, Cu, Pb, Sn
Since the powder is used, the R-Fe solid solution in the sintered body structure obtained after sintering is an R- (Fe-M) solid solution, and the corrosion resistance is improved. The first object of the present invention is achieved. In addition, Ni, Cu, etc. are added only to the powder that becomes the core of the liquid phase during sintering and become the main component of the liquid phase, and these elements are added to the powder that mainly becomes the solid phase during sintering. Therefore, the sintered compact obtained by mixing and molding both powders has a magnetic phase (R ₂ Fe ₁₄ B phase) in the metal structure of the resulting sintered body.
Near the interface and only in the R-Fe solid solution phase, Cu, Ni, Pb, Sn, etc.
It is possible to concentrate elements that lower Br.
That is, a sintered body structure in which the reduction of the high saturation magnetization of the R ₂ Fe ₁₄ B phase is suppressed as much as possible is obtained, and the second object of the present invention is achieved. In the present invention, R-Fe-M, R-Fe-MB (M or more of one or more of Ni, Cu, Pb, and Sn) powders, which are nuclei of a liquid phase during sintering and are main components, are mixed with a liquid quenched alloy. The powder or alloy powder obtained from ribbons (amorphous and microcrystalline) was made of R-Fe
-M, R-Fe-MB ingots are inferior in grindability.
During the sintering, the particle size distribution of the pulverized powder is widened, and during sintering, R-Fe-M solid solution phase powder serving as the core of the liquid phase and R ₂ Fe
_Since uniform mixing with the ₁₄ B phase powder cannot be performed, the structure of the sintered body becomes non-uniform and the magnet characteristics are deteriorated, so that the effect of the second item of the present invention is reduced. Therefore, the R-Fe-M and R-Fe-MB powders need to be liquid quenched alloy powders having high grindability or alloy powders obtained from ribbons (amorphous and microcrystalline). In the present invention, R-Fe-M or R-Fe-M comprising liquid quenched alloy powder or ribbon (amorphous and microcrystalline)
The reason why the M (Ni, Cu, Sn, Pb) value of the -B powder is set to 10 wt% or more is that the M value lower than this value is a characteristic of the present invention.
This is because the improvement in corrosion resistance of the Fe solid solution phase is insufficient. or
Ni, Cu ≤ 40 wt%, Pb ≤ 25 wt%, Sn ≤ 15 wt%, and the upper limit of 55 wt% in the composite addition of these elements is that, for M values larger than this, Cu, which exists in the magnetic crystal grains, Pb, Sn
Or too many values, also because causing the deterioration of magnetic properties due to the amount of Laves (Laves) phase degrading _I Hc of the magnet in the sintered body is too large in Ni. The addition amount of the liquid quenched alloy powder and the powder consisting of the ribbon (amorphous and microcrystalline) is 10 to 30 vol%.
The reason for this is that no improvement in corrosion resistance is obtained in a region less than 10 vol%, and in the region exceeding 30 vol%, the deterioration of the magnet properties is remarkable as described above, which does not meet the object of the present invention. According to the present invention, an R ₂ Fe ₁₄ B phase obtained by pulverizing an ingot obtained by a conventional method is used as a main phase, and a powder which mainly becomes a solid phase during sintering is converted into a liquid which mainly becomes a liquid phase during sintering. -Fe-M or R-Fe
-M-B (M = Ni, Cu, Pb, Sn or more) Raw powder is obtained from liquid quenched alloy powder or ribbon (amorphous and microcrystalline), and then compacted by mixing and molding these powders. By sintering in the same manner as in the past, a crystal having excellent corrosion resistance and excellent magnet properties can be obtained, which is extremely useful in practice. Give the R ₂ Fe ₁₄ B phase ingot having a composition of 26.7Nd-1.0B-Febal by high-frequency heating (wt%) in an argon atmosphere using a <Example -1> purity 99 wt% or more of Nd-Fe-B Further, coarse grinding was performed using a disk mill. And this powder was used as I material. Next, using Nd, Fe, B, Ni, Cu, Sn, and Pb equivalent to the above, 60Nd-
1.0B-10Ni, 57Nd-1.0B-18Ni, 50Nd-1.0B-40Ni, 60Nd
−1.0B−10Cu, 60Nd−1.0B−21Cu, 45Nd−1.0B−39Cu, 60N
d−1.0B−10Pb, 60Nd−1.0B−17Pb, 60Nd−1.0B−25Pb, 60
Nd-1.0B-10Sn, 60Nd-1.0B-15Sn, (All wt%, Fe
Were obtained by a single roll method. Then, 15 kinds of coarse powders obtained by coarsely pulverizing these amorphous ribbon pieces
Material. Then, for each of these 15 types of II materials, I material is added, and 30Nd-1.0B- (Fe-M) bal (M = Ni, Cu, Sn,
15 types of coarse powders having a weighed composition of Pb) were obtained. these
15 kinds of coarse powders were averaged in particle diameter of 3-5 μm using a ball mill.
And finely ground. Next, the obtained fine powder was placed in a magnetic field of 20 kOe, and 1.
A compact was obtained by molding at a pressure of 0 ton / cm ² . These compacts
Sintered in Ar at 1000-1200 ° C for 0-2 hr. After that, 400 ~ 80
After heating at 0 ° C. for 0.5 to 10 hours, it was rapidly cooled. 30 for comparison
An ingot having a composition of Nd-1.0B-febal (wt%) was obtained in the same manner as described above. After that, coarse pulverization, fine pulverization in a magnetic field, sintering and heat treatment were performed in the same manner as above to obtain a sintered body. Then, these sintered bodies were processed into 10 mm × 10 mm × 8 mm, and then subjected to electrolytic Ni plating as plating under a copper plate and frommate treatment. Table 1 shows the magnet properties of these test pieces whose thickness was measured to be 3 to 20 μm and the results of a corrosion resistance test conducted by applying a 60 ° C. × 90% humidity test for 300 hours. Table 1 shows that all of the test pieces according to the present invention show corrosion resistance as compared with the test piece of the comparative example, and also show excellent magnet properties in terms of magnet properties as a permanent magnet. <Example-2> 60Nd-1.0B-5Sn-5Pb, 50Nd-1.0B-20Cu-10Pb, 50 using Nd, Fe, B, Ni, Cu, Pb, Sn of the same purity as in Example-1.
Nd−1.0B−10Cu−20Ni, 50Nd−1.0B−20Ni−5Sn, 50Nd−
1.0B-15Ni-10Pb, 60Nd-1.0B-10Cu-5Sn-5Pb, 50Nd-
Amorphous ribbon strips having a composition of 1.0B-15Ni-6Cu-3Pb (all Fe-bal, wt%) were obtained by a single roll method in Ar. Then, these amorphous ribbon pieces were roughly pulverized, and the resulting coarse powder was used as a III material. Next, these 10 kinds of III
Each material is added with the ingot powder of the material I obtained in Example 1 and has a composition of 30Nd-1.0B- (Fe-M) bal (M = at least one of Ni, Cu, Sn, Pb) wt%. Various kinds of coarse powders were obtained. Further, these ten kinds of coarse powders were subjected to fine pulverization, molding in a magnetic field, sintering, heat treatment, and processing for corrosion-resistant plating and chemical conversion in the same manner as in Example 1 to obtain test pieces (10 × 10 × 8). Next, these test pieces were subjected to a 60 ° C. × 90% extreme temperature and humidity test in the same manner as in Example 1. Table 2 shows the magnet properties of these test pieces and the results of the constant temperature / humidity test results of the comparative material of Example-1. Table 2 shows that all of the magnet test pieces according to the present invention have excellent corrosion resistance as compared with the test piece of the comparative material, and also show excellent magnet properties in terms of magnet properties as permanent magnets. <Example-3> Of the sintered bodies obtained in Example-1, 60Nd-1.0B-21C
u-Febal, 60Nd-1.0B-17Pb-Febal (wt%) and 60Nd-1.0B-10Cu-20Ni-Fe of the sintered body obtained in Example 2
For the sintered body obtained by adding bal (wt%), spot analysis was performed at intervals of 2 μm into the particles from near the Nd ₂ Fe ₁₄ B phase interface to investigate the concentration distribution of each element using EDX. . The results are shown in Tables 3 to 5, respectively. Cu from third to fifth table, Ni, Pb, it can be seen that the element of Sn is concentrated near the interface Nd ₂ Fe ₁₄ B grains. Here, the table will be briefly described. Table 1 shows that the amorphous Nd-Fe-B-
M (M = a kind of Ni, Cu, Pb, Sn) magnet properties of the sintered body obtained by mixing, and 60 ℃ × 90% of the sample obtained by subjecting these sintered bodies to electrolytic Ni plating and zinc chromate treatment Humidity test (30
0hr) shows the results. Table 2 shows that the amorphous Nd-Fe-B-
M (M = Ni, Cu, Pb, Sn, two or more types) and the magnetic properties of the sintered bodies obtained by mixing them, and the sample obtained by subjecting these sintered bodies to electrolytic Ni plating and zinc chromate treatment at 60 ° C x It shows the results of a 90% humidity test (300 hours). Table 3 shows 60Nd-1.0B-21Cu-Febal in Example 3.
5 shows EDX spot analysis results of a sintered body obtained by mixing (wt%) amorphous powder. Tables 4 and 5 show 60Nd-1 in Example 3 respectively.
0B-17Pb-Febal, 60Nd-1.0B-10Cu-20Ni-Febal amorphous powder EDX
It is a spot analysis result. [Effect of the Invention] As shown in the above examples, when a Nd-Fe-B-based magnet is manufactured by the powder metallurgy method, the crystalline Nd ₂ Fe ₁₄ B phase obtained by the conventional manufacturing method is used as a main phase. R-Fe-M or F-Fe-BM powder, which is a raw material powder that mainly becomes a liquid phase during sintering, was obtained from an amorphous alloy or a microcrystalline alloy, and then these powders were mixed and molded. By sintering the green compact, the oxidation resistance can be improved compared with the conventional
It is possible to impart the original corrosion resistance of oxidation-resistant plating, chemical conversion coating, and the like. In particular, since a compact formed by mixing a liquid phase component and a solid phase component is sintered, Nd ₂ Fe ₁₄ B
A sintered body having a metal structure enriched with elements such as Ni, Cu, Pb, and Sn that enhances corrosion resistance and degrades magnet properties is obtained only in the vicinity of the phase interface. A sintered magnet having excellent properties can be obtained. Although only Nd-Fe-B has been described above, it can be easily inferred that the same effect can be expected for rare earth element (R) -Fe-B based alloys including Y.

Claims

(57) [Claims] R ₂ T ₁₄ B-based alloy magnet containing R, Fe, and B as main components (where R
Is a rare earth element containing Y, and T is a transition metal. ) A method of producing by powder metallurgy, R ₂ T ₁₄ B phase crystalline alloy powder R-Fe-M or R-Fe-M-B ( M is Ni, Cu, Pb, Sn
Rare earth permanent magnet excellent in oxidation resistance characterized by sintering a powder compact containing 10 to 30 vol% of liquid quenched alloy powder or alloy powder obtained from thin ribbon (amorphous and microcrystalline) Manufacturing method. 2. In the method for manufacturing a rare earth magnet excellent in oxidation resistance according to claim 1, when one kind is selected from M (Ni, Cu, Pb, Sn), Ni and Cu: 10 to 40 wt%, Pb: 10-
A method for producing a rare earth permanent magnet excellent in oxidation resistance, characterized in that the content is 25 wt% and Sn: 10 to 15 wt%. 3. In the method for manufacturing a rare earth magnet excellent in oxidation resistance according to claim 1, when two or more elements are selected from M (Ni, Cu, Pb, Sn), the total of these elements is determined. A method for producing a rare earth permanent magnet excellent in oxidation resistance, characterized in that the weight is 10 to 55 wt%.