JP3255344B2 - Sintered permanent magnet - Google Patents
Sintered permanent magnetInfo
- Publication number
- JP3255344B2 JP3255344B2 JP11959896A JP11959896A JP3255344B2 JP 3255344 B2 JP3255344 B2 JP 3255344B2 JP 11959896 A JP11959896 A JP 11959896A JP 11959896 A JP11959896 A JP 11959896A JP 3255344 B2 JP3255344 B2 JP 3255344B2
- Authority
- JP
- Japan
- Prior art keywords
- permanent magnet
- main phase
- alloy
- sintered
- sintered body
- 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.)
- Expired - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
- H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
- H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
Description
【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION
【０００１】[0001]
【発明の属する技術分野】本発明は、R-Fe-B系の希土類
磁石の性能改善に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the performance of R-Fe-B rare earth magnets.
【０００２】[0002]
【従来の技術】焼結型希土類永久磁石の中でR-Fe-B系(R
はYを含む希土類元素のうちの１種又は２種以上)焼結型
永久磁石は高性能磁石として注目され、広い分野で使用
されている。このR-Fe-B系焼結型永久磁石は、基本的に
はR2Fe14B相(主相)、RFe7B6相(Brich相)、R85Fe15相(Rr
ich相)の３相から成る構造を有している。組成的に希土
類元素に豊んだRrich相の存在と、このような３相構造
に由来して、R-Fe-B系焼結型永久磁石はSm-Co系焼結型
永久磁石に比べて耐蝕性が劣り、この永久磁石の開発当
初から現在に至るまで欠点の１つとなっている。R-Fe-B
系焼結型永久磁石の腐蝕のメカニズムについての定説は
無いが、Rrich相を起点とした腐蝕の形態が一般的であ
ることから、Rrich相を陽極とした陽極腐蝕との見方も
ある。確かに、R-Fe-B系焼結型永久磁石の希土類元素の
量を減少することによって、その焼結体内部のRrich相
の量は減少し、かつ相の形態は微細化し、これに対応し
て永久磁石の耐蝕性は向上する。従って、希土類元素の
量を減少することは、R-Fe-B系焼結型永久磁石の耐蝕性
改善の一つの方法である。2. Description of the Related Art Among sintered rare earth permanent magnets, R-Fe-B (R
(One or more of the rare earth elements containing Y) Sintered permanent magnets are attracting attention as high-performance magnets and are used in a wide range of fields. This R-Fe-B based sintered permanent magnet is basically composed of R2Fe14B phase (main phase), RFe7B6 phase (Brich phase), R85Fe15 phase (Rr
ich phase). Due to the existence of the Rrich phase which is rich in rare earth elements in composition and such a three-phase structure, the R-Fe-B based sintered permanent magnet is smaller than the Sm-Co based sintered magnet. Poor corrosion resistance is one of the drawbacks from the beginning of the development of this permanent magnet to the present. R-Fe-B
Although there is no established theory on the mechanism of corrosion of the sintered sintered permanent magnet, there is also a view that anodic corrosion using the Rrich phase as an anode is common because of the general form of corrosion starting from the Rrich phase. Indeed, by reducing the amount of rare earth elements in the R-Fe-B sintered permanent magnet, the amount of the Rrich phase inside the sintered body is reduced, and the morphology of the phase becomes finer. As a result, the corrosion resistance of the permanent magnet is improved. Therefore, reducing the amount of the rare earth element is one method of improving the corrosion resistance of the sintered R-Fe-B permanent magnet.
【０００３】R-Fe-B系を含む焼結型の希土類永久磁石
は、原料金属を溶解し鋳型に注湯して得られたインゴッ
トを粉砕，成形，焼結，熱処理，加工するという粉末冶
金的な工程によって製造されるのが一般的である。しか
し、インゴットを粉砕して得られる合金粉末は、希土類
元素を多量に含むため化学的に非常に活性であり、大気
中において酸化して含有酸素量が増加する。これによっ
て、焼結後の焼結体では希土類元素の一部が酸化物を形
成し、磁気的に有効な希土類元素が減少する。このた
め、実用的な磁気特性の水準、例えばiHc≧13kOeを実現
するためには、R-Fe-B系焼結型永久磁石の希土類元素の
量を増やす必要があり、重量百分比率で31％を越える希
土類元素の添加量が実用材料では採用されている。この
ため、これまでのR-Fe-B系焼結型永久磁石の耐蝕性は十
分ではなかった。[0003] A sintered rare earth permanent magnet containing an R-Fe-B system is a powder metallurgy in which the ingot obtained by melting a raw material metal and pouring it into a mold is ground, formed, sintered, heat-treated and processed. It is generally manufactured by a general process. However, the alloy powder obtained by pulverizing the ingot is chemically very active because it contains a large amount of rare earth elements, and oxidizes in the atmosphere to increase the oxygen content. Thereby, in the sintered body after sintering, a part of the rare earth element forms an oxide, and the magnetically effective rare earth element is reduced. Therefore, in order to achieve a practical level of magnetic characteristics, for example, iHc ≧ 13 kOe, it is necessary to increase the amount of the rare earth element in the R-Fe-B based sintered permanent magnet, and the percentage by weight is 31%. The amount of rare earth element added exceeds that in practical materials. For this reason, the corrosion resistance of conventional R-Fe-B based sintered permanent magnets was not sufficient.
【０００４】[0004]
【発明が解決しようとする課題】本発明は、以上述べた
R-Fe-B系焼結型永久磁石の耐蝕性を大幅に改善しようと
するものである。SUMMARY OF THE INVENTION The present invention has been described above.
It is intended to significantly improve the corrosion resistance of R-Fe-B based sintered permanent magnets.
【０００５】[0005]
【問題を解決するための手段】本発明者らは、R-Fe-B系
焼結型永久磁石の耐蝕性を改善するため種々検討した結
果、特定範囲量の希土類量と酸素量のR-Fe-B系焼結型永
久磁石において、その磁石主相結晶粒径を特定値以下と
することによって、耐蝕性が向上することを見い出して
本発明に至ったものである。[Means for Solving the Problems] The present inventors have conducted various studies to improve the corrosion resistance of R-Fe-B based sintered permanent magnets. The present invention has been found to improve the corrosion resistance of Fe-B based sintered permanent magnets by reducing the crystal grain size of the main phase of the magnet to a specific value or less.
【０００６】以下、本発明を具体的に説明する。本発明
における焼結型永久磁石は、重量百分率でR(RはYを含む
希土類元素のうちの１種又は２種以上)28.0〜33.0％,B
0.5〜2.0％,O 0.3〜0.7％,残部Feの組成を有し、磁石主
相の総面積に対し、結晶粒径が10μｍ以下の主相結晶粒
の面積の和が80％以上、結晶粒径が13μｍ以上の主相結
晶粒の面積の和が10％以下であることを特徴とする。ま
た、本発明焼結型永久磁石において、Feの一部をNb 0.1
〜2.0％,Al 0.02〜2.0％,Co 0.3〜5.0％,Ga 0.01〜0.5
％,Cu 0.01〜1.0％のうち１種又は２種以上で置換する
ことができる。Hereinafter, the present invention will be described specifically. The sintered permanent magnet in the present invention has a weight percentage of R (R is one or more of the rare earth elements including Y) 28.0-33.0%, B
It has a composition of 0.5-2.0%, O 0.3-0.7%, and the balance Fe, and the sum of the area of the main phase crystal grains having a crystal grain size of 10 μm or less with respect to the total area of the magnet main phase is 80% or more. The total area of the main phase crystal grains having a diameter of 13 μm or more is 10% or less. Further, in the sintered permanent magnet of the present invention, a part of Fe is Nb 0.1
~ 2.0%, Al 0.02 ~ 2.0%, Co 0.3 ~ 5.0%, Ga 0.01 ~ 0.5
%, Cu 0.01 to 1.0%.
【０００７】本発明者らは、上記組成を有するR-Fe-B系
焼結型永久磁石の耐蝕性に結晶粒径依存性があり、磁石
主相結晶粒径を特定値以下にすることによって、特に優
れた耐蝕性が発現されることを見い出した。磁石結晶粒
径の定義と測定には種々の方法があり得、一義的ではな
いが、発明者らは磁石主相の総面積に対する粒径が一定
寸法以下の主相結晶粒の面積の和の割合と、同じく磁石
主相の総面積に対する粒径が一定寸法以上の主相結晶粒
の面積の和の割合によって、磁石結晶粒径の状態を示す
尺度とした。以下この尺度を用いて本発明の効果を説明
することとする。また、この割合を算出するに当たって
の計測は、対象とするR-Fe-B系焼結型永久磁石の結晶組
織を、OLYMPUS社製顕微鏡(商品名VANOX)で観察し、この
画像をNIRECO社製画像処理装置(商品名LUZEX２)に直接
投入して行った。The present inventors have determined that the corrosion resistance of an R-Fe-B sintered permanent magnet having the above composition depends on the crystal grain size. In particular, it was found that excellent corrosion resistance was exhibited. There are various methods for defining and measuring the magnet crystal grain size, which are not unique.However, the inventors have calculated the sum of the area of the main phase crystal grains whose grain size is equal to or less than a certain dimension with respect to the total area of the magnet main phase. The ratio and the ratio of the sum of the areas of the main phase crystal grains having a certain size or more to the total area of the magnet main phase were used as a scale indicating the state of the magnet crystal grain size. Hereinafter, the effect of the present invention will be described using this scale. The measurement in calculating this ratio was performed by observing the crystal structure of the target R-Fe-B sintered permanent magnet with an OLYMPUS microscope (trade name: VANOX), and by using this image manufactured by NIRECO. The test was performed by directly charging the image processing device (product name LUZEX2).
【０００８】本発明者らは、特許請求範囲に示す組成を
有するR-Fe-B系焼結型永久磁石の主相結晶粒径と耐蝕性
の関係について下記の様な評価を行い、図１に示すよう
な結果を得た。図１は、磁石主相結晶の総面積に対す
る、結晶粒径が10μｍ以下の主相結晶粒の面積の和の割
合と、同じく磁石主相結晶の総面積に対する結晶粒径が
13μｍ以上の主相の結晶粒の面積の和の割合と、耐蝕性
の加速試験での、Niメッキのハクリ開始が生じるまでの
経過的間との関係を示したものである。○印は重量百分
比率でNd 22.8％,Pr 6.7％,Dy 2.0％,B 1.0％,Al 1.0
％,O 0.45％,C 0.08％,N 0.015％,残部Feの組成を有す
る焼結体、□印は重量百分比率でNd 31.0％,Dy 1.0％,B
1.05％,Al 0.05％,Co 2.0％,Ga 0.09％,O 0.55％,C 0.
07％,N 0.008％,残部Feの組成を有する焼結体、△印は
重量百分比率でNd 23.0％,Pr 5.0％,Dy 4.5％,B1.1％,N
b 1.0％,Al 0.2％,Co 2.0％,Cu 0.08％,O 0.35％,C 0.0
6％,N 0.030％,残部Feの組成を有する焼結体を示す。こ
の場合の加速試験では、磁石を10mm×10mm×2mmの寸法
に加工後、その表面に15μｍのNiメッキを施し、次いで
試料を2気圧,120℃,湿度100％の条件に放置した。図１
から、磁石主相の結晶の総面積に対し、結晶粒径が10μ
ｍ以下の主相結晶粒の面積の和が80％以上で、かつ結晶
粒径が13μｍ以上の主相結晶粒の面積の和が10％以下で
ある場合において、特許請求範囲に示す組成を有するR-
Fe-B系焼結型永久磁石の耐蝕性が特に優れたものになる
ことがわかる。従って、磁石主相結晶粒の大きさは、上
記に規定される。The present inventors conducted the following evaluation on the relationship between the main phase crystal grain size and the corrosion resistance of the R-Fe-B based sintered permanent magnet having the composition shown in the claims. The result as shown in FIG. FIG. 1 shows the ratio of the sum of the areas of the main phase crystal grains having a crystal grain size of 10 μm or less to the total area of the magnet main phase crystals and the crystal grain size to the total area of the magnet main phase crystals.
It shows the relationship between the ratio of the sum of the areas of the crystal grains of the main phase of 13 μm or more and the elapse of time until the start of Ni plating peeling in an accelerated corrosion resistance test. ○ marks are Nd 22.8%, Pr 6.7%, Dy 2.0%, B 1.0%, Al 1.0 by weight percentage.
%, O 0.45%, C 0.08%, N 0.015%, Sintered body having composition of Fe, balance is Nd 31.0%, Dy 1.0%, B
1.05%, Al 0.05%, Co 2.0%, Ga 0.09%, O 0.55%, C 0.
Sintered body having composition of 07%, N 0.008%, balance Fe, △ mark is Nd 23.0%, Pr 5.0%, Dy 4.5%, B1.1%, N
b 1.0%, Al 0.2%, Co 2.0%, Cu 0.08%, O 0.35%, C 0.0
The figure shows a sintered body having a composition of 6%, N 0.030%, and the balance Fe. In the accelerated test in this case, the magnet was machined to a size of 10 mm × 10 mm × 2 mm, the surface thereof was plated with Ni of 15 μm, and then the sample was left at 2 atm, 120 ° C., and 100% humidity. FIG.
From the total crystal area of the magnet main phase, the crystal grain size is 10μ
When the sum of the areas of the main phase crystal grains of m or less is 80% or more, and the sum of the areas of the main phase crystal grains having a crystal grain size of 13 μm or more is 10% or less, the composition has the composition described in the claims. R-
It can be seen that the corrosion resistance of the Fe-B based sintered permanent magnet is particularly excellent. Therefore, the size of the crystal grains of the magnet main phase is defined above.
【０００９】この原因を推定すると、比較的大きな主相
結晶粒が存在する永久磁石焼結体においては、相対的に
主相結晶粒の間の空隙部、具体的には粒界３重点がその
種たる部分であり、ここには極めて酸化されやすいＮｄ
rich相が存在しているが、このＮｄrich相で充填されて
いる空隙部の体積が大きくなる。腐食破壊をもたらす因
子、例えば本加速試験では水分であるが、この様な因子
の浸透性が良く、結晶粒界の破壊が連鎖反応的に起こり
やすい状態にあるものと考えられる。以上は、特許請求
の範囲に示す組成を有するR-Fe-B系焼結型永久磁石の耐
食性に主相結晶粒径依存性があることを、本発明者等の
研究結果の一例を示すことによって説明したものであ
る。[0009] Assuming the cause, in a permanent magnet sintered body in which relatively large main phase crystal grains are present, the gaps between the main phase crystal grains, specifically, the triple point of the grain boundary, are relatively large. This is the seed part, where Nd
Although the rich phase exists, the volume of the void portion filled with the Ndrich phase increases. Factors causing corrosion destruction, for example, moisture in the present accelerated test, are considered to be in a state where the penetration of such factors is good and destruction of crystal grain boundaries is likely to occur in a chain reaction. The above shows that the corrosion resistance of the R-Fe-B based sintered permanent magnet having the composition shown in the claims is dependent on the main phase crystal grain size, and shows an example of the research results of the present inventors. It is explained by
【００１０】特許請求範囲の組成を有するR-Fe-B系焼結
型永久磁石の主相の結晶粒径を上記の規定範囲のものに
制御する方法は必ずしも一義的ではなく、種々の方法あ
るいはそれらの方法の組合せによって達成することがで
きるが、発明者らの研究では、通常の方法ではかなりの
困難を伴う。一般に、R-Fe-B系焼結型永久磁石の製造に
おいては、原料粗粉を微粉砕によって微粉化し、この微
粉を磁界中で金型成形して成形体を得、これを焼結して
焼結体とする方法が採られる。例えば、微粉砕をジェッ
トミルを用いて行う場合には、粉砕時のガスの圧力や粗
粉の供給速度等を制御することにより、所定の平均粒度
や粒度分布を持つ微粉を得ることができる。また、必要
に応じて、分級をおこなうことにより、微粉の粒度分布
を制御することもできる。このようにして作製した微粉
を成形し、焼結するにあたっては、さらに適切な焼結温
度・時間・パターンを選択することによって、R-Fe-B系
焼結型永久磁石の主相の結晶粒径を上記の規定範囲のも
のとすることは必ずしも不可能ではない。しかし、多く
の条件を設定し、これを制御する必要があり、所定の結
晶粒径を有する焼結体を再現性よく製造するのははなは
だ困難であることが判った。The method for controlling the crystal grain size of the main phase of the R-Fe-B based sintered permanent magnet having the composition defined in the claims to be within the above-specified range is not necessarily unique. Although it can be achieved by a combination of these methods, our studies involve considerable difficulty with conventional methods. Generally, in the manufacture of R-Fe-B based sintered permanent magnets, raw material coarse powder is pulverized into fine powder, and the fine powder is molded in a magnetic field to obtain a molded body, which is then sintered. A method of forming a sintered body is employed. For example, when the pulverization is performed using a jet mill, fine powder having a predetermined average particle size and particle size distribution can be obtained by controlling the pressure of gas at the time of pulverization, the supply rate of coarse powder, and the like. Further, if necessary, the particle size distribution of the fine powder can be controlled by performing classification. In forming and sintering the fine powder produced in this way, by selecting an appropriate sintering temperature, time and pattern, the crystal grains of the main phase of the R-Fe-B sintered permanent magnet are selected. It is not always impossible to make the diameter fall within the above specified range. However, it is necessary to set and control many conditions, and it has been found that it is extremely difficult to produce a sintered body having a predetermined crystal grain size with good reproducibility.
【００１１】本発明者らは特許請求範囲の組成を有する
R-Fe-B系焼結型永久磁石の主相の結晶粒径を上記の規定
範囲とするのに容易で量産上適した方法を探索した結
果、いわゆるストリップキャスト法と呼ばれる方法で製
造された所定の組成を有するR-Fe-B系急冷薄帯状合金
を、所定の温度範囲で熱処理し、これを粉砕して原料粗
粉とする方法を見い出した。また熱処理後の薄帯状合金
を粉砕するにあたっては、水素吸蔵により自然崩壊させ
た後脱水素処理を施してから行うことが微粉砕性能を高
めるうえで有効である。図２は、重量百分比率でNd 22.
7％,Pr 7.6％,Dy 1.5％,B 1.05％,Al 0.05％,O0.01％,N
0.004％,C 0.007％,残部Feの組成を有する、ストリッ
プキャスト法で製造された薄帯状合金の断面組織である
(as cast)。デンドライト状の微細な組織が存在してい
る。写真の中で白色に観察される相は希土類量が少なく
永久磁石焼結体の主相に相当する相、黒色に観察される
相は希土類量が多い永久磁石焼結体のRrich相に相当す
る相である。このRrich相は微粉砕時に破壊の起点とな
るので、このRrich相が図２に示すように微細に分散し
ている帯状合金を使用した場合、粒径が細かくて均一な
微粉が確率的に生成しやすい。従って、微粉砕時や焼結
時の多くの条件を厳密に管理することなく、比較的容易
にしかも再現性よく特許請求範囲の粒径分布を有する焼
結体が製造可能となるのである。しかしこの薄帯状合金
(急冷鋳造のまま)をこのまま直接粉砕して原料粗粉と
し、これを微粉砕しても、良好な微粉の粒度分布は得ら
れず、これを成形・焼結した焼結体では、本発明にかか
る主相結晶粒径は得られない。この理由は、急冷鋳造に
よって薄帯状合金の表面が硬化し、微粉砕時の被粉砕性
をいちじるしく悪化させるからである。We have the claimed composition
As a result of searching for a method that is easy and suitable for mass production to keep the crystal grain size of the main phase of the R-Fe-B based sintered permanent magnet within the above specified range, it was manufactured by the so-called strip casting method. A method of heat-treating a rapidly quenched R-Fe-B-based thin strip alloy having a predetermined composition in a predetermined temperature range and pulverizing the same to obtain a raw material coarse powder was found. Further, in crushing the ribbon-shaped alloy after the heat treatment, it is effective to perform a dehydrogenation treatment after naturally disintegrating by absorbing hydrogen and then perform a dehydrogenation treatment in order to enhance the fine crushing performance. Figure 2 shows Nd 22.
7%, Pr 7.6%, Dy 1.5%, B 1.05%, Al 0.05%, O0.01%, N
This is a cross-sectional structure of a thin strip alloy manufactured by the strip casting method, having a composition of 0.004%, C 0.007%, and the balance of Fe.
(as cast). A dendrite-like fine structure exists. In the photograph, the phase observed in white corresponds to the main phase of the permanent magnet sintered body with a small amount of rare earth, and the phase observed in black corresponds to the Rrich phase of the permanent magnet sintered body with a large amount of rare earth. Phase. Since this Rrich phase becomes a starting point of fracture at the time of pulverization, when a band-shaped alloy in which this Rrich phase is finely dispersed as shown in FIG. 2 is used, a fine powder having a fine particle size and uniformity is stochastically generated. It's easy to do. Therefore, a sintered body having a particle size distribution according to the present invention can be produced relatively easily and with good reproducibility without strictly controlling many conditions during pulverization and sintering. But this strip-shaped alloy
The raw material coarse powder is directly pulverized as it is (as it is quenched casting), and even if this is finely pulverized, a good fine powder particle size distribution cannot be obtained. Cannot be obtained. The reason for this is that the surface of the ribbon-shaped alloy is hardened by quenching casting, which significantly deteriorates the crushability during fine pulverization.
【００１２】本発明者らは、この問題を解決する手段と
して、この薄帯状合金を特定温度範囲で熱処理して薄帯
状合金表面の硬化を除去することが有効であることを見
い出した。熱処理の温度は800℃〜1100℃とされる。こ
れは、熱処理温度が800℃未満では硬化の除去が不十分
だからである。また、1100℃より高い温度では、熱処理
時に薄帯状合金間で反応が生じ、後工程での処理に困難
が生じるからである。活性な希土類元素を多量に含有す
る薄帯状合金であるため、熱処理は不活性ガス雰囲気中
又は実質的な真空中で行う必要があることは言うまでも
ない。また、前記のように、熱処理後の薄帯状合金に水
素を吸蔵させて自然崩壊させ、脱水素処理をおこなった
後、これを粗粉化することは、微粉砕性を高めるうえで
さらに有効である。これは、熱処理による薄帯状合金表
面の硬化の除去効果に加え、水素による薄帯状合金内部
の主にはRrich相のぜい化効果が加わることによる。As a means for solving this problem, the present inventors have found that it is effective to heat-treat the ribbon-shaped alloy in a specific temperature range to remove the hardening of the surface of the ribbon-shaped alloy. The temperature of the heat treatment is set to 800 ° C to 1100 ° C. This is because if the heat treatment temperature is lower than 800 ° C., the removal of the curing is insufficient. Further, at a temperature higher than 1100 ° C., a reaction occurs between the ribbon-shaped alloys during the heat treatment, and it becomes difficult to perform the treatment in a subsequent step. It is needless to say that the heat treatment needs to be performed in an inert gas atmosphere or a substantial vacuum because the alloy is a ribbon-shaped alloy containing a large amount of active rare earth elements. In addition, as described above, after absorbing the hydrogen into the ribbon-shaped alloy after the heat treatment to cause natural collapse, and after performing the dehydrogenation treatment, coarsening the powder is more effective in increasing the pulverizability. is there. This is because, in addition to the effect of removing the hardening of the surface of the ribbon-shaped alloy due to the heat treatment, the effect of embrittlement of mainly the Rrich phase inside the ribbon-shaped alloy due to hydrogen is added.
【００１３】表１に、薄帯状合金を各種条件で熱処理(1
Hr)あるいは粉砕して粗粉とし、これを同一条件で微粉
砕し、成形・焼結した場合の焼結体の主相結晶粒径の状
態を示す。Table 1 shows that the thin strip alloy was heat treated under various conditions (1.
Hr) or a coarse powder obtained by pulverization, which is finely pulverized under the same conditions, and shows the state of the main phase crystal grain size of the sintered body when molded and sintered.
【００１４】[0014]
【表１】 [Table 1]
【００１５】表１から、薄帯状合金を800℃以上の温度
で熱処理し、これを用いることによって、特許請求範囲
に示す主相粒径の割合を有する焼結体が得られることが
わかる。また、前述したように、水素処理の有効性も明
かである。同時に表１から、700℃での熱処理での主相
粒径の状態は、急冷鋳造したままでのものとほぼ同水準
である。700℃の熱処理温度では、薄帯合金の表面硬化
の除去に不十分であることがわかる。同時に本発明者ら
は、薄帯状合金の800℃以上の温度での熱処理が、磁気
特性のうち特にBrの向上効果をもたらすことを見い出し
た。結果を同じく表１に示す。表１から、急冷鋳造状態
と700℃の熱処理の薄帯状合金による永久磁石焼結体のB
rは12.8〜12.9KGであるが、800℃と900℃の熱処理の薄
帯状合金を使用した場合には、Brは13.1KGと急激に増加
する。熱処理温度が1000℃では、結果として得られるBr
は微増し、13.2KGとなる。1100℃,1200℃の熱処理温度
では、Brの増加は飽和に達し、13.2KGと変わらない。表
１に示した薄体状合金のうち、急冷鋳造後の薄体状合金
の金属組織写真を図２に、急冷鋳造後１０００℃で熱処
理した薄体状合金の金属組織写真を図３に示す。図２、
図３を比較すると、熱処理により、薄体状合金内の主相
に相当する白色組織、Ｒrich相に相当する黒色組織のい
ずれもが粗大化していることがわかる。これらのことか
ら本発明者等は、急冷鋳造のままの薄体状合金では主相
およびＲrich相に相当する相から構成される組織が微細
であるために、これを用いて微粉を製造した場合、微粉
の内に多結晶状態のままのものが確率的に多く存在し、
微粉を磁界中で金型成形する際の配向性の低下を招き、
永久磁石焼結体のＢｒ低下をもたらしているものと考え
る。７００℃の熱処理温度では、組織の成長が不十分で
配向性の改善には至らない。熱処理温度の上昇にしたが
って薄体状合金の内部組織が粗大化しているが、これに
よって多結晶状態の微粉の発生の確率が低下し、Ｂｒが
改善されると考えられるが、表１の結果から判断する限
り、８００℃の熱処理温度でその効果はかなりででいる
ものと考えられる。薄体状合金の熱処理温度のさらなる
増加にしたがって、得られる焼結体のＢｒは向上するも
のの１０００℃以上の熱処理温度では飽和の傾向を示
す。これは、薄体状合金内部の組織がある程度粗大化
し、多結晶状態の微粉が確率的にほとんど発生しない状
態に達した段階では、熱処理温度をさらに上げて組織の
粗大化を促進させても、それは得られる焼結体のＢｒの
向上として反映しないということで理解できる。From Table 1, it can be seen that the heat treatment of the ribbon-shaped alloy at a temperature of 800 ° C. or more, and the use of the heat-treated alloy yields a sintered body having a main phase particle size ratio as defined in the claims. Also, as described above, the effectiveness of the hydrogen treatment is clear. At the same time, from Table 1, the state of the main phase grain size in the heat treatment at 700 ° C. is almost the same level as that in the as-quenched state. It can be seen that the heat treatment temperature of 700 ° C. is insufficient for removing the surface hardening of the ribbon alloy. At the same time, the present inventors have found that heat treatment of the ribbon-shaped alloy at a temperature of 800 ° C. or more brings about an effect of improving Br among magnetic properties. The results are also shown in Table 1. From Table 1, it can be seen that the B of the permanent magnet sintered body by the strip alloy in the quenched casting state and the heat treatment at 700 ° C.
Although r is 12.8 to 12.9 KG, Br increases sharply to 13.1 KG when a thin strip alloy heat-treated at 800 ° C. and 900 ° C. is used. At a heat treatment temperature of 1000 ° C., the resulting Br
Slightly increased to 13.2KG. At the heat treatment temperatures of 1100 ° C and 1200 ° C, the increase of Br reaches saturation and remains unchanged at 13.2KG. Among the thin alloys shown in Table 1, a photograph of the metal structure of the thin alloy after quenching casting is shown in FIG. 2, and a photograph of the metal structure of the thin alloy heat-treated at 1000 ° C. after quenching casting is shown in FIG. . FIG.
3A and 3B, it is understood that both the white structure corresponding to the main phase and the black structure corresponding to the Rrich phase in the thin alloy are coarsened by the heat treatment. From these facts, the present inventors have found that, in a thin alloy as-quenched, the structure composed of the main phase and the phase corresponding to the Rrich phase is fine, and when the fine powder is produced using this, , Among the fine powders, there are stochastically many in the polycrystalline state,
Invites a decrease in orientation when molding the fine powder in a magnetic field,
It is considered that Br of the permanent magnet sintered body is reduced. At a heat treatment temperature of 700 ° C., the growth of the structure is insufficient and the orientation cannot be improved. It is considered that the internal structure of the thin alloy is coarsened with an increase in the heat treatment temperature, which reduces the probability of generation of fine powder in a polycrystalline state and improves Br. As far as it is judged, the effect is considered to be significant at the heat treatment temperature of 800 ° C. As the heat treatment temperature of the thin alloy further increases, Br of the obtained sintered body increases, but tends to be saturated at a heat treatment temperature of 1000 ° C. or higher. This is because, when the structure inside the thin alloy is coarsened to a certain extent and polycrystalline fine powder has reached a state where little powder is generated with probability, even if the heat treatment temperature is further increased to promote the coarsening of the structure, It can be understood that it is not reflected as an improvement in Br of the obtained sintered body.
【００１６】以上詳細に説明したように、ストリップキ
ャスト法による所定の組成の急冷鋳造薄帯状合金を、特
定の温度範囲において熱処理し、あるいはこれに水素吸
蔵処理を施して自然崩壊させ、これを粉砕して粗粉化す
ることによって、微粉砕時の粉砕性が改善され、これを
用いて製造された永久磁石焼結体は、耐蝕性にきわめて
優れた特許請求範囲に示した主相結晶粒径を有するもの
となるのであるが、それのみならず、高い磁気特性を有
するものにもなるのである。なお、薄帯状合金の800〜1
100℃での熱処理時間は、少なくとも15分以上好ましく
は30分以上行う必要がある。As described in detail above, a quenched cast strip alloy having a predetermined composition by a strip casting method is heat-treated in a specific temperature range, or subjected to a hydrogen absorbing treatment to spontaneously disintegrate and pulverize it. By pulverizing, the pulverizability at the time of fine pulverization is improved, and the permanent magnet sintered body manufactured using this is excellent in corrosion resistance in the main phase crystal grain size indicated in the claims. However, not only that, but also those having high magnetic properties. In addition, 800-1
The heat treatment time at 100 ° C. needs to be at least 15 minutes or more, preferably 30 minutes or more.
【００１７】以下では、本発明のR-Fe-B系焼結型永久磁
石の組成の限定理由を述べる。希土類元素の量は、重量
百分率で28.0〜33.0％とされる。希土類元素の量が31.0
％を越えると、焼結体内部のRrich相の量が多くなり、
かつ形態も粗大化して耐蝕性が悪くなる。一方、希土類
元素の量が28.0％未満であると、焼結体の緻密化に必要
な液相量が不足して焼結体密度が低下し、同時に磁気特
性のうち残留磁束密度Brと保磁力iHcが共に低下する。
従って、希土類元素の量は28.0〜33.0％とされる。ま
た、希土類元素の量を31.0％以上とすることにより、高
い焼結体密度を有する焼結体を容易に得ることができ
る。Oの量は重量百分率で0.3〜0.7％とされる。Oの量が
0.7％を越える場合には、希土類元素の一部が酸化物を
形成し、磁気的に有効な希土類元素が減少して保磁力iH
cが低下する。一方、微粉砕工程での酸化によって、最
終焼結体のO量を0.3％未満とすることは困難であり、O
量は0.3〜0.7％とする。The reasons for limiting the composition of the R-Fe-B sintered permanent magnet of the present invention will be described below. The amount of the rare earth element is 28.0-33.0% by weight. The amount of rare earth elements is 31.0
%, The amount of the Rrich phase inside the sintered body increases,
In addition, the form becomes coarse and the corrosion resistance deteriorates. On the other hand, if the amount of the rare earth element is less than 28.0%, the amount of the liquid phase required for densification of the sintered body is insufficient, and the density of the sintered body is reduced. iHc decreases together.
Therefore, the amount of the rare earth element is set to 28.0 to 33.0%. Further, by setting the amount of the rare earth element to 31.0% or more, a sintered body having a high sintered body density can be easily obtained. The amount of O is between 0.3 and 0.7% by weight. O amount
If it exceeds 0.7%, a part of the rare earth element forms an oxide, and the magnetically effective rare earth element decreases, and the coercive force iH
c decreases. On the other hand, it is difficult to reduce the O content of the final sintered body to less than 0.3% due to oxidation in the pulverization step.
The amount should be 0.3-0.7%.
【００１８】Cの量は重量百分率で0.15％以下とするこ
とが好ましい。Cの量が0.15％より多い場合には、希土
類元素の一部が炭化物を形成し、磁気的に有効な希土類
元素が減少して保磁力iHcが低下する。C量は、0.12％以
下とすることがより好ましく、0.10％以下とすることが
さらに好ましい。一方、溶解によって作製するインゴッ
トのC量の水準は最大0.008％であり、最終焼結体のC量
をこの値以下とすることは困難であり、焼結体のC量は
0.01〜0.15％とすることが好ましい。Ｎの量は、重量百
分率で0.002〜0.04％とすることが好ましい。Ｎの量が
0.04％を超えると、希土類元素の一部が窒化物を形成し
磁気的に有効な希土類元素が減少して保磁力ｉＨｃが低
下する。また、微粉砕の過程で若干の窒化を伴うことか
ら、最終焼結体のＮ量を0.002％未満とすることは困難
である。従ってＮ量は0.002〜0.04％とすることが好ま
しい。The amount of C is preferably not more than 0.15% by weight. When the amount of C is more than 0.15%, part of the rare earth element forms carbide, and the magnetically effective rare earth element decreases, and the coercive force iHc decreases. The C content is more preferably 0.12% or less, and further preferably 0.10% or less. On the other hand, the level of C in the ingot produced by melting is 0.008% at the maximum, and it is difficult to reduce the C content of the final sintered body to this value or less.
It is preferably set to 0.01 to 0.15%. The amount of N is preferably 0.002 to 0.04% by weight. The amount of N
If it exceeds 0.04%, a part of the rare earth element forms a nitride, the magnetically effective rare earth element decreases, and the coercive force iHc decreases. In addition, it is difficult to reduce the amount of N in the final sintered body to less than 0.002% because a slight nitridation is involved in the process of fine pulverization. Therefore, the N content is preferably set to 0.002 to 0.04%.
【００１９】本発明のR-Fe-B系焼結型永久磁石においい
ては、Feの一部をNb,Al,Co,Ga,Cuのうち１種類又は２種
類以上で置換することができ以下に各元素の置換量(こ
こでは置換後の永久磁石の全組成に対する重量百分率)
の限定の理由を説明する。Nbの置換量は0.1〜2.0％とさ
れる。Nbの添加によって、焼結過程でNbのほう化物が生
成し、これが結晶粒の異常粒成長を抑制する。Nbの置換
量が0.1％より少ない場合には、結晶粒の異常粒成長の
抑制効果が十分ではなくなる。一方、Nbの置換量が2.0
％を越えると、Nbのほう化物の生成量が多くなるため残
留磁束密度Brが低下する。Alの置換量は0.02〜2.0％と
される。Alの添加は保磁力iHcを高める効果がある。Al
の置換量が0.02％より少ない場合には、保磁力の向上効
果が少ない。置換量が2.0％を越えると、残留磁束密度B
rが急激に低下する。Coの置換量は0.3〜5.0％とされ
る。Coの添加はキューリ点の向上即ち飽和磁化の温度係
数の改善をもたらす。Coの置換量が0.3％より少ない場
合には、温度係数の改善効果は小さい。Coの置換量が5.
0％を越えると、残留磁束密度Br、保磁力iHcが共に急激
に低下する。Gaの置換量は0.01〜0.5％とされる。Gaの
微量添加は保磁力iHcの向上をもたらすが、置換量が0.0
1％より少ない場合には、添加効果は小さい。一方、Ga
の置換量が0.5％を越えると、残留磁束密度Brの低下が
顕著になるとともに保磁力iHcも低下する。Cuの置換量
は0.01〜1.0％とされる。Cuの微量添加は保磁力iHcの向
上をもたらすが、置換量が1.0％を越えるとその添加効
果は飽和する。添加量が0.01％より少ない場合には、保
磁力iHcの向上効果は小さい。In the R-Fe-B sintered permanent magnet of the present invention, part of Fe can be replaced by one or more of Nb, Al, Co, Ga and Cu. The substitution amount of each element (in this case, the weight percentage based on the total composition of the permanent magnet after substitution)
Will be explained. The substitution amount of Nb is set to 0.1 to 2.0%. By the addition of Nb, borides of Nb are generated during the sintering process, and this suppresses abnormal grain growth. If the substitution amount of Nb is less than 0.1%, the effect of suppressing abnormal grain growth of crystal grains is not sufficient. On the other hand, when the substitution amount of Nb is 2.0
%, The amount of Nb boride generated increases, so that the residual magnetic flux density Br decreases. The substitution amount of Al is set to 0.02 to 2.0%. The addition of Al has the effect of increasing the coercive force iHc. Al
When the substitution amount of is less than 0.02%, the effect of improving the coercive force is small. When the replacement amount exceeds 2.0%, the residual magnetic flux density B
r drops sharply. The substitution amount of Co is set to 0.3 to 5.0%. The addition of Co improves the Curie point, that is, improves the temperature coefficient of saturation magnetization. When the substitution amount of Co is less than 0.3%, the effect of improving the temperature coefficient is small. The amount of Co substitution is 5.
If it exceeds 0%, both the residual magnetic flux density Br and the coercive force iHc sharply decrease. The substitution amount of Ga is set to 0.01 to 0.5%. The addition of a small amount of Ga improves the coercive force iHc, but the substitution amount is 0.0
If less than 1%, the effect of addition is small. On the other hand, Ga
When the amount of substitution exceeds 0.5%, the residual magnetic flux density Br decreases remarkably, and the coercive force iHc also decreases. The substitution amount of Cu is set to 0.01 to 1.0%. Addition of a small amount of Cu improves the coercive force iHc, but when the substitution amount exceeds 1.0%, the effect of addition is saturated. When the addition amount is less than 0.01%, the effect of improving the coercive force iHc is small.
【００２０】[0020]
【発明の実施の態様】以下、本発明を実施例をもって具
体的に説明するが、本発明の内容はこれに限定されるも
のではない。 (実施例１)重量百分率でNd 23.5％,Pr 7.0％,Dy 1.5％,
B 1.05％,Al 0.10％,O 0.03％,C0.005％,N 0.004％,残
部Feの組成を有する、厚さが0.2〜0.5mmの薄帯状合金
を、ストリップキャスト法で作製した。この薄帯状の合
金を、Arガス雰囲気中で1000℃で2時間加熱した。次に
水素炉を使用し、この薄帯状の合金を常温で水素ガス雰
囲気中で水素吸蔵させ、自然崩壊させた。次いで炉内を
真空排気しつつ550℃まで薄帯状の合金を加熱し、その
温度で1時間保持して脱水素処理を行った。崩壊した合
金を窒素ガス雰囲気中で機械的に破砕して、32mesh以下
の原料粗粉とした。この原料粗粉の組成を分析したとこ
ろ、Nd 23.5％,Pr 7.0％,Dy 1.5％,B 1.05％,Al 0.10
％,O 0.14％,C 0.02％,N 0.007％,残部Feという分析値
を得た。この原料粗粉50kgをジェットミル内に装入した
後、ジェットミル内部をN2ガスで置換し、N2ガス中の酸
素濃度を酸素分析計値で0.100vol％とした。次いで、粉
砕圧力7.0kg/cm2、原料粗粉の供給量10kg/Hrの条件で粉
砕した。微粉の平均粒度は4.3μｍであった。この微粉
を、金型キャビティ内で12kOeの配向磁界を印加しなが
ら0.8ton/cm2の成形圧で成形した。配向磁界の印加方向
は、成形方向と垂直である。成形体は、4.0×10-4torr
の条件下で15℃/分の昇温速度で1100℃まで昇温し、そ
の温度で2時間保持して焼結した。焼結体の組成を分析
したところ、Nd 23.5％,Pr 7.0％,Dy 1.5％,B 1.05％,A
l0.10％,O 0.55％,C 0.07％,N 0.012％,残部Feという分
析値を得た。この焼結体の、磁石主相結晶の総面積に対
する、結晶粒径が10μｍ以下の主相結晶粒の面積の和は
94％、結晶粒径が13μｍ以上の主相結晶粒の面積の和は
3％であった。この焼結体にArガス雰囲気中で900℃×2
時間と550℃×1時間の熱処理を各１回施した。機械加工
後磁気特性を測定したところ、表２に示すような良好な
値を得た。この永久磁石の耐蝕性を評価するために、磁
石を10mm×10mm×2mmの一定寸法に加工後、その表面に1
0μｍのNiメッキを施した。次いでこの試料を2気圧,120
℃,湿度100％の条件に放置し、時間の経過に対するNiメ
ッキのハクリ程度を調べた。表２に示すように、2000時
間を経過してもNiメッキに異常が認められず、良好な耐
蝕性を示した。DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. (Example 1) Nd 23.5%, Pr 7.0%, Dy 1.5%, by weight percentage
A strip alloy having a composition of 1.05% of B, 0.10% of Al, 0.03% of O, 0.005% of C, 0.004% of N, and the balance of Fe and having a thickness of 0.2 to 0.5 mm was prepared by a strip casting method. This ribbon-shaped alloy was heated at 1000 ° C. for 2 hours in an Ar gas atmosphere. Next, using a hydrogen furnace, the thin ribbon-shaped alloy was occluded with hydrogen in a hydrogen gas atmosphere at room temperature, and naturally collapsed. Next, the ribbon-shaped alloy was heated to 550 ° C. while the inside of the furnace was evacuated, and was held at that temperature for 1 hour to perform a dehydrogenation treatment. The collapsed alloy was mechanically crushed in a nitrogen gas atmosphere to obtain a raw material coarse powder of 32 mesh or less. Analysis of the composition of this raw material coarse powder revealed that Nd was 23.5%, Pr was 7.0%, Dy was 1.5%, B was 1.05%, and Al was 0.10%.
%, O 0.14%, C 0.02%, N 0.007% and balance Fe were obtained. After 50 kg of the raw material coarse powder was charged into the jet mill, the inside of the jet mill was replaced with N2 gas, and the oxygen concentration in the N2 gas was set to 0.100 vol% by an oxygen analyzer. Next, pulverization was performed under the conditions of a pulverization pressure of 7.0 kg / cm2 and a supply amount of raw material coarse powder of 10 kg / Hr. The average particle size of the fine powder was 4.3 μm. The fine powder was molded at a molding pressure of 0.8 ton / cm2 while applying an orientation magnetic field of 12 kOe in the mold cavity. The direction of application of the orientation magnetic field is perpendicular to the molding direction. The molded body is 4.0 × 10-4torr
The temperature was raised to 1100 ° C. at a rate of 15 ° C./min under the conditions described above, and the temperature was maintained for 2 hours for sintering. When the composition of the sintered body was analyzed, Nd 23.5%, Pr 7.0%, Dy 1.5%, B 1.05%, A
Analysis values of l0.10%, O 0.55%, C 0.07%, N 0.012%, and the balance Fe were obtained. The sum of the area of the main phase crystal grains having a crystal grain size of 10 μm or less with respect to the total area of the magnet main phase crystals of this sintered body is
94%, the sum of the areas of the main phase grains having a grain size of 13 μm or more is
3%. 900 ° C × 2 in an Ar gas atmosphere
Heat treatment at 550 ° C. × 1 hour was performed once each. When the magnetic properties were measured after machining, good values as shown in Table 2 were obtained. In order to evaluate the corrosion resistance of this permanent magnet, after processing the magnet to a fixed size of 10 mm × 10 mm × 2 mm,
0 μm Ni plating was applied. Next, the sample was placed at 2 atm, 120
It was left under conditions of 100 ° C. and 100% humidity, and the degree of peeling of the Ni plating over time was examined. As shown in Table 2, no abnormalities were observed in the Ni plating even after the lapse of 2,000 hours, indicating good corrosion resistance.
【００２１】(実施例２)重量百分率でNd 19.5％,Pr 6.5
％,Dy 5.5％,B 1.0％,Nb 0.5％,Al 0.2％,Co 2.0％,Ga
0.1％,O 0.02％,C 0.005％,N 0.003％,残部Feの組成を
有する、厚さが0.2〜0.4mmの薄帯状合金を、ストリップ
キャスト法で作製した。この薄帯状の合金を、Arガス雰
囲気中で1100℃で1時間加熱した。次に水素炉を使用
し、この薄帯状の合金を常温で水素ガス雰囲気中で水素
吸蔵させ、自然崩壊させた。次いで炉内を真空排気しつ
つ550℃まで薄帯状の合金を加熱し、その温度で1時間保
持して脱水素処理を行った。崩壊した合金を窒素ガス雰
囲気中で機械的に破砕して、32mesh以下の原料粗粉とし
た。この原料粗粉の組成を分析したところ、Nd 19.5％,
Pr 6.5％,Dy 5.5％,B 1.0％,Nb 0.5％,Al 0.2％,Co 2.0
％,Ga 0.10％,O 0.12％,C 0.02％,N 0.007％,残部Feと
いう分析値を得た。この原料粗粉50kgをジェットミル内
に装入した後、ジェットミル内部をN2ガスで置換し、N2
ガス中の酸素濃度を酸素分析計値で0.15％とした。次い
で、粉砕圧力8.0kg/cm2、原料粗粉の供給量12kg/Hrの条
件で粉砕した。微粉の平均粒度は4.6μｍであった。こ
の微粉を、金型キャビティ内で8kOeの配向磁界を印加し
ながら1.5ton/cm2の成形圧で成形した。配向磁界の印加
方向は、成形方向と垂直である。 成形体は、5.0×10-
4torrの条件下で15℃/分の昇温速度で1080℃まで昇温
し、その温度で3時間保持して焼結した。焼結体の組成
を分析したところ、Nd 19.5％,Pr 6.5％,Dy 5.5％,B 1.
0％,Nb 0.5％,Al 0.2％,Co 2.0％,Ga 0.10％,O 0.48％,
C 0.06％,N 0.008％,残部Feという分析値を得た。この
焼結体の、磁石主相結晶の総面積に対する、結晶粒径が
10μｍ以下の主相結晶粒の面積の和は90％、結晶粒径が
13μｍ以上の主相結晶粒の面積の和は6％であった。こ
の焼結体にArガス雰囲気中で900℃×2時間と600℃×1時
間の熱処理を各１回施した。機械加工後磁気特性を測定
したところ、表２に示すような良好な値を得た。この永
久磁石の耐蝕性を評価するために、磁石を10mm×10mm×
2mmの一定寸法に加工後、その表面に10μｍのNiメッキ
を施した。次いでこの試料を2気圧,120℃,湿度100％の
条件に放置し、時間の経過に対するNiメッキのハクリ程
度を調べた。表２に示すように、2000時間を経過しても
Niメッキに異常が認められず、良好な耐蝕性を示した。
また、得られた永久磁石の金属組織写真を図４に示す。
図５の金属組織写真に比し、組織が微細かつ均一である
ことがわかる。Example 2 Nd 19.5% by weight, Pr 6.5
%, Dy 5.5%, B 1.0%, Nb 0.5%, Al 0.2%, Co 2.0%, Ga
A strip alloy having a composition of 0.1%, 0.02% of O, 0.005% of C, 0.003% of N, and the balance of Fe and having a thickness of 0.2 to 0.4 mm was produced by a strip casting method. This ribbon-shaped alloy was heated at 1100 ° C. for 1 hour in an Ar gas atmosphere. Next, using a hydrogen furnace, the thin ribbon-shaped alloy was occluded with hydrogen in a hydrogen gas atmosphere at room temperature, and naturally collapsed. Next, the ribbon-shaped alloy was heated to 550 ° C. while the inside of the furnace was evacuated, and was held at that temperature for 1 hour to perform a dehydrogenation treatment. The collapsed alloy was mechanically crushed in a nitrogen gas atmosphere to obtain a raw material coarse powder of 32 mesh or less. Analysis of the composition of this raw material powder revealed that Nd was 19.5%,
Pr 6.5%, Dy 5.5%, B 1.0%, Nb 0.5%, Al 0.2%, Co 2.0
%, Ga 0.10%, O 0.12%, C 0.02%, N 0.007% and the balance Fe were obtained. After charging 50 kg of this raw material powder into a jet mill, the inside of the jet mill is replaced with N2 gas,
The oxygen concentration in the gas was set to 0.15% by an oxygen analyzer value. Next, pulverization was performed under the conditions of a pulverizing pressure of 8.0 kg / cm2 and a supply amount of raw material coarse powder of 12 kg / Hr. The average particle size of the fine powder was 4.6 μm. This fine powder was molded in a mold cavity at a molding pressure of 1.5 ton / cm2 while applying an orientation magnetic field of 8 kOe. The direction of application of the orientation magnetic field is perpendicular to the molding direction. The molded body is 5.0 × 10-
The temperature was raised to 1080 ° C. at a rate of 15 ° C./min under the condition of 4 torr, and kept at that temperature for 3 hours for sintering. When the composition of the sintered body was analyzed, Nd 19.5%, Pr 6.5%, Dy 5.5%, B1.
0%, Nb 0.5%, Al 0.2%, Co 2.0%, Ga 0.10%, O 0.48%,
The analytical values of C 0.06%, N 0.008%, and the balance Fe were obtained. The crystal grain size of this sintered body with respect to the total area of the magnet main phase crystals is
The sum of the areas of the main phase crystal grains of 10 μm or less is 90%, and the crystal grain size is
The sum of the areas of the main phase crystal grains of 13 μm or more was 6%. This sintered body was subjected to heat treatment once each in 900 ° C. × 2 hours and 600 ° C. × 1 hour in an Ar gas atmosphere. When the magnetic properties were measured after machining, good values as shown in Table 2 were obtained. In order to evaluate the corrosion resistance of this permanent magnet, a magnet of 10 mm x 10 mm x
After processing to a constant dimension of 2 mm, the surface was plated with Ni of 10 μm. Next, this sample was left under the conditions of 2 atm, 120 ° C., and 100% humidity, and the degree of peeling of Ni plating over time was examined. As shown in Table 2, even after 2000 hours
No abnormalities were observed in the Ni plating, indicating good corrosion resistance.
FIG. 4 shows a photograph of the metal structure of the obtained permanent magnet.
It can be seen that the structure is finer and more uniform than the metal structure photograph of FIG.
【００２２】(実施例３)重量百分率でNd 25.8％,Pr 5.5
％,Dy 1.2％,B 1.05％,Al 0.08％,Co 2.0％,Ga0.09％,C
u 0.1％,O 0.03％,C 0.005％,N 0.005％,残部Feの組成
を有する、厚さが0.1〜0.5mmの薄帯状合金を、ストリッ
プキャスト法で作製した。この薄帯状の合金を、Arガス
雰囲気中で900℃で2時間加熱した。次に水素炉を使用
し、この薄帯状の合金を常温で水素ガス雰囲気中で水素
吸蔵させ、自然崩壊させた。次いで炉内を真空排気しつ
つ550℃まで薄帯状の合金を加熱し、その温度で1時間保
持して脱水素処理を行った。崩壊した合金を窒素ガス雰
囲気中で機械的に破砕して、32mesh以下の原料粗粉とし
た。この原料粗粉の組成を分析したところ、Nd 25.8％,
Pr 5.5％,Dy 1.2％,B 1.05％,Al 0.08％,Ga 0.09％,Cu
0.1％,O 0.14％,C 0.03％,N 0.009％,残部Feという分析
値を得た。この原料粗粉50kgをジェットミル内に装入し
た後、ジェットミル内部をArガスで置換し、Arガス中の
酸素濃度を酸素分析計値で0.050vol％とした。次いで、
粉砕圧力7.5kg/cm2、原料粗粉の供給量9kg/Hrの条件で
粉砕した。微粉の平均粒度は4.7μｍであった。この原
料スラリーを、金型キャビティ内で8kOeの配向磁界を印
加しながら0.6ton/cm2の成形圧で湿式成形した。配向磁
界の印加方向は、成形方向と垂直である。成形体は、4.
0×10-4torrの条件下で１５℃／分の昇温速度で１１０
０℃まで昇温し、その温度で2時間保持して焼結した。
焼結体の組成を分析したところ、Nd 25.8％,Pr 5.5％,D
y 1.2％,B 1.05％,Al0.08％,Ga 0.09％,Cu 0.1％,O 0.3
5％,C 0.07％,N 0.025％,残部Feという分析値を得た。
この焼結体の、磁石主相結晶の総面積に対する、結晶粒
径が10μｍ以下の主相結晶粒の面積の和は88％、結晶粒
径が13μｍ以上の主相結晶粒の面積の和は7％であっ
た。この焼結体にArガス雰囲気中で900℃×2時間と580
℃×1時間の熱処理を各１回施した。機械加工後磁気特
性を測定したところ、表２に示すような良好な値を得
た。この永久磁石の耐蝕性を評価するために、磁石を10
mm×10mm×2mmの一定寸法に加工後、その表面に10μｍ
のNiメッキを施した。次いでこの試料を2気圧,120℃,湿
度100％の条件に放置し、時間の経過に対するNiメッキ
のハクリ程度を調べた。表２に示すように、2000時間を
経過してもNiメッキに異常が認められず、良好な耐蝕性
を示した。Example 3 Nd 25.8% by weight, Pr 5.5
%, Dy 1.2%, B 1.05%, Al 0.08%, Co 2.0%, Ga 0.09%, C
A strip-like alloy having a composition of 0.1% of O, 0.03% of O, 0.005% of C, 0.005% of N and the balance of Fe and having a thickness of 0.1 to 0.5 mm was prepared by a strip casting method. This ribbon-shaped alloy was heated at 900 ° C. for 2 hours in an Ar gas atmosphere. Next, using a hydrogen furnace, the thin ribbon-shaped alloy was occluded with hydrogen in a hydrogen gas atmosphere at room temperature, and naturally collapsed. Next, the ribbon-shaped alloy was heated to 550 ° C. while the inside of the furnace was evacuated, and was held at that temperature for 1 hour to perform a dehydrogenation treatment. The collapsed alloy was mechanically crushed in a nitrogen gas atmosphere to obtain a raw material coarse powder of 32 mesh or less. Analysis of the composition of this raw material powder showed that Nd was 25.8%,
Pr 5.5%, Dy 1.2%, B 1.05%, Al 0.08%, Ga 0.09%, Cu
Analysis values of 0.1%, 0.14% of O, 0.03% of C, 0.009% of N, and the balance of Fe were obtained. After 50 kg of the raw material coarse powder was charged into the jet mill, the inside of the jet mill was replaced with Ar gas, and the oxygen concentration in the Ar gas was adjusted to 0.050 vol% by an oxygen analyzer. Then
The pulverization was performed under the conditions of a pulverization pressure of 7.5 kg / cm2 and a supply amount of the raw material coarse powder of 9 kg / Hr. The average particle size of the fine powder was 4.7 μm. This raw material slurry was wet-molded in a mold cavity at a molding pressure of 0.6 ton / cm2 while applying an orientation magnetic field of 8 kOe. The direction of application of the orientation magnetic field is perpendicular to the molding direction. The molded body is 4.
Under the condition of 0 × 10 -4 torr at a heating rate of 15 ° C./min, 110
The temperature was raised to 0 ° C., and kept at that temperature for 2 hours for sintering.
When the composition of the sintered body was analyzed, Nd 25.8%, Pr 5.5%, D
y 1.2%, B 1.05%, Al 0.08%, Ga 0.09%, Cu 0.1%, O 0.3
Analysis values of 5%, C 0.07%, N 0.025%, and the balance Fe were obtained.
The sum of the area of the main phase crystal grains having a crystal grain size of 10 μm or less in the sintered body relative to the total area of the magnet main phase crystals is 88%, and the sum of the areas of the main phase crystal grains having a crystal grain size of 13 μm or more is 7%. The sintered body was heated in an Ar gas atmosphere at 900 ° C for 2 hours and 580
Heat treatment was performed once each at a temperature of 1 ° C. × 1 hour. When the magnetic properties were measured after machining, good values as shown in Table 2 were obtained. In order to evaluate the corrosion resistance of this permanent magnet,
After processing to a fixed size of mm × 10 mm × 2 mm, 10 μm on the surface
Was plated with Ni. Next, this sample was left under the conditions of 2 atm, 120 ° C., and 100% humidity, and the degree of peeling of Ni plating over time was examined. As shown in Table 2, no abnormalities were observed in the Ni plating even after the lapse of 2,000 hours, indicating good corrosion resistance.
【００２３】(比較例１)実施例１で作製した薄帯状の合
金を、熱処理をおこなわずに直接水素炉に入れ、常温で
水素ガス雰囲気中で水素吸蔵させ、自然崩壊させた。そ
の後、実施例１と同じ条件で脱水素処理と機械的破砕を
おこない、32mesh以下の原料粗粉とした。この原料粗粉
の組成を分析したところ、重量百分率でNd 23.5％,Pr
7.0％,Dy1.5％,B 1.05％,Al 0.10％,O 0.11％,C 0.02
％,N 0.006％,残部Feという分析値を得た。この原料粗
粉を、実施例１と同一の条件で微粉砕した。得られた微
粉の平均粒度は4.6μｍと、実施例１の場合に比べて粗
かった。成形、焼結、熱処理、耐蝕性の評価などの以降
の工程も、実施例１と同一の条件で行った。焼結体の組
成を分析したところ、Nd 23.5％,Pr 7.0％,Dy 1.5％,B
1.05％,Al 0.10％,O 0.51％,C 0.06％,N 0.015％,残部F
eという分析値を得た。この焼結体の、磁石主相結晶の
総面積に対する、結晶粒径が10μｍ以下の主相結晶粒の
面積の和は77％、結晶粒径が13μｍ以上の主相結晶粒の
面積の和は14％であった。この永久磁石の磁気特性を評
価したところ、表２に示すように、実施例１の値に比べ
てBr,iHc共若干低い値であった。また、この永久磁石の
耐蝕性は、表２に示すように1000時間を経過してもNiメ
ッキに異常が認められず実用上全く問題ない水準にある
ことがわかったが、1500時間の経過でNiメッキのわずか
なハク離が発生し、実施例１で製造した焼結体との比較
では耐蝕性に劣ることが判明した。(Comparative Example 1) The ribbon-shaped alloy produced in Example 1 was directly placed in a hydrogen furnace without heat treatment, and hydrogen was occluded at room temperature in a hydrogen gas atmosphere to be naturally collapsed. Thereafter, dehydrogenation treatment and mechanical crushing were performed under the same conditions as in Example 1 to obtain raw material coarse powder of 32 mesh or less. Analysis of the composition of this raw material powder showed that Nd 23.5%, Pr
7.0%, Dy1.5%, B 1.05%, Al 0.10%, O 0.11%, C 0.02
%, N 0.006%, and the balance Fe. This raw material powder was pulverized under the same conditions as in Example 1. The average particle size of the obtained fine powder was 4.6 μm, which was coarser than that in Example 1. Subsequent processes such as molding, sintering, heat treatment, and evaluation of corrosion resistance were performed under the same conditions as in Example 1. When the composition of the sintered body was analyzed, Nd 23.5%, Pr 7.0%, Dy 1.5%, B
1.05%, Al 0.10%, O 0.51%, C 0.06%, N 0.015%, balance F
An analysis value of e was obtained. The sum of the area of the main phase crystal grains having a crystal grain size of 10 μm or less of the total area of the magnet main phase crystals of this sintered body is 77%, and the sum of the areas of the main phase crystal grains having a crystal grain size of 13 μm or more is 14%. When the magnetic properties of the permanent magnet were evaluated, as shown in Table 2, the values of Br and iHc were slightly lower than those of Example 1. Further, as shown in Table 2, the corrosion resistance of this permanent magnet was found to be at a level where no abnormalities were observed in the Ni plating even after 1000 hours and there was no problem in practical use. Slight separation of Ni plating occurred, and it was found that the corrosion resistance was inferior to that of the sintered body manufactured in Example 1.
【００２４】(比較例２)実施例２と同一の組成を有する
R-Fe-B系合金インゴットを作製した。この合金の組成分
析値は重量百分比率でNd 19.5％,Pr 6.5％,Dy 5.5％,B
1.0％,Nb 0.5％,Al 0.2％,Co 2.0％,Ga 0.1％,O 0.01
％,C 0.004％,N 0.002％,残部Feであった。合金の組織
中にα-Feの析出が認められたため、これを消去するた
め、合金インゴットにアルゴンガス雰囲気中で1100℃×
6時間の液体化処理を施した。次に合金インゴットを水
素炉中に入れ、常温で水素吸蔵させて自然崩壊させた。
自然崩壊後の合金を、実施例２と同一の条件で脱水素処
理と機械的破砕し、32mesh以下の原料粗粉とした。この
原料粗粉の組成を分析したところ、重量百分率でNd 19.
5％,Pr 6.5％,Dy5.5％,B 1.0％,Nb 0.5％,Al 0.2％,Co
2.0％,Ga 0.1％,O 0.09％,C 0.02％,N 0.006％,残部Fe
という分析値を得た。この原料粗粉を、実施例２と同一
の条件で微粉砕した。得られた微粉の平均粒度は5.1μ
ｍと、実施例１の場合に比べて粗かった。成形、焼結、
熱処理、耐蝕性の評価などの以降の工程も、実施例２と
同一の条件でおこなった。焼結体の組成を分析したとこ
ろ、Nd 19.5％,Pr 6.5％,Dy 5.5％,B 1.0％,Nb 0.5％,A
l 0.2％,Co 2.0％,Ga 0.10％,O 0.42％,C 0.06％,N 0.0
07％,残部Feという分析値を得た。この焼結体の、磁石
主相結晶の総面積に対する、結晶粒径が10μｍ以下の主
相結晶粒の面積の和は65％、結晶粒径が13μｍ以上の主
相結晶粒の面積の和は19％であった。金属組織写真を図
５に示す。この永久磁石の磁気特性を評価したところ、
表２に示すように、実施例２の値とほぼ同等の良好な値
であった。また、この永久磁石の耐蝕性は、表２に示す
ように700時間を経過してもNiメッキに異常が認められ
ず実用上全く問題ない水準にあることがわかったが、10
00時間の経過でNiメッキの一部にわずかなハク離が発生
し、実施例２で製造した永久磁石との比較では耐蝕性に
劣ることが判明した。Comparative Example 2 The same composition as in Example 2 was used.
R-Fe-B alloy ingots were prepared. The composition analysis value of this alloy is Nd 19.5%, Pr 6.5%, Dy 5.5%, B
1.0%, Nb 0.5%, Al 0.2%, Co 2.0%, Ga 0.1%, O 0.01
%, C 0.004%, N 0.002%, and the balance was Fe. Since α-Fe precipitation was observed in the structure of the alloy, the alloy ingot was placed at 1100 ° C in an argon gas atmosphere to eliminate this.
Liquefaction treatment was performed for 6 hours. Next, the alloy ingot was placed in a hydrogen furnace, and hydrogen was absorbed at room temperature to cause natural collapse.
The alloy after spontaneous collapse was subjected to dehydrogenation treatment and mechanical crushing under the same conditions as in Example 2 to obtain a raw material coarse powder of 32 mesh or less. When the composition of this raw material powder was analyzed, Nd 19.
5%, Pr 6.5%, Dy5.5%, B 1.0%, Nb 0.5%, Al 0.2%, Co
2.0%, Ga 0.1%, O 0.09%, C 0.02%, N 0.006%, balance Fe
Analysis value was obtained. This raw material powder was pulverized under the same conditions as in Example 2. The average particle size of the obtained fine powder is 5.1μ
m and coarser than the case of Example 1. Molding, sintering,
Subsequent processes such as heat treatment and evaluation of corrosion resistance were performed under the same conditions as in Example 2. When the composition of the sintered body was analyzed, Nd 19.5%, Pr 6.5%, Dy 5.5%, B 1.0%, Nb 0.5%, A
l 0.2%, Co 2.0%, Ga 0.10%, O 0.42%, C 0.06%, N 0.0
An analysis value of 07%, with the balance being Fe, was obtained. The sum of the area of the main phase crystal grains having a crystal grain size of 10 μm or less in the total area of the magnet main phase crystals of the sintered body is 65%, and the sum of the areas of the main phase crystal grains having a crystal grain size of 13 μm or more is 19%. A photograph of the metal structure is shown in FIG. When evaluating the magnetic properties of this permanent magnet,
As shown in Table 2, it was a good value almost equal to the value of Example 2. Further, as shown in Table 2, the corrosion resistance of this permanent magnet was found to be at a level that was not problematic in practical use without any abnormalities in Ni plating even after 700 hours.
After the elapse of 00 hours, a slight separation occurred in a part of the Ni plating, and it was found that the corrosion resistance was poor in comparison with the permanent magnet manufactured in Example 2.
【００２５】[0025]
【表２】 [Table 2]
【発明の効果】本発明により、磁気特性を低下させず
に、優れた耐食性を有するR-Fe-B系焼結型永久磁石が得
られる。According to the present invention, an R-Fe-B sintered permanent magnet having excellent corrosion resistance can be obtained without deteriorating magnetic properties.
【図１】 磁石主相結晶の総面積に対する結晶粒径が10
μｍ以下の主相結晶粒の面積の和の割合と、磁石主相結
晶の総面積に対する結晶粒径が13μｍ以上の主相の結晶
粒の面積の和の割合と、耐蝕性の加速試験での、Niメッ
キのハクリ開始が生じるまでの経過的間との関係を示し
た図である。[Fig. 1] The crystal grain size is 10 with respect to the total area of the magnet main phase crystal.
The ratio of the sum of the areas of the main phase crystal grains of μm or less, the ratio of the sum of the areas of the crystal grains of the main phase having a crystal grain size of 13 μm or more with respect to the total area of the magnet main phase crystals, FIG. 5 is a diagram showing a relationship between the time until the start of peeling of Ni plating occurs.
【図２】 ストリップキャスト法で作製した薄帯状合金
の断面の金属組織写真である。FIG. 2 is a photograph of a metal structure of a cross section of a thin strip alloy produced by a strip casting method.
【図３】 ストリップキャスト法で作製した薄帯状合金
を１０００℃で熱処理した後の断面の金属組織写真であ
る。FIG. 3 is a photograph of a metallographic structure of a cross section after heat treatment at 1000 ° C. of a ribbon-shaped alloy produced by a strip casting method.
【図４】 磁石主相の総面積に対する結晶粒径が10μｍ
以下の主相結晶粒の面積の和が９０％、結晶粒径が13μ
ｍ以上の主相結晶粒の面積の和が６％である焼結型永久
磁石の金属組織写真である。FIG. 4 shows a crystal grain size of 10 μm with respect to the total area of the magnet main phase.
The sum of the areas of the following main phase crystal grains is 90%, and the crystal grain size is 13μ.
It is a metallographic photograph of the sintered permanent magnet in which the sum of the areas of the main phase crystal grains of m or more is 6%.
【図５】 磁石主相の総面積に対する結晶粒径が10μｍ
以下の主相結晶粒の面積の和が６５％,結晶粒径が13μ
ｍ以上の主相結晶粒の面積の和が１９％の焼結型永久磁
石の金属組織写真である。FIG. 5 shows a crystal grain size of 10 μm with respect to the total area of the magnet main phase.
The sum of the areas of the following main phase grains is 65% and the grain size is 13μ
It is a metallographic photograph of the sintered permanent magnet in which the sum of the areas of the main phase crystal grains of m or more is 19%.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平７−201545（ＪＰ，Ａ) 特開 平５−135931（ＪＰ，Ａ) 特開 平６−231921（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01F 1/032 - 1/08 C22C 38/00 303 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-201545 (JP, A) JP-A-5-135931 (JP, A) JP-A-6-231921 (JP, A) (58) Field (Int.Cl. 7 , DB name) H01F 1/032-1/08 C22C 38/00 303
Claims (3)
うちの１種又は２種以上)28.0〜33.0％,B 0.5〜2.0％,O
0.3〜0.7％,残部Feの組成を有し、磁石主相結晶粒の総
面積に対し、結晶粒径が10μｍ以下の主相結晶粒の面積
の和が80％以上,結晶粒が13μｍ以上の主相結晶粒の面
積の和が10％以下であることを特徴とする焼結型永久磁
石。1. R in weight percentage (R is one or more of rare earth elements including Y) 28.0-33.0%, B 0.5-2.0%, O
0.3 to 0.7%, with the balance of Fe, the sum of the area of the main phase crystal grains having a crystal grain size of 10 μm or less to the total area of the magnet main phase crystal grains is 80% or more, and the crystal grains are 13 μm or more. A sintered permanent magnet, wherein the sum of the areas of the main phase crystal grains is 10% or less.
％,Co 0.3〜5.0％,Ga 0.01〜0.5％,Cu 0.01〜1.0％のう
ち１種または２種以上で置換する請求項１に記載の焼結
型永久磁石。2. A part of Fe is Nb 0.1 to 2.0%, Al 0.02 to 2.0%.
2. The sintered permanent magnet according to claim 1, wherein the sintered permanent magnet is replaced by one or more of%, Co 0.3 to 5.0%, Ga 0.01 to 0.5%, and Cu 0.01 to 1.0%. 3.
項１または２に記載の焼結型永久磁石。3. The sintered permanent magnet according to claim 1, wherein the value of the coercive force iHc is 13.0 kOe or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11959896A JP3255344B2 (en) | 1996-04-17 | 1996-04-17 | Sintered permanent magnet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11959896A JP3255344B2 (en) | 1996-04-17 | 1996-04-17 | Sintered permanent magnet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09283313A JPH09283313A (en) | 1997-10-31 |
| JP3255344B2 true JP3255344B2 (en) | 2002-02-12 |
Family
ID=14765359
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11959896A Expired - Lifetime JP3255344B2 (en) | 1996-04-17 | 1996-04-17 | Sintered permanent magnet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3255344B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100592471B1 (en) * | 1998-10-14 | 2006-06-23 | 히다찌긴조꾸가부시끼가이사 | R-T-B type sintered permanent magnet |
| WO2005015580A1 (en) | 2003-08-12 | 2005-02-17 | Neomax Co., Ltd. | R-t-b sintered magnet and rare earth alloy |
| JP6728861B2 (en) * | 2015-03-25 | 2020-07-22 | Tdk株式会社 | Rare earth magnets |
| JP6728860B2 (en) * | 2015-03-25 | 2020-07-22 | Tdk株式会社 | Rare earth magnets |
| JP6728862B2 (en) * | 2015-03-25 | 2020-07-22 | Tdk株式会社 | Rare earth magnets |
-
1996
- 1996-04-17 JP JP11959896A patent/JP3255344B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09283313A (en) | 1997-10-31 |
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