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• • H—ELECTRICITY
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  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
  • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
  • H01F1/047—Alloys characterised by their composition
  • H01F1/053—Alloys characterised by their composition containing rare earth metals
  • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
  • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
  • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
  • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
  • H01F1/0578—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together bonded together
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  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
  • H01F41/0266—Moulding; Pressing
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  • C22C2202/02—Magnetic

Definitions

• the present invention relates to an iron-based rare earth boron isotropic nanocomposite magnet alloy, a method for producing an iron-based rare earth boron isotropic nanocomposite magnet alloy, and a method for producing a resin-bonded permanent magnet.
• Nanocomposite isotropic magnets composed of hard magnetic phases such as Nd-Fe-B and Sm-Fe-N, which are composed of microcrystalline grains with sizes on the order of nanometers to submicrometers
• microcrystalline isotropic magnets have been developed.
• Nanocomposite isotropic magnets (hereinafter referred to as , “nanocomposite magnets”) have been developed, but these rare earth iron-based isotropic magnets, which are composed of crystal grains on the order of nanometers to submicrometers, are magnetostatic because of their fine crystal grains.
• Computer simulations using micromagnetics have revealed that in addition to interaction, each crystal grain is magnetically coupled by exchange interaction, resulting in excellent magnetic properties, and has been used as a high-performance permanent magnet material. It has been put into practical use.
• microcrystalline rare earth iron-based isotropic magnets have been manufactured using epoxy resin-based thermosetting resin or nylon-based
• a resin-bound type magnet (commonly known as a bonded magnet) mixed with thermoplastic resin such as polyphenylene sulfide (PPS) is used as a net-shape magnet with a high degree of freedom in shape, and is used in optical drives, spindle motors for hard disks, and mobile phones. It has been mainly used in the electronic parts industry, typically for vibration motors (pager motors) and various sensors.
• the volume ratio of the ferromagnetic phase exhibiting hard or soft magnetism, which is responsible for magnetic properties, should be maximized, and the volume ratio of the non-magnetic phase, which forms grain boundaries of the hard magnetic phase, should be minimized.
• the main phase is a hard magnetic RE 2 Fe 14 B type (RE is a rare earth element) compound, and the non-magnetic grain boundary phase containing boron surrounds the main phase. Due to the presence of , magnetic mutual adoption between the main phase particles is adjusted, and an intrinsic coercive force HcJ of 700 kA/m or more, which is applicable to various high-performance motors, is obtained.
• isotropic rare earth iron boron magnet materials that can be applied to various electric motors such as EVs and HEVs are An intrinsic coercive force HcJ ⁇ 1200 kA/m is required, which has been difficult to obtain with magnetic materials.
• the basic composition is based on a stoichiometric composition, in order to achieve an intrinsic coercive force HcJ ⁇ 1200 kA/m that can be applied to various electric motors such as EVs and HEVs, the main phase ratio of RE 2 Fe 14 B must be changed. It is necessary to increase the RE concentration to 12.5 at%, which is a higher RE concentration than the stoichiometric composition of RE 2 Fe 14 B.
• the Nd 2 Fe 14 B phase and the ⁇ -Fe phase or the Fe-B phase are the same.
• the exchange interaction between each crystal grain causes it to behave as if it were a single magnet, resulting in excellent permanent magnetic properties.
• an RE-Fe-B based isotropic permanent magnet material that exhibits sufficient magnetic properties has not been found.
• Patent Document 1 discloses an anisotropic sintered magnet having an RE 2 Fe 14 B tetragonal crystal structure as a main phase, but the magnet has a RE 2 Fe 14 B tetragonal crystal structure on the order of micrometers. It is a magnet that has a metal structure composed of grains, and exhibits good magnetic properties by aligning the magnetic moment in the C-axis direction of the RE 2 Fe 14 B tetragonal crystal by magnetic orientation. , good magnetic properties cannot be obtained as an isotropic magnet in which magnetic moments are randomly arranged, and it cannot be used as a practical magnet.
• Patent Document 2 discloses a hard magnetic material having an RE 2 Fe 14 B tetragonal crystal structure consisting of at least 10 atomic % of rare earth elements, about 0.5 atomic % or more and about 10 atomic % or less of boron, and the balance iron.
• the disclosure discloses an isotropic permanent magnet with a main phase having a high intrinsic coercive force HcJ of up to 1460 kA/m
• the grain size of RE 2 Fe 14 B type crystal grains is 20 nm or more, It even includes crystal grains with a diameter of 400 nm or less, which exceeds the single domain crystal grain size of RE 2 Fe 14 B-type crystal grains.
• the magnetization decreases, and even in the example in which the best magnetic properties are obtained, the residual magnetic flux density Br remains at a maximum of 0.83 T and the maximum energy product (BH) max remains at a maximum of 103 kJ/m 3 . Therefore, magnetic characteristics applicable to various electric motors such as EVs and HEVs have not been realized.
• Patent Document 3 and Patent Document 4 disclose iron-based rare earth isotropic nanocomposite magnets. These iron-based rare earth isotropic nanocomposite magnets mainly contain ⁇ -Fe phase as a soft magnetic phase, so although it is possible to obtain a high residual magnetic flux density Br of 0.9T or more, demagnetization is difficult. Since the squareness of the curve is poor and the demagnetization strength and heat resistance are poor, it is not suitable as a permanent magnet material for use in automobiles and white goods.
• Patent Document 5 discloses that in an iron-based rare earth isotropic nanocomposite magnet that mainly contains an iron-based boride phase as a soft magnetic phase, the ⁇ -Fe phase is precipitated during the cooling process of the molten alloy due to the addition of Ti. - It is disclosed that the growth can be suppressed and the precipitation and growth of the Nd 2 Fe 14 B phase can be promoted preferentially. However, since Ti easily combines with boron (B), and the TiB2 phase is crystallized during the crystallization process, the absolute amount of boron required to generate the main Nd 2 Fe 14 B phase decreases. However, there is a problem in that the expected intrinsic coercive force HcJ cannot be obtained from the rare earth element content concentration.
• Patent Document 6 discloses an iron-based rare earth isotropic nanocomposite magnet that mainly contains an iron-based boride phase as a soft magnetic phase, and if Ti and carbon (C) are added, the following effects can be achieved. It teaches that it can be obtained.
• the liquidus temperature of the molten alloy decreases by 5°C or more (for example, about 10°C or more and about 40°C or less).
• the viscosity of the molten metal hardly increases because crystallization of coarse TiB 2 phase and the like is suppressed even if the molten metal temperature is lowered accordingly.
• the challenge is to reduce the grain size to an average grain size of 10 nm or more and less than 70 nm so that the exchange interaction can work effectively, and at the same time adjust the interparticle interactions and maximize the coercive force.
• the present inventors have created a permanent magnet material with unprecedented excellent magnetic properties by making the grain boundary phase adjacent to the main phase consisting of an RE 2 Fe 14 B-type hard magnetic compound hard magnetic or semi-hard magnetic.
• additive elements such as Ti, it was found that it was difficult to suppress the decrease in the residual magnetic flux density Br while maintaining a high intrinsic coercive force HcJ. .
• the present invention has been made in view of the above circumstances, and its main purpose is to ensure the magnetic alloy characteristics necessary for application to various electric motors such as EVs and HEVs, and the residual magnetic flux density,
• An iron-based rare earth boron-based isotropic nanocomposite magnet alloy that can improve the intrinsic coercive force HcJ and maximum energy product (BH) max compared to existing iron-based rare earth boron-based isotropic magnet alloys, and the iron-based rare earth
• the object of the present invention is to provide a method for manufacturing a boron-based isotropic nanocomposite magnet alloy, and a method for manufacturing a resin-bonded permanent magnet containing the iron-based rare earth boron-based isotropic nanocomposite magnet alloy.
• the iron-based rare earth boron isotropic nanocomposite magnet alloy of the present invention has a composition formula T 100-xyz (B 1-n C n ) x RE y Zr z M m (T is from the group consisting of Fe, Co, and Ni). At least one selected element is a transition metal element that always includes Fe, RE is at least one rare earth element that always includes at least Nd among Nd and Pr, and M is Al, Si, V, Cr, and Ti.
• composition ratio x, y and z is 4.2 atom% ⁇ x ⁇ 5.0 atom%, 12.5 atom% ⁇ y ⁇ 14.0 atom%, 0 atom% ⁇ z ⁇ 2.0 atom%, 0.0 atom% ⁇ It has an alloy composition satisfying m ⁇ 5.0 atomic % and 0.0 ⁇ n ⁇ 0.5, and has a lower B content than the stoichiometric composition of the RE 2 Fe 14 B-type tetragonal compound.
• the main phase is a RE 2 Fe 14 B-type tetragonal compound with an average crystal grain size of 10 nm or more and less than 70 nm, which is finer than the single domain critical diameter, and Fe 17 in the grain boundary phase surrounding the main phase. It has a metal structure containing phases richer in Fe than the main phase, such as RE 2 phase and ⁇ -Fe phase.
• the width of the thickest portion of the grain boundary phase can be 1 nm or more and less than 150 nm.
• a metal structure in which the ratio of the main phase is 70 volume % or more and less than 99 volume %, and the ratio of the grain boundary phase is 1 volume % or more and less than 30 volume %. can have
• the method for manufacturing the iron-based rare earth boron isotropic nanocomposite magnet alloy of the present invention is based on the composition formula T 100-xyz (B 1-n C n ) x RE y Zr z M m (T is Fe, Co, and Ni).
• RE 2 is sprayed onto the surface of a rotating roll whose main component is Cu, Mo, W, or an alloy containing at least one of these metals at an average tapping rate of 200 g/min or more and less than 2000 g/min.
• the above method for producing a resin-bonded permanent magnet includes the step of preparing an iron-based rare earth boron isotropic nanocomposite magnet alloy powder produced by the above method for producing an iron-based rare earth boron isotropic nanocomposite magnet alloy. , After adding a thermosetting resin to the above iron-based rare earth boron-based isotropic nanocomposite magnet alloy powder, filling it into a mold and forming a compression molded body by compression molding, the thermosetting resin is polymerized.
• the method may include a step of heat treatment at a temperature higher than the temperature.
• the above method for producing a resin-bonded permanent magnet includes a step of preparing an iron-based rare earth boron isotropic nanocomposite magnet alloy powder produced by the above method for producing an iron-based rare earth boron isotropic nanocomposite magnet alloy. , a step of adding a thermoplastic resin to the iron-based rare earth boron-based isotropic nanocomposite magnet alloy powder to prepare an injection molding compound, and then injection molding the compound.
• rare earth boron-based materials can ensure magnetic properties such as residual magnetic flux density Br, intrinsic coercive force HcJ, and maximum energy product (BH) max, which are necessary as permanent magnets for various electric motors such as EVs and HEVs.
• a directional nanocomposite magnet alloy can be provided. Further, according to the present invention, it is possible to provide a method for manufacturing the above-mentioned rare earth boron-based isotropic nanocomposite magnet alloy. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a resin-bonded permanent magnet containing the rare earth boron isotropic nanocomposite magnet alloy.
• FIG. 1 is a cross-sectional view schematically showing an example of an iron-based rare earth boron-based isotropic magnet alloy of the present invention.
• (a) is an apparatus configuration diagram of a heat treatment furnace for realizing flash annealing
• (b) is a diagram showing the state of the rapidly solidified alloy moving inside the furnace core tube.
• FIG. 2 is a conceptual diagram of thermal history due to flash annealing performed in the present invention.
• 3 is a powder X-ray diffraction profile of the rapidly solidified alloy obtained in Example 9. This is a powder X-ray diffraction profile of the rapidly solidified alloy obtained in Example 9 after flash annealing (crystallization heat treatment). It is an elemental mapping image obtained in Example 24. It is a powder X-ray diffraction profile of the rapidly solidified alloy after flash annealing (crystallization heat treatment) obtained in Comparative Example 7.
• a method for producing powder and a method for producing a resin-bonded permanent magnet of the present invention will be explained. Note that the present invention is not limited to the following configuration, and may be modified as appropriate without departing from the gist of the present invention. Furthermore, the present invention also includes a combination of a plurality of individual preferred configurations described below.
• the rare earth boron-based isotropic nanocomposite magnet alloy of the present invention has a composition formula T 100-xyz (B 1-n C n ) x RE y Zr z M m (T is selected from the group consisting of Fe, Co and Ni).
• RE is at least one rare earth element selected from among Nd and Pr, and M is Al, Si, V, Cr, Ti, Mn.
• composition ratios x, y and z are 4.2 atom% ⁇ x ⁇ 5.0 atom%, 12.5 atom% ⁇ y ⁇ 14.0 atom%, 0 atom% ⁇ z ⁇ 2.0 atom%, 0.0 atom% ⁇ m ⁇ , respectively.
• 5.0 atomic % and has an alloy composition satisfying 0.0 ⁇ n ⁇ 0.5, and has a B content concentration lower than the stoichiometric composition of the RE 2 Fe 14 B-type tetragonal compound.
• the main phase is a RE 2 Fe 14 B-type tetragonal compound with an average crystal grain size of 10 nm or more and less than 70 nm, which is finer than the single domain critical diameter, and a Fe 17 RE 2 phase in the grain boundary phase surrounding the main phase. It is characterized by having a metal structure containing a phase richer in Fe than the main phase, such as an ⁇ -Fe phase or an ⁇ -Fe phase.
• the width of the thickest part of the grain boundary phase is preferably 1 nm or more and less than 150 nm.
• An example of such an iron-based rare earth boron isotropic magnetic alloy of the present invention is shown in FIG.
• composition ratio of the main phase and the grain boundary phase is not necessarily limited, but the ratio of the main phase is 70 volume % or more and less than 99 volume %, and the ratio of the grain boundary phase is 1 volume % or more and less than 30 volume %. is preferred.
• the rare earth boron-based isotropic nanocomposite magnet alloy of the present invention is characterized by a low boron content concentration, and the boron (B) content concentration in the alloy composition range in which a magnet alloy having the RE 2 Fe 14 B phase as the main phase is obtained. is in the range of 4.2 atomic % or more and less than 5.0 atomic %, which is lower than the stoichiometric composition of the RE 2 Fe 14 B-type tetragonal compound, and at the same time contains Zr in the range of 2.0 atomic % or less.
• the rare earth boron isotropic nanocomposite magnet alloy of the present invention by making the rare earth element (RE) and iron (Fe) surplus in the same alloy structure, the main phase RE A grain boundary phase consisting of surplus RE and Fe that is not required for the generation of the 2 Fe 14 B phase is formed.
• the iron-based rare earth boron isotropic magnetic alloy of the present invention has, for example, Fe 17 RE 2 phase or ⁇ -Fe surrounding the RE 2 Fe 14 B phase with an average crystal grain size of 10 nm or more and less than 70 nm. It is possible to have a unique fine metal structure in which there is a grain boundary phase with a width of 1 nm or more and less than 150 nm at the thickest portion including a phase richer in Fe than the main phase such as a phase.
• the inventors have found that by realizing the above-mentioned unique uniform fine metal structure , the main phase RE2Fe14B phase and the grain boundary phase, which is uniformly present around the main phase and is mainly composed of RE and Fe, are bound by strong exchange interaction in addition to static magnetostatic interaction, but when the binding of the exchange interaction (exchange coupling) becomes strong, the intrinsic coercivity HcJ of the magnet alloy decreases.
• the grain boundary phase contains a phase richer in Fe than the main phase, such as the Fe17RE2 phase or the ⁇ -Fe phase, and the decrease in HcJ of the RE2Fe14B phase is suppressed, and a high maximum energy product (BH)max can be obtained by improving the squareness of the demagnetization curve and the residual magnetic flux density Br applicable to various electric motors for EVs, HEVs, etc.
• BH maximum energy product
• the boron content concentration is less than 4.2 atomic %, the formation of the RE 2 Fe 14 B phase, which is the main phase, is inhibited, so that both the intrinsic coercive force HcJ and the residual magnetic flux density Br are significantly reduced.
• the boron content concentration exceeds 5.0 at%, phases richer in Fe than the main phase such as Fe 17 RE 2 phase and ⁇ -Fe phase do not precipitate in the grain boundary phase, so the residual magnetic flux density Br: 0
• it is possible to achieve .81T or more it is not possible to obtain an intrinsic coercive force HcJ: 1200 kA/m or more while maintaining a maximum energy product (BH) max: 110 kJ/m 3 or more.
• the boron content concentration is set to 4.2 atomic % or more and 5.0 atomic % or less, the formation of the RE 2 Fe 14 B phase necessary to obtain the intrinsic coercive force HcJ ⁇ 1200 kA/m or more is suppressed.
• the above magnetic properties can be obtained because RE containing phases richer in Fe than the main phase such as Fe 17 RE 2 phase and ⁇ -Fe phase and grain boundary phases mainly composed of Fe are generated uniformly without damage. it is conceivable that.
• Patent Document 2 Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6 all use microcrystalline isotropic permanent magnet materials in which the intrinsic coercive force HcJ is borne by a RE 2 Fe 14 B-type tetragonal compound.
• the magnitude of the intrinsic coercive force HcJ largely depends on the volume ratio of the RE 2 Fe 14 B-type tetragonal compound, and the higher the volume ratio of the RE 2 Fe 14 B phase, the lower the intrinsic coercive force HcJ. If the volume ratio of the RE 2 Fe 14 B phase is low, the specific coercive force HcJ will be low.
• the anisotropic RE 2 Fe 14 B sintered magnet described in Patent Document 1 heavy rare earth elements such as Dy and Tb are included in the RE 2 Fe 14 B type tetragonal compound as the main phase, and RE 2 Fe 14 B By increasing the anisotropic magnetic field of the tetragonal compound, the intrinsic coercive force HcJ is improved.
• the above-mentioned fine isotropic permanent magnet material and anisotropic sintered magnet both have a RE 2 Fe 14 B-type tetragonal compound as the main phase, the main phase size of the anisotropic sintered magnet is 1 ⁇ m.
• the diameter is approximately 10 ⁇ m or less, which is greater than the single magnetic domain critical diameter of the RE 2 Fe 14 B-type tetragonal compound. Therefore, although an anisotropic sintered magnet is in a multi-domain state before magnetization, the magnetic moment is aligned in the magnetization direction (C-axis direction) by magnetization, and by turning it into a single-domain state, it exhibits permanent magnet characteristics. Therefore, the intrinsic coercive force HcJ of an anisotropic sintered magnet represents the ability to keep the magnetic moments aligned in the same direction, and therefore the anisotropy of the RE 2 Fe 14 B-type tetragonal compound Increasing the magnetic field improves the intrinsic coercive force HcJ.
• the metal structure of the magnet alloy is uniformly refined and the exchange coupling that acts between particles is achieved.
• an isotropic nanocomposite magnet having a subphase of a ferromagnetic compound consisting of B and B can be obtained.
• the iron-based rare earth boron isotropic nanocomposite magnet of the present invention suppresses a significant decrease in the residual magnetic flux density Br, which cannot be achieved with conventional iron-based rare earth boron isotropic magnets.
• a high intrinsic coercive force HcJ can be obtained without addition of heavy rare earth elements such as Dy and Tb.
• the iron-based rare earth boron isotropic nanocomposite magnet alloy of the present invention which is characterized by a low boron content concentration, has a low residual magnetic flux density Br by replacing a portion of boron (B) with carbon (C). It has been found that the intrinsic coercive force HcJ can be improved without causing a decrease, and furthermore, by combining carbon (C) substitution and heavy rare earth element addition, the effect of improving the intrinsic coercive force HcJ can be increased.
• the alloy composition of the iron-based rare earth boron isotropic nanocomposite magnet alloy of the present invention is expressed by the composition formula T 100-xyz (B 1-n C n ) x RE y Zr z M m (T is Fe, Co, and Ni).
• the composition ratio x , y and z are respectively 4.2 atom% ⁇ x ⁇ 5.0 atom%, 12.5 atom% ⁇ y ⁇ 14.0 atom%, 0 atom% ⁇ z ⁇ 2.0 atom%, 0.0 It has a composition satisfying atomic % ⁇ m ⁇ 5.0 atomic % and 0.0 ⁇ n ⁇ 0.5.
• ICP mass spectrometry or fluorescent X-ray spectrometry is used to analyze the composition of the entire magnetic alloy according to the present invention.
• a combustion-infrared absorption method may be used in combination, if necessary.
• the transition metal element T containing Fe as an essential element occupies the remainder of the above-mentioned elements. Desired hard magnetic properties can also be obtained by replacing a part of Fe with one or both of Co and Ni, which are ferromagnetic elements like Fe. However, if the amount of substitution with respect to Fe exceeds 30%, the magnetic flux density will be significantly reduced, so the amount of substitution is preferably in the range of 0% or more and 30% or less. Note that the addition of Co not only contributes to improving magnetization, but also has the effect of lowering the viscosity of the molten metal and stabilizing the rate of pouring from the nozzle during rapid cooling of the molten metal, so the amount of Co replacement is 0. It is more preferable that it is .5% or more and 30% or less, and from the viewpoint of cost effectiveness, it is even more preferable that the Co substitution amount is 0.5% or more and 10% or less.
• the iron-based rare earth boron isotropic nanocomposite magnet alloy of the present invention when the composition ratio x of B+C becomes less than 4.2 atomic %, the amount of B+C required to generate a RE 2 Fe 14 B-type tetragonal compound decreases. As a result, the magnetic properties are deteriorated and the amorphous formation ability is greatly reduced, so that the ⁇ -Fe phase is precipitated during rapid solidification of the molten metal, and as a result, the squareness of the demagnetization curve is impaired.
• the composition ratio x of B+C exceeds 5.0 at%, RE containing phases richer in Fe than the main phase such as Fe 17 RE 2 phase and ⁇ -Fe phase and grain boundary phases mainly composed of Fe are formed. Since it is not generated and the intrinsic coercive force HcJ decreases, there is a possibility that the above-mentioned magnetic properties cannot be secured. Therefore, the composition ratio x is limited to a range of 4.2 atomic % or more and 5.0 atomic % or less.
• the composition ratio x is preferably 4.4 atomic % or more and 4.9 atomic % or less, and more preferably 4.5 atomic % or more and 4.9 atomic % or less.
• the substitution ratio of C to B exceeds 50%, it is not preferable because the ability to form an amorphous layer decreases significantly. Therefore, the substitution ratio of C to B is limited to a range of 0% or more and 50% or less, that is, 0.0 ⁇ n ⁇ 0.5.
• the substitution ratio of C to B is preferably 2% or more and 30% or less, and more preferably 3% or more and 15% or less.
• the composition ratio y of at least one rare earth element RE that necessarily includes at least Nd among Nd and Pr becomes less than 12.5 at%
• Fe 17 RE containing a phase richer in Fe than the main phase such as the RE 2 phase and the ⁇ -Fe phase and a grain boundary phase mainly composed of Fe may not be generated, and the above-mentioned magnetic properties may not be secured.
• the composition ratio y exceeds 14.0 at %, the magnetization decreases significantly. Therefore, the composition ratio y is limited to a range of 12.5 atomic % or more and 14.0 atomic % or less.
• composition ratio y is preferably 12.6 atomic % or more and 14.0 atomic % or less from the viewpoint of ensuring stability of the intrinsic coercive force HcJ, and from the viewpoint of ensuring a high residual magnetic flux density Br. More preferably, the content is 8 atomic % or more and 13.5 atomic % or less.
• Zr is an essential additive element for uniformly refining the magnet alloy and for generating a phase richer in Fe than the main phase at the grain boundary. If the composition ratio z of Zr exceeds 2.0 atom %, the magnetization will decrease and a residual magnetic flux density Br of 0.81 T or more cannot be obtained, so the composition ratio z should be in the range of 2.0 atom % or less. limited to.
• composition ratio z is preferably 0.6 atomic % or more and 2.0 atomic % or less from the viewpoint of improving the squareness of the demagnetization curve, and 0.6 atomic % or more and 2.0 atomic % or less from the viewpoint of ensuring a high residual magnetic flux density Br. More preferably, it is 7 atomic % or more and 1.5 atomic % or less.
• the iron-based rare earth boron isotropic magnet alloy of the present invention contains Al, Si, V, Cr, Ti, Mn, Cu, Zn, Ga, Nb, Mo, Ag, Hf, Ta, W, Pt, Au and One or more metal elements M selected from the group consisting of Pb may be added. Addition of metallic element M improves the amorphous formation ability, improves the intrinsic coercive force HcJ by making the metal structure uniform and fine after crystallization heat treatment, and improves the squareness of the demagnetization curve, improving magnetic properties. do.
• composition ratio m of these metal elements M exceeds 5.0 at%, the magnetization will decrease, so the composition ratio m is limited to a range of 0.0 at% or more and 5.0 at% or less. be done. Further, the composition ratio m is preferably 0.0 atomic % or more and 3.0 atomic % or less, and more preferably 0.0 atomic % or more and 2.0 atomic % or less.
• RE The average crystal grain size of the 2 Fe 14 B-type tetragonal compound is limited to a range of 10 nm or more and less than 70 nm.
• the average crystal grain size of the RE 2 Fe 14 B-type tetragonal compound is preferably 15 nm or more and 60 nm or less, more preferably 15 nm or more and 50 nm or less.
• the average crystal grain size of a RE 2 Fe 14 B-type tetragonal compound is determined by measuring the grain size of each particle at three or more locations using a transmission electron microscope (TEM) using the line segment method. means the average value of the equivalent circle diameter.
• TEM transmission electron microscope
• RE and Fe-based grains containing phases richer in Fe than the main phase such as the Fe 17 RE 2 phase and ⁇ -Fe phase, surrounding the main phase consisting of the RE 2 Fe 14 B-type tetragonal compound mentioned above.
• the width of the interphase is less than 1 nm, the bonding force acting between the main phase particles increases, leading to a decrease in the intrinsic coercive force HcJ.
• the width of the thickest part of the grain boundary phase becomes 150 nm or more, the interparticle bond becomes weaker, and the squareness of the demagnetization curve decreases.
• the width of the thickest part of the grain boundary phase is not necessarily limited, but is preferably 1 nm or more and less than 150 nm, more preferably 2 nm or more and 100 nm or less, and preferably 2 nm or more and 10 nm or less. More preferred.
• the width of the grain boundary phase was determined by performing image analysis on a bright field image taken using a scanning transmission electron microscope under conditions of an accelerating voltage of 200 kV and an observation magnification of 900,000 times.
• the composition ratio of the main phase to the grain boundary phase is such that the ratio of the main phase is 70% by volume or more and less than 99% by volume, and the ratio of the grain boundary phase is 1. It is preferably at least 30% by volume. This makes it easier to realize magnetic properties such as residual magnetic flux density Br: 0.81 T or more, intrinsic coercive force HcJ: 1200 kA/m or more but less than 1700 kA/m, and maximum energy product (BH) max: 110 kJ/m 3 or more.
• the main phase ratio is preferably 80 volume% or more and less than 99 volume%, and more preferably 90 volume% or more and less than 98 volume%.
• the composition ratio of the main phase and the grain boundary phase was determined by image analysis of a bright field image taken using a scanning transmission electron microscope at an acceleration voltage of 200 kV and an observation magnification of 900,000 times. Ta.
• the iron-based rare earth boron isotropic nanocomposite magnet alloy of the present invention has a residual magnetic flux density Br of 0.81 T or more and a maximum energy product (BH) max of 110 kJ/m 3 or more while It is possible to express an extremely high intrinsic coercive force HcJ of 1200 kA/m or more and less than 1700 kA/m, which has never been possible as an isotropic magnetic alloy based on iron-based rare earth boron.
• the characteristic coercive force HcJ of the system isotropic magnet is 1200 kA/m or less, which makes it difficult to apply it to various electric motors such as EVs and HEVs that require miniaturization and high heat resistance.
• the intrinsic coercive force HcJ is preferably 1200 kA/m or more, more preferably 1250 kA/m or more. Note that if the intrinsic coercive force HcJ is 1700 kA/m or more, the magnetizability is significantly reduced, so the intrinsic coercive force HcJ is preferably 1700 kA/m or less, more preferably 1600 kA/m or less.
• the residual magnetic flux density Br when an embedded magnet rotor (IPM type rotor) is adopted, it is possible to drive at a higher operating point (permeance) than the SPM type.
• the residual magnetic flux density Br is preferably 0.81T or more, and more preferably 0.82T or more. preferable.
• the residual magnetic flux density Br is set to 0.81T or more when applied to a DC brushless motor as an isotropic bonded magnet, the operating point (permeance Pc) of the magnet is about 3 or more and 10 or less. If the residual magnetic flux density Br ⁇ 0.81T, within this Pc range, the effective magnetic flux at 120°C in an anisotropic Nd-Fe-B sintered magnet with a maximum energy product (BH) max of 300 kJ/m 3 or more This is because Bm of the same level as Bm can be obtained. In addition, it is more preferable that the residual magnetic flux density Br is 0.82T or more.
• the reason why the intrinsic coercive force HcJ is set to 1200 kA/m or more is that when the intrinsic coercive force HcJ is less than 1200 kA/m, when applied to a DC brushless motor as an isotropic bonded magnet, the heat resistant temperature of the motor is guaranteed to be 120°C. This is because the desired motor characteristics may not be obtained due to thermal demagnetization.
• the reason why the intrinsic coercive force HcJ was set to less than 1700 kA/m is that when the intrinsic coercive force HcJ is 1700 kA/m or more, the magnetization property decreases significantly and the magnetic path becomes longer due to polar anisotropic magnetization. In this case, the magnetic path is not connected and the necessary effective magnetic flux Bm cannot be obtained.
• the reason why the maximum energy product (BH) max is set to 110 kJ/m 3 or more is that when the maximum energy product (BH) max is less than 110 kJ/m 3 , the squareness ratio of the demagnetization curve (residual magnetization Jr/saturation magnetization Js) is less than 0.8, so if it is applied to a DC brushless motor as an isotropic bonded magnet, the magnetic properties will deteriorate due to the reverse magnetic field generated during motor operation, and the desired motor characteristics may not be obtained. It is.
• the method for manufacturing the iron-based rare earth boron isotropic nanocomposite magnet alloy according to the present invention is based on the composition formula T 100-xyz (B 1-n C n ) x RE y Zr z M m (T is Fe, Co, and Ni).
• RE 2 is sprayed onto the surface of a rotating roll whose main component is Cu, Mo, W, or an alloy containing at least one of these metals at an average tapping rate of 200 g/min or more and less than 2000 g/min.
• the present invention is characterized by comprising a step of producing a rapidly solidified alloy having 1% by volume or more of either a crystalline phase containing an Fe 14 B phase or an amorphous phase.
• RE is at least one rare earth element that does not substantially contain La and Ce, but as an example, as described above, it is at least one rare earth element that necessarily contains at least Nd among Nd and Pr. be able to. The details are as described above.
• the average melting rate per orifice provided at the tip of the nozzle is limited to a range of 200 g/min or more and less than 2000 g/min.
• the average hot water tapping rate is preferably 300 g/min or more and 1500 g/min or less, more preferably 400 g/min or more and 1300 g/min or less.
• the hole placed at the tip of the nozzle for tapping the molten metal does not have to be a circular orifice; it can be square, triangular, elliptical, etc., regardless of its shape, as long as the hole shape can ensure the specified metal tapping rate.
• the nozzle material is acceptable as long as it is a refractory material that does not react or does not easily react with the molten alloy, but it is preferably a ceramic material, SiC, C, or BN, which has less wear on the nozzle orifice due to the molten metal during tapping. BN is more preferred, and hard BN containing additives is even more preferred.
• the rapidly solidified atmosphere is preferably an oxygen-free or low-oxygen atmosphere because by preventing oxidation of the molten alloy, the increase in molten metal viscosity can be suppressed and a stable tapping rate can be maintained.
• the inside of the rapid solidification equipment is evacuated to 20 Pa or less, preferably 10 Pa or less, more preferably 1 Pa or less, and then an inert gas is introduced into the rapid solidification equipment. It is necessary to carry out rapid solidification with the oxygen concentration at 500 ppm or less, preferably 200 ppm or less, more preferably 100 ppm or less.
• rare gases such as helium and argon, and nitrogen can be used, but since nitrogen reacts relatively easily with rare earth elements and iron, rare gases such as helium and argon are preferable, and from the viewpoint of cost. Argon gas is more preferred.
• the rotating roll that rapidly cools the molten alloy has Cu, Mo, W, or an alloy containing at least one of these metals as a main component. It is preferable to have a material. This is because these base materials have excellent thermal conductivity and durability.
• the heat resistance and hardness of the base material surface of the rotating roll can be increased, and the melting and hardening of the base material surface of the rotating roll during rapid solidification can be prevented. Deterioration can be suppressed.
• the diameter of the rotating roll is, for example, ⁇ 200 mm or more and ⁇ 20000 mm or less.
• the rapid solidification time is short, 10 seconds or less, there is no need to water-cool the rotating roll, but if the rapid solidification time exceeds 10 seconds, flow cooling water inside the rotating roll to suppress the temperature rise of the rotating roll base material. It is preferable to do so. It is preferable that the water cooling capacity of the rotating roll is calculated according to the latent heat of solidification per unit time and the tapping rate, and is optimally adjusted as appropriate.
• the method for producing the iron-based rare earth boron isotropic nanocomposite magnet alloy of the present invention includes heating the above-mentioned rapidly solidified alloy at a temperature increasing rate of 10°C/sec or more and less than 200°C/sec to a temperature higher than the crystallization temperature. , further comprising the step of performing flash annealing to reach a certain temperature range of 850° C. or less and then rapidly cooling after 0.1 sec or more and less than 7 min .
• the main phase is an RE 2 Fe 14 B-type tetragonal compound having a B content concentration lower than the stoichiometric composition of the compound and an average crystal grain size of 10 nm or more and less than 70 nm, and Fe 17 surrounding the main phase.
• the temperature increase rate during flash annealing is less than 10° C./sec, a fine metal structure cannot be obtained due to excessive grain growth, leading to a decrease in the intrinsic coercive force HcJ and residual magnetic flux density Br. If the temperature increase rate is 200°C/sec or more, crystal grain growth will not be in time, and the main phase will be a RE 2 Fe 14 B-type tetragonal compound with an average crystal grain size of 10 nm or more and less than 70 nm, which is necessary to develop a permanent magnet.
• the temperature increase rate is preferably 10 °C/sec or more and less than 200 °C/sec, more preferably 30 °C/sec or more and 200 °C/sec or less, and 40 °C/sec or more and 180 °C/sec or more. It is more preferable that it is less than sec.
• the holding time is preferably 0.1 sec or more and less than 7 min, more preferably 0.1 sec or more and 2 min or less, and even more preferably 0.1 sec or more and 30 sec or less.
• the rapidly solidified alloy is heated to 400°C at a cooling rate of 2°C/sec or more and 200°C/sec or less. It is preferable to cool down to below. If the cooling rate is less than 2°C/sec, the crystal structure will become coarser, and if it exceeds 200°C/sec, the alloy may be oxidized. Therefore, the temperature decreasing rate is preferably 2°C/sec or more and 200°C/sec or less, more preferably 5°C/sec or more and 200°C/sec or less, and 5°C/sec or more and 150°C/sec. It is more preferable that it is the following.
• the atmosphere for the above flash annealing is preferably an inert gas atmosphere in order to prevent oxidation of the rapidly solidified alloy.
• inert gas rare gases such as helium and argon, and nitrogen can be used, but since nitrogen reacts relatively easily with rare earth elements and iron, rare gases such as helium and argon are preferable, and from the viewpoint of cost. Argon gas is more preferred.
• the method for producing a powder made of an iron-based rare earth boron isotropic nanocomposite magnet alloy of the present invention includes grinding the above rapidly solidified alloy or the above rapidly solidified alloy subjected to the flash annealing.
• the method may further include a step of producing an isotropic nanocomposite magnet alloy powder.
• the rapidly solidified alloy obtained through the above steps may be roughly cut or crushed into strips of, for example, 50 mm or less, before flash annealing (crystallization heat treatment). Furthermore, by pulverizing the magnet alloy of the present invention after flash annealing (crystallization heat treatment) to a suitable average powder particle size in the range of 20 ⁇ m or more and 200 ⁇ m or less, the above magnet Various resin-bonded permanent magnets (commonly known as plastic magnets or bonded magnets) can be manufactured using alloy powder through known processes.
• the method for producing a resin-bonded permanent magnet of the present invention is a step of preparing an iron-based rare earth boron isotropic nanocomposite magnet alloy powder produced by the above method for producing an iron-based rare earth boron isotropic nanocomposite magnet alloy. After adding a thermosetting resin to the above iron-based rare earth boron-based isotropic nanocomposite magnet alloy powder, the mixture is filled into a mold and compressed to form a compression molded body. and a step of heat treatment at a temperature higher than the polymerization temperature.
• the method for producing a resin-bonded permanent magnet of the present invention is a step of preparing an iron-based rare earth boron isotropic nanocomposite magnet alloy powder produced by the above method for producing an iron-based rare earth boron isotropic nanocomposite magnet alloy. and a step of adding a thermoplastic resin to the iron-based rare earth boron-based isotropic nanocomposite magnet alloy powder to prepare an injection molding compound, and then injection molding the compound.
• iron-based rare earth nanocomposite magnet powder is mixed with epoxy, polyamide, polyphenylene sulfide (PPS), liquid crystal polymer, acrylic, polyether, etc., and molded into a desired shape.
• PPS polyphenylene sulfide
• hybrid magnet powder may be used, which is a mixture of permanent magnet powder such as SmFeN magnet powder and hard ferrite magnet powder.
• the magnet alloy powder of the present invention When used for injection molded bonded magnets, it is preferably ground so that the average particle size is 100 ⁇ m or less, and the more preferable average crystal grain size of the powder is 20 ⁇ m or more and 100 ⁇ m or less.
• resin-bonded permanent magnets can be molded regardless of the molding method. It is possible to improve the moldability during processing and the corrosion resistance and heat resistance of the resulting resin-bonded permanent magnet. In addition, even if surface treatments such as resin coating, chemical conversion treatment, or plating are applied to the surface of a resin-bonded permanent magnet after molding, the corrosion resistance and heat resistance of the resin-bonded permanent magnet will be affected in the same way as the surface treatment of magnet alloy powder. can be improved.
• the method for producing the iron-based rare earth boron isotropic nanocomposite magnet alloy of the present invention is not limited to the above-mentioned method, and can be used to produce an iron-based rare earth boron isotropic magnet having the above-mentioned composition, average crystal grain size, etc.
• Other manufacturing methods can be used if the alloy can be manufactured. For example, by using flash annealing, it is possible to form a fine metal structure whose main phase is a RE 2 Fe 14 B-type tetragonal compound with an average crystal grain size of 10 nm or more and less than 70 nm.
• the method is not limited to flash annealing, and other methods can also be used.
• the surface speed of the rotating roll that rapidly cools the molten alloy may be adjusted, and the rapidly solidified alloy structure may be adjusted to 50% higher than the alloy structure that provides optimal magnetic properties.
• Good magnetic properties can be obtained when a homogeneous fine metal structure is formed of crystal grains that are about 20% smaller.
• the bottom part is divided into appropriately different diameters (0.
• the sample was set in a work coil in a single-roll quenching device.
• argon gas was introduced to the quenching atmosphere pressure shown in Table 1, and the master alloy was remelted by high-frequency induction heating.
• the molten alloy was discharged from a nozzle orifice at a spray pressure of 30 kPa onto the surface of a rotating roll rotating at a roll surface speed (Vs) of 30 kPa to produce a rapidly solidified alloy.
• Vs roll surface speed
• the distance between the nozzle tip and the rotating roll surface was set to 0.8 mm.
• the main component of the rotating roll was copper.
• the obtained rapidly solidified alloy had either a crystalline phase containing the Nd 2 Fe 14 B phase or an amorphous phase at 1% by volume or more.
• FIG. 4 shows a powder X-ray diffraction profile of the rapidly solidified alloy obtained in Example 9. From FIG. 4, the presence of the Nd 2 Fe 14 B phase was already confirmed in the rapidly solidified state.
• the rapidly solidified alloy obtained in the above process is coarsely pulverized to a size of several mm or less to form a rapidly solidified alloy powder, and then heated in a flash annealing furnace (crystallization heat treatment furnace, furnace tube: made of transparent quartz, outer diameter 15 mm x inner diameter 12.5 mm). ⁇ length 1000 mm, heating zone 300 mm, cooling zone 500 mm by cooling fan), the coarse powder of the rapidly solidified alloy was introduced into the raw material hopper, and heat treatment was performed at a work cut-out speed of 20 g/min.
• the inclination angle of the furnace tube, the rotation speed of the furnace tube, and the vibration frequency of the furnace tube were appropriately adjusted along with the heat treatment temperature and heat treatment time shown in Table 2 so that the temperature increase rate shown in Table 2 was obtained.
• the rapidly solidified alloy powder passes through the furnace tube while moving through a combination of stirring due to the rotating motion of the furnace core tube and hopping phenomenon due to the vibration of the furnace tube, so that the rapidly solidified alloy powder is not solidified as a single piece, but as a powder. They were placed under unique heat treatment conditions where they were individually subjected to thermal history. Examples of the heat treatment furnace and heat history in the flash annealing process are shown in FIGS. 2 and 3, respectively.
• FIG. 5 shows a powder X-ray diffraction profile of the rapidly solidified alloy obtained in Example 9 after flash annealing (crystallization heat treatment).
• the peak of the Fe 17 RE 2 phase which was not seen in Figure 4, can be seen in Figure 5 after flash annealing (crystallization heat treatment), indicating that the composite in which the Nd 2 Fe 14 B phase and the Fe 17 RE 2 phase are mixed. The organization was confirmed.
• FIG. 6 shows an elemental mapping image obtained in Example 24 as a representative example.
• the left image of FIG. 6 is a bright-field STEM image, where the main phase and grain boundary phase are visible.
• the right diagram in FIG. 6 is a mapping image of Fe, and it can be confirmed that Fe is rich in the position corresponding to the grain boundary phase in the left diagram.
• the width of the thickest portion of the grain boundary phase was 1 nm or more and less than 150 nm.
• the grain boundary phase observed in Example 24 had various thicknesses, but the width of the thickest part was 2 nm to 117 nm.
• the composition ratio of the main phase to the grain boundary phase is such that the ratio of the main phase is 70 volume % or more and less than 99 volume %, and the ratio of the grain boundary phase is 1 volume % or more and less than 30 volume %. Met.
• the ratio of the grain boundary phase was 18 volume %, and the ratio of the main phase was 82 volume %.
• An iron-based rare earth boron isotropic magnet alloy obtained by flash annealing (crystallization heat treatment) as shown in Table 2 is used to measure approximately 7 mm in length x approximately 0.9 mm or more in width and 2.3 mm or less in width and 18 ⁇ m or more in thickness.
• After preparing a sample for evaluating magnetic properties of 25 ⁇ m or less it was magnetized in the longitudinal direction with a pulsed magnetic field of 3.2 MA/m. Thereafter, in order to suppress the influence of the demagnetizing field, the sample for evaluating magnetic properties was set in the longitudinal direction, and the room temperature magnetic properties were measured using a vibrating sample magnetometer (VSM). Table 3 shows the results.
• Example 9 the flash annealed (crystallization heat treated) magnetic powder obtained in Example 9 was pulverized using a pin disk mill to have an average particle size of 125 ⁇ m. Then, 2 mass% of epoxy resin diluted with methyl ethyl ketone (MEK) was added to the pulverized magnetic powder, mixed and kneaded, and then 0.1 mass% of calcium stearate was added as a lubricant to prepare a compound for compression molded bonded magnets.
• MEK methyl ethyl ketone
• the above compression-molded bonded magnet compound was compression-molded at a pressure of 1568 MPa (16 ton/cm 2 ) to obtain a compression-molded body having a shape of 10 mm in diameter x 7 mm in height.
• An isotropic compression-molded bonded magnet was obtained by performing curing heat treatment at 180° C. for 1 hour in a gas atmosphere.
• the compact density of the obtained isotropic compression molded bonded magnet was 6.3 g/cm 3 (true specific gravity of magnetic powder 7.5 g/cm 3 )
• the magnetic powder filling rate was 84 volume %. .
• the magnetic properties of the isotropic compression molded bonded magnet obtained using the magnetic powder of Example 9 were measured with a BH tracer after being magnetized in the longitudinal direction with a pulsed magnetic field of 3.2 MA/m. , residual magnetic flux density Br: 0.71 T, intrinsic coercive force HcJ: 1223 kA/m, and maximum energy product (BH) max: 82.2 kJ/m 3 .
• the flash annealed (crystallization heat treated) magnetic powder obtained in Example 9 was pulverized using a pin disk mill to have an average particle size of 75 ⁇ m. Then, while heating and stirring the pulverized magnetic powder, a titanate coupling agent was sprayed to a concentration of 0.75 mass% to perform a coupling treatment, and stearic acid amide was added as a lubricant to 0.5 mass%, and nylon 12 resin powder 4. After adding and mixing .75 mass%, a compound for injection molded bonded magnets was produced at an extrusion temperature of 170° C. using a continuous extrusion kneader.
• Injection molding was performed using the above compound for injection molded bonded magnets at an injection temperature of 250° C. to produce an isotropic injection molded bonded magnet having a shape of 10 mm in diameter x 7 mm in height.
• the compact density of the obtained isotropic injection molded bonded magnet was 4.6 g/cm 3 (true specific gravity of magnetic powder 7.5 g/cm 3 )
• the magnetic powder filling rate was 61 volume %. .
• the magnetic properties of the isotropic injection molded bonded magnet obtained using the magnetic powder of Example 9 were measured with a BH tracer after being magnetized in the longitudinal direction with a pulsed magnetic field of 3.2 MA/m. , residual magnetic flux density Br: 0.51T, intrinsic coercive force HcJ: 1218kA/m, maximum energy product (BH) max: 60.1kJ/ m3 , and is a general-purpose isotropic material despite injection molding. It was found that magnetic properties equivalent to those of a compression-molded bonded Nd-Fe-B magnet can be obtained.
• the bottom part is divided into appropriately different diameters (0.
• the sample was set in a work coil in a single-roll quenching device.
• argon gas was introduced to the quenching atmosphere pressure shown in Table 1, and the master alloy was remelted by high-frequency induction heating.
• the molten alloy was discharged from a nozzle orifice at a spray pressure of 30 kPa onto the surface of a rotating roll rotating at a roll surface speed (Vs) of 30 kPa to produce a rapidly solidified alloy.
• Vs roll surface speed
• the distance between the nozzle tip and the rotating roll surface was set to 0.8 mm.
• the rapidly solidified alloy obtained in the above process is coarsely pulverized to a size of several mm or less to form a rapidly solidified alloy powder, and then heated in a flash annealing furnace (crystallization heat treatment furnace, furnace tube: made of transparent quartz, outer diameter 15 mm x inner diameter 12.5 mm). ⁇ length 1000 mm, heating zone 300 mm, cooling zone 500 mm by cooling fan), the coarse powder of the rapidly solidified alloy was introduced into the raw material hopper, and heat treatment was performed at a work cut-out speed of 20 g/min.
• the inclination angle of the furnace tube, the rotation speed of the furnace tube, and the vibration frequency of the furnace tube were appropriately adjusted along with the heat treatment temperature and heat treatment time shown in Table 2 so that the temperature increase rate shown in Table 2 was obtained.
• FIG. 7 shows a powder X-ray diffraction profile of the rapidly solidified alloy after flash annealing (crystallization heat treatment) obtained in Comparative Example 7. From FIG. 7, it was confirmed that Comparative Example 7 had a single-phase metal structure with the Nd 2 Fe 14 B phase as the main phase.
• elemental mapping also shows that a grain boundary phase enriched with Fe and RE as seen in Example 9 exists at the grain boundaries of the main phase consisting of the main constituent elements of Nd, Fe, and B. I found out that there isn't. This point was also the same in other comparative examples.
• An iron-based rare earth boron isotropic magnet alloy obtained by flash annealing (crystallization heat treatment) as shown in Table 2 is used to measure approximately 7 mm in length x approximately 0.9 mm or more in width and 2.3 mm or less in width and 18 ⁇ m or more in thickness.
• After preparing a sample for evaluating magnetic properties of 25 ⁇ m or less it was magnetized in the longitudinal direction with a pulsed magnetic field of 3.2 MA/m. Thereafter, in order to suppress the influence of the demagnetizing field, the sample for evaluating magnetic properties was set in the longitudinal direction, and the room temperature magnetic properties were measured using a vibrating sample magnetometer (VSM). Table 3 shows the results.
• the alloy compositions described in Comparative Examples 1 to 12 have the magnetic properties of Br: 0.81T or more, HcJ: 1200kA/m or more, less than 1700kA/m, and (BH)max: 110kJ/m 3 or more. It was found that it could not be obtained by using the above and manufacturing methods.
• the residual magnetic flux density Br and the intrinsic coercive force HcJ are in a trade-off relationship, and it is difficult to achieve both a high residual magnetic flux density Br and a high intrinsic coercive force HcJ.
• the width of the thickest part of the grain boundary phase is 1 nm or more and less than 150 nm
• the exchange interaction works effectively and can improve the properties of both.
• Example 11 and Comparative Example 5 have comparable high intrinsic coercivity HcJ, but Example 11 achieves a higher residual magnetic flux density Br than Comparative Example 5.

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