JP2012190893A - Magnetic substance and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic substance which can be used for a magnet having a good magnetic characteristic, and a method for manufacturing the same.SOLUTION: The magnetic substance 4 substantially consists of magnetic phases 13 and an inorganic phase 12 interposed between the magnetic phases 13 so as not to generate magnetic interaction between them. The magnetic phase 13 contains more than 80 vol% of α"FeNphase. For example, the inorganic phase 12 consists of CrCo component. Powder consisting of FeCrCo system alloy as a raw material is molded in order to prepare a powder molding part 2, the powder molding part 2 is subjected to a heat treatment to separate into a Fe phase 11 and the inorganic phase 12 mainly containing CrCo component. A phase separation processing member 3 is subjected to a heat treatment under a pressurized state in a nitrogen gas atmosphere in order to nitride Fe in the Fe phase 11, generate a α"FeNphase and obtain the magnetic substance 4. The magnetic substance 4 has good magnetic characteristic, because a main component of the magnetic phase is a α"FeNphase having good magnetic characteristic, and the usage of Co can be reduced because the content of Co is less than 10 atom%.

Description

  The present invention relates to a magnetic body that can be suitably used for a permanent magnet, and a method for manufacturing the same. In particular, the present invention relates to a magnetic material suitable for use in a magnet having excellent magnetic properties.

  As permanent magnets used in motors and generators, metal magnets made of metal materials such as Al-Ni-Co-Fe alloys and Fe-Cr-Co alloys, typically called alnico magnets In addition, a Fe—Cr—Co magnet described in Patent Document 1 and a ferrite magnet made of ferrite containing iron oxide as a main component are widely used. Further, rare earth magnets containing rare earth elements such as Nd (neodymium) and Sm (samarium) are used as permanent magnets that are particularly excellent in magnetic properties.

  A metal-based magnet such as an Fe-Cr-Co-based magnet is typically manufactured by subjecting a cast material to heat treatment for phase separation (Patent Document 1 specification, page 2, lower left column, lines 6 to 12). See line). A typical manufacturing process is shown in FIG. A molten alloy such as an Fe—Cr—Co alloy is prepared and cast, and the resulting ingot 100 is heat treated. By this heat treatment, two-phase separation (spinodal decomposition) of the magnetic phase 130 mainly composed of a ferromagnetic material such as FeCo phase and the inorganic phase 120 mainly composed of a weak magnetic material (or non-magnetic material) such as CrCo phase is performed. A magnet 400 is obtained. The inorganic phase 120 is interposed so that no magnetic interaction occurs between the adjacent magnetic phases 130. Typically, the heat treatment includes solution treatment → magnetic field application treatment (including treatment at a predetermined temperature in the cooling step from solution treatment) → aging treatment. By applying a magnetic field, the magnetic phase 130 is formed into a long and narrow single-domain particle having a large shape anisotropy, more specifically, a nano-order having a width of several nm to several tens of nm, and a length of A nano-sized shape with a very large aspect ratio, such as a micro-order of about a dozen μm. By having such an elongated rod-like magnetic phase 130, the metal magnet exhibits a high coercive force and is excellent in magnetic properties.

JP-A-53-094216

  Although rare earth magnets are excellent in magnetic properties, the magnetic properties vary greatly with temperature. In recent years, the use of rare earth elements has been desired to be reduced in consideration of inferior resource procurement stability and unstable price fluctuations.

  Ferrite magnets have much lower magnetic properties than rare earth magnets and cannot be used for high performance applications.

  On the other hand, metal magnets such as alnico magnets and Fe—Cr—Co magnets are superior in magnetic properties to ferrite magnets and very stable in temperature. In particular, Fe-Cr-Co magnets have the same magnetic characteristics as alnico magnets and are excellent in plastic workability and cutting workability, and thus have a high degree of freedom in shape. However, since metal magnets are inferior in cost performance compared to rare earth magnets and ferrite magnets, efforts have not been made to improve performance since the advent of rare earth magnets. In order to improve the performance of the metal-based magnet, it is important how the saturation magnetization of the nano-sized magnetic phase 130 can be increased.

  For example, when the magnetic phase is an Fe phase, the saturation magnetization of Fe is about 2T, and the saturation magnetization of the nano-sized FeCo described above is lower than about 2.3T to 2.4T, further improving the saturation magnetization of the magnetic phase. Is desired. Further, when the magnetic phase is an Fe phase, spinodal decomposition is relatively difficult to occur, and the separability between the magnetic phase and the inorganic phase is relatively low. Therefore, conventional metal magnets generally contain 20 atomic% or more of Co in order to make the FeCo phase exist. However, since Co is also desired to be reduced in recent years, it is desired to develop a material having a lower Co content and further excellent magnetic properties.

  Then, one of the objectives of this invention is providing the magnetic body from which the magnet excellent in a magnetic characteristic is obtained. Another object of the present invention is to provide a method for producing the magnetic material.

The present inventor has studied the composition of the magnetic phase in order to improve the magnetic characteristics and to make a metal-based magnet made of a material with less Co. As described above, Fe has a low saturation magnetization and is inferior in magnetic properties. On the other hand, among the iron nitrides, α ”Fe ₁₆ N ₂ (tetragonal, a = 5.72Å, c = 6.29Å, crystal symbol: I4 / mmm), which is a nitrogen intrusion type iron nitride, has a saturation magnetization of 2.8. It has been proved by the principle calculation and the experiment with a thin film that the T grade and the magnetic property are very excellent.Therefore, a method of manufacturing a magnetic material having the α ″ Fe ₁₆ N ₂ phase as a main component of the magnetic phase is examined. As a result, an iron alloy with less Co was prepared, and after a nano-order Fe phase appeared by phase-separation heat treatment, nitriding was performed under specific conditions to nitride Fe, so that α ”Fe ₁₆ N ₂ phase The present inventors have obtained the knowledge that a magnetic material having a magnetic phase mainly composed of can be obtained.The present invention is based on the above knowledge.

The magnetic body of the present invention is substantially composed of a magnetic phase mainly composed of iron nitride and an inorganic phase interposed so that no magnetic interaction occurs between the magnetic phases, and the Co content is 5 atoms. % And less than 10 atomic%, and the magnetic phase contains 80% by volume or more of α ″ Fe ₁₆ N ₂ phase.

The said magnetic body of this invention can be manufactured with the following manufacturing methods of the magnetic body of this invention, for example. The method for producing a magnetic body of the present invention is substantially composed of a magnetic phase containing Fe element by heat treatment of an iron alloy and an inorganic phase interposed so that no magnetic interaction occurs between the magnetic phases. This method relates to a method of manufacturing a magnetic body, and includes the following preparation step, separation step, and nitriding step.
Preparation step: A step of preparing a material made of an iron alloy containing Fe at 75 atomic% or more, containing a metal element other than Fe, and containing Co at 5 atomic% or more and less than 10 atomic%.
Separation step: a step of subjecting the material to a phase separation heat treatment to separate it into an Fe phase and an inorganic phase composed of an inorganic material containing the metal element and interposed between the Fe phases.
Nitriding step: The phase separation material obtained in the separation step is subjected to a nitriding heat treatment under the following conditions to nitride the Fe in the Fe phase to form an α ″ Fe ₁₆ N ₂ phase, and in the magnetic phase A step of producing a magnetic material having an α ″ Fe ₁₆ N ₂ phase content of 80% by volume or more.
Nitriding heat treatment condition: Pressurized state exceeding atmospheric pressure. And it heats at the temperature of 200 degreeC or more and 400 degrees C or less in nitrogen element containing gas atmosphere.

When nitriding in a non-pressurized state such as under atmospheric pressure after separating the Fe phase from the iron alloy, the temperature during the heat treatment needs to be relatively high in order to increase the reactivity of nitrogen. Then, it is not a tetragonal iron nitride in which N atoms intrude into the c-axis direction Fe lattice with directionality, but a cubic crystal or hexagon formed when N atoms enter between Fe lattices in multiple directions. Crystalline iron nitride: Fe ₄ N and Fe ₃ N are produced. The cubic and hexagonal iron nitrides are inferior in magnetic properties to those of Fe alone. On the other hand, the detailed mechanism is not clear, but when nitriding in a pressurized state as described above, the lattice of Fe in a specific direction in the phase separation treatment material is distorted to form a nitrogen intrusion path, and Fe even at a low temperature region in which the N atom hardly penetrate between lattices, N atoms is in alpha easily incorporated into Fe lattices "easily Fe ₁₆ N ₂ is formed, is considered. also, alpha" Fe ₁₆ It is considered that N ₂ is easily formed, and as a result, formation of Fe ₄ N and the like is suppressed, and α ″ Fe ₁₆ N ₂ can be sufficiently formed.

In the production method of the present invention, a magnetic material (typically, the magnetic material of the present invention) in which the main component (80% by volume or more) of the magnetic phase is an α ″ Fe ₁₆ N ₂ phase is obtained. Is an α ″ Fe ₁₆ N ₂ phase, the magnetic material of the present invention is 1.4 times more saturated than the case where the main component of the magnetic phase is the Fe phase, and 1.2 times more saturated than the case where it is the FeCo phase. Magnetization is large. Therefore, the magnetic body of the present invention is superior in magnetic properties compared to conventional metal magnets in which the magnetic phase is Fe phase or the magnetic phase is FeCo phase. In addition, according to the magnetic body of the present invention, since the main component of the magnetic phase is the α ″ Fe ₁₆ N ₂ phase, since the FeCo phase is not substantially generated, the amount of Co used can be reduced. Conventional FeCrCo In the system magnet, the Co content is about 10 atomic% to 30 atomic%, and many commercially available products have a content of 20 atomic% or more, whereas in the magnetic material of the present invention, the Co content is 5%. At least less than 10% by mass and less Co than conventional FeCrCo-based magnets As described above, the magnetic material of the present invention exhibits magnetic properties without using a large amount of rare metals such as rare earth elements and Co. In addition, the production method of the present invention uses a metal material as a starting material, and typically produces a magnetic material by a powder metallurgy method, so that an arbitrary shape can be obtained. The magnetic material can be easily manufactured, and the productivity of the magnetic material is excellent.

  As one form of the magnetic body of the present invention, there is a form in which the inorganic phase contains 80% by volume or more of a CrCo component mainly composed of CrCo (80 atomic% or more).

  A typical example of the metal species constituting the magnetic body of the present invention is FeCrCo-based alloy (Co: 5 atomic% or more and less than 10 atomic%). When the constituent metal of the magnetic body of the present invention is an FeCrCo-based alloy, the inorganic phase is mainly composed of CrCo, and its content is high and there are few impurities, so that it is possible to suppress the magnetic phases from exerting magnetic interactions with each other. . In addition, when the constituent metal is composed of an FeCrCo-based alloy, the inorganic phase containing CrCo as the main phase is excellent in plastic workability and cutting workability. Easy to get.

  As one form of the magnetic body of the present invention, a form in which the distance between the magnetic phases is 5 nm or more is mentioned.

  In the present invention, a state where “the magnetic interaction (magnetic exchange interaction) does not occur between the magnetic phases” typically means that the magnetic phases are separated from each other to some extent. In the above configuration, since a distance at which no magnetic interaction occurs between the magnetic phases is secured, for example, a high coercive force due to a large aspect ratio of the magnetic phase is prevented from being reduced or lost due to the magnetic interaction. it can. Therefore, the said form can fully utilize the magnetic characteristic of the said magnetic phase.

  As one form of the magnetic body of the present invention, a form in which the width of the magnetic phase is 100 nm or less can be mentioned.

  The metal-based magnet described above has excellent magnetic properties when the width of the magnetic phase is extremely fine (thin), such as nano-order. Therefore, the said form is excellent in a magnetic characteristic.

  As one form of the production method of the present invention, the iron alloy is an FeCrCo-based alloy, and in the separation step, after the material is heated to 1000 ° C. or higher, the temperature lowering rate in the cooling step to 550 ° C. is 5.0 ° C./sec or higher. In the temperature range of 550 ° C. to 450 ° C., the temperature drop rate in the phase separation temperature range of the material is 0.05 ° C./sec or more and 5 ° C./sec or less.

  A preferable range of the phase separation temperature range and the temperature decrease rate is determined by the composition of the material. The above-mentioned form made of a FeCrCo-based alloy rapidly cools a specific temperature range as described above, and performs a good separation between the Fe phase and the CrCo phase by controlling the temperature drop rate even in the phase separation temperature range. Can do.

  As one form of this invention manufacturing method, the form which makes the said raw material prepared at the said preparatory process the powder compact which shape | molded the powder which consists of the said iron alloy is mentioned.

In the powder molded body, there are grain boundaries of each particle constituting the raw material powder, and this grain boundary may exist after the separation step. Then, by pressurizing this grain boundary to form a fine gap, and using this gap as a nitrogen ingress path in the nitriding step, even if the magnetic body to be produced is large, that is, the powder compact is Even if it is large, the molded body can generate the α ″ Fe ₁₆ N ₂ phase satisfactorily over the entire region from the surface layer to the inside, and the proportion of the α ″ Fe ₁₆ N ₂ phase is high, and It is easy to obtain a magnetic body in which the α ”Fe ₁₆ N ₂ phase is present without any unevenness. In addition, since the relative density of the powder compact can be easily adjusted, the above form is obtained after the separation process or the nitriding process. The material with the desired relative density can be easily prepared according to the relative density of the phase separation material and magnetic material to be processed, and the powder compact can be easily formed without special processing even in complex three-dimensional shapes. In particular, FeCrCo alloy is excellent in plastic workability as described above, Therefore, the above-mentioned form is (1) a magnetic material having excellent magnetic properties can be obtained, (2) the yield of raw materials is high, (3) the degree of freedom of shape is high, and (4) relative to the magnetic material. It has an excellent effect that the density can be easily adjusted, and the relative density means an actual density (percentage) with respect to the true density.

  As one form of the manufacturing method of the present invention, when the above-described powder molded body is used as a raw material, the preparation step includes preparing the raw material so that the relative density of the phase separation material is 94% or less. Can be mentioned.

If the relative density of the phase separation treatment material is 94% or less, sufficient open pores can be secured, so that the above-described nitrogen ingress path can be secured sufficiently in the nitriding process, and an α ″ Fe ₁₆ N ₂ phase is generated. Therefore, the above embodiment can efficiently produce a magnetic material having a high proportion of the α ″ Fe ₁₆ N ₂ phase, and a magnetic material having excellent magnetic properties can be obtained. In this embodiment, the relative density of the powder compact may be adjusted so that the relative density of the phase separation material is 94% or less. It should be noted that the relative density of the powder compact and the relative density of the phase separation treatment material change slightly during the phase separation treatment and tend to be substantially the same.

  As one mode of the production method of the present invention, a mode in which the pressure in the nitriding step is 70 MPa or more and 300 MPa or less can be mentioned.

In the above-described embodiment, by pressurizing in the range of 70 MPa to 300 MPa, the phase separation treatment material can be sufficiently distorted and a sufficient nitrogen intrusion path can be secured. Therefore, the above embodiment can produce an α ″ Fe ₁₆ N ₂ phase efficiently and reliably in the nitriding step, and produce a magnetic material having excellent magnetic properties.

  As one form of the manufacturing method of the present invention, when the above-mentioned powder molded body is used as a raw material and a phase separation treatment material having a relative density of 94% or less is manufactured, the magnetic body manufactured through the nitriding step is 300 MPa The form which comprises the pressurization process which performs the above pressurization and makes it a high-density magnetic body with a relative density over 94% is mentioned.

  In the above embodiment, the low-density magnetic body can be densified after the nitriding step, and finally a high-density magnetic body can be obtained, and a magnetic body having superior magnetic characteristics can be obtained.

  The magnetic body of the present invention is superior in magnetic properties as compared with conventional metal magnets. The method for producing a magnetic body of the present invention can satisfactorily produce the above-described magnetic body of the present invention.

FIG. 1 is a process explanatory view schematically showing a process for producing a magnetic body of the present invention produced in a test example. FIG. 2 is a process explanatory view schematically showing an example of a process for producing a conventional metal magnet.

Hereinafter, the present invention will be described in more detail.
[Magnetic material]
(component)
The magnetic body of the present invention contains Fe as a main component (contains 75 atomic% or more), and contains Co and a metal element other than Fe (excluding Co). However, Co is contained at 5 atomic% or more and less than 10 atomic%. As unavoidable impurities, compounds derived from lubricants (BN (boron nitride), MoS (molybdenum sulfide), etc.) used for molding powder moldings and casting molds, Fe ₄ N, Fe ₃ formed during production It is allowed to contain nitrides such as N and CrN and nitrides of inevitable impurity elements in the raw material. The content of inevitable impurities excluding iron nitride other than α ″ Fe ₁₆ N ₂ and cobalt nitride is preferably 1% by mass or less with respect to the total mass of the magnetic body of the present invention.

  The Fe is mainly contained in the magnetic phase, and the metal elements other than Fe and Co are mainly contained in the inorganic phase. Examples of the metal elements other than Fe and Co include Cr, Ba, Sr, Pt, and rare earth elements (Nd, Sm, Ce, Pr, Dy, Tb, Y, etc.). In the form containing Cr, the inorganic phase is mainly composed of the CrCo component. When the above metal elements other than Cr are contained, there is a possibility that an inorganic phase having high crystal magnetic anisotropy is obtained as described later. The total content of metallic elements other than Fe and Co is preferably 25 atomic% or less. For example, in the form containing Cr, Cr: 5 atom% to 20 atom%, Co: 5 atom% to 10 atom% can be mentioned. As will be described later, depending on the composition of the inorganic phase, in addition to the metal element, one or more elements selected from oxygen, nitrogen, boron and carbon can be contained. The total content of elements such as oxygen is preferably 5 atomic% to 15 atomic%.

  Content of each element which comprises this invention magnetic body can be adjusted by changing suitably the composition of the iron alloy used for the raw material of this invention magnetic body.

(Organization)
≪Existence form of each phase≫
The magnetic body of the present invention is substantially composed of a magnetic phase and an inorganic phase having a composition different from the main component of the magnetic phase, and is composed of a structure in which an inorganic phase is interposed between a plurality of magnetic phases. The content of the magnetic phase is typically about 60% to 70% by volume, and the content of the inorganic phase is typically about 30% to 40% by volume. And it becomes a magnetic body excellent in a magnetic characteristic by interposing an inorganic phase so that magnetic actions may not mutually influence magnetic actions between magnetic phases. In order to prevent the magnetic interaction from occurring, it is preferable that the magnetic phases are separated to some extent as described above. Typically, the distance between the magnetic phases is preferably 5 nm or more. As the distance is longer, magnetic interaction is less likely to occur, and 10 nm or more is more preferable. However, the increase in the distance leads to an increase in the inorganic phase that does not function as the main magnetic phase, resulting in a decrease in magnetic properties and an increase in the size of the magnetic material due to the increase in the inorganic phase. Therefore, the distance between the magnetic phases is preferably less than the maximum width of the magnetic phase, typically 30 nm or less.

≪Magnetic phase shape≫
Typical examples of the shape of the magnetic phase include a rod shape, a granular shape, and a film shape, and can be changed according to manufacturing conditions. The width of the magnetic phase means the length of the short side in the case of a rod, the maximum diameter in the case of a granule, and the thickness in the case of a film. When the width of the magnetic phase is nano-order such as 100 nm or less, preferably 50 nm or less, the single domain structure can be stabilized and the magnetic phase can be fully utilized. In addition, if the width of the magnetic phase is 10 nm or more, and further 20 nm or more, it is possible to prevent a decrease in ferromagnetism due to the phenomenon (superparamagnetism) in which spontaneous magnetization disappears due to fluctuations in electron motion due to heat. The relative proportion of the magnetic phase with respect to the inorganic phase is difficult to decrease, that is, the magnetic phase is relatively sufficiently easy to be present, so that the magnetic properties are hardly deteriorated or do not substantially decrease. The magnetic phase is rod-shaped and has a large length with respect to its width, that is, a form with a large aspect ratio, more specifically, the width is nano-order as described above, and the length is several μm to several tens μm In the micro order (when the aspect ratio is 10 or more), the magnetic properties are excellent and preferable. In the case of a film, the larger the film formation region (area) with respect to the thickness, the better the magnetic characteristics.

  The distance between the magnetic phases is the distance between adjacent magnetic phases in the width direction of the magnetic phase when the magnetic phase is rod-shaped, the distance between adjacent points in the adjacent magnetic phase, In this case, it means the average thickness of the inorganic phase interposed between layers made of a magnetic phase.

≪Composition of magnetic phase≫
The magnetic phase has a saturation magnetization larger than iron among iron nitrides, and is mainly composed of a ferromagnetic α ″ Fe ₁₆ N ₂ phase. Specifically, the magnetic phase is 100 vol% and α ″. Contains Fe ₁₆ N ₂ phase at 80 volume% or more. The higher the proportion of the α ″ Fe ₁₆ N ₂ phase in the magnetic phase, the better the magnetic material, and therefore it is preferable that the α′Fe ₁₆ N ₂ phase is essentially composed of only the α ″ Fe ₁₆ N ₂ phase. Examples of inevitable impurities contained in the magnetic phase include Fe, Fe ₄ N, and Fe ₃ N. Fe has magnetism, but is less magnetic than α ″ Fe ₁₆ N ₂ , so it is preferable to have a lower Fe content. In addition, compounds with inferior magnetic properties such as Fe ₄ N and Fe ₃ N can be used as much as possible. It is preferably not included.

  For the confirmation of the composition of the magnetic phase and the composition of the inorganic phase and the shape of the magnetic phase, which will be described later, and the measurement of the distance between the magnetic phases, for example, take a cross-section of the magnetic material and use a transmission electron microscope (TEM) as described later. The peak intensity (peak area) of an image or X-ray diffraction can be used. In addition, energy dispersive X-ray spectroscopy (EDX) can be used for composition analysis. When a powder compact is used as a raw material, depending on the relative density of the powder compact and heat treatment conditions, the grain boundary of each particle constituting the raw material powder may be confirmed by observation with an optical microscope. Therefore, the fact that the grain boundaries of the powder particles can be confirmed when the magnetic material is observed can be one of the indicators that the powder compact is used.

≪Inorganic phase≫
The inorganic phase is a phase containing a metal element other than Fe (excluding Co) and Co, and is typically interposed between the magnetic phases, and the magnetic phases typically interact with each other magnetically. This is a phase for preventing interlocking, that is, a phase for breaking the magnetic interaction. Typically, the inorganic phase may be in the form of a nonmagnetic material. Examples of the non-magnetic material include a form mainly containing an alloy component including a CrCo alloy which is a weak magnetic material (or non-magnetic material) (containing 70% by volume or more with an inorganic phase being 100% by volume). Also, the lower the proportion of Fe remaining in the inorganic phase, the easier it is to prevent magnetic interaction between the magnetic phases. The higher the alloy component in the inorganic phase, the easier it becomes a form in which the residual ratio of Fe is relatively low. Therefore, the alloy component in the inorganic phase is 80% by volume or more, more preferably 90% by volume or more, It is preferable that it is substantially composed only of a CrCo component. Examples of inevitable impurities contained in the inorganic phase include residues such as the above-described lubricant. The CrCo component preferably has a high proportion of CrCo alloy, preferably 80 atomic% or more, particularly preferably 90 atomic% or more. Examples of inevitable impurities contained in the CrCo component include nitrides such as CrN described above and nitrides and oxides of inevitable impurities contained in the starting material.

Other inorganic phase alpha "form of a magnetic material other than Fe ₁₆ N _2, i.e., the main component is alpha" and the first magnetic phase is Fe ₁₆ N ₂ phase, the main component is α "Fe ₁₆ N ₂ except And a second magnetic phase, which is an inorganic phase, which may be a magnetic material of which the constituent material of the inorganic phase, which is the second magnetic phase, is mainly composed of an α ″ Fe ₁₆ N ₂ phase. The crystal magnetic anisotropy is stronger than that of the first magnetic phase, and the magnetic magnetic anisotropy is such that the generation distance of the magnetic interaction is longer than that of the first magnetic phase. Here, the α ″ Fe ₁₆ N ₂ phase, which is the main component of the first magnetic phase, can be both a hard magnetic material and a soft magnetic material. The inorganic phase is composed of a non-magnetic material as described above. In this case, the α ″ Fe ₁₆ N ₂ phase functions as a hard magnetic material, and the orientation of the magnetic domains is easily aligned in the longitudinal direction of the α ″ Fe ₁₆ N ₂ phase. On the other hand, the form in which the inorganic phase is a magnetic material is The inorganic phase, which is the second magnetic phase, functions as a hard magnetic material, and the first magnetic phase, whose main component is the α ”Fe ₁₆ N ₂ phase, functions as a soft magnetic material for the so-called nanocomposite magnet (exchange spring magnet). By doing so, it can be a very powerful magnet. The constituent materials of such inorganic phases include, for example, rare earth magnets (Sm—Co compounds, Nd—Fe—B compounds, Sm—Fe—N compounds, etc.), ferrite magnets (Ba—Fe—O compounds, Sr—Fe—). O compound), Pt—Fe alloy magnet, Pt—Co alloy magnet and the like. By controlling the progress of the spinodal decomposition, a part of Fe atoms is actively left in the inorganic phase, and the remaining Fe is used to generate the constituent material and a material equivalent to the constituent material. The inorganic phase of the magnetic phase is preferably excellent in manufacturability. Among the elements constituting the constituent material of the inorganic phase, for example, elements other than Fe are included in the raw material, and after the spinodal decomposition before nitriding treatment, or after nitriding treatment, voids between particles constituting the phase separation treatment material etc. It can be present by diffusing desired elements and compounds. In addition, a desired element or compound may be preferentially invaded into the inorganic phase by subjecting the phase separation material or the like to an appropriate heat treatment or a chemical reaction. In the form in which the inorganic phase functions as a hard magnetic body and the first magnetic phase functions as a soft magnetic body, if the first magnetic phase is rod-shaped, there is a risk of problems due to the exertion of hard magnetism due to the shape, It is considered that the first magnetic phase is preferably spherical or film-like.

[Production method]
(Preparation process)
In the production method of the present invention, a raw material made of an iron alloy having a composition capable of generating a desired magnetic phase and inorganic phase is prepared as a raw material. In particular, in the production method of the present invention, an iron alloy containing 75 atomic% or more of Fe (for example, FeCrCo alloy (Fe: 75 atomic% to 90 atomic%) or the like) is used, so that the magnetic phase is 60 vol% to A 70% by volume magnetic material can be produced. In the production method of the present invention, the content of Co in the iron alloy is 5 atomic% or more and less than 10 atomic%. As the form of the material, for example, a casting material used in the manufacture of a metal magnet such as a conventional FeCrCo magnet can be used. However, in order to efficiently nitride a target in the nitriding process described later in the view of increasing the degree of freedom of the shape or in the presence of open pores, the material is a powder form, typically a powder made of an iron alloy having a desired composition It is preferable to use a powder molded body obtained by molding.

  When the raw material is a powder compact, the powder to be used is, for example, a melt cast ingot made of a desired iron alloy or a foil obtained by a rapid solidification method is pulverized by a pulverizer such as a jaw crusher, a jet mill or a ball mill. Or by using an atomizing method such as a gas atomizing method. In particular, use of the atomizing method is preferable because a powder having an average particle size of 10 μm to 500 μm can be produced with high productivity. You may further grind | pulverize the powder manufactured by the atomizing method so that it may become a desired magnitude | size. By appropriately changing the pulverization conditions and the production conditions, the particle size distribution of the powder and the shape of the particles can be adjusted. A powder having an average particle size of 10 μm to 500 μm, particularly 50 μm to 200 μm, is excellent in fluidity and easy to be filled in a mold, and is easy to mold and can be used for mass production.

If the powder is provided with an insulating coating made of an insulating material on the outer periphery of each particle, a magnet having high electrical resistance can be obtained. For example, when this magnet is used in a motor, eddy current loss can be reduced. Insulating coatings include, for example, crystalline films of oxides such as Si, Al, Ti, amorphous glass films, ferrites such as Me-Fe-O (Me = Ba, Sr, Ni, Mn, etc.) Examples thereof include a film made of a metal oxide such as magnetite (Fe ₃ O ₄ ), a resin such as a silicone resin, and an organic-inorganic hybrid compound such as a silsesquioxane compound. For the purpose of improving thermal conductivity, Si-N or Si-C ceramic coating may be applied. The crystalline film, glass film, oxide film, ceramic film and the like may have an antioxidant function, and in this case, oxidation of particles can be prevented during molding. In the form of providing both the insulating coating and the ceramic coating, it is preferable to provide the insulating coating so as to be in contact with the surface of the particles and to provide the ceramic coating thereon. When a powder having a coating such as an insulating coating is used, each particle constituting the powder is preferably nearly spherical in order to suppress damage to the coating during compression molding.

  A mixed powder obtained by mixing a component such as a wax or a resin that can be removed by heating or vaporizing in the step after molding of the powder molded body can be used as a raw material of the powder molded body. When mixed powder is used, the friction between the mold and the powder can be reduced by wax or the like, and the insulation coating can be prevented from being damaged by the resin. By performing the phase separation treatment after removing the wax and the like, a phase separation treatment material having sufficient open pores can be obtained.

When the above-mentioned powder (which may be the above mixed powder) is filled into a mold having a desired shape and the powder and the mold are not substantially heated (the temperature reached when the mold self-heats by continuous molding (generally 80 In the case of the following), a powder molded body having a desired shape is obtained by pressure molding at an appropriate pressure (for example, 0.5 GPa to 2.0 GPa). As the pressure is increased, a powder compact having a higher relative density tends to be obtained. However, if the relative density is too high, it may be difficult to secure a sufficient nitrogen ingress path in the nitriding process, and the α ”Fe ₁₆ N ₂ phase may not be sufficiently generated. When used, it is preferable to adjust the relative density of the powder compact so that the relative density of the phase separation treatment material obtained in the separation step is 94% or less as described above. If it is too low, the ratio of the magnetic phase will be reduced, so 90% or more is preferable.In addition, since the deformation of the powder can be promoted by appropriately heating the molding die during molding, the pressure is increased to the above range. The powder compact can be formed in an air atmosphere, provided that it is a non-oxidizing atmosphere (for example, an inert atmosphere that does not react with constituent elements of the powder compact such as Ar), or a low oxygen atmosphere. (Oxygen: 100 vol ppm or less) In this case, oxidation of the powder compact can be prevented, and if the constituent elements such as Fe contained in the raw material powder are oxidized, the spinodal decomposition tends to be inhibited. It is preferable because it can suppress a decrease in magnetic properties due to oxidation.

  When using a cast material (ingot) as a raw material, it is more difficult to form open pores than when using the above mixed powder, but, for example, a member made of a material having a higher melting point than the raw material melt (foam metal, etc.) It is considered that a phase separation treatment material having open pores can be obtained by mixing the material with molten raw material and removing the member by an appropriate chemical method. Alternatively, instead of forming open pores, it is conceivable to use a material in which a member made of a nitrogen permeable material is mixed with a raw material melt.

(Separation process)
The separation step can be basically performed in the same manner as the heat treatment for phase separation in the conventional method for producing a metal magnet. Typically, depending on the composition of the material, in the solution treatment step (step of solution treatment) for heating to a temperature according to the composition of the material to homogenize the composition and the cooling process from the solution treatment temperature. And a phase separation step (step of performing a phase separation treatment) that is maintained (or cooled) in a phase separation temperature range. A magnetic field may be appropriately applied in the heat treatment step in the phase separation temperature range. An aging step may be further performed after the phase separation step.

  The solution treatment is performed at a temperature higher than that at which spinodal decomposition occurs for the purpose of eliminating the concentration gradient (segregation) of each element constituting the material. As the heating temperature is higher, segregation can be reduced. Depending on the composition of the iron alloy, the solution heating temperature and the heating time may be selected. When the said iron alloy is a FeCrCo type-alloy, heating temperature: 700 degreeC-1200 degreeC, heating time: 10 minutes-10 hours are mentioned.

  When the iron alloy is an FeCrCo-based alloy, after the solution treatment step, the temperature lowering rate from the heating temperature of the solution treatment step to a specific temperature, specifically, the temperature near the upper limit of the phase separation temperature range is increased to 550 ° C. It is preferable to control and quench. When the temperature range from the heating temperature in the solution treatment step to 550 ° C. is gradually cooled, a concentration gradient occurs, and two-phase separation may start in a relatively high temperature range around 600 ° C. Further, as a result of coarsening of the respective decomposed phases generated at around 600 ° C., there is a risk of deteriorating magnetic properties. By setting the temperature decrease rate in the above temperature range to 5.0 ° C./sec or more, the generation of the concentration gradient can be suppressed, and the above effect can be obtained as the temperature decrease rate increases. Accordingly, the rate of temperature drop during the rapid cooling is preferably 5 ° C./sec or more, particularly 7.5 ° C./sec or more. To lower the temperature drop rate to 5.0 ° C / sec or more, use a fan (air cooling), introduce cooling gas, or move the material from the furnace heating zone to the cooling part such as water-cooled copper plate or water-cooled jacket For example. The temperature drop rate can be adjusted by adjusting the fan output, the flow rate of the cooling gas, the temperature and distance of the cooling section such as the water cooling jacket.

  In addition, it is preferable to control the temperature lowering rate even in a phase separation temperature range (for example, a temperature range included in a temperature range of 550 ° C. to 450 ° C.) according to the composition of the material. The phase separation temperature range typically includes a temperature range of the center temperature ± 50 ° C. of the phase separation temperature determined from an equilibrium diagram or a differential thermal analysis curve (DTA curve). In the FeCrCo alloy, the center temperature of the phase separation temperature is about 500 ° C.

  When the temperature drop rate is 0.05 ° C / sec or more, phase separation can be performed satisfactorily and growth of the separated Fe phase can be suppressed to achieve a nano-order fine shape as described above. A magnetic phase having excellent magnetic properties can be formed. The higher the rate of temperature drop, the easier it is to suppress the above growth, 0.1 ° C / sec or higher, especially 0.2 ° C / sec or higher is preferable, but if it is too large, phase separation cannot be performed sufficiently, so the temperature drop rate is 5 ° C / sec or lower. Is preferably 1 ° C./sec or less, more preferably 0.5 ° C./sec or less. In the production method of the present invention, it is proposed to positively control the temperature lowering rate (slow cooling condition) in the phase separation temperature region in the specific range as described above. In order to set the temperature drop rate to 1 ° C./sec or less, for example, the temperature in the furnace may be adjusted by adjusting the output of the heater. For example, in order to set the cooling rate to over 1 ° C / sec, the fan, cooling gas, water-cooled copper plate, water-cooling jacket, etc. are used as described above. To adjust. By this phase separation, it is possible to form a phase separation material in which the Fe phase is mainly composed of Fe (preferably substantially only Fe) and the inorganic phase is mainly composed of a CrCo component or the like. The Fe phase becomes a precursor of the magnetic phase.

  In particular, when the magnetic field is applied as described above during the temperature drop in the phase separation temperature range, the Fe phase is made into a nano-sized rod having a very large aspect ratio such as the above-described width of nano-order and length of micro-order. It can be made granular if no magnetic field is applied. In the nitriding step described later, the shape of the Fe phase formed in the separation step is substantially maintained and becomes the shape of the magnetic phase. Therefore, in the separation process, it is preferable to select the conditions of the separation process so that a magnetic phase having a desired shape is obtained and to form an Fe phase having a desired shape. The width and length of the Fe phase can be adjusted by the magnitude of the applied magnetic field. Further, the magnitude of the magnetic field to be applied can be selected according to the composition of the material. By nitriding the nano-sized rod-shaped Fe phase as described later, a magnetic body having a nano-sized rod-shaped magnetic phase having excellent magnetic properties can be produced.

  The separation step can be performed in an inert atmosphere (for example, an inert gas atmosphere such as Ar) or a reduced pressure atmosphere (a vacuum atmosphere whose pressure is lower than the standard atmospheric pressure). The final degree of vacuum is, for example, 10 Pa or less. In addition, when performing the solution treatment in a high-temperature range over 1000 degreeC and a phase-separation process independently, only a phase-separation process can be performed in air | atmosphere.

  In the separation step, it is preferable to cool to 200 ° C. or less as soon as possible after completing a predetermined heating time (a time during which the phase separation reaction proceeds and the unreacted phase is sufficiently reduced). By doing so, it is difficult to produce cooling spots in the material (phase separation treatment material) that has undergone the separation step, and it is possible to prevent a problem that the nano-sized magnetic phase is locally coarsened by the cooling spots and the magnetic properties are deteriorated. Therefore, in addition to controlling the rate of temperature drop in the phase separation temperature region as described above, it is proposed to increase the cooling rate after passing through the phase separation temperature region. For example, quenching using forced cooling means such as immersing a heated material in a liquid cooling medium such as oil or water can be mentioned.

  It is preferable to further perform an aging treatment so as not to substantially change the size of the decomposed phase obtained through the separation step, since the separation of the Fe phase and the inorganic phase (typically CrCo) can proceed completely. A nitriding step to be described later may also serve as the aging treatment. Moreover, when it is desired to leave Fe in the inorganic phase as described above, the remaining amount of Fe can be adjusted by adjusting the aging conditions.

(Nitriding process)
The atmosphere containing nitrogen element in the nitriding step is a single atmosphere of only nitrogen (N ₂ ), an ammonia (NH ₃ ) atmosphere, a gas containing nitrogen such as nitrogen (N ₂ ) or ammonia, an inert gas such as Ar, An atmosphere of a mixed gas with a gas not containing nitrogen such as hydrogen (H ₂ ) can be given. The atmosphere containing hydrogen is effective in preventing oxidation of the phase separation material in the nitriding step. By setting the heating temperature in the nitriding step to 200 ° C. to 400 ° C., the phase separation treatment material and the nitrogen element easily react, and the Fe phase in the phase separation treatment material easily generates α ″ Fe ₁₆ N _2. In addition, the nano-sized magnetic phase can be prevented from coarsening, and the retention time can be 0.5 to 100 hours.

In particular, the production method of the present invention is characterized in that the nitriding treatment is performed in a pressurized state exceeding atmospheric pressure. By applying pressure as described above, the crystal lattice of the nano-sized Fe phase in the phase separation material is distorted, and the lattice spacing in a certain direction is widened. N atoms invade preferentially between these extended lattices with a regular orientation. As a result, a desired magnetic phase: α ″ Fe ₁₆ N ₂ can be stably formed even in a low temperature range of 400 ° C. or lower. The Fe phase formed in this way can be sufficiently nitrided. , Α ”Fe ₁₆ N ₂ phase can be generated efficiently, and formation of compounds such as Fe ₄ N and Fe ₃ N with poor magnetic properties is suppressed by suppressing excessive nitriding of Fe (substitution of Fe atoms by N atoms) it can. As described above, the pressure is preferably 70 MPa to 300 MPa, and 70 MPa to 150 MPa is easy to use. As the method of pressurization, any of uniaxial press pressurization as in powder molding and isotropic pressurization using an appropriate pressure medium can be used. Further, the pressurization is preferably performed so as to expand the lattice in one direction of the Fe phase. Specifically, it is preferable that the material is expanded in a uniaxial direction orthogonal to the compression direction of the material, that is, the uniaxial direction is an expansion direction (unconstrained direction). When the pressure is 150 MPa or less, plastic deformation in which atoms move does not substantially occur, and only elastic deformation in which the lattice expands occurs. Therefore, the space between the lattices can be expanded well and the collapse of the material can be prevented. Note that it is expected that the space between the lattices can be expanded even if a treatment for applying a tensile stress to the material is performed.

Note that iron nitride can also be generated when the nitriding treatment is performed at atmospheric pressure. However, since it is necessary to increase the reaction temperature, the probability of excessive incorporation of N atoms into the Fe lattice increases, and a compound having poor magnetic properties such as Fe ₄ N is likely to be formed. It is easy to obtain.

(Pressurization process)
When the magnetic body that has undergone the nitriding step is pressed to make it dense as described above, a magnetic body (high-density magnetic body) that has superior magnetic properties can be obtained. A pressure of 300 MPa to 1 GPa is easy to use. Unlike the above-described nitriding step, this pressurization is preferably performed by press molding in a state in which the mold is constrained so as not to be elastically deformed, or a hydrostatic pressure pressurization method is used.

(Other manufacturing methods)
In order to produce a magnetic body having a magnetic phase in which the α ”Fe ₁₆ N ₂ phase is a film, a substrate made of an inorganic material (which may be non-magnetic or magnetic as described in the inorganic phase column) In addition, α ″ Fe ₁₆ N ₂ is formed, or the above-described nitriding step is performed after forming Fe. In particular, by repeatedly performing α ″ Fe ₁₆ N ₂ film formation → inorganic material film formation, Fe film formation → nitridation → inorganic material film formation, a magnetic material having excellent magnetic properties can be obtained.α ″ Fe ₁₆ Known film formation methods can be used for N ₂ and Fe film formation and inorganic material film formation. The Fe film formation → nitridation step may be a single step using a film formation method such as sputtering by plasma in an atmosphere containing nitrogen. It is preferable to use a substrate made of a material having a crystal structure with high consistency with the lattice plane of α ″ Fe ₁₆ N ₂ crystal. Examples of such a substrate include Si, Ti, Al, and Mg. Examples of the inorganic material to be formed include oxides such as Si, Ti, Al, and Mg, rare earth magnets (Sm-Co compounds, Nd-Fe-B compounds, Sm-Fe -N compounds, etc.), ferrite magnets (Ba-Fe-O compounds, Sr-Fe-O compounds, etc.), Pt-Fe alloy magnets, Pt-Co alloy magnets, etc. α ”Fe ₁₆ N _two- phase film The thickness is preferably 30 nm or less as described above, and the film thickness of the inorganic phase is preferably 5 nm or more and the film thickness of the α ″ Fe ₁₆ N ₂ phase as described above. However, considering the productivity of the magnetic material, It is preferable to use the above-mentioned powder molded body or the like as a material.

Hereinafter, more specific embodiments of the present invention will be described with reference to test examples.
[Test example]
A magnetic material made of FeCrCo alloy was fabricated and the magnetic properties were investigated. Here, a powder molded body made of an FeCrCo alloy was used as a raw material, and it was produced by a procedure of preparation step → separation step → nitriding step.

  An iron alloy containing 75 atomic% or more of Fe element: A molten metal of Fe-17.5 atomic% Cr-7.5 atomic% Co (Co content: about 8 mass%) was prepared (Fig. 1 (I)), and the average particle size Is produced by gas atomization method (Ar atmosphere). The average particle size is set to a particle size (50% particle size) with an integrated weight of 50% by a laser diffraction particle size distribution device. Each particle 1 constituting the obtained alloy powder (FIG. 1 (II)) is composed of a single-phase structure having the above composition.

  The FeCrCo alloy powder was compression-molded (molding pressure: 1 GPa) to produce a cylindrical powder compact 2 having a diameter: φ10 mm × height: 10 mm (FIG. 1 (III)). The relative density of the obtained powder compact 2 was determined to be 92%. The relative density is measured using a commercially available density measuring device, and the true density of the cast material using the molten metal consisting of Fe-17.5 atomic% Cr-7.5 atomic% Co is calculated. / Calculated by calculating true density.

  The obtained powder compact 2 was heated to 1150 ° C. in high-purity Ar gas (Ar: 99.9999% or more (volume ratio)) with an oxygen concentration of 10 volume ppm or less, and heated at 1150 ° C. for 1 hour ( In the cooling step from the above heating temperature, the solution is rapidly cooled to 550 ° C. at a rate of temperature decrease of 5.0 ° C./sec. This temperature drop rate was adjusted by introducing a cooling gas into the heating furnace used for the solution treatment. After this rapid cooling, the temperature is lowered while applying a magnetic field while controlling the temperature range of 540 ° C to 480 ° C (phase separation temperature range of Fe-17.5 atomic% Cr-7.5 atomic% Co) to the temperature decreasing rate: 0.5 ° C / second (16MA / m (20kOe)). This temperature drop rate was adjusted by controlling the temperature in the heating furnace used for the solution treatment. By this separation step, a phase separation treatment material 3 (low density sintered body) having two phases of Fe phase 11 containing Fe and inorganic phase 12 containing CrCo component is obtained.

  Taking a cross section of the obtained phase separation treatment material 3, and observing this cross section with an optical microscope (100 times), the grain boundary 10 of each particle constituting the powder used as a raw material is recognized, the triple point between the particles A gap 20 was observed in the portion (not shown). Further, in the phase separation treatment material 3, the cross section in the direction perpendicular to the direction of application of the magnetic field at the time of temperature reduction was taken, and after thinning by ion milling, observed with a transmission electron microscope: TEM (about 50000 times), each In the grains, it was confirmed that an inorganic phase 12 was interposed between rod-shaped Fe phases 11 as conceptually shown in FIG. 1 (IV). Note that the shape of the grain boundary 10 in FIG. 1 is a model and is different from the actual shape. Further, when the composition of each of the above phases was identified from the X-ray diffraction result of the cross section of the phase separation treatment material 3 and the spot analysis of the electron diffraction at the time of TEM observation, the Fe phase 11 contained Fe, and the inorganic phase 12 was confirmed to contain CrCo (85% by volume relative to 100% by volume of the inorganic phase). Furthermore, it was confirmed that the relative density of the obtained phase-separated material 3 was substantially the same as that of the powder compact 2.

  The obtained phase separation treatment material 3 was inserted into a uniaxially pressurized hot press furnace and subjected to heat treatment at 350 ° C. for 5 hours under a pressure of 100 MPa in a nitrogen atmosphere to obtain a magnetic body 4 (FIG. 1). (V)).

Taking a cross section of the obtained magnetic body 4, and observing this cross section with an optical microscope (100 times), the grain boundary 10 of each particle constituting the powder used as the raw material is recognized, the phase separation treatment material 3 It was confirmed that the gap 20 of the triple point portion confirmed in (2) was maintained. In addition, as with the observation of the phase-separation treatment material 3, the magnetic body 4 was subjected to a cross section in the direction perpendicular to the direction in which the magnetic field was applied when the temperature was lowered, and as a result of TEM analysis and X-ray diffraction, 13 is a phase mainly composed of α ″ Fe ₁₆ N ₂ phase (93% by volume (≧ 80% by volume or more) with respect to 100% by volume of magnetic phase), and inorganic phase 12 is a phase mainly composed of CrCo component. (85% by volume with respect to 100% by volume of the inorganic phase) was confirmed, the content of the magnetic phase 13 in the powder material was 70% by volume, and the content of the inorganic phase 12 was 30% by volume. %.

  Using the cross-sectional TEM observation image, the width and length of the magnetic phase 13 and the distance between the magnetic phases 13 were measured, and the width of the magnetic phase 13 was 25 nm (100 nm on average in the entire magnetic phase in the observation image. The nano-order of the following), the length is in the micro-order of 0.3 μm to 3 μm, and the nano-sized rod has a very large aspect ratio. The distance between the magnetic phases is 11 nm (5 nm or more) on average in the entire magnetic phase in the observed image, and it can be confirmed that the inorganic phase 12 is interposed so that no magnetic interaction occurs between the magnetic phases 13. It was.

  When the magnetic properties of the obtained magnetic body 4 were examined using a BH tracer (DCBH tracer manufactured by Riken Denshi Co., Ltd.), the intrinsic coercivity iHc: 1.02 kOe (81.2 kA / m), residual magnetization Br (T): It was 1.25T.

  Further, the obtained magnetic body 4 was pressed at a pressure of 400 MPa with an isostatic press to perform densification. When the structure of the magnetic body (high-density magnetic body) obtained after pressurization was observed with an optical microscope in the same manner as described above, it was confirmed that the void at the triple point portion was reduced. Further, when the relative density of the obtained magnetic body (high density magnetic body) was measured in the same manner as described above, the relative density was improved to 99%.

  When the magnetic properties of the obtained magnetic material (high-density magnetic material) were examined using a BH tracer (DCBH tracer manufactured by Riken Denshi Co., Ltd.), the intrinsic coercivity iHc: 1.11 kOe (88.3 kA / m), residual magnetization Br (T): 1.36T and magnetic properties were improved.

As described above, an iron alloy having a Co content of less than 10 atomic% is subjected to spinodal separation treatment and then subjected to nitriding treatment in a pressurized state, thereby mainly producing an α ″ Fe ₁₆ N ₂ phase. It can be seen that a magnetic material having a magnetic phase can be obtained, that the magnetic material has excellent magnetic properties, and that the magnetic properties can be further improved by densifying the magnetic material.

The above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the content of α ”Fe ₁₆ N ₂ phase in the magnetic phase, the composition of the inorganic phase, the distance between the magnetic phases, the size and shape of the magnetic phase, the composition of the iron alloy constituting the material, the production conditions (heating temperature, heating Time, temperature drop rate, etc.) can be appropriately changed.

  The magnetic body of the present invention can be suitably used as a permanent magnet, for example, a permanent magnet used in various motors, in particular, a high-speed motor provided in a hybrid vehicle (HEV), a hard disk drive (HDD), or the like. In addition, the magnetic body of the present invention is expected to be usable for electromagnetic wave interference / absorbing materials up to a frequency region (terahertz region) where the skin depth of the magnetic phase is close to the width of the magnetic phase. The manufacturing method of the magnetic body of the present invention can be suitably used for manufacturing the magnetic body of the present invention.

1 Particle 2 Powder compact 3 Phase separation material 4 Magnetic material
10 Grain boundary 11 Fe phase 12 Inorganic phase 13 Magnetic phase 20 Crevice
100 Ingot 120 Inorganic phase 130 Magnetic phase 400 Magnet

Claims (10)

Substantially composed of a magnetic phase mainly composed of iron nitride and an inorganic phase interposed so as not to cause magnetic interaction between the magnetic phases;
Co content is 5 atomic% or more and less than 10 atomic%,
The magnetic phase is characterized in that it contains at least 80% by volume of α ″ Fe ₁₆ N ₂ phase.   2. The magnetic body according to claim 1, wherein the inorganic phase contains 80% by volume or more of a CrCo component mainly composed of CrCo.   3. The magnetic body according to claim 1, wherein a distance between the magnetic phases is 5 nm or more.   4. The magnetic body according to claim 1, wherein the width of the magnetic phase is 100 nm or less. Manufacture of a magnetic body that heat-treats an iron alloy to manufacture a magnetic body substantially composed of a magnetic phase containing an Fe element and an inorganic phase interposed so that no magnetic interaction occurs between the magnetic phases. A method,
A preparatory step of preparing a material made of an iron alloy containing Fe element in an amount of 75 atomic% or more, a metal element other than Fe, and Co in an amount of 5 atomic% or more and less than 10 atomic%;
A phase separation heat treatment is performed on the material, and a separation step of separating an Fe phase and an inorganic phase composed of an inorganic material containing the metal element and interposed between the Fe phases;
The phase separation treated material obtained by the separation step is subjected to a nitriding heat treatment at a temperature of 200 ° C. or more and 400 ° C. or less in a pressurized state exceeding atmospheric pressure and in a nitrogen element-containing gas atmosphere. Nitriding Fe to produce an α ″ Fe ₁₆ N ₂ phase by nitriding Fe, and producing a magnetic body in which the content of α ″ Fe ₁₆ N ₂ phase in the magnetic phase is 80% by volume or more. A method for producing a magnetic material. The iron alloy is a FeCrCo alloy,
In the separation step, after the material is heated to 1000 ° C. or higher, the rate of temperature decrease in the cooling step to 550 ° C. is 5.0 ° C./sec or more, and in the temperature range of 550 ° C. to 450 ° C. in the phase separation temperature range of the material. 6. The method for producing a magnetic body according to claim 5, wherein the temperature lowering rate is 0.05 ° C./sec or more and 5 ° C./sec or less.   7. The method for producing a magnetic body according to claim 5, wherein the material prepared in the preparation step is a powder compact obtained by molding a powder made of the iron alloy.   8. The method of manufacturing a magnetic body according to claim 7, wherein in the preparation step, the material is prepared so that a relative density of the phase separation material is 94% or less.   9. The method of manufacturing a magnetic body according to claim 5, wherein the pressurization in the nitriding step is 70 MPa or more and 300 MPa or less.   9. The pressing process according to claim 8, further comprising pressing the magnetic body manufactured through the nitriding process to a pressure of 300 MPa or more to obtain a high-density magnetic body having a relative density of more than 94%. Of manufacturing a magnetic material.

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