JP2012164764A - Magnetic material and method for manufacturing the same - Google Patents
Magnetic material and method for manufacturing the same Download PDFInfo
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本発明は、ナノサイズの結晶粒が集合してなる高保磁力を発現する磁性体とその製造方法に関する。 The present invention relates to a magnetic body that exhibits a high coercive force formed by agglomeration of nano-sized crystal grains and a method for producing the same.
Ｎｄ−Ｆｅ−Ｂ系を代表とする希土類（永久）磁石は、非常に高い磁気特性を示す。この希土類磁石を用いると、電磁機器や電動機の小型化、高出力化、高密度化さらには環境負荷の低減化等を図ることが可能となる。このため、幅広い分野で希土類磁石の利用が検討されている。この希土類磁石の実用化に際して、厳しい環境下でも高い磁気特性が長期的に安定して発揮されることが求められる。このような観点から、希土類磁石の磁化（残留磁束密度）のみならず、その保磁力を向上させる研究開発が盛んに行われている。 Rare earth (permanent) magnets typified by the Nd—Fe—B system exhibit very high magnetic properties. When this rare earth magnet is used, it is possible to reduce the size, increase the output, increase the density, and reduce the environmental load of the electromagnetic device and the electric motor. For this reason, the use of rare earth magnets is being studied in a wide range of fields. When this rare earth magnet is put to practical use, it is required that high magnetic properties be stably exhibited over a long period even in a severe environment. From such a viewpoint, research and development for improving not only the magnetization (residual magnetic flux density) of a rare earth magnet but also its coercive force are being actively conducted.
従来は、ジルコニウム（Ｄｙ）やテルビウム（Ｔｂ）等の重希土類元素を、磁石合金に直接添加したり、磁石表面から拡散させることにより、異方性磁界を高くして保磁力の向上が図られてきた。最近では、さらなる保磁力の向上やＤｙ等の稀少元素の使用量を削減するため、主相を構成するＮｄ２Ｆｅ１４Ｂ結晶粒の微細化が進められている。これらに関連する記載が下記の特許文献等にある。 Conventionally, by adding a heavy rare earth element such as zirconium (Dy) or terbium (Tb) directly to the magnet alloy or diffusing from the magnet surface, the anisotropic magnetic field is increased and the coercive force is improved. I came. Recently, in order to further improve the coercive force and reduce the amount of rare elements such as Dy, the Nd 2 Fe 14 B crystal grains constituting the main phase have been refined. There are descriptions related to these in the following patent documents.
上記の特許文献１および特許文献２では、急冷凝固させた薄片の破砕粉からなる磁石片に、ＤｙＦ３等を塗布してＤｙ等を表面から内部に拡散させている。 In Patent Document 1 and Patent Document 2 described above, DyF 3 or the like is applied to a magnet piece made of crushed powder of a thin piece that has been rapidly cooled and solidified to diffuse Dy and the like from the surface to the inside.
また特許文献３では、磁石合金溶湯の急冷速度を制御して、単磁区粒子径以下（＜１００ｎｍ）の結晶粒からなる純三元系Ｎｄ−Ｆｅ−Ｂ磁石を得ている。また特許文献４では、ＨｆＣを添加した磁石合金溶湯を急冷して、結晶粒を微細化させた希土類永久磁石を得ている。ちなみに特許文献３では、アモルファス相の出現を抑制するために、急冷速度の上限を制限している。また特許文献４では、急冷凝固後の加熱により、出現したアモルファス相を結晶化させている。 Further, in Patent Document 3, a pure ternary Nd—Fe—B magnet composed of crystal grains having a single domain particle diameter or less (<100 nm) is obtained by controlling the quenching speed of the molten magnet alloy. In Patent Document 4, a rare earth permanent magnet having crystal grains refined is obtained by quenching a molten magnet alloy to which HfC is added. Incidentally, in patent document 3, in order to suppress the appearance of an amorphous phase, the upper limit of the rapid cooling rate is limited. In Patent Document 4, the appearing amorphous phase is crystallized by heating after rapid solidification.
このように従来は、磁石合金の溶湯を急冷凝固させて微細な結晶粒からなる希土類磁石を得ており、結晶粒界にＤｙ等を拡散させる場合は、その晶出後に拡散処理を別途行っていた。 In this way, conventionally, a rare earth magnet made of fine crystal grains is obtained by rapidly solidifying a melt of a magnet alloy, and when diffusing Dy or the like in a crystal grain boundary, a diffusion treatment is separately performed after the crystallization. It was.
本発明は、このような従来のものとは異なり、結晶粒の形態や製法が新規な磁性体およびその製造方法を提供することを目的とする。 The object of the present invention is to provide a magnetic material having a novel crystal grain shape and manufacturing method, and a method for manufacturing the same, unlike such conventional ones.
本発明者が鋭意研究し試行錯誤を重ねた結果、希土類元素（Ｒ１）と鉄（Ｆｅ）とホウ素（Ｂ）からなる非晶質体に拡散材を付着させた付着非晶質体を加熱することにより、Ｒ１２Ｆｅ１４Ｂ結晶粒の生成と、結晶粒間にできる粒界相の生成とが並行してなされることを新たに発見した。しかも、その結晶粒は従来の結晶粒と形態が異なることもわかった。この画期的な成果を発展させることにより、以降に述べるような本発明を完成するに至った。 As a result of extensive research and trial and error by the present inventors, the attached amorphous body in which the diffusing material is attached to the amorphous body made of rare earth element (R1), iron (Fe), and boron (B) is heated. Thus, it has been newly discovered that the generation of R1 2 Fe 14 B crystal grains and the generation of a grain boundary phase formed between the crystal grains are performed in parallel. Moreover, it was also found that the crystal grains are different in form from the conventional crystal grains. By developing this groundbreaking result, the present invention as described below has been completed.
《磁性体》
（１）本発明の磁性体は、Ｒ１とＦｅとＢの正方晶金属間化合物（Ｒ１２Ｆｅ１４Ｂ）の結晶粒からなる主相と該結晶粒間に形成された粒界相とを有する磁性体であって、前記結晶粒は、最長幅が５００ｎｍ以下の角丸形状をしており、前記粒界相は、最小幅が１ｎｍ以上であることを特徴とする。
<Magnetic material>
(1) The magnetic body of the present invention has a main phase composed of crystal grains of a tetragonal intermetallic compound of R1, Fe, and B (R1 2 Fe 14 B) and a grain boundary phase formed between the crystal grains. A magnetic material, wherein the crystal grains have a rounded round shape with a maximum width of 500 nm or less, and the grain boundary phase has a minimum width of 1 nm or more.
（２）本発明の磁性体は、先ず、微細なＲ１２Ｆｅ１４Ｂの結晶粒（適宜「Ｒ１２Ｆｅ１４Ｂ結晶粒」または「結晶粒」という。）からなる主相と、それら結晶粒間に存在する薄い粒界相とからなり、Ｄｙ等の稀少元素を拡散等させるまでもなく高い保磁力を発現する。従って、本発明の磁性体によれば、高磁気特性の希土類磁石を工業的に安定して供給し得る。 (2) The magnetic body of the present invention first comprises a main phase composed of fine R1 2 Fe 14 B crystal grains (referred to as “R1 2 Fe 14 B crystal grains” or “crystal grains” as appropriate), and those crystal grains. It consists of a thin grain boundary phase existing between them, and exhibits a high coercive force without diffusing rare elements such as Dy. Therefore, according to the magnetic body of the present invention, a rare earth magnet having high magnetic properties can be supplied industrially stably.
次に本発明の磁性体は、Ｒ１２Ｆｅ１４Ｂ結晶粒が単に微細なだけではなく、従来の結晶粒と異なる角丸形状をしている（図１Ｂ、図３Ａ〜図３Ｃ参照）。現状、結晶粒の形状と磁気特性（特に保磁力）との相関は必ずしも定かではないが、次のような理由により、結晶粒の角丸形状が保磁力の向上に寄与していると考えられる。すなわち、結晶粒が丸みを帯びた角丸形状をしていることにより、結晶粒の角部における反磁界が低減される。その結果、結晶粒における逆磁区の生成等が抑制され、磁性体の保磁力が著しく高まったと考えられる。 Next, in the magnetic body of the present invention, the R1 2 Fe 14 B crystal grains are not only fine, but also have rounded shapes different from those of conventional crystal grains (see FIGS. 1B and 3A to 3C). At present, the correlation between crystal grain shape and magnetic properties (especially coercive force) is not necessarily clear, but it is thought that the rounded shape of crystal grains contributes to the improvement of coercive force for the following reasons. . That is, the demagnetizing field at the corners of the crystal grains is reduced due to the rounded round shape of the crystal grains. As a result, it is considered that the generation of reverse magnetic domains in the crystal grains is suppressed and the coercive force of the magnetic material is remarkably increased.
なお本発明でいう「角丸形状」は、結晶粒ごとに形状やサイズは多少異なるため、厳密に定義することは容易ではないが、少なくとも、Ｒ１２Ｆｅ１４Ｂ結晶粒を磁化容易軸（ｃ軸）に平行な面で切断したときの断面形状を、走査透過型電子顕微鏡（ＳＴＥＭ）等で観察した場合に、特に角張った部位が観られないことを意味する。例えば、従来の結晶粒のような方形状ではなく、その方形状を構成する角部が略円弧状になっている形状である。 The “rounded corner shape” as used in the present invention has a slightly different shape and size for each crystal grain, so it is not easy to define exactly, but at least the R1 2 Fe 14 B crystal grain has an easy axis (c This means that when the cross-sectional shape when cut along a plane parallel to the (axis) is observed with a scanning transmission electron microscope (STEM) or the like, a particularly angular portion is not observed. For example, it is not a square shape like a conventional crystal grain, but a shape in which corner portions constituting the square shape are substantially arc-shaped.
また、結晶粒の最長幅は、前記断面形状に現れたｃ軸に垂直な方向における結晶粒の最大長さである。多数の結晶粒がある場合、各結晶粒の最長幅の相加平均をもって、本発明でいう「最長幅」とする。 The longest width of the crystal grain is the maximum length of the crystal grain in the direction perpendicular to the c-axis appearing in the cross-sectional shape. When there are a large number of crystal grains, the arithmetic average of the longest width of each crystal grain is defined as the “longest width” in the present invention.
さらに、粒界相の最小幅は、前記断面形状に現れた結晶粒間の距離の最小長さである。この場合も、各粒界相の最小幅の相加平均をもって、本発明でいう「最小幅」とする。 Further, the minimum width of the grain boundary phase is the minimum length of the distance between crystal grains appearing in the cross-sectional shape. Also in this case, the arithmetic average of the minimum widths of the grain boundary phases is set as the “minimum width” in the present invention.
結晶粒の最長幅は、５００ｎｍ以下、３００ｎｍ以下、２５０ｎｍ以下さらには２００ｎｍ以下であると磁気特性の向上を図れてより好ましい。この最長幅の下限値は特に限定されないが、２０ｎｍ以上さらには３０ｎｍ以上であると、熱擾乱の影響を受けにくくなり好ましい。 The longest width of the crystal grains is more preferably 500 nm or less, 300 nm or less, 250 nm or less, and even 200 nm or less, since it is possible to improve the magnetic characteristics. The lower limit of the longest width is not particularly limited, but is preferably 20 nm or more, more preferably 30 nm or more, because it is less susceptible to thermal disturbance.
粒界相は、結晶粒を包囲して各結晶粒を孤立させることにより、磁性体の保磁力を向上させ得る。もっとも、この粒界相が厚くなると磁性体の磁化が相対的に低下する。そこで粒界相の最小幅は、１ｎｍ以上さらには２ｎｍ以上であり、その最大幅は１５ｎｍさらには１０ｎｍ以下であると好ましい。 The grain boundary phase can improve the coercive force of the magnetic material by surrounding the crystal grains and isolating each crystal grain. However, as the grain boundary phase becomes thicker, the magnetization of the magnetic material relatively decreases. Therefore, the minimum width of the grain boundary phase is preferably 1 nm or more and further 2 nm or more, and the maximum width is preferably 15 nm or more and 10 nm or less.
磁性体の厚さ（ｃ軸方向の長さ）は特に問わない。もっとも本発明のように、ナノサイズの結晶粒や粒界相が集合してできたナノ結晶集合体（ひいては磁性体）は、厚さが１〜５００ｎｍさらには５〜２００ｎｍの薄膜状であると製造が容易である。 The thickness of the magnetic material (the length in the c-axis direction) is not particularly limited. However, as in the present invention, a nanocrystal aggregate (and hence a magnetic substance) formed by aggregating nanosized crystal grains and grain boundary phases is a thin film having a thickness of 1 to 500 nm, and further 5 to 200 nm. Easy to manufacture.
《磁性体の製造方法》
（１）本発明は磁性体としてのみならず、それに適した製造方法としても把握される。すなわち本発明は、Ｒ１とＦｅとＢからなる非晶質体内に拡散し得る拡散元素を含む拡散材を、該非晶質体へ付着させた付着非晶質体を得る付着工程と、該付着非晶質体を加熱して、Ｒ１２Ｆｅ１４Ｂの結晶粒からなる主相と該結晶粒間に形成され該拡散元素を含む粒界相とを並行して形成させ得る加熱工程とを備え、上述した本発明の磁性体が得られることを特徴とする磁性体の製造方法でもよい。
<Method for manufacturing magnetic material>
(1) The present invention is understood not only as a magnetic material but also as a manufacturing method suitable for it. That is, the present invention provides an attachment step of obtaining an attached amorphous body in which a diffusing material containing a diffusing element that can diffuse into an amorphous body composed of R1, Fe, and B is attached to the amorphous body; A heating step of heating the crystalline body so that a main phase composed of crystal grains of R1 2 Fe 14 B and a grain boundary phase formed between the crystal grains and containing the diffusing element can be formed in parallel. A method for producing a magnetic material characterized in that the magnetic material of the present invention described above can be obtained.
（２）本発明の製造方法によれば、角丸形状の微細な結晶粒と薄い粒界相とからなる磁性体を容易に製造することができる。本発明の製造方法により、そのような結晶粒や粒界相が形成される理由は必ずしも定かではないが、現状では次のように考えられる。 (2) According to the production method of the present invention, it is possible to easily produce a magnetic body composed of rounded round crystal grains and a thin grain boundary phase. The reason why such crystal grains and grain boundary phases are formed by the production method of the present invention is not necessarily clear, but at present, it is considered as follows.
先ず従来のように、磁石合金の溶湯を急冷凝固させて得た非晶質体を加熱してＲ１２Ｆｅ１４Ｂ結晶粒を晶出させた場合、結晶粒はその成長と共に隣接する結晶粒間で相互にぶつかり合いながら晶出する。このため、結晶粒がぶつかりあった部分で、結晶粒は角ばった形状（方形状）となる。なお、結晶粒の晶出後に熱処理や拡散処理を別途施さない限り、その晶出過程中に粒界相が形成されることはない。 First, when an amorphous body obtained by rapidly solidifying a magnetic alloy melt is heated to crystallize R1 2 Fe 14 B crystal grains as in the prior art, the crystal grains grow between the adjacent crystal grains as they grow. Crystallize while colliding with each other. For this reason, the crystal grains have an angular shape (rectangular shape) at the portion where the crystal grains collide. Note that a grain boundary phase is not formed during the crystallization process unless heat treatment or diffusion treatment is separately performed after the crystallization of crystal grains.
次に本発明の製造方法の場合、Ｒ１−Ｆｅ−Ｂ非晶質体に拡散材を付着させて加熱することにより、Ｒ１２Ｆｅ１４Ｂ結晶粒の晶出（生成）および成長と、粒界相の形成が並行して進行する。つまり粒界相が、結晶粒の生成および成長に誘起されつつ、その結晶粒を包囲するように形成される。このような晶出過程を経る場合、粒界相は緩衝帯（層）となって成長時の結晶粒の衝突を抑制する。こうして本発明の製造方法によると、丸みを帯びたナノサイズの結晶粒が薄い粒界相により包み込まれたような結晶組織が形成されたと考えられる。 Next, in the case of the production method of the present invention, a diffusing material is attached to the R1-Fe-B amorphous body and heated, so that crystallization (generation) and growth of R1 2 Fe 14 B crystal grains, and grain boundaries Phase formation proceeds in parallel. That is, the grain boundary phase is formed so as to surround the crystal grains while being induced by the generation and growth of the crystal grains. In such a crystallization process, the grain boundary phase becomes a buffer zone (layer) and suppresses collision of crystal grains during growth. Thus, according to the production method of the present invention, it is considered that a crystal structure in which rounded nano-sized crystal grains are encapsulated by a thin grain boundary phase is formed.
ちなみに本発明の製造方法によれば、非晶質体からＲ１２Ｆｅ１４Ｂ結晶粒が晶出する際の結晶化温度が、従来の結晶化温度（６６５℃）よりも低い。これは、非晶質体内へ拡散した拡散元素が、非晶質体としての安定性を下げ、Ｒ１２Ｆｅ１４Ｂ結晶の核生成エネルギーを低下させたためと考えられる。なお、これを逆に観ると、本発明でいう拡散元素（さらには粒界構成元素）は、非晶質体中においてＲ１２Ｆｅ１４Ｂ結晶の核生成エネルギーを低下させる元素であると好ましいといえる。 Incidentally, according to the production method of the present invention, the crystallization temperature when the R1 2 Fe 14 B crystal grains are crystallized from the amorphous body is lower than the conventional crystallization temperature (665 ° C.). This is presumably because the diffusion element diffused into the amorphous body lowered the stability as the amorphous body and lowered the nucleation energy of the R1 2 Fe 14 B crystal. In reverse, when the diffusion element (and the grain boundary constituent element) referred to in the present invention is preferably an element that reduces the nucleation energy of the R1 2 Fe 14 B crystal in the amorphous body. I can say that.
いずれにしても本発明の製造方法によれば、上述したような特異なナノ結晶集合体からなる磁性体を容易に得ることが可能となる。ちなみに、こうして得られた磁性体は、Ｄｙ等の稀少元素を用いるまでもなく、例えば、２０ｋＯｅ以上、２５ｋＯｅ以上さらに２７ｋＯｅ以上の高い保磁力を発現し得る。 In any case, according to the production method of the present invention, it is possible to easily obtain a magnetic material composed of the unique nanocrystal aggregate as described above. Incidentally, the magnetic material thus obtained does not need to use a rare element such as Dy, and can exhibit a high coercive force of, for example, 20 kOe or more, 25 kOe or more, and 27 kOe or more.
《その他》
（１）本発明に係るナノ結晶集合体や磁性体は、巨視的な形態を問わない。つまり、薄膜体でも、その薄膜体が基板上に積層された積層体でも、薄膜体を粉砕した粉砕粉でも、その粉砕粉を成形した成形体でも、さらにはその成形体を焼結させた焼結体でもよい。また本発明の磁性体は、バルクのような素材であっても最終的な希土類磁石であってもよく、着磁の有無を問わない。
<Others>
(1) The nanocrystal aggregate and magnetic body according to the present invention may be in any macroscopic form. That is, a thin film body, a laminated body in which the thin film body is laminated on a substrate, a pulverized powder obtained by pulverizing a thin film body, a molded body obtained by molding the pulverized powder, and a sintered body obtained by sintering the molded body. It may be a ligation. Further, the magnetic body of the present invention may be a material such as a bulk or a final rare earth magnet, regardless of whether it is magnetized.
（２）本明細書でいう「ｘ〜ｙ」は、特に断らない限り下限値ｘおよび上限値ｙを含む。また本明細書に記載した種々の数値や数値範囲内に含まれる数値を、新たな下限値または上限値としては、「ａ〜ｂ」のような数値範囲を任意に設定し得る。 (2) “x to y” in the present specification includes the lower limit value x and the upper limit value y unless otherwise specified. In addition, as numerical values included in various numerical values and numerical ranges described in the present specification, new numerical values such as “ab” can be arbitrarily set as the lower limit value or the upper limit value.
発明の実施形態を挙げて本発明をより詳しく説明する。本明細書中から任意に選択した一つまたは二つ以上の構成を上述した本発明に付加し得る。本明細書で説明する内容は、磁性体のみならずその製造方法にも適用される。製造方法に関する構成は、プロダクトバイプロセスとして理解すれば物に関する構成になり得る。いずれの実施形態が最良であるか否かは、対象、要求性能等によって異なる。 The present invention will be described in more detail with reference to embodiments of the invention. One or more configurations arbitrarily selected from the present specification may be added to the present invention described above. The contents described in this specification are applied not only to the magnetic material but also to the manufacturing method thereof. A configuration related to a manufacturing method can be a configuration related to an object if understood as a product-by-process. Which embodiment is the best depends on the target, required performance, and the like.
《主相と粒界相》
（１）主相
主相は、希土類元素（Ｒ１）、ＦｅおよびＢの正方晶金属間化合物であるＲ１２Ｆｅ１４Ｂの結晶粒からなる。Ｒ１は一種のみならず二種以上であってもよい。本明細書でいう希土類元素には、スカンジウム（Ｓｃ）、イットリウム（Ｙ）、ランタノイドを含む。ランタノイドは、ランタン（Ｌａ）、セリウム（Ｃｅ）、プラセオジム（Ｐｒ）、ネオジム（Ｎｄ）、サマリウム（Ｓｍ）、ユウロピウム（Ｅｕ）、ガドリニウム（Ｇｄ）、テルビウム（Ｔｂ）、ジスプロシウム（Ｄｙ）、ホルミウム（Ｈｏ）、エルビウム（Ｅｒ）、ツリウム（Ｔｍ）、イッテルビウム（Ｙｂ）およびルテチウム（Ｌｕ）などがある。もっともＲ１は、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、ＴｍおよびＹｂの少なくとも１種以上であると好ましく、特にコストや磁気特性の観点からＲ１はＮｄであるとよい。この点は後述のＲ２についても同様である。
《Main phase and grain boundary phase》
(1) Main phase The main phase consists of crystal grains of rare earth element (R1), R1 2 Fe 14 B which is a tetragonal intermetallic compound of Fe and B. R1 may be not only one type but also two or more types. The rare earth elements referred to in this specification include scandium (Sc), yttrium (Y), and lanthanoids. Lanthanoids include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium ( Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). However, R1 is preferably at least one of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb. R1 is particularly Nd from the viewpoint of cost and magnetic properties. Good. This also applies to R2 described later.
（２）粒界相
粒界相は、結晶粒を孤立させて磁性体の保磁力の向上に寄与し、またＲ１２Ｆｅ１４Ｂ結晶の核生成エネルギーを低下させ、角丸形状の結晶粒を安定的に形成させ得る粒界構成元素を含むと好ましい。この粒界構成元素は、結晶粒の構成元素（Ｒ１、ＦｅおよびＢ）以外であって、例えば、アルミニウム（Ａｌ）、銅（Ｃｕ）、マンガン（Ｍｎ）、チタン（Ｔｉ）、バナジウム（Ｖ）、クロム（Ｃｒ）、ガリウム（Ｇａ）、イットリウム（Ｙ）、ジルコニウム（Ｚｒ）、ニオブ（Ｎｂ）、モリブデン（Ｍｏ）、ハフニウム（Ｈｆ）、タンタル（Ｔａ）、タングステン（Ｗ）、銀（Ａｇ）、金（Ａｕ）、白金（Ｐｔ）、ルテニウム（Ｒｕ）、スズ（Ｓｎ）、酸素（Ｏ）、窒素（Ｎ）、Ｃ（炭素）、水素（Ｈ）、マグネシウム（Ｍｇ）、ケイ素（Ｓｉ）、ニッケル（Ｎｉ）、コバルト（Ｃｏ）、ゲルマニウム（Ｇｅ）および鉛（Ｐｂ）からなる元素群中の一種以上である。特に粒界構成元素はＣｕであり、粒界相はＲ１および／またはＲ１と異なる希土類元素（Ｒ２）とＣｕからなると好ましい。ここでＲ１およびＲ２は異種でも同種でもよいが、Ｒ１およびＲ２が共にＮｄであれば磁性体の磁気特性向上およびコスト低減を図れて好ましい。
(2) Grain boundary phase The grain boundary phase contributes to the improvement of the coercive force of the magnetic material by isolating the crystal grains, and also reduces the nucleation energy of the R1 2 Fe 14 B crystal. It preferably contains a grain boundary constituent element that can be stably formed. This grain boundary constituent element is other than the constituent elements (R1, Fe and B) of the crystal grains, for example, aluminum (Al), copper (Cu), manganese (Mn), titanium (Ti), vanadium (V). , Chromium (Cr), gallium (Ga), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), hafnium (Hf), tantalum (Ta), tungsten (W), silver (Ag) , Gold (Au), platinum (Pt), ruthenium (Ru), tin (Sn), oxygen (O), nitrogen (N), C (carbon), hydrogen (H), magnesium (Mg), silicon (Si) , Nickel (Ni), cobalt (Co), germanium (Ge) and lead (Pb). In particular, the grain boundary constituent element is Cu, and the grain boundary phase is preferably composed of R1 and / or a rare earth element (R2) different from R1 and Cu. Here, R1 and R2 may be different types or the same type, but it is preferable that both R1 and R2 are Nd in order to improve the magnetic characteristics and reduce the cost of the magnetic material.
《非晶質体と拡散材》
（１）非晶質体
本発明の磁性体のベースとなるＲ１−Ｆｅ−Ｂの非晶質体は、具体的な組成を問わない。もっとも、正方晶金属間化合物（Ｒ１２Ｆｅ１４Ｂ）の生成に適した組成、例えば、非晶質体全体を１００原子％としたとき、Ｒ１：８〜３０原子％、Ｂ：４〜２０原子％、Ｆｅ：残部からなる組成が好ましい。Ｒ１リッチな組成の場合、粒界相の形成が容易となり、ひいては磁性体の保磁力が向上し易くなる。さらには非晶質体は、Ｒ１、ＦｅおよびＢ以外に、種々の改質元素を少量含有してもよいし、当然に不可避不純物を含む。この点は拡散材についても同様である。
《Amorphous material and diffusion material》
(1) Amorphous body The R1-Fe-B amorphous body serving as the base of the magnetic body of the present invention may be of any specific composition. However, a composition suitable for the formation of a tetragonal intermetallic compound (R1 2 Fe 14 B), for example, when the whole amorphous body is 100 atomic%, R1: 8-30 atomic%, B: 4-20 atomic %, Fe: A composition comprising the balance is preferred. In the case of the R1-rich composition, the formation of the grain boundary phase is facilitated, and as a result, the coercive force of the magnetic material is easily improved. Furthermore, the amorphous body may contain a small amount of various modifying elements in addition to R1, Fe and B, and naturally contains unavoidable impurities. This also applies to the diffusing material.
ところで、このような非晶質体は、所望組成の合金溶湯の急冷凝固、所望組成の合金等をターゲットとしたスパッタリング、蒸着等によって形成され得る（非晶質体形成工程）。この形成時の温度が高温の場合、非晶質体よりも結晶質体の形成が容易となり好ましくない。そこで非晶質体形成工程は５９０℃以下さらには５６０℃以下でなされると好ましい。 By the way, such an amorphous body can be formed by rapid solidification of a molten alloy having a desired composition, sputtering, vapor deposition or the like using an alloy having a desired composition as a target (amorphous body forming step). When the temperature at the time of formation is high, formation of a crystalline material is easier than that of an amorphous material, which is not preferable. Therefore, the amorphous body forming step is preferably performed at 590 ° C. or lower, more preferably 560 ° C. or lower.
スパッタリング等により非晶質体を形成する基材は、その材質や形態を問わない。もっとも、非晶質体から晶出する結晶粒がエピタキシャル成長し易い基材を用いると、結晶方位が特定方向に揃った配向度の大きな（つまり残留磁化の大きな）ナノ結晶集合体ひいては磁性体を得ることができる。具体的には、Ｒ１２Ｆｅ１４Ｂ結晶粒と格子定数がほぼ等しい結晶からなる基材、表面が平坦な基材あるいは熱膨張係数が近接している基材を用いるとよい。例えば、酸化マグネシウム（ＭｇＯ）の単結晶からなるＭｇＯ単結晶基材、Ｗ、Ｍｏ、Ｃｕ、Ｓｉ、Ａｌ２Ｏ３、ＳｉＯ２の単結晶基材などである。この際、基材の積層面（ミラー指数でいう（００１）面）を磁化容易軸（ｃ軸）に垂直な面とするとよい。 The base material on which the amorphous body is formed by sputtering or the like may be of any material or form. However, when a base material on which crystal grains crystallized from an amorphous material are easy to grow epitaxially is used, a nanocrystal aggregate with a high degree of orientation (that is, a large residual magnetization) with a crystal orientation aligned in a specific direction, and thus a magnetic material is obtained. be able to. Specifically, it is preferable to use a base material made of a crystal having substantially the same lattice constant as that of the R1 2 Fe 14 B crystal grains, a base material having a flat surface, or a base material having a close thermal expansion coefficient. For example, an MgO single crystal base material made of a single crystal of magnesium oxide (MgO), a single crystal base material of W, Mo, Cu, Si, Al 2 O 3 , SiO 2 or the like. At this time, the laminated surface of the base material (the (001) surface in terms of the Miller index) is preferably a surface perpendicular to the easy magnetization axis (c-axis).
なお、基材自体がそのような結晶構造をもたない場合は、そのような結晶構造をもつ下地層を基材の表面に形成してもよい。勿論、基材および下地層が共にそのような結晶構造をもつとより好ましい。この下地層の構成材として、Ｍｏ、Ｔａ、Ｗ、Ｔｉ、Ｃｒ、Ｖ、Ｎｂなどがある。なお下地層も、例えば、スパッタリングにより形成し得る。 In addition, when the base material itself does not have such a crystal structure, an underlayer having such a crystal structure may be formed on the surface of the base material. Of course, it is more preferable that both the base material and the underlayer have such a crystal structure. Examples of the constituent material of the underlayer include Mo, Ta, W, Ti, Cr, V, and Nb. The underlayer can also be formed by sputtering, for example.
（２）拡散材
拡散材は、非晶質体内に拡散し得る拡散元素を含むものであればよい。拡散元素は粒界構成元素を兼ね、上述した粒界構成元素に関する内容は拡散元素にも該当する。但し、拡散元素がＲ１２Ｆｅ１４Ｂ結晶粒中に固溶すると、磁性体の磁気特性の低下を招くため、拡散元素は結晶粒内に非固溶なものほど好ましい。
(2) Diffusion material A diffusion material should just contain the diffusion element which can be diffused in an amorphous body. The diffusion element also serves as a grain boundary constituent element, and the above-described content relating to the grain boundary constituent element also applies to the diffusion element. However, if the diffusing element is dissolved in the R1 2 Fe 14 B crystal grains, the magnetic properties of the magnetic material are deteriorated. Therefore, it is preferable that the diffusing element is insoluble in the crystal grains.
拡散材は、比較的低温で液相を生じて濡れ性に優れると、拡散元素の非晶質体内への拡散が容易となり好ましい。具体的にいうと、拡散材は、Ｒ１−Ｆｅ−Ｂの共晶点（Ｎｄ−Ｆｅ−Ｂ系なら６６５℃）よりも低い温度で液相を生じるものであると好ましい。 A diffusing material that produces a liquid phase at a relatively low temperature and has excellent wettability is preferable because diffusion of the diffusing element into the amorphous body is facilitated. Specifically, it is preferable that the diffusing material generates a liquid phase at a temperature lower than the eutectic point of R1-Fe—B (665 ° C. in the case of Nd—Fe—B).
このような拡散材として、例えば、Ｒ−Ｃｕ系合金、Ｒ−Ａｌ系合金等がある（Ｒ：Ｒ１および／またはＲ２）。特に共晶点の低いＮｄ−Ｃｕ合金（共晶点：５２０℃）が好適である。この銅合金の組成は特に限定されないが、例えば、全体を１００原子％としたときにＣｕが２０〜９０原子％で残部がＮｄであると好ましい。 Examples of such a diffusing material include an R—Cu alloy, an R—Al alloy, and the like (R: R1 and / or R2). In particular, an Nd—Cu alloy having a low eutectic point (eutectic point: 520 ° C.) is suitable. The composition of the copper alloy is not particularly limited. For example, when the whole is 100 atomic%, Cu is preferably 20 to 90 atomic% and the balance is Nd.
《磁性体の製造方法》
本発明の希土類磁石の製造方法は主に付着工程と加熱工程とからなる。
（１）付着工程
付着工程は、Ｒ１−Ｆｅ−Ｂ非晶質体へ拡散材を付着させた付着非晶質体（図１Ａ参照）を得る工程である。ここでいう「付着」は、拡散元素が非晶質体内へ拡散し得る程度に、非晶質体と拡散材とが接触していれば足りる。従って、非晶質体と拡散材とは脱離可能でもよく、必ずしも溶着等している必要はない。もっとも、拡散材が非晶質体の少なくとも一面を被覆していると、効率的な拡散が可能となり好ましい。
<Method for manufacturing magnetic material>
The method for producing a rare earth magnet of the present invention mainly comprises an adhesion step and a heating step.
(1) Adhesion process An adhesion process is a process of obtaining the adhesion amorphous body (refer FIG. 1A) which made the diffusion material adhere to R1-Fe-B amorphous body. The “adhesion” here is sufficient if the amorphous body and the diffusing material are in contact with each other to such an extent that the diffusing element can diffuse into the amorphous body. Therefore, the amorphous body and the diffusing material may be detachable, and are not necessarily welded. However, it is preferable that the diffusing material covers at least one surface of the amorphous body because efficient diffusion is possible.
このような付着工程は、例えば、拡散材をターゲットとして非晶質体に対してスパッタリングすることでなされる。このとき、全体組成が所望組成となっていれば、ターゲット自体は、単種でも複数種でもよい。これにより、一般的に製造困難な組成の拡散材も非晶質体へ付着可能となる。なお、これらのことは本明細書で述べるスパッタリング全般についていえることである。
（２）加熱工程
加熱工程は、付着非晶質体を加熱して、Ｒ１２Ｆｅ１４Ｂの結晶粒からなる主相と結晶粒間に拡散元素を含む粒界相とを並行して生成させる工程である。これにより角丸形状の結晶粒が粒界相で被包されたナノ結晶集合体（図１Ｂ参照）が得られる。このときの加熱温度は、拡散材の液相温度（共晶点）以上であると好ましい。Ｎｄ−Ｆｅ−Ｂ系非晶質体にＮｄ−Ｃｕ系拡散材を付着させた付着非晶質体を加熱する場合なら、その加熱温度は５４０〜６８０℃さらには５６０〜６６０℃で加熱すると好ましい。
Such an adhesion process is performed, for example, by sputtering an amorphous body using a diffusion material as a target. At this time, if the overall composition is a desired composition, the target itself may be a single type or a plurality of types. Accordingly, a diffusion material having a composition that is generally difficult to manufacture can be attached to the amorphous body. These can be said for the general sputtering described in this specification.
(2) Heating step In the heating step, the attached amorphous body is heated to generate a main phase composed of R1 2 Fe 14 B crystal grains and a grain boundary phase containing a diffusing element between the crystal grains in parallel. It is a process. As a result, a nanocrystal aggregate (see FIG. 1B) in which rounded crystal grains are encapsulated in the grain boundary phase is obtained. The heating temperature at this time is preferably equal to or higher than the liquid phase temperature (eutectic point) of the diffusing material. In the case of heating the attached amorphous body in which the Nd—Fe—B based amorphous material is adhered to the Nd—Fe—B based amorphous body, the heating temperature is preferably 540 to 680 ° C., more preferably 560 to 660 ° C. .
（３）その他
加熱工程後に得られたナノ結晶集合体の酸化等を抑止するため、その表面に保護被膜（保護層）を設けると好適である。このような保護被膜の形成も前述したスパッタリングにより行える。そのターゲットには、Ｃｒ、Ａｇ、Ａｕ、Ｐｄ、Ｐｔ、Ｍｏ、Ｃｕ、Ｔｉ、Ｔａ、Ｒｕ、Ｖ、Ｈｆ、Ｗ、Ｉｒ、Ａｌ、Ｎｂなどの単体、合金または化合物などを用いることができる。このスパッタリングは通常、室温域で行えば足りる。
(3) Others In order to suppress oxidation and the like of the nanocrystal aggregate obtained after the heating step, it is preferable to provide a protective film (protective layer) on the surface. Such a protective film can also be formed by the sputtering described above. As the target, a simple substance such as Cr, Ag, Au, Pd, Pt, Mo, Cu, Ti, Ta, Ru, V, Hf, W, Ir, Al, and Nb, an alloy, a compound, or the like can be used. Usually, it is sufficient to perform this sputtering at room temperature.
《磁性体》
本発明の磁性体は、磁気ディスクなどの磁気記録媒体、電動機のロータまたはステータなどに用いることができる
<Magnetic material>
The magnetic material of the present invention can be used for a magnetic recording medium such as a magnetic disk, a rotor or a stator of an electric motor, or the like.
実施例を挙げて本発明をより具体的に説明する。
《試料の製造》
図２に示すような試料を表１に示すように種々製造した。
（１）基材および下地層
先ず、試料（磁性体）を形成する基材としてＭｇＯ単結晶基板（以下単に「基板」という。）を用意した。このＭｇＯ単結晶基板は、（００１）面が基板面になるように加工し、表面粗度を小さくするため研磨を行ったものである（フルウチ化学株式会社製、ＭｇＯ（１００）単結晶）。
The present invention will be described more specifically with reference to examples.
<Production of sample>
Various samples as shown in FIG. 2 were produced as shown in Table 1.
(1) Base Material and Underlayer First, an MgO single crystal substrate (hereinafter simply referred to as “substrate”) was prepared as a base material for forming a sample (magnetic material). This MgO single crystal substrate is processed so that the (001) plane becomes the substrate surface and polished to reduce the surface roughness (MgO (100) single crystal manufactured by Furuuchi Chemical Co., Ltd.).
この基板の（００１）面上にＭｏからなる平坦な下地層を形成した（下地層形成工程）。この下地層は、Ｍｏをスパッタリングにより積層した後、加熱処理して形成した。下地層の厚さは２０ｎｍとした。ちなみに、Ｍｏは、Ｎｄ２Ｆｅ１４Ｂ結晶配向面（ｃ面）と格子整合性の高いｂ.ｃ.ｃ.材料である。なお、本実施例では基板上にＭｏ下地層を直接形成したが、その形成前に基板上にＣｒからなるシード層（厚さ数ｎｍ程度）を形成しておいてもよい。 A flat underlayer made of Mo was formed on the (001) plane of this substrate (underlayer forming step). This underlayer was formed by laminating Mo by sputtering and then heat-treating it. The thickness of the underlayer was 20 nm. Incidentally, Mo is a bcc material having high lattice matching with the Nd 2 Fe 14 B crystal orientation plane (c plane). In this embodiment, the Mo underlayer is directly formed on the substrate, but a seed layer (thickness of about several nm) made of Cr may be formed on the substrate before the formation.
なお、本実施例で用いたスパッタリングは、マグネトロンスパッタ法に基づき、積層（成膜）前の到達真空度を１ｘ１０−８Ｐａ以下、製膜形状をφ８ｍｍとして行った。また、各層の厚さ（層厚）は、積層速度と積層時間の積から算出した。本実施例では、積層速度を０．４〜１Å／ｓとした。 Sputtering used in this example was performed based on a magnetron sputtering method with an ultimate vacuum before lamination (film formation) of 1 × 10 −8 Pa or less and a film forming shape of φ8 mm. The thickness of each layer (layer thickness) was calculated from the product of the lamination speed and the lamination time. In this example, the stacking speed was set to 0.4 to 1 cm / s.
（２）Ｎｄ−Ｆｅ−Ｂ層の形成（非晶質体形成工程）
上述のスパッタリングにより、基板を加熱しつつ下地層上にＮｄ−Ｆｅ−Ｂ層を形成した。基板の加熱温度は表１に示すように試料毎に変更した。ターゲットには、Ｎｄ、Ｆｅ、Ｆｅ８０Ｂ２０（単位：原子％）合金を用いた。こうして厚さ２０ｎｍのＮｄ−Ｆｅ−Ｂ層を形成した。
(2) Formation of Nd—Fe—B layer (amorphous body forming step)
By the above-described sputtering, an Nd—Fe—B layer was formed on the base layer while heating the substrate. The heating temperature of the substrate was changed for each sample as shown in Table 1. As a target, an Nd, Fe, Fe 80 B 20 (unit: atomic%) alloy was used. Thus, a 20 nm thick Nd—Fe—B layer was formed.
（３）Ｎｄ−Ｃｕ層の形成（付着工程）
Ｎｄ−Ｆｅ−Ｂ層を形成した基板を室温域まで冷却し、室温域で、Ｎｄ−Ｆｅ−Ｂ層上へＮｄ−Ｃｕ層（拡散層、拡散材）を上述したスパッタリングにより積層した。このときターゲットには、Ｎｄ３０Ｃｕ７０（原子％）の銅合金を用いた。Ｎｄ−Ｃｕ層の厚さは全試料とも１ｎｍとした。なお、比較のため、このＮｄ−Ｃｕ層の形成を行わない試料も並行して用意した。
(3) Formation of Nd—Cu layer (attachment process)
The substrate on which the Nd—Fe—B layer was formed was cooled to room temperature, and an Nd—Cu layer (diffusion layer, diffusion material) was laminated on the Nd—Fe—B layer at room temperature by sputtering as described above. At this time, a copper alloy of Nd 30 Cu 70 (atomic%) was used as a target. The thickness of the Nd—Cu layer was 1 nm for all samples. For comparison, a sample on which this Nd—Cu layer was not formed was also prepared in parallel.
（４）拡散結晶化（加熱工程）
Ｎｄ−Ｃｕ層の有る基板およびＮｄ−Ｃｕ層の無い基板を、表１に示す各温度で加熱した。この熱処理は、前述した１ｘ１０−８Ｐａ以下の真空雰囲気中で１時間行った。
(4) Diffusion crystallization (heating process)
A substrate with an Nd—Cu layer and a substrate without an Nd—Cu layer were heated at each temperature shown in Table 1. This heat treatment was performed for 1 hour in the aforementioned vacuum atmosphere of 1 × 10 −8 Pa or less.
（５）保護層の形成
この熱処理後、基板を室温域まで冷却し、室温域で、各試料の最表面に、ＣｒあるいはＭｏからなる保護層を上述したスパッタリングにより形成した。保護層の厚さは全試料とも１０ｎｍとした。こうして図２に示す積層体（Ｎｄ−Ｃｕ層が残存している場合）からなる試料が得られた。
(5) Formation of protective layer After this heat treatment, the substrate was cooled to room temperature, and a protective layer made of Cr or Mo was formed on the outermost surface of each sample in the room temperature by sputtering as described above. The thickness of the protective layer was 10 nm for all samples. Thus, a sample made of the laminate shown in FIG. 2 (when the Nd—Cu layer remained) was obtained.
《各試料の測定》
上述した各試料の保磁力を超伝導量子干渉型磁束計（ＳＱＵＩＤ）により測定した。その結果を表１に併せて記載した。なお、表１中に示した保磁力増加率は、上述したＮｄ−Ｃｕ層の無い試料の保磁力（Ｈ０）に対する、Ｎｄ−Ｃｕ層の有る試料の保磁力（Ｈ１）の比率（Ｈ１／Ｈ０）である。
<< Measurement of each sample >>
The coercivity of each sample described above was measured with a superconducting quantum interference magnetometer (SQUID). The results are also shown in Table 1. Incidentally, the coercive force increased rate shown in Table 1, the ratio of relative coercivity of sample without a Nd-Cu layer as described above (H 0), the coercive force of the sample having the Nd-Cu layer (H 1) (H 1 / H 0 ).
またＮｄ−Ｆｅ−Ｂ層が非晶質か結晶質かは、Ｘ線回折法およびＳＴＥＭ観察により判断した。
《試料の観察》
（１）Ｎｄ−Ｆｅ−Ｂ層（非晶質）にＮｄ−Ｃｕ層を積層した試料（試料Ｎｏ．Ａ３参照）と、Ｎｄ−Ｆｅ−Ｂ層（非晶質）にＮｄ−Ｃｕ層を積層しなかった試料（試料Ｎｏ．Ａ３参照）と、Ｎｄ−Ｆｅ−Ｂ層（結晶質）にＮｄ−Ｃｕ層を積層した試料（試料Ｎｏ．Ａ９参照）とについて、各積層断面を走査透過型電子顕微鏡（ＳＴＥＭ）で観察した。それらの画像をそれぞれ図３Ａ〜図３Ｃに示した。
（２）試料Ｎｏ．Ａ３（Ｎｄ−Ｃｕ層有り）の積層断面をＳＴＥＭで観察した画像を図４Ａに、また同試料をより広範囲でＳＴＥＭ観察した画像を図４Ｂに示した。なお、図４Ｂでは、Ｎｄ−Ｆｅ−Ｂ層中に観察された複数の結晶粒に、順次、粒子１〜８を付した。これら粒子１〜粒子８の最長幅を図４ＢのＳＴＥＭ像から読み取り、その結果を表２にまとめた。
（３）図４Ａに示した試料Ｎｏ．Ａ３の断面を、エネルギー分散型Ｘ線分光法（ＥＤＸ）により観察した。得られた各元素の分布像を図５Ａ〜図５Ｅにそれぞれ示した。
Whether the Nd-Fe-B layer is amorphous or crystalline was determined by X-ray diffraction and STEM observation.
<< Observation of sample >>
(1) A sample (see sample No. A3) in which an Nd—Cu—layer is laminated on an Nd—Fe—B layer (amorphous), and an Nd—Cu layer is laminated on an Nd—Fe—B layer (amorphous). For the sample (see sample No. A3) that was not performed and the sample (see sample No. A9) in which the Nd—Cu layer was laminated on the Nd—Fe—B layer (crystalline) (see sample No. A9) It observed with the microscope (STEM). The images are shown in FIGS. 3A to 3C, respectively.
(2) Sample No. FIG. 4A shows an image obtained by observing a laminated section of A3 (with an Nd—Cu layer) with a STEM, and FIG. 4B shows an image obtained by observing the sample in a wider range with a STEM. In FIG. 4B, particles 1 to 8 are sequentially attached to a plurality of crystal grains observed in the Nd—Fe—B layer. The longest widths of these particles 1 to 8 were read from the STEM image of FIG. 4B and the results are summarized in Table 2.
(3) Sample No. shown in FIG. The cross section of A3 was observed by energy dispersive X-ray spectroscopy (EDX). The obtained distribution images of each element are shown in FIGS. 5A to 5E.
《各試料の評価》
（１）結晶粒と粒界相
先ず図３Ａから明らかなように、非晶質のＮｄ−Ｆｅ−Ｂ層にＮｄ−Ｃｕ層を積層して加熱した試料では、角丸形状の微細な結晶粒（ナノサイズ結晶粒）と、それら結晶粒間に非常に薄い粒界相が同時に形成されていた。
<< Evaluation of each sample >>
(1) Crystal Grain and Grain Boundary Phase First, as apparent from FIG. 3A, in a sample heated by laminating an Nd—Cu—layer on an amorphous Nd—Fe—B layer, fine crystal grains with rounded corners are used. (Nano-sized crystal grains) and a very thin grain boundary phase were simultaneously formed between the crystal grains.
一方、図３Ｂからわかるように、Ｎｄ−Ｃｕ層を積層せずに非晶質のＮｄ−Ｆｅ−Ｂ層のみを加熱した試料では、そのような角丸形状の結晶粒は形成されず、粗大な結晶粒が副相と共に晶出した。さらに図３Ｃからわかるように、結晶質のＮｄ−Ｆｅ−Ｂ層へＮｄ−Ｃｕ層を積層して加熱した試料では、粒界相が形成されるものの、結晶粒は角張った比較的長大なものとなった。 On the other hand, as can be seen from FIG. 3B, in the sample in which only the amorphous Nd—Fe—B layer is heated without laminating the Nd—Cu layer, such rounded crystal grains are not formed. Crystal grains crystallized with the subphase. Furthermore, as can be seen from FIG. 3C, in the sample heated by laminating the Nd—Cu layer on the crystalline Nd—Fe—B layer, a grain boundary phase is formed, but the crystal grains are relatively long and angular. It became.
（２）結晶粒のサイズ
図４Ａ、図４Ｂおよび表２から、非晶質のＮｄ−Ｆｅ−Ｂ層とＮｄ−Ｃｕ層との積層体を加熱して得られた試料は、結晶粒の最長幅がいずれも５００ｎｍ以下、具体的には５０〜１５０ｎｍであり、相加平均すると約７５ｎｍ程度であった。また、それら結晶粒間にできた粒界相の最小幅はいずれも１ｎｍ以上さらには２ｎｍ以上あった。
(2) Size of Crystal Grain From FIGS. 4A, 4B and Table 2, the sample obtained by heating the laminate of the amorphous Nd—Fe—B layer and the Nd—Cu layer is the longest of the crystal grains. All of the widths were 500 nm or less, specifically 50 to 150 nm, and an arithmetic average was about 75 nm. In addition, the minimum width of the grain boundary phase formed between the crystal grains was 1 nm or more, further 2 nm or more.
（３）結晶粒および粒界相の構成元素
先ず、図５Ａおよび図５Ｂから明らかなように、Ｆｅは主に結晶粒中に存在し、粒界相中に殆ど存在していない。またＮｄは結晶粒中および粒界相中に存在している。次に、図５Ｃから明らかなように、Ｃｕは結晶粒および粒界相を含む広い領域に分布しているが、図５Ｄおよび図５Ｅから明らかなように下地層のＭｏおよび保護層のＣｒは、結晶粒や粒界相にほとんど存在していない。これらのことから、上述した結晶粒はＮｄ２Ｆｅ１４Ｂからなる結晶粒であり、粒界相はＮｄとＣｕの合金または化合物からなるといえる。
(3) Constituent Elements of Crystal Grain and Grain Boundary Phase First, as is apparent from FIGS. 5A and 5B, Fe is mainly present in the crystal grain and hardly present in the grain boundary phase. Nd exists in the crystal grains and the grain boundary phase. Next, as is clear from FIG. 5C, Cu is distributed over a wide region including the crystal grains and the grain boundary phase, but as is clear from FIGS. 5D and 5E, the Mo of the underlayer and the Cr of the protective layer are , Hardly exist in crystal grains and grain boundary phases. From these facts, it can be said that the crystal grains described above are crystal grains made of Nd 2 Fe 14 B, and the grain boundary phase is made of an alloy or compound of Nd and Cu.
（４）非晶質体の形成
先ず表１の試料Ｎｏ．Ａ１〜Ａ１２より、非晶質のＮｄ−Ｆｅ−Ｂ層は、基板の加熱温度をＮｄ−Ｆｅ−Ｂの共晶点（結晶化温度）より低い５９０℃以下で形成されることが解る。
(4) Formation of amorphous body First, sample No. From A1 to A12, it is understood that the amorphous Nd—Fe—B layer is formed at a heating temperature of the substrate at 590 ° C. or lower which is lower than the eutectic point (crystallization temperature) of Nd—Fe—B.
次に試料Ｎｏ．Ａ１〜Ａ６より、非晶質のＮｄ−Ｆｅ−Ｂ層上にＮｄ−Ｃｕ層を積層して加熱した試料は、いずれも保磁力が飛躍的に向上することがわかる。特に非晶質のＮｄ−Ｆｅ−Ｂ層の形成温度が低い程、保磁力増加率が大きくなった。もっとも、保磁力自体は、非晶質のＮｄ−Ｆｅ−Ｂ層の形成温度が３２５〜５９０℃、４５０〜５９０℃さらには５２５〜５９０℃のときに大きくなった。 Next, sample no. From A1 to A6, it can be seen that the coercive force of the samples heated by laminating the Nd—Cu layer on the amorphous Nd—Fe—B layer is dramatically improved. In particular, the lower the formation temperature of the amorphous Nd—Fe—B layer, the greater the coercivity increase rate. However, the coercive force itself increased when the amorphous Nd—Fe—B layer was formed at temperatures of 325 to 590 ° C., 450 to 590 ° C., and further 525 to 590 ° C.
（５）拡散・結晶化
表１の試料Ｎｏ．Ｂ１〜Ｂ９より明らかなように、非晶質のＮｄ−Ｆｅ−Ｂ層上にＮｄ−Ｃｕ層を積層した試料の加熱温度が５１０〜６８０℃さらには５４０〜６７０℃であると、保磁力増加率が大きくなることがわかる。また、その加熱温度をさらには５６０〜６６０℃とすると、保磁力自体も非常に大きくなることがわかる。
(5) Diffusion / crystallization Sample No. of Table 1 As apparent from B1 to B9, when the heating temperature of the sample in which the Nd—Cu layer is laminated on the amorphous Nd—Fe—B layer is 510 to 680 ° C., further 540 to 670 ° C., the coercive force is increased. It can be seen that the rate increases. It can also be seen that when the heating temperature is further 560 to 660 ° C., the coercive force itself becomes very large.
（６）総括
表１に示した各試料の結果から、３００〜５９０℃さらには３２５〜５９０℃で加熱しつつ形成した非晶質なＮｄ−Ｆｅ−Ｂ層上に、Ｎｄ−Ｃｕ層を積層した積層体を、さらに５４０〜６８０℃さらには５６０〜６６０℃で加熱することにより、Ｄｙ等の稀少元素を用いるまでもなく、３０ｋＯｅ前後の大きな保磁力を発現する磁性体が得られることがわかった。そして、このような磁性体は、角丸形状の結晶粒（主相）とそれを包囲する粒界相とにより構成されたナノサイズの結晶集合体からなることが明らかとなった。
(6) Summary From the results of each sample shown in Table 1, an Nd—Cu layer was laminated on an amorphous Nd—Fe—B layer formed while heating at 300 to 590 ° C., further 325 to 590 ° C. It is found that by heating the laminated body at 540 to 680 ° C., further at 560 to 660 ° C., a magnetic body that exhibits a large coercive force of about 30 kOe can be obtained without using rare elements such as Dy. It was. And it became clear that such a magnetic body consists of a nano-sized crystal | crystallization aggregate | assembly comprised by the round-corner-shaped crystal grain (main phase) and the grain-boundary phase surrounding it.
Claims (13)
前記結晶粒は、最長幅が５００ｎｍ以下の角丸形状をしており、
前記粒界相は、最小幅が１ｎｍ以上であることを特徴とする磁性体。 A main phase composed of crystal grains of a rare earth element (R1), iron (Fe), and boron (B) tetragonal intermetallic compound (R1 2 Fe 14 B), and a grain boundary phase formed between the crystal grains A magnetic material,
The crystal grains have a rounded corner shape with a maximum width of 500 nm or less,
The magnetic substance characterized in that the grain boundary phase has a minimum width of 1 nm or more.
前記粒界相の最小幅は、１５ｎｍ以下である請求項１に記載の磁性体。 The longest width of the crystalline is 20 nm or more,
The magnetic body according to claim 1, wherein a minimum width of the grain boundary phase is 15 nm or less.
該付着非晶質体を加熱して、Ｒ１２Ｆｅ１４Ｂの結晶粒からなる主相と該結晶粒間に形成され該拡散元素を含む粒界相とを並行して形成させる加熱工程とを備え、
請求項１〜７のいずれかに記載の磁性体が得られることを特徴とする磁性体の製造方法。 An attachment step of obtaining an attached amorphous body in which a diffusion material containing a diffusing element that can diffuse into the amorphous body composed of R1, Fe, and B is attached to the amorphous body;
Heating the adhering amorphous body to form a main phase composed of R1 2 Fe 14 B crystal grains and a grain boundary phase formed between the crystal grains and containing the diffusing element in parallel. Prepared,
A method for producing a magnetic body, wherein the magnetic body according to claim 1 is obtained.
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