JP2011061038A - Rare-earth magnet, method for manufacturing the same, and magnet composite member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a rare-earth magnet of highly coercive force. <P>SOLUTION: The method of manufacturing a rare-earth magnet has a sticking step for sticking a permeating material (Nd-Cu alloy) that can produce liquid phase onto a surface of a magnetic alloy containing a rare-earth element (R1) at a temperature lower than its eutectic point and a permeating step for heating after the sticking step to permeate and diffuse the permeating material into the grain boundary of the magnetic crystal grain of alloy. This will lead a rare-earth magnet to be obtained in which the crystal grain is encapsulated at least by a constituent element of the permeating material, thus enhancing the coercive force of the rare-earth magnet. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rare earth magnet having a high coercive force, a manufacturing method thereof, and a magnet composite member using the rare earth magnet.

  Rare earth magnets (particularly 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. However, when a rare earth magnet is put to practical use, it is required that the high magnetic properties of the rare earth magnet be stable in the long term even under severe conditions. From such a viewpoint, research and development for improving not only the residual magnetic flux density of the rare earth magnet but also its heat resistance and coercive force are actively conducted. The related description is disclosed in the following documents, for example.

JP 2008-235343 A JP 2008-263179 A JP 2009-43776 A JP 2009-43813 A JP 2009-54754 A

  In any of the above patent documents, in order to increase the coercive force of an R—Fe—B magnet composed of rare earth elements (R), iron (Fe), and boron (B), the constituent elements of the main phase (R—Fe -B) proposes thermal diffusion of elements other than rare earth elements such as Dy and Tb as well as non-rare earth elements such as Al and Si to the crystal grain boundaries of the main phase. However, such a thermal diffusion method cannot always sufficiently increase the coercive force of the rare earth magnet. In addition, the use of rare elements such as Dy is not preferable industrially because it involves supply concerns.

  The present invention has been made in view of such circumstances. That is, to provide a rare earth magnet having improved coercive force by improving the properties of the crystal grain interface of the magnetic alloy by a method different from the conventional method, a manufacturing method thereof, and a magnet composite member using the rare earth magnet. Objective.

  As a result of extensive research and trial and error, the present inventor has come up with a method of modifying the interface of crystal grains of a magnetic alloy, which is different from the conventional one. Succeeded in getting. By developing this result, the present invention described below has been completed.

《Rare earth magnet manufacturing method》
(1) That is, in the method for producing a rare earth magnet of the present invention, a liquid phase can be generated on the surface of a magnetic alloy containing a rare earth element (hereinafter referred to as “R1”) at a temperature lower than the eutectic point of the magnetic alloy. An adhering step for adhering the material, and an infiltration step for infiltrating and diffusing the infiltrating material into the grain boundary of the crystal grains of the magnetic alloy by heating after the adhering step, wherein the crystal grain is at least a constituent element of the infiltrating material. An encapsulated rare earth magnet is obtained.

(2) The production method of the present invention makes it possible to obtain a rare earth magnet having a greatly improved coercive force. The reason and mechanism for obtaining such an excellent rare earth magnet are not necessarily clear, but at present, it is considered as follows.
In the present invention, after the penetrating material is attached to the surface of the magnetic alloy in the attaching step, the penetrating material is infiltrated into the crystal grain boundary of the magnetic alloy by heating it in the infiltrating step. Thereby, the interface of the crystal grains of the magnetic alloy can be smoothly and evenly encapsulated by the penetrating material or its constituent elements. As a result, the interfacial properties of the crystal grains that greatly affect the coercive force are greatly improved, the interfacial energy state is made uniform or stabilized, the domain wall movement and the generation of reverse magnetic domains are suppressed, and the crystal grains or aggregates thereof are formed. It is thought that the coercive force of rare earth magnets has increased significantly.

(3) The heating temperature (penetration heating temperature) performed in the permeation process is not particularly limited, but the coercive force of the rare earth magnet is controlled while suppressing adverse effects on the magnetic properties such as the degree of orientation of the rare earth magnet and the residual magnetic flux density. It is within the range that can be increased. Specifically, the osmotic heating temperature is preferably lower than the eutectic point (eutectic temperature) of the magnetic alloy and is equal to or higher than the liquidus temperature at which the osmotic material generates a liquid phase.
Here, the eutectic point and the liquidus temperature vary depending on their constituent elements or compositions, and are not generally specified. For example, the ternary eutectic point of a typical Nd—Fe—B magnet is 665 ° C. If the rare-earth magnet has a magnetic phase mainly composed of two elements as a main phase, the binary eutectic point of the constituent two elements may be set as the eutectic point. Of course, when a modified element that improves magnetic properties such as cobalt (Co) or gallium (Ga) is included, the above eutectic point is a multi-element eutectic point including these elements.
The liquid phase temperature is a temperature at which the liquid phase appears from at least a part of the penetrating material. Therefore, at the above osmotic heating temperature, the osmotic material may be in a solid-liquid coexistence state. The liquidus temperature varies depending on the composition of the penetrant, but if the liquidus temperature is in the vicinity of the eutectic point of the penetrant, the penetrating step of the present invention can be performed at a lower temperature, which is efficient.

(4) The composition of the penetrant is not particularly limited in the present invention, but is preferably a composition that can obtain a relatively low liquidus temperature. Moreover, in order to encapsulate the crystal grain interface uniformly, it is preferable that the crystal grain of the magnetic alloy is made of an element excellent in wettability. Furthermore, if the constituent elements of the penetrating material encapsulating the crystal grains are solid-solved in the crystal grains of the magnetic alloy, the encapsulating becomes insufficient, or the magnetic properties of the rare earth magnet are deteriorated. Therefore, the constituent element of the penetrating material is preferably insoluble in the magnetic alloy.

(5) The form of the magnetic alloy or rare earth magnet in the present invention is not limited as long as it is composed of crystal grains. For example, it may be a single crystal grain, a powder particle, a film, or a bulk like a sintered body.

《Rare earth magnet》
(1) The present invention is grasped not only as the above-described manufacturing method but also as a high coercivity rare earth magnet obtained thereby.

(2) For example, the present invention provides a crystal grain comprising a magnetic alloy containing R1 and a penetrating material capable of producing a liquid phase at a temperature lower than the eutectic point of the magnetic alloy or at least a constituent element of the penetrating material. It may also be a rare earth magnet characterized by comprising a grain boundary portion encapsulating. Thus, the rare earth magnet composed of one crystal grain and the grain boundary portion enclosing the interface of the crystal grain is the minimum unit (basic unit) of the rare earth magnet in the present invention. In other words, other rare earth magnets can be grasped as an assembly of the minimum units. Incidentally, when the grain size of the crystal grains is 1 to 500 nm or the grain boundary width between the grain boundary part and the crystal grains is 1 to 10 nm, a rare earth magnet excellent in magnetic characteristics including coercive force is obtained, which is preferable.

《Magnet composite member》
(1) The present invention can also be grasped as a magnet composite member composed of the rare earth magnet and a base material to which the rare earth magnet is bonded.

(2) In order to obtain a magnet composite member having not only high coercive force but also very high orientation (anisotropy), the rare earth magnet includes a magnetic layer made of a magnetic alloy containing R1, and the magnetic layer. And a base layer having a crystal structure consistent with the oriented crystal plane of the magnetic layer and / or a protective layer that suppresses oxidation of the magnetic layer. . An example of such a rare earth magnet is a thin film magnet having a thickness of 1 to 200 nm.

<Others>
Unless otherwise specified, “x to y” in the present specification includes a lower limit value x and an upper limit value y. Moreover, the various lower limit value or upper limit value described in this specification can be arbitrarily combined to constitute a range such as “ab”. Furthermore, any numerical value included in the range described in the present specification can be used as an upper limit value or a lower limit value for setting the numerical value range.

It is sectional drawing which showed typically the rare earth magnet which concerns on this invention. It is the perspective sectional view showing typically the lamination magnet which is one of the rare earth magnets. It is a graph which shows the relationship between the coercive force of the laminated magnet, and the thickness of a magnetic layer. It is the photograph which observed the multilayer thin film magnet which is one of the rare earth magnets of this invention by energy dispersive X ray spectroscopy (EDX). (A) is an overall image, (b) is a Cr image, (c) is an Fe image, (d) is a Cu image, and (e) in FIG. It is a Mo image, and the same figure (f) is a Nd image.

  The present invention will be described in more detail with reference to embodiments of the invention. The contents described in this specification, including the following embodiments, are appropriately applied not only to the method for producing a rare earth magnet according to the present invention but also to the rare earth magnet and the magnet composite member. One or more configurations arbitrarily selected from the configurations listed below may be further added to the configuration described above to form the present invention. Any of the following configurations can be selected in a superimposed manner or arbitrarily across categories. For example, if it is the structure regarding a component composition, it is related not only to a thing but to a manufacturing method. In addition, a configuration related to a manufacturing method can be a configuration related to a product if understood as a product-by-process. Note that which embodiment is the best depends on the target, required performance, and the like.

《Magnetic alloy》
(1) The magnetic alloy according to the present invention is a binary or ternary or higher alloy containing a rare earth element (R1). This magnetic alloy includes so-called intermetallic compounds.
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 of the magnetic alloy of the present invention is preferably at least one of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb. In particular, from the viewpoint of cost and magnetic properties, it is practical that R1 is one or more of Pr, Nd, or Sm.

The binary magnetic alloys, for _example, SmCo-based alloy, such as SmCo _5, Sm 2 _{Co 17,} there is a PrCo alloy such as PrCo _5. A typical ternary magnetic alloy is an R1-Fe-B alloy such as Nd ₂ Fe ₁₄ B. However, not only the main phase composed of R1 ₂ Fe ₁₄ B but also the presence of the R1 rich phase can increase the coercivity of the rare earth magnet. Therefore, based on such various viewpoints, the R1-Fe-B-based magnetic alloy has 8 to 30% R1 and 4 to 20 when the whole is 100 atomic% (hereinafter simply expressed as%). % B and the remaining Fe are preferable. If either element is too small or excessive, it affects the volume fraction of the main phase R1 ₂ Fe ₁₄ B ₁ phase (2-14-1 phase), and a heterogeneous phase is generated, which may deteriorate the magnetic properties. The lower limit value or upper limit value of R1 can be arbitrarily selected and set within the above range, but in particular, when R1 is 9 to 15%, a rare earth magnet having high orientation and excellent magnetic properties is easily obtained. Further, the lower limit value or upper limit value of B can be arbitrarily selected and set within the above range. Particularly, when B is 8 to 16%, a fine structure is easily obtained, which is effective for improving the coercive force of the rare earth magnet. . Furthermore, Fe is basically the main balance, but if it is given, it is preferable that Fe is 69 to 82%, and the upper limit value or lower limit value of Fe can be arbitrarily selected and set within the range. However, the remaining Fe other than R1 and B may vary depending on the presence ratio of elements (modifying elements) and inevitable impurities effective in improving various characteristics of the rare earth magnet.

(2) The above-described modifying elements include cobalt (Co), lanthanum (La), gallium (Ga), niobium (Nb), which are effective in improving magnetic properties such as coercive force, which improve the heat resistance of rare earth magnets, Aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), germanium (Ge), zirconium (Zr), There is at least one of molybdenum (Mo), indium (In), tin (Sn), hafnium (Hf), tantalum (Ta), tungsten (W), and lead (Pb). The combination of the modifying elements is arbitrary. Moreover, the content is usually a very small amount, for example, preferably about 0.01 to 10%.
Inevitable impurities are impurities contained in the raw material, impurities mixed in at each step, and the like, and are elements that are difficult to remove due to cost or technical reasons. Examples of the inevitable impurities of the rare earth magnet according to the present invention include calcium (Ca), sodium (Na), potassium (K), oxygen (O), nitrogen (N), carbon (C), hydrogen (H), argon ( Ar) and the like. Note that the rare earth elements, the modifying elements, and the inevitable impurities described here are also appropriately applicable to the penetrating material and the sputtering raw material described later.

《Penetration material》
(1) The penetrant of the present invention is an alloy that can generate a liquid phase at a temperature (liquid phase temperature) lower than the eutectic point of the magnetic alloy described above. The composition of the penetrating material is not particularly limited. However, the permeation material penetrates into the crystal grain boundary of the magnetic alloy in the permeation process involving heat treatment, and at least the constituent elements of the permeation material encapsulate the crystal grains, thereby modifying the interfacial properties of the crystal grains, thereby rare earth magnets. It is necessary to improve the coercive force. From such a viewpoint, the material of the penetrating material of the present invention is selected.
First, the main constituent elements of the penetrant are Al, Mg, Cu, Ti, V, Cr, Ga, Y, Zr, Nb, Mo, Hf, Ta, W, silver (Ag), gold (Au), platinum ( There are (non-rare earth) metal elements such as Pt) or ruthenium (Ru). Further, the penetrating material may contain a nonmetallic element such as O, N, C or H as appropriate.

(2) Next, from the viewpoint of the permeability of the magnetic alloy to the crystal grain boundaries, the penetrating material is liable to be in a liquid phase at a relatively low temperature, and preferably has excellent wettability with respect to the crystal grain interface. It is.
The preferable liquidus temperature of the penetrating material depends on the composition of the magnetic alloy (that is, the eutectic point) and cannot be specified unconditionally. However, if the magnetic alloy is an R1-Fe-B magnet, the liquidus temperature is It is preferable in it being 350-625 degreeC. If the liquidus temperature is excessive, the magnetic alloy is liable to form a liquid phase, which is not preferable. If the liquidus temperature is too low, the heat resistance of the rare earth magnet tends to decrease, which is not preferable.
Examples of the (metal) simple substance that becomes a liquid phase at a relatively low temperature as described above include Al and Mg. Most elemental elements have a high melting point, and are difficult to form a liquid phase in the temperature range as described above. Therefore, it is preferable that the liquidus temperature can be lowered by combining two or more elements. Such multi-component penetrants need not be complete alloys or compounds from the beginning. That is, it may be alloyed at the stage of adhering on the surface of the magnetic alloy (magnetic layer) or during the permeation process.
As described above, the penetrating material of the present invention only needs to be capable of forming a liquid phase at a temperature lower than the eutectic point of the magnetic alloy, and does not necessarily have to exist as a material such as an ingot or a bulk.

(3) R2-Cu alloy (Nd-Cu alloy, Nd-Al alloy, Dy-Cu alloy, Dy-Al alloy, Pr-Cu alloy, Pr-Al alloy, Tb-Cu alloy as specific penetration material , Tb-Al alloy) and the like. Further, among those having excellent wettability, if the magnetic alloy is an R1-Fe-B alloy, there are an R2-Cu alloy and an R2-Al alloy. In particular, when both R1 and R2 are Nd, the eutectic point of the ternary alloy of Nd—Fe—B is 665 ° C., so the Nd—Cu alloy (eutectic point: 520 ° C.) is used as the penetrating material. Is preferred.
Here, Nd of the Nd—Cu alloy has an effect of increasing the coercive force of the Nd—Fe—B alloy. Cu has excellent wettability with respect to the magnet alloy and hardly dissolves in the magnet alloy. For this reason, Cu that has penetrated into the crystal grain boundary surely encapsulates the crystal grains of the magnetic alloy, and modifies the interface of the crystal grains without deteriorating its magnetic properties, thereby increasing its coercive force. In addition, Nd and Cu are metals that are stable and easy to procure, and are suitable for industrial use. Therefore, the Nd—Cu alloy is one of excellent penetrants that satisfy the above-described conditions.

  As long as such properties are exhibited, the composition of the Nd—Cu alloy is not particularly limited. However, the Nd—Cu alloy is preferably 10 to 95% of Cu and the balance of Nd when the whole is 100 atomic%. If the amount of Cu is too small, it is difficult to obtain the above effect with a small amount of Nd—Cu alloy. Further, if Cu is excessive, the liquidus temperature of the Nd—Cu alloy increases, which is not preferable. Cu in the Nd—Cu alloy is preferably 20 to 90%, more preferably 30 to 83%.

《Rare earth magnet manufacturing method》
The method for producing a rare earth magnet of the present invention mainly comprises an adhesion step and an infiltration step.
(1) Attachment process An adhesion process is a process of making the above-mentioned penetration material adhere to the surface of a magnetic alloy containing rare earth elements (R1). The form of the magnetic alloy at this time may be any of an ingot shape, a powder shape, a layer shape, a particle shape, and the like. Here, a case of manufacturing a layered (film-like) rare earth magnet will be described as an example.

  First, a prerequisite magnetic layer is formed on the surface of a substrate (magnetic layer forming step). This magnetic layer forming step can be easily formed by sputtering using a magnetic alloy as a target raw material. In addition, the material and form of the base material on which the magnetic layer is formed are not particularly limited. However, if a base material suitable for crystal growth of the magnetic layer is used, a magnetic alloy crystal is epitaxially grown and the crystal orientation is aligned in a specific direction (that is, oriented). A magnet (rare earth magnetic thin film) can be obtained. Incidentally, for epitaxial growth, it is preferable that the lattice constants of the crystal on the substrate side (including the underlayer described later) and the crystal of the magnetic layer are substantially equal, and the thermal expansion coefficients of both are closer. When the magnetic alloy is an R1-Fe-B alloy, examples of such a base material include a MgO single crystal base material made of a single crystal of magnesium oxide (MgO), a single crystal base material of W, Mo, Cu, and Si. is there. Here, when the direction perpendicular to the laminated surface of the base material is the direction of the easy axis of magnetization (c-axis) of the magnetic layer, the laminated surface is a (001) plane referred to as a Miller index.

  In addition, when the substrate itself does not have such a crystal structure, an underlayer having such a crystal structure may be formed on the surface of the substrate. Of course, it is more preferable that both the base material and the underlayer have such a crystal structure. In any case, it is preferable to form an underlayer having a crystal structure consistent with the oriented crystal plane of the magnetic layer on the surface of the base material before the magnetic layer formation step (underlayer formation step). Such an underlayer includes a seed layer and a buffer layer. The seed layer is a layer that promotes crystal growth of the buffer layer, and the buffer layer is a layer that serves as a foundation for promoting the formation of the magnetic layer. When the magnetic alloy is an R1-Fe-B alloy, Mo, Ta, W, Ti, Cr, V, Nb, and the like are suitable as the constituent material of the underlayer. In addition, it is preferable that a base layer formation process is a process of planarizing by heat processing, after forming a base material by sputtering, for example.

  In this way, a permeation layer made of a permeation material is formed on the magnetic layer formed on the substrate or the underlayer (permeation layer forming step). This permeation layer forming step can also be performed by the aforementioned sputtering. At this time, the target raw material may be single type or plural types. That is, the permeation layer forming step (attachment step) may be a sputtering step in which sputtering is performed using a single raw material composed of a permeation material or a plurality of raw materials whose combined total composition is the composition of the permeation material. Thereby, in general, it is possible to substantially use a penetrating material which is difficult to produce an alloy or a compound. Incidentally, this can be said for the general sputtering described in this specification.

  By the way, the layer thickness ratio (t2 / t1) of the thickness (t2) of the permeation layer to the thickness (t1) of the magnetic layer exceeds 0 (0%) and is 0 to 0.1 (0 to 10%). It is preferable that it is in the range. The lower limit side of the layer thickness ratio is preferably 0.01 (1%) or more, 0.015 (1.5%) or more, further 0.02 (2%) or more. When the layer thickness ratio is too small, the penetrating material is insufficient with respect to the magnetic layer, and the crystal grains of the magnetic layer cannot be sufficiently encapsulated with the penetrating material. Conversely, if the layer thickness ratio is excessive, the volume fraction of the magnetic layer decreases, which is not preferable.

(2) Penetration process The penetration process is a process in which the penetration material attached to the surface of the magnetic alloy in the adhesion step is heated to penetrate and diffuse the penetration material into the grain boundaries of the magnetic alloy. As a result, a rare earth magnet in which crystal grains of the magnetic alloy are encapsulated with at least the constituent element of the penetrating material is obtained, and the coercive force of the rare earth magnet can be increased. As described above, the heating temperature at this time is preferably lower than the eutectic point of the rare earth magnet and higher than or equal to the liquidus temperature (eutectic point) of the penetrating material. In addition, the crystal grains of the magnetic alloy may be encapsulated by the entire penetrating material or only by some constituent elements.

By the way, it is preferable to provide a protective film on the surface of the magnetic alloy after the permeation step to prevent oxidation or the like. In particular, the protective coating is effective when the magnetic alloy is easily oxidized like the R1-Fe-B magnetic alloy.
If the rare earth magnet is a laminated magnet as described above, it is preferable that the manufacturing method of the present invention further includes a protective layer forming step for forming a protective layer for suppressing oxidation of the magnetic layer after the permeation step. Such a protective layer can also be formed by the aforementioned sputtering. As the target, a simple substance such as Cr, Ag, Au, Pd, Pt, Mo, Cu, Ti, Ta, Ru, V, Hf, W, and Ir, an alloy, a compound, or the like can be used. Usually, it is sufficient to perform this sputtering at room temperature.

《Rare earth magnet》
The rare earth magnet of the present invention encapsulates crystal grains by crystal grains made of a magnetic alloy containing R1 and a penetrating material capable of producing a liquid phase at a temperature lower than the eutectic point of the magnetic alloy or at least constituent elements of the penetrating material. (See FIG. 1).

  The form of the rare earth magnet of the present invention is not limited as long as one crystal grain and the grain boundary portion surrounding the crystal grain are the basic unit (minimum unit). That is, the basic unit is also the rare earth magnet of the present invention, and the rare earth magnet of the present invention such as particles or ingots in which the basic units are aggregated, powders in which the particles are aggregated, and sintered bodies obtained by sintering the powders. It is. It is preferable that the crystal grains have a grain size of 1 to 500 nm because a rare earth magnet having very excellent magnetic properties can be obtained.

  The rare earth magnet of the present invention may be in the form of a layer or a thin film. That is, the rare earth magnet of the present invention may be a laminated magnet composed of a magnetic layer made of a magnetic alloy containing R1 formed on a substrate and a permeation layer formed on the surface thereof. The laminated magnet further includes an underlayer formed between the magnetic layer and the base material and having a crystal structure consistent with the oriented crystal plane of the magnetic layer, and a protective layer that suppresses oxidation of the magnetic layer. Is preferred. The rare earth magnet of the present invention may be a thin film magnet having a thickness of 1 to 200 nm, further 5 to 100 nm, of the rare earth magnet excluding the base material. Such a thin film magnet has a high orientation, a high residual magnetic flux density, a high coercive force, and an excellent magnetic property.

《Magnet composite member》
Examples of the magnet composite member using the rare earth magnet of the present invention include a magnetic case, a magnetic recording medium such as a magnetic disk, and a rotor or stator of an electric motor.

The present invention will be described more specifically with reference to examples.
<Production of sample>
Various samples (magnet composite member, laminated magnet) as shown in FIG. 2 were produced as follows.
(1) Underlayer Formation Step An MgO single crystal substrate (hereinafter simply referred to as “substrate”) was prepared as a base material for bonding laminated magnets. 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.).

A flat seed layer (first underlayer) made of Cr and a flat buffer layer (second underlayer) made of Mo were formed on the (001) plane of this substrate (underlayer forming step). Mo in the buffer layer is a bc.c. material having high lattice matching with the crystal orientation plane (c-plane) of the Nd ₂ Fe ₁₄ B phase (unit: atomic%, the same applies hereinafter). In order to control the Mo crystal growth and form a smooth and good quality buffer layer, a seed layer made of Cr was provided. All of these underlayers were formed by laminating each underlayer by sputtering and then heat-treating. The seed layer thickness was 1 nm, and the buffer layer thickness was 20 nm.

Sputtering 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 formation shape of φ8 mm. Moreover, the thickness (layer thickness) of each layer of each sample was calculated from the product of the stacking speed and the stacking time. Incidentally, the laminating speed was set to 0.4 to 1 kg / s in this example.

(2) Magnetic layer formation process The magnetic layer was formed on the buffer layer of the heated board | substrate by the above-mentioned sputtering (magnetic layer formation process). Nd (R1), Fe, and Fe-20 at% B alloy were used as targets. Sputtering was performed on a substrate heated to 625 ° C. to form a magnetic layer having a thickness of 30 nm.

(3) Penetration layer formation process (attachment process)
The substrate on which the magnetic layer was formed was cooled, and the above-described sputtering was performed at room temperature to form a permeation layer on the magnetic layer (permeation layer formation step, sputtering step). As the target at this time, two kinds of raw materials, Nd (R2) raw material and Cu raw material, were used. And said sputtering was performed so that the whole composition of a osmosis | permeation layer might become the composition (Cu density | concentration: atomic%) shown in Table 1. FIG. In this way, a permeation layer made of Nd—Cu alloys (penetration materials) of various compositions was laminated on the magnetic layer. The thickness of each penetration layer is as shown in Table 1.

  In addition, sample No. in Table 1 A1 to A3 are cases where the permeation layer was not laminated. A4 is the case where only Nd is laminated on the magnetic layer. Sample No. As A2, 30 nm of a magnetic layer containing Cu corresponding to 0.5 nm was formed.

(4) Penetration process The heat treatment which heats the various board | substrates in which the osmosis | permeation layer was formed to each temperature shown in Table 1 was given. This heat treatment was performed for 60 minutes in the above-described vacuum atmosphere of 1 × 10 ⁻⁸ Pa or less. However, sample No. About A1 and A2, the osmosis | permeation process is not performed.

(5) Protective layer formation process The board | substrate after the infiltration process was cooled, and the above-mentioned sputtering was performed in the room temperature range, and the protective layer which consists of Cr was formed in the outermost surface. All the protective layers had a thickness of 10 nm.

(6) Furthermore, sample no. A3 and Sample No. Other samples in which the thickness of the magnetic layer of C1 was variously changed between 8 and 100 nm were also manufactured (see FIG. 3).

<< 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.
As an example, sample no. 4A to 4F show images obtained by observing the laminated cross section of C1 by energy dispersive X-ray spectroscopy (EDX) using a transmission electron microscope (TEM).

<< Evaluation of each sample >>
(1) Sample No. A1 to A4
As can be seen from Table 1, sample no. In the case of A1 and A3, the coercive force is as low as about 12 to 13 kOe (9.5 to 10.3 × 10 ⁵ A / m) regardless of the presence or absence of heat treatment.
In contrast to these, sample Nos. 1 and 2 were subjected to heat treatment by providing an Nd layer on the magnetic layer. In the case of A4, the coercive force is slightly improved. In addition, Cu was mixed in the magnetic layer and sample No. In the case of A2, the coercive force is further improved. The reason why the coercive force is increased in this way is thought to be that Nd and Cu are introduced into the crystal grain boundary of the Nd—Fe—B alloy and the interfacial properties of the crystal grains are improved. However, the amount of increase in their coercive force is slight.

(2) Sample No. B1 to B5 are obtained by variously changing the heating temperature in the infiltration step performed after the formation of the infiltration layer made of the Nd-64% Cu alloy (infiltration material). From Table 1, sample No. whose heating temperature is 400-600 degreeC is shown. It can be seen that the coercive force is greatly improved in B2 to B4. Especially sample No. whose heating temperature is 500-600 degreeC. B3 and B4 have significantly improved coercive force. The reason for this is considered to be that the above-described penetrating material became a liquid phase in the temperature range and sufficiently penetrated into the crystal grain boundary of the penetrating material. Therefore, it can be said that the heating temperature in the infiltration step is preferable in the range of 350 to 625 ° C.
The ternary eutectic point of the magnetic alloy constituting the magnetic layer is 665 ° C., and the eutectic point of the Nd—Cu alloy constituting the permeation layer is 520 ° C.

(3) Sample No. C1 to C4 are obtained by variously changing the thickness of the permeation layer made of an Nd-64% Cu alloy (penetration material) formed on the magnetic layer. The heating temperature in the infiltration process was uniformly 400 ° C.
As can be seen from Table 1, the coercive force does not change much even if the thickness of the permeation layer changes. However, sample no. From C2 and C3, it is considered that a higher coercive force can be obtained when the thickness of the permeation layer is in the range of 0.6 to 2 nm.

(4) Sample No. D1 to D6 are obtained by variously changing the composition ratio of the Nd—Cu alloy (penetrating material) constituting the osmotic layer. The heating temperature in the infiltration process was uniformly 500 ° C.
From Table 1, it became clear that high coercive force is maintained in any case even if the Cu concentration of the permeation layer varies in a wide range. In particular, sample no. As can be seen from D2 to D5, it can be said that a higher coercive force can be obtained in a Cu concentration range of 20 to 90 at%.

(5) In addition, the above-mentioned sample No. A3 (no penetration layer) or sample no. A plurality of samples were prepared in which only the thickness of the magnetic layer C1 (with a permeation layer) was changed. The results of measuring the coercivity of these samples are summarized in the graph of FIG.
From this result, it can be seen that the coercive force is improved as a whole by performing the heat treatment by providing the permeation layer according to the present invention regardless of the thickness of the magnetic layer.
In particular, it was found that the sample having a magnetic layer thickness of 10 nm (the thickness ratio of the osmotic layer to the magnetic layer is 5%) has a remarkably high coercive force of about 26 kOe. Therefore, when the magnetic layer is relatively thin and the ratio of the thickness of the permeation layer to the magnetic layer is around 5%, the interface of the crystal grains of the magnetic alloy is smoothly encapsulated by Cu or Nd, and the coercive force Was found to be significantly increased.

(6) This is because the sample No. shown in FIG. It is also clear from the EDX photographic image for C1. That is, from FIG. 4D and FIG. 4F, it was confirmed that the interface of the crystal grains constituting the magnetic layer was almost uniformly encapsulated with Cu and Nd. Moreover, it became clear from FIG. 4 that the grain boundary width formed between the grains is 1 to 10 nm. Moreover, it became clear from FIG.4 (d) that Cu hardly dissolves in the inside of the crystal grain. Further, from FIGS. 4B, 4C, and 4E, it was confirmed that Cr, Fe, and Mo constituting the layers other than the permeation layer were hardly present at the grain boundaries of the crystal grains.

Claims (17)

An adhesion step of adhering a penetrating material capable of generating a liquid phase at a temperature lower than the eutectic point of the magnetic alloy to the surface of the magnetic alloy containing a rare earth element (hereinafter referred to as “R1”);
Including a permeation step of heating and diffusing the permeation material into the grain boundaries of the magnetic alloy by heating after the adhesion step,
A method for producing a rare earth magnet, characterized in that a rare earth magnet in which the crystal grains are encapsulated with at least a constituent element of the penetrating material is obtained.   2. The method for producing a rare earth magnet according to claim 1, wherein the attaching step is a sputtering step in which a single raw material made of the penetrating material or a plurality of raw materials whose combined total composition becomes the composition of the penetrating material is sputtered as a target. .   The said magnetic alloy consists of 8-30 atomic% R1, 4-20 atomic% boron (B), and the balance iron (Fe) when the whole is 100 atomic%. Method for producing rare earth magnets.   The method for producing a rare earth magnet according to claim 1, wherein the permeation material is a copper (Cu) alloy.   The method for producing a rare earth magnet according to claim 4, wherein the copper alloy is an R2-Cu alloy made of an alloy of Cu and a rare earth element (hereinafter referred to as "R2").   6. The method for producing a rare earth magnet according to claim 5, wherein R1 and R2 are neodymium (Nd).   The method for producing a rare earth magnet according to any one of claims 3 to 6, wherein a heating temperature in the infiltration step is 350 to 625 ° C. And a magnetic layer forming step of forming a magnetic layer made of the magnetic alloy on the surface of the substrate,
The method for producing a rare earth magnet according to claim 1, wherein the attaching step is a penetrating layer forming step of forming a penetrating layer made of the penetrating material on the magnetic layer.   The method for producing a rare earth magnet according to claim 8, wherein a layer thickness ratio (t2 / t1) of the thickness (t2) of the permeation layer to the thickness (t1) of the magnetic layer is 0.1 or less.   Furthermore, before the said magnetic layer formation process, the base layer formation process of forming the base layer which has a crystal structure consistent with the orientation crystal plane of the said magnetic layer on the surface of the said base material is provided. Method for producing rare earth magnets.   Furthermore, the manufacturing method of the rare earth magnet in any one of Claims 8-10 provided with the protective layer formation process which forms the protective layer which suppresses the oxidation of the said magnetic layer after the said penetration | infiltration process.   A rare earth magnet obtained by the production method according to claim 1.   A crystal grain made of a magnetic alloy containing R1, and a penetrating material capable of producing a liquid phase at a temperature lower than the eutectic point of the magnetic alloy, or a grain boundary portion encapsulating the crystal grain with at least a constituent element of the penetrating material; A rare earth magnet comprising a grain boundary portion having a width of 1 to 10 nm.   The rare earth magnet according to claim 13, wherein the crystal grains have a particle diameter of 1 to 500 nm.   A magnet composite member comprising: a base material; and the rare earth magnet according to claim 12 bonded to the base material.   The rare earth magnet includes a magnetic layer made of a magnetic alloy containing R1, an underlayer formed between the magnetic layer and the base material and having a crystal structure consistent with an orientation crystal plane of the magnetic layer, and the magnetic layer The magnet composite member according to claim 15, which is a laminated magnet having a protective layer that suppresses oxidation of the layer.   The magnet composite member according to claim 15 or 16, wherein the rare earth magnet is a thin film magnet having a thickness of 1 to 200 nm.