EP0633581B1 - R-Fe-B permanent magnet materials and process of producing the same - Google Patents

R-Fe-B permanent magnet materials and process of producing the same Download PDF

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Publication number
EP0633581B1
EP0633581B1 EP93308184A EP93308184A EP0633581B1 EP 0633581 B1 EP0633581 B1 EP 0633581B1 EP 93308184 A EP93308184 A EP 93308184A EP 93308184 A EP93308184 A EP 93308184A EP 0633581 B1 EP0633581 B1 EP 0633581B1
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atomic
permanent magnet
accordance
producing
alloy
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German (de)
English (en)
French (fr)
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EP0633581A1 (en
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Yuji Kaneko
Naoyuki Ishigaki
Koki Tokuhara
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Proterial Ltd
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Sumitomo Special Metals Co Ltd
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Priority claimed from JP19288693A external-priority patent/JP3415208B2/ja
Priority claimed from JP20719193A external-priority patent/JP3151088B2/ja
Priority claimed from JP20719093A external-priority patent/JP3151087B2/ja
Priority claimed from JP5207192A external-priority patent/JPH0745412A/ja
Priority claimed from JP21217193A external-priority patent/JP3299000B2/ja
Application filed by Sumitomo Special Metals Co Ltd filed Critical Sumitomo Special Metals Co Ltd
Publication of EP0633581A1 publication Critical patent/EP0633581A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0573—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 obtained by reduction or by hydrogen decrepitation or embrittlement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/02—Compacting only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/02—Compacting only
    • B22F3/04—Compacting only by applying fluid pressure, e.g. by cold isostatic pressing [CIP]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2202/00—Treatment under specific physical conditions
    • B22F2202/05—Use of magnetic field
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

  • the present invention relates to permanent magnet materials composed mainly of R (where R represents at least one rare earth element), Fe and B, and a process of producing the same, particularly, it relates to R-Fe-B permanent magnet materials and to processes of producing the same.
  • R represents at least one rare earth element
  • Fe and B a rare earth element
  • Such materials are typically powdered and then molded into shape and sintered to form magnets.
  • an R-Fe-B permanent magnet (Japanese Patent Application Laid Open No. Sho 59-46008), is typically used as a high performance permanent magnet.
  • a high magnetic characteristic is obtained by a magnet material structure having a main phase of ternary tetragonal compounds and an R-rich phase, and such magnets are used in a broad field from general domestic electric appliance to peripheral equipment of large-sized computers.
  • R-Fe-B permanent magnets having various structures have been proposed so as to exhibit various magnetic characteristics depending on their proposed uses.
  • the residual magnetic flux density (Br) of an Fe-B sintered magnet can be expressed as the following Equation (1).
  • Equation (1) Br ⁇ (Is• ⁇ )•f• ⁇ / ⁇ 0 •(1- ⁇ ) ⁇ 2/3
  • the volume fraction of the R 2 Fe 14 B matrix phase may be increased, (2) the density of the magnet may be raised to the theoretical maximum density, and further, 3) the degree of orientation of the main phase crystal grains in a easily magnetizing axial direction may be enhanced.
  • the item 3 it is usual in a process of producing an R-Fe-B permanent magnet, to adopt a process of press molding in the magnetic field in order to make the direction of the easy magnetization axes of the main phase crystal grains uniform.
  • the residual magnetic flux density (Br) value and the value of the squareness of the demagnetization curve ⁇ (Br2/4(BH)max ⁇ change depending on the direction of magnetic field application and the pressing direction, and are influenced by the applied magnetic field intensity.
  • a cast piece having a specific thickness is formed from an R-Fe-B molten alloy by the double roll casting method, and according to a common powder metallurgical process, the cast piece is ground coarsely by means of a stamp mill, a jaw crusher or the like, and then comminuted into powders having a mean grain size of 3 to 5 ⁇ m by a mechanical pulverizing process in a disk mill a ball mill, grinder, a jet mill or the like, and thereafter pressed in a magnetic field, sintered, and annealed.
  • the pulverizing efficiency at the time of pulverization can not be improved significantly.
  • magnetic characteristics can not be greatly improved at the time of pulverization, because not only grain boundary pulverization but also intergranular pulverization occurs, and since the R-rich phase is not in a RH 2 phase stable against oxidation, or since the R-rich phase is fine and has a large surface area, it is poor in oxidation resistance, with the result that oxidation proceeds during the process and high magnetic characteristics can not be obtained.
  • Enhancement of the residual magnetic flux density (Br) of an R-Fe-B sintered magnet can be achieved by increasing a content of the R 2 Fe 14 B phase of the main phase which is the ferro-magnetic phase. That is, it is important to make the magnet composition close to the stoichiometric composition of R 2 Fe 14 B.
  • the alloy ingot prepared by melting the alloy having the aforementioned composition and casting in the mold, as the starting material, particularly as ⁇ -Fe crystallized in the alloy ingot and the R-rich phase is locally present throughout, the alloy is difficult to pulverize and has discrepancies in composition.
  • the B-rich phase and the R-rich phase are indispensable phases for producing a dense R-Fe-B sintered magnet.
  • an R-Fe-B permanent magnet material as defined in Claim 1 hereof.
  • an R-rich phase which is finely dispersed produces hydrides to cause volume expansion and eventual spontaneous decay of the alloy, thereafter the main phase crystal grains constituting the alloy can be comminuted and the powder having a uniform grain distribution can be produced.
  • the R-rich phase is finely dispersed and the R 2 Fe 14 B phase is also comminuted, thus when the alloy powder which is dehydrogenated and stabilized is comminuted production efficiency is greatly improved, and by orientation using a pulsed magnetic field and pressing, the R-Fe-B permanent magnet of excellent magnetic properties can be obtained.
  • the present invention also provide various processes for the production of such a magnet material. These processes are defined in Claims 9, 11 and 18 hereof.
  • an alloy of the desired final composition is directly strip cast and further processed by hydrogenation, dehydrogenation, comminution, magnetic orientation, molding, sintering and annealing.
  • a main phase base alloy and an adjusting alloy are produced separately, and then after hydrogenation, dehydrogenation and comminution the resulting powders are blended together prior to magnetic orientation, molding, sintering and annealing.
  • an adjusting alloy powder containing a Nd 2 Fe 17 phase obtained by the strip casting process with the R-Fe-B alloy powder containing the R 2 Fe 14 B phase as the main phase also obtained by the strip casting process, due to the reaction between the Nd 2 Fe 17 phase in the adjusting alloy powder and the B-rich and Nd-rich phase in the main phase of R-Fe-B alloy powder, the B-rich phase and Nd-rich phase which are deleterious for permanent magnetic characteristics can be adjusted and decreased, the resulting magnet performance can be improved, and further, oxygen content in the alloy powder can be reduced, and an alloy powder having a composition responsive to various magnetic characteristics is provided easily.
  • an adjusting alloy powder containing an R-Co intermetallic compound phase obtained by the strip casting process with an R-Fe-B alloy powder containing the R 2 Fe 14 B phase as the main phase obtained by the strip casting process, even when the liquid-phase sintering can not be effected only by the main phase of R-Fe-B alloy powder due to the shortage of R-rich and B-rich phases, the R-Co intermetallic compound phase of the adjusting alloy powder is melted to supply a liquid phase for high densification thus the resulting magnet performance can be improved, and further, oxygen content in the alloy powder can be decreased and an alloy powder having a composition responsive to various magnetic characteristics is again provided easily.
  • Fig. 1 is an explanatory view of a press machine, in which a pulse magnetic field and a static magnetic field can be applied together.
  • Fig. 2 is a graph showing the relationship between time and magnetic field intensity of a pulse magnetic field.
  • the R-rich phase is finely dispersed and the R 2 Fe 14 B phase is also fine. Furthermore, in a process of making the alloy ingot by using a usual mold, when the alloy composition is brought close to the stoichiometric composition of the R 2 Fe 14 B phase, crystallization of ⁇ -Fe primary crystals is unavoidable, causing a large deterioration of the pulverizing efficiency in the following process. And hence, though means for providing heat treatment and eliminating ⁇ -Fe is taken to homogenize the alloy ingot, since the main phase crystal grains become coarse and segregation of the R-rich phase proceeds, iHc of the sintered magnet is only improved with difficulty.
  • a molten alloy consisting of 12 atomic % to 16 atomic % R (where, R represents at least one rare earth element), 4 atomic % to 8 atomic % B, 5000 ppm or less O 2 , Fe (of which a part is optionally replaced by one or both of Co and Ni) and unavoidable impurities, into a cast piece whose main phase is an R 2 Fe 14 B phase, the cast piece is contained in a pressure vessel which can take in and discharge air, the air in the pressure vessel is replaced by hydrogen for hydrogenation of the cast piece.
  • the cast material is then dehydrogenated, and is thereafter comminuted into a fine powder of 1 ⁇ m to 10 ⁇ m mean particle size under an inert gas, the fine powder is packed into a mold and oriented by applying the pulse magnetic field of 10 kOe (796 kA/m) or more instantaneously, then molded, sintered and annealed, thereby to obtain a permanent magnet material which has magnetic properties such that when the maximum energy product value is expressed in kJ/m 3 and the coercive force iHc is measured in kA/m, the total value [(BH)max ⁇ 7.96]+ [iHc ⁇ 79.6] is 59 or more, and such that when the residual magnetic flux density (Br) is measured in tenths of one Tesla (kiloGauss), the squareness of the demagnetization curve ⁇ (Br 2 ⁇ 1.99)/(BH)max ⁇ is 1.01 to 1.045
  • an R 2 Fe 17 phase in an R-Fe alloy such as a Nd-Fe alloy is an intermetallic compound having an easily magnetizing direction in a C phase when its Curie point is in the vicinity of room temperature, and conventionally, in an R-Fe-B sintered permanent magnet, when the amount of B is less than 6 atomic %, for example, an R 2 Fe 17 phase is produced in the magnet and this weakens its coercivity.
  • an adjusting alloy powder containing the Nd 2 Fe 17 phase and the R-Fe-B alloy powder containing the R 2 Fe 14 B phase as the main phase react as follows during the sintering, and act to increase the R 2 Fe 14 B phase as the main phase. 13/17 Nd 2 Fe 17 + 1/4 Nd 1.1 Fe 4 B 4 + 133/680 Nd ⁇ Nd 2 Fe 14 B
  • the Nd 2 Fe 14 B phase is newly produced by a reaction between the Nd 2 Fe 17 phase in the adjusting alloy powder and the B-rich phase and Nd-rich phase in the main phase R-Fe-B alloy powder, in a permanent magnet obtained by using only the alloy powder containing the R 2 Fe 14 B phase as the main phase of the conventional process, the amount of the B-rich phase and Nd-rich phase (which is one of the factors deleterious for magnetic characteristics) can be reduced at the time of the sintering reaction.
  • R-Fe-B permanent magnet material powders may be obtained by mixing a necessary amount of main phase alloy powder containing the R 2 Fe 14 B phase as its main phase and an adjusting alloy powder containing the R 2 Fe 17 phase also obtained by rapid cooling and solidifying of a molten alloy formed by the strip casting process.
  • reasons for producing the main phase alloy powder and adjusting alloy powder from the alloy obtained by the strip casting process in the present invention are that, by strip casting, a main phase alloy powder can be obtained from an alloy cast piece, in which the R 2 Fe 14 B main phase is fine and the B-rich phase and Nd-rich phases are sufficiently dispersed, and in which crystallization of Fe primary crystals is suppressed, and furthermore, an adjusting alloy powder in which the R 2 Fe 17 phase is dispersed uniformly can be obtained from a strip cast alloy piece.
  • the R 2 Fe 14 B phase is fine and the B-rich phase and R-rich phase are uniformly dispersed in the main phase material powders, pulverizing is improved considerably, and a powder having a uniform particle distribution can be obtained. Furthermore, when producing the magnet, since the crystal structure is fine, a high coercive force is obtained.
  • an advantage of producing the adjusting alloy powder containing the R 2 Fe 17 phase by the strip casting process is that, since the R 2 Fe 17 phase can be made fine and dispersed sufficiently at the time of mixing with the main phase alloy powder, the reaction takes place uniformly.
  • the alloy ingot In the usual alloy melting process using a mold, since ⁇ -Fe and the other R-Fe (Co) compound phase are crystallized on the resulting alloy ingot, in order to obtain stable material alloy powders, the alloy ingot must be heated and homogenized, causing the production cost ofthe alloy powder to increase and the R 2 Fe 17 phase to grow.
  • the adjusting alloy powder by a direct reducing and diffusing process, such problems are encountered that, unreacted Fe grains remain or individual grain compositions differ from each other, and it is very difficult to homogenize the mixture of alloy powders.
  • an alloy powder made close to the stoichiometric composition of the R 2 Fe 14 B phase can be liquid-phase sintered.
  • the magnet composition can be made close to the stoichiometric composition of the R 2 Fe 14 B phase.
  • the Nd-rich phase serving as a supply source of the liquid phase produces Nd-oxides during the process by unavoidable material oxidation, so that the amount of liquid phase necessary for sintering can not be secured.
  • a high sufficiently densification can not be achieved, so that the composition must be set in advance with some tolerance margins. Any such deviations from the optimum composition can be reduced or even eliminated by the present invention.
  • the R 2 Fe 14 B phase in the main phase material powders is fine and the B-rich phase and Nd-rich phase are dispersed uniformly, the comminution is considerably improved at the time of producing the magnet, and a powder having a uniform grain distribution can be produced. Furthermore, since the crystal structure is fine, a high coercivity can be obtained when producing the magnet. Particularly, even when the alloy powder composition is made close to the stoichiometric composition of the R 2 Fe 14 B phase, crystallization of the ⁇ -Fe primary crystal is eliminated and a uniform structure is obtained.
  • advantages of producing the adjusting alloy powder containing the R-Co intermetallic compound phase by the strip casting process are that, such problems as follow can be solved.
  • the Co(Fe) phase and the other R-Co(Fe) compound phase are crystallized in the resulting alloy ingot, and the phases are locally present throughout, therefore, in order to obtain stable material alloy powders, the alloy ingot must be heated and homogenized, causing increase in the production cost of the alloy powder.
  • un-reacted Co and Fe grains remain or individual grain compositions differ from each other, thus it is very difficult to homogenize that whole alloy powder.
  • Magnetic characteristics of the R-Fe-B permanent magnet according to the present invention are achieved as follows: when the maximum energy product value (BH)max is expressed in kJ/m 3 , and the coercive force iHc is expressed in kA/m, the total value ( BH ) max 7.96 + iHc 79.6 ⁇ 59 ; and also, when the residual magnetic flux density (Br) is expressed in tenths of one Tesla, (kiloGauss) the squareness of the demagnetization curve ⁇ (Br 2 ⁇ 1.99)/(BH)max ⁇ has a value of between 1.01 and 1.045.
  • a + B is 59 or more, in which A is a maximum energy product value (BH) max expressed in MGOe and B is a coercive force iHc expressed in kOe, and that the squareness of demagnetization curve ⁇ (Br 2 /4A ⁇ value is 1.01 to 1.045 (Br being expressed in tenths of one Tesla [kG]), and A again being a maximum energy product value (BH) max expressed in MGOe.
  • BH maximum energy product value
  • composition and production conditions suitably, the necessary magnetic characteristics are obtained.
  • a cast piece of the magnet materials having a structure in which the main R 2 Fe 14 B phase and the R-rich phase are finely separated is produced by strip casting a molten alloy having a specific composition by a single roll process or a double roll process.
  • the resulting cast piece is a sheet whose thickness is 0.03 mm to 10 mm.
  • the single roll process and the double roll process may both be used depending on the desired thickness of the cast piece, the double roll process is preferably adopted when the plate thickness is thick, and the single roll process is preferably used when the plate thickness is thin.
  • a sectional structure of the R-Fe-B alloy having a given composition obtained by the strip casting process is such that, the main phase R 2 Fe 14 B crystal size is finer than about one tenth or more as compared with that of a conventional ingot obtained by casting in a mold.
  • crystal sizes are 0.1 ⁇ m to 50 ⁇ m in a short axial direction and 5 ⁇ m to 200 ⁇ m in a long axial direction, and the R-rich phase is finely dispersed surrounding the main phase crystal grain, and even in local regions, the size is below 20 ⁇ m.
  • Crystal grains of the main phase alloy powder and the adjusting alloy powder obtained by the strip casting process have the same properties.
  • Rare earth elements which may constitute R contained in the permanent magnet alloy ingot of the present invention may contain yttrium (Y), and are the rare earth elements including light rare earths and heavy rare earths.
  • the light rare earths are sufficient, and particularly, Nd and Pr are preferable. Though, usually, one kind of R is sufficient, in practice, mixtures (such as mischmetal, didymium, etc.) of two or more rare earth elements will often be used for the reason of availability, and Sm, Y, La, Ce, Gd etc. can be used as a mixture with other R, particularly, Nd, Pr and the like.
  • the R is not necessarily made up of pure rare earth element(s), and those containing unavoidable impurities in production may be used according to what is commercially available.
  • R is an indispensable element of the alloy for producing the R-Fe-B permanent magnet, in that sufficiently high magnetic characteristics cannot be obtained below 12 atomic %, particularly, a high coercive force can not be obtained, and when exceeding 16 atomic %, the residual magnetic flux density (Br) is lowered and a permanent magnet having the best characteristics can not be obtained. And hence, R is within the range of 12 atomic % to 16 atomic %, the optimum range being 12.5 atomic % to 14 atomic %.
  • B is an indispensable element of the alloy for producing the R-Fe-B permanent magnet, whereby the high coercive force (iHc) cannot be obtained below 4 atomic %, and when exceeding 8 atomic %, the residual magnetic flux density (Br) is lowered, so that the best permanent magnet cannot be obtained. And hence, the B is 4 atomic % to 8 atomic %, the optimum range being 5.8 atomic % to 7 atomic %.
  • the reason for restricting O 2 below 5000 ppm is that, when exceeding 5000 ppm, the R-rich phase is oxidized and insufficient liquid phase is produced at sintering, resulting in lowered density, so that a high magnetic flux density cannot be obtained and weathering resistance is also reduced.
  • An optimum range of O 2 is between 200 to 3000 ppm.
  • the starting material powders in the present invention as well as powders of the magnet material composition, it is also possible to blending an R-Fe-B alloy powder containing an R 2 Fe 14 B main phase in which the amount of R, to be described later, is 11 atomic % to 20 atomic %, and an R-Fe-B alloy powder containing the R 2 Fe 17 phase, in which the amount of R is below 20 atomic % in order to adjust the total amounts of R, B and Fe to the required magnet composition,.
  • the magnet composition can be adjusted by blending the main phase R-Fe-B alloy powder, in which the amount of B is 4 atomic % to 12 atomic % or more, and an adjusting R-Fe-B alloy powder containing the R 2 Fe 17 phase, in which the amount ofB is below 6 atomic %, or an adjusting R-Fe alloy powder containing the R 2 Fe 17 phase, in which B is not contained.
  • the magnet composition can be adjusted by blending an adjusting R-Co (can be substituted by Fe) alloy powder containing an R-Co intermetallic compound (Nd 3 -Co, Nd-Co 2 and the like).
  • Al ⁇ 9.5 atomic % or less Ti ⁇ 4.5 atomic % or less, V ⁇ 9.5 atomic % or less, Cr ⁇ 8.5 atomic % or less, Mn ⁇ 8.0 atomic % or less, Bi ⁇ 5 atomic % or less, Nb ⁇ 12.5 atomic % or less, Ta ⁇ 10.5 atomic % or less, Mo ⁇ 9.5 atomic % or less, W ⁇ 9.5 atomic % or less, Sb ⁇ 2.5 atomic % or less, Ge ⁇ 7 atomic % or less, Sn ⁇ 3.5 atomic % or less, Zr ⁇ 5.5 atomic % or less and Hf ⁇ 5.5 atomic % or less, to the alloy powder containing the R, B, Fe alloys or the R-Fe-B alloy containing Co or the blended R 2 Fe 14 B phase as the main phase, or to the adjusting alloy powder containing the R 2 Fe 17 phase and the adjusting alloy powder containing the R-Co intermetallic compound phase, a high coercivity of the permanent magnet alloy is promoted.
  • R-B-Fe permanent magnet of the present invention it is necessary that the R 2 Fe 14 B phase of the main phase of a crystal phase presents above 90%, preferably, above 94%.
  • R-Fe-B sintered magnets, which are produced in large numbers at present, has the R 2 Fe 14 B phase of up to 90%.
  • the high magnetic characteristics of the present invention in which the value [(BH)max ⁇ 7.96]+[iHc ⁇ 79.6] is above 59, can not be obtained below 90%.
  • a degree of orientation of the magnet of the present invention is calculated from the aforementioned equation 1, it is necessary that the degree of orientation of the magnet is above 85% to hold the value [(BH)max ⁇ 7.96]+[iHc ⁇ 79.6] above 59.
  • the degree of orientation is below 85%, the squareness of demagnetization curve is poor and the high residual magnetic flux density (Br) is lowered, resulting in a low (BH) max value.
  • the degree of orientation is preferably above 92%.
  • the squareness of the demagnetization curve ⁇ (Br 2 ⁇ 1.99)/(BH)max ⁇ theoretically shows a value of 1.00, since the above-mentioned degree of orientation is inevitably disturbed in the practical permanent magnet material, it has been limited to 1.05 even after many improvement in the past: in the permanent magnet materials of the present invention obtained by the aforementioned specific process, the value of the squareness of demagnetization curve is 1.01 to 1.045.
  • R is preferably 11 atomic % to 20 atomic %, more preferably, 13 atomic % to 16 atomic %.
  • a high coercive force (iHc) can not be obtained when B is below 4 atomic %, and since the residual magnetic flux density (Br) is lowered when exceeding 12 atomic %, the best permanent magnet can not be obtained, so B is preferably 4 atomic % to 12 atomic %, more preferably, 6 atomic % to 10 atomic %.
  • Fe is preferably within the range of 65 atomic % to 82 atomic %.
  • Fe is preferably below 65 atomic %, the rare earth element(s) and B become relatively abundant, and the R-rich phase and the B-rich phase increase; when exceeding 82 atomic %, the rare earth elements and B decrease relatively, and the residual Fe increases, resulting in a non-uniform alloy powder.
  • Fe is preferably 74 atomic % to 81 atomic %.
  • Co is preferably below 10 atomic % and Ni is preferably below 3 atomic %.
  • Fe is preferably in the range of 55 atomic % to 72 atomic %.
  • the R-rich phase increases in production of the alloy powder and causes oxidation when R exceeds 20 atomic %, thus R is preferably 5 to 15 atomic %.
  • B is below 6 atomic %, since only the R 2 Fe 14 B phase is present and the amount of B in the main phase alloy powder can be adjusted, B is preferably below 6 atomic %.
  • the balance of the main phase powder is composed of Fe and unavoidable impurities, Fe is preferably 85 atomic % to 95 atomic %.
  • R is preferably 11 atomic % to 15 atomic %, more preferably, 12 atomic % to 14 atomic %.
  • B is preferably 4 atomic % to 12 atomic %, more preferably, 6 atomic % to 10 atomic %.
  • Fe is preferably 73 atomic % to 85 atomic %.
  • Fe is below 73 atomic %, the rare earth elements and B become abundant relatively and the R-rich phase and the B-rich phase increase, when exceeding 85 atomic %, the rare earth elements and B decrease relatively and the residual Fe increases, results in the non-uniform alloy powder, thus Fe is, more preferably, 76 atomic % to 82 atomic %.
  • Co is preferably below 10 atomic % and Ni below 3 atomic %.
  • Fe is preferably 63 atomic % to 82 atomic %.
  • the R-rich phase increases and tends to cause oxidation in production of the alloy powder when R exceeds 45 atomic %: R is preferably 10 to 20 atomic %.
  • Co is preferably 55 atomic % to 95 atomic %.
  • Fe and Ni may be substituted for Co in the adjusting alloy powder. Since the oxidation resistance of the adjusting alloy powder is reduced when the amount of Fe is increased, and the coercive force of the magnet is lowered when the amount ofNi is increased, Fe is preferably below 50 atomic % and Ni below 10 atomic %. When replacing a part of Co with Fe or Ni, Co is preferably 5 atomic % to 45 atomic %.
  • the magnet composition alloy powder, the main phase alloy powder containing the R 2 Fe 14 B phase as the main phase, and the adjusting alloy powder containing the R 2 Fe 17 phase or the R-Co intermetallic compound phase are produced by, for example, a known strip casting process by a single roll process or a double roll process.
  • Hydrogenation processing is that, for example, a cast piece cut into a predetermined size and having the thickness of 0.03 mm to 10 mm is inserted into a material case, which is covered and charged into a pressure vessel which can be closed tightly, after closing the pressure vessel tightly, the pressure therein is reduced sufficiently, whereafter H 2 gas at 200 Torr (26.6 kPa) to 50 kg/cm 2 (4.9 MPa) pressure is introduced so that hydrogen is occluded by the cast piece.
  • the hydrogenation reaction is an exothermic reaction
  • the H 2 gas having a predetermined pressure is supplied for a fixed time, while providing a piping around the pressure vessel for supplying cooling water to suppress the temperature rise in the pressure vessel, so that the H 2 gas is absorbed and the cast piece decays spontaneously and is pulverized.
  • the pulverized alloy is then cooled and dehydrogenated in vacuum.
  • the processed alloy powder grains Since fine cracks are produced in the processed alloy powder grains, it can be comminuted by a ball mill, a jet mill and the like, and the alloy powder having the necessary grain size of 1 ⁇ m to 80 ⁇ m can be obtained.
  • air in the processing pressure vessel may be replaced by inert gas beforehand, and with the inert gas being later replaced by the H 2 gas.
  • the pulverization is reduced when the hydrogen pressure is below 200 Torr (26.6 kPa), and though it may be preferable from a viewpoint of hydrogenation and pulverization to exceed 50 kg/cm 2 (4.9 MPa), it is not so from the viewpoint of the apparatus and safety, so that the H 2 gas pressure is preferably 200 Torr to 50 kg/cm 2 .
  • the H 2 gas pressure is preferably 2 kg/cm 2 to 10 kg/cm 2 .
  • the pulverization time due to the Hydrogenation varies depending on the closed pressure vessel size, the size of the cut piece and the H 2 gas pressure, it takes more than 5 minutes.
  • the alloy powder pulverized by hydrogenation is subjected to a primary dehydrogenation in vacuum after cooling. Then, when the pulverized alloy is heated at 100°C to 750°C in vacuum or in argon gas, and subjected to a secondary dehydrogenation for 0.5 hours or longer, the H 2 gas in the pulverized alloy can be completely removed, and oxidation of the powder or a molded body due to prolonged storage is prevented, so that deterioration of the magnetic characteristics of the resulting permanent magnet can be prevented.
  • the above-mentioned primary dehydrogenation in vacuum may be omitted, and the decayed powder may be directly dehydrogenated in vacuum or in an argon gas atmosphere at 100°C or higher.
  • the resulting decayed powder may be, subsequently, subjected to dehydrogenation in the pressure vessel atmosphere at 100°C or higher.
  • the decayed powder may be taken out from the pressure vessel for pulverization, whereafter dehydrogenation processing including heating to 100°C or higher in the pressure vessel may be effected again.
  • the preferable dehydrogenation temperature is 200°C to 600°C.
  • the processing time varies depending on the processing amount, it usually takes 0.5 hours or longer.
  • Comminution is suitably effected by a jet mill under an inert gas (e.g. N 2 , Ar). It goes without saying that a ball mill or a grinder may be used for comminuting the powder using an organic solvent (e.g. benzene, toluene and the like).
  • an inert gas e.g. N 2 , Ar
  • a ball mill or a grinder may be used for comminuting the powder using an organic solvent (e.g. benzene, toluene and the like).
  • Mean grain sizes ofthe powder at comminution is preferably 1 ⁇ m to 10 ⁇ m.
  • the comminuted powder becomes very active and susceptible to oxidation, with the possibility of spontaneous ignition.
  • the mean grain size of the fine powder is, more preferably, 2 to 4 ⁇ m.
  • the mold may be made of, besides non-magnetic metals and oxides, organic compounds such as plastics, rubber and the like.
  • the charging density of the powder is from a bulk density (charging density 1.4 g/cm 3 ) in a quiescent state of the powder, up to the solidifying bulk density (charging density 3.0 g/cm 3 ) after tapping.
  • the charging density is restricted to 1.4 to 3.0 g/cm 3 .
  • a pulse magnetic field by an air-core coil and a capacitor power source is applied for orientation of the powder.
  • the pulse magnetic field may be applied repeatedly, while compressing the powder by upper and lower punches.
  • the pulse magnetic field duration is preferably 1 ⁇ sec to 10 sec, more preferably 5 ⁇ sec to 100 msec, and an applying frequency of the magnetic field is preferably 1 to 10 times, more preferably, 1 to 5 times.
  • the oriented powder may be solidified by a hydrostatic press.
  • hydrostatic pressing can be effected as it is.
  • Pressure by the hydrostatic pressing process is preferably 0.5 ton/cm 2 to 5 ton/cm 2 (49 to 490 MPa), more preferably, 1 ton/cm 2 to 3 ton/cm 2 (98 to 294 MPa).
  • Pressure by the magnetic field pressing process is likewise preferably 0.5 ton/cm 2 to 5 ton/cm 2 (49 to 490 MPa), more preferably, 1 ton/cm 2 to 3 ton/cm 2 (98 to 294 MPa).
  • a sheet cast piece having a thickness of about 1 mm is prepared from a molten alloy having compositions of Nd 13.0 - B 6.0- Fe 81 obtained by melting in a high frequency melting furnace, by using a double-roll type strip caster including two copper rolls of 200 mm diameter. Crystal grain sizes of the cast piece are 0.5 ⁇ m to 15 ⁇ m in a short axial direction and 5 ⁇ m to 80 ⁇ m in a long axial direction. An R-rich phase which is finely separated into about 3 ⁇ m is present surrounding a main phase. The oxygen content is 300 ppm.
  • the cast piece of 1000 g cut into a 50 mm square or smaller is placed in a closed pressure vessel which can take in and discharge air, and N 2 gas is introduced into the pressure vessel for 30 minutes. After flushing out the air, H 2 gas at 3 kg/cm 2 (about 300 kPa) pressure is fed into the pressure vessel for 2 hours to cause the cast piece to decay spontaneously by hydrogenation. The decayed cast is retained in vacuum at 500°C for 5 hours for dehydrogenation, and thereafter it is cooled to room temperature and ground into 100 mesh.
  • the molded body taken out from the mold is sintered at 1090°C for 3 hours to obtain a permanent magnet after one hour annealing at 600°C. Magnetic characteristics and density, crystal grain size, degree of orientation, the squareness of demagnetization curve main phase amount and oxygen content are shown in Table 1.
  • a molten alloy having the same composition as that of Embodiment 1 is strip cast to obtain a sheet cast piece having the sheet thickness of about 0.5 ⁇ m
  • Crystal grain sizes in the cast piece are 0.3 ⁇ m to 12 ⁇ m in a short axial direction and 5 ⁇ m to 70 ⁇ m in a long axial direction, and an R-rich phase finely separated into about 3 ⁇ m is present surrounding the main phase.
  • the cast piece is comminuted by a jet mill under the same condition as Embodiment 1 to obtain an alloy powder of about 3.4 ⁇ m mean grain size.
  • the powder is molded in a magnetic field of about 12 kOe (955 kA/m), after, first, having been oriented in a pulse magnetic field of about 30 kOe (2387 kA/m), by a press machine, in which, as shown in Fig.
  • An alloy ofNd 13.5 - Dy 0.5 - B 6.5 - Co 1.0 - Fe 78.5 is formed and strip cast as in Embodiment 1 to obtain a sheet cast piece.
  • the cast piece of 100 g cut into a 50 mm square or smaller is decayed spontaneously by hydrogenation as in Embodiment 1, and dehydrogenated in vacuum for 6 hours. Then, after coarse grinding, it is comminuted in a jet mill to obtain powder of 3.5 ⁇ m mean grain size.
  • the resulting powder is oriented in a pulse magnetic field as in Embodiment 1, and a molded body obtained by hydrostatic pressing is sintered similarly. Magnetic characteristics and density, crystal grain size, degree of orientation, the squareness of demagnetization curve, main phase amount and O 2 content are shown in Table 1.
  • the powder obtained at the same condition as the Embodiment 1 is pressed and molded in the magnetic field of about 12 kOe (955 kA/m) by the usual magnetic field press machine in dried state, then sintered and annealed at the same condition as in Embodiment 1.
  • oxidation occurred during the pressing thus densification to a sufficient sinter density was impossible, and the magnetic characteristics could not be measured and only the density and O 2 content are measured (Table 1).
  • Coarse powder obtained under the same conditions as Embodiment 1 is comminuted in a ball mill, using toluene as a solvent, to obtain the fine powder of 3.5 ⁇ m mean grain size, which is pressed and molded in the magnetic field of about 12 kOe (955 kA/m) by the usual magnetic field press machine in a wet state, then sintered and annealed under the same conditions as Embodiment 1.
  • a molten alloy having the composition of Nd 14- B 6.0-Fe 80 obtained by melting in a high-frequency melting furnace is cast in an iron mold.
  • crystallization of a-Fe primary crystals is seen, so it was heated at 1050°C for 10 hours in a homogenizing process.
  • Crystal grain sizes of the resulting ingot are 30 to 150 ⁇ m in a short axial direction and 100 ⁇ m to several mm in a long axial direction, and an R-rich phase is segregated with grain sizes of about 150 ⁇ m locally.
  • the coarse powder is obtained by the hydrogenation and dehydrogenation processes of Embodiment 1. Furthermore, the coarse powder is comminuted by a jet mill under the same conditions as Embodiment 1, and the resulting alloy powder of about 3.7 ⁇ m mean grain size is pressed and molded in the magnet field of about 12 kOe (955 kA/m) for sintering and heat treatment at the same conditions as the Embodiment 1. Magnetic characteristics and density, crystal grain size, degree orientation, the squareness of demagnetization curve, main phase amount and O 2 content of the resulting permanent magnet are shown in Table 1.
  • the alloy powder is pressed in the magnetic field of about 12 kOe (955 kA/m), sintered and annealed to obtain the permanent magnet. Magnetic characteristics and density, crystal grain size, degree of orientation, the squareness of demagnetization curve, main phase amount and O 2 content of the resulting permanent magnet are shown in Table 1.
  • An alloy having the composition ofNd 13.5- Dy 0.5- B 6.5 - Co 1.0 - Fe 78.5 is cast by the same method as the Comparative Example 3. Since ⁇ -Fe primary crystals are present in the resulting alloy ingot, it is subjected to heat treatment at 1050°C for 6 hours. After coarsely grinding the alloy ingot, it is subjected to hydrogenation as in Embodiment 1, and then dehydrogenated in vacuum. The coarse powder is ground coarsely and comminuted in a jet mill to obtain a powder of 3.7 ⁇ m mean grain size.
  • the powder is pressed in the magnetic field of about 12 kOe (955 kA/m), then sintered and heated under the same condition as the Embodiment 1. Magnetic characteristics and density, crystal grain size, degree of orientation, the squareness of demagnetization curve, main phase amount and O 2 content of the resulting permanent magnet are shown in Table 1.
  • the fine powder is pressed in the magnetic field of about 12 kOe (955 kA/m), then sintered and annealed at the same condition as the Embodiment 1. Magnetic characteristics and density, crystal grain size, degree of orientation the squareness of the demagnetization curve, main phase amount and O 2 content of the resulting permanent magnet are shown in Table 1.
  • These materials are melted in an Ar atmosphere so as to obtain an alloy having a predetermined composition, then cast by a strip casting process using copper rolls to obtain a cast piece having a plate thickness of about 2 mm.
  • the cast piece is coarsely ground by a hydrogenation processing, and comminuted by a jaw crusher, a disk mill or the like to obtain 800 g of powder of about 10 ⁇ m mean grain size.
  • the resulting powder consisting of 14.9 atomic % Nd, 0.1 atomic % Pr, 0.3 atomic % Dy, 8.0 atomic % B and Fe, is observed by an x-ray diffraction EPMA, as a result, it is confirmed that O 2 content is about 800 ppm.
  • the R 2 Fe 14 B main phase is about 5 ⁇ m in a short axial direction and 20 to 80 ⁇ m in a long axial direction, and the R-rich phase is finely dispersed surrounding the main phase.
  • 30% adjusting alloy powder is blended with the main phase alloy powder.
  • the material powders are fed into a grinder such as a jet mill or the like to pulverize into about 3 'Lm, the resulting fine powder is filled into a rubber mold, and is subjected to hydrostatic pressing at 2.5 T/cm 2 (245MPa)by a hydrostatic press machine, after applying a pulse magnetic field of 60 kOe(4775 kA/m) instantaneously for orientation, thereby to obtain a molded body of 8 mm ⁇ 15 mm ⁇ 10 mm,
  • the molded body is sintered at 1100°C in an Ar atmosphere for 3 hours, and annealed at 550°C for one hour. Magnetic characteristics ofthe resulting magnet are shown in table 2.
  • the R 2 Fe 14 B main phase is about 50 ⁇ m in a short axial direction and about 500 ⁇ m in a long axial direction, the R-rich phase having grain sizes of 50 ⁇ m is locally present throughout. Also, ⁇ -Fe of 5 to 10 ⁇ m is seen in the main phase.
  • the molded body is sintered in an Ar atmosphere at 1100°C for 3 hours, and annealed at 550°C for one hour. Magnetic characteristics of the resulting magnet are also shown in Table 2.
  • the main phase alloy powder of Comparative Example 1 is used, and as materials for the adjusting alloy powder,
  • Component analysis made by the same method as Embodiment 4 shows 10.8 atomic % Nd, 0.1 atomic % Pr, 0.4 atomic % Dy, 2.4 atomic % B and Fe (balance).
  • the resulting powder shows 13.8 atomic % Nd, 0.1 atomic % Pr, 0.3 atomic % Dy, 6.3 atomic % B and Fe Balance).
  • the oxygen content is about 800 ppm.
  • the crystal size ofthe R 2 Fe 14 B main phase is about 6 ⁇ m in a short axial direction and 20 to 80 ⁇ m in a long axial direction, and the R-rich phase is present as a fine phase surrounding the main phase.
  • main phase alloy powder of 10 ⁇ m mean grain size having a composition different from the Embodiment 4 is obtained by the process of that Embodiment.
  • the resulting powder consists of 14 atomic % Nd, 0.1 atomic % Pr, 0.5 atomic % Dy, 8 atomic % B and Fe.
  • the oxygen content is about 80 ppm.
  • the R 2 Fe 14 B main phase has a grain size of about 0.5 to 15 ⁇ m in a short axial direction and 5 to 90 ⁇ m in a long axial direction, and the R-rich phase is dispersed finely to surround the main phase.
  • the adjusting alloy powder containing an R 2 Fe 17 phase 125 g of Nd metal of 99% purity, 5 g of Dy metal of 99% purity and 275 g of an electrolytic iron of 99% purity are used, and a cast piece having a plate thickness of about 2 mm is obtained by the same strip casting process as the main phase alloy.
  • powder is prepared by the same process as the main phase alloy.
  • the composition of the resulting powder is 11.0 atomic % Nd, 0.05 atomic % Pr, 0.4 atomic % Dy and Fe.
  • EPMA observation on the cast piece structure shows it to consist of an R 2 Fe 17 phase, partly R 2 Fe 14 B, and an R-rich phase: ⁇ -Fe is not seen.
  • the oxygen content at 10 ⁇ m mean grain size is 700 ppm.
  • 25 % adjusting alloy powder is blended with the main phase alloy powder.
  • the material powders are charged into a grinder such as a jet mill to comminute it into about 3 ⁇ m, then packed into a rubber mold, and the resulting fine powder is subjected to hydrostatic pressing at 2.5 T/cm 2 (245 MPa) pressure by an isostatic press machine to obtain a molded body of 8 mm x 15 mm x 10 mm, after applying a pulse magnet field of 60 kOe (4775 kA/m) instantaneously for orientation.
  • the molded body is sintered in an Ar atmosphere at 1100°C for 3 hours, and annealed at 550°C for one hour. Magnetic characteristics of the resulting magnet are shown in Table 3.
  • the main phase alloy powder an alloy having the same composition as the Embodiment 5 is cast in an iron mold to obtain powder of about 10 ⁇ m mean grain size by the same method as Embodiment 4.
  • Composition is 14 atomic % Nd, 0.1 atomic % Pr, 0.5 atomic % Dy, 8 atomic % B and Fe (balance), the oxygen content is about 900 ppm.
  • the crystal grain size is about 50 ⁇ m in a short axial direction and about 500 ⁇ m in a long axial direction, and an R-rich phase (50 ⁇ m) is locally present throughout. Also, 5 to 10 ⁇ m crystals of ⁇ -Fe are present in the main phase.
  • the adjusting alloy powder containing the R 2 Fe 17 phase is produced by the same direct reducing and diffusing process as Comparative Example 7, by using 280 g of Nd 2 O 3 (purity 98%), 12 g of Dy 2 O 3 (purity 99%) and 750 g of iron powder (purity 99%).
  • Components are 11.0 atomic % Nd, 0.05 atomic % Pr, 0.9 atomic % Dy and Fe.
  • the oxygen content is 1500 ppm.
  • 25% adjusting alloy powder is blended with the main phase alloy powder, and charged into a jet mill or the like to comminute it to about 3 ⁇ m
  • the resulting fine powder is oriented in the magnet field of about 10 kOe (796 kA/m), and molded at about 1.5 T/cm 2 (about 150 MPa) pressure at right angles to the magnetic field to obtain a molded body of 8 mm ⁇ 15 mm ⁇ 10 mm.
  • the molded body is sintered in an Ar atmosphere at 1100°C for 3 hours, and annealed at 550°C for one hour. Magnetic characteristics ofthe resulting magnet are also shown in Table 3.
  • an adjusting alloy powder is prepared by melting 350 g of a Nd metal, 10 g of a Dy metal and 750 g of an electrolytic iron of 99% purity in the Ar atmosphere, and cast in the iron mold.
  • a large amount of ⁇ -Fe is crystallized, homogenizing is effected at 1000°C for 12 hours.
  • it consists of 11.0 atomic % Nd, 0.05 atomic % Pr, 0.4 atomic % Dy and Fe (balance).
  • a Nd metal As starting materials, 300 g of a Nd metal, 13 g of a Dy metal, 50 g of a Fe-B alloy containing 20% B and 645 g of an electrolytic iron of 99% purity are used, and melted in an Ar atmosphere so as to obtain an alloy having a predetermined composition, then, by the strip casting process using copper rolls, a cast piece having a plate thickness of about 2 mm is obtained. Furthermore, the cast piece is pulverized by hydrogenation, and jaw crusher, disk mill and the like to obtain 800 g of powder of about 10 ⁇ m mean grain size.
  • the resulting powder consists of 13.3 atomic % Nd, 0.1 atomic % Pr, 0.5 atomic % Dy, 6 atomic % B and Fe (balance).
  • the oxygen content is about 800 ppm.
  • the R 2 Fe 14 B main phase crystal size is about 0.3 to 15 ⁇ m in a short axial direction and about 5 to 90 ⁇ m in a long axial direction, and an R-rich phase is present as a fine phase surrounding the main phase.
  • the resulting powder consists of 11 atomic % Nd, 0.1 atomic % Pr, 1.0 atomic % Dy, 8 atomic % B and Fe (balance), as is observed by x-ray diffraction EPMA, and it is confirmed that it mostly consists of a R 2 Fe 14 B phase.
  • the oxygen content is about 800 ppm.
  • the R 2 Fe 14 B main phase crystal size is about 0.5 to 1.5 ⁇ m in a short axial direction and 5 to 90 ⁇ m in a long axial direction, and the R-rich phase is finely dispersed surrounding the main phase.
  • the cast piece structure consists of the R 3 Co phase and partly the R 2 Co 17 phase, and the R 3 Co phase is finely dispersed.
  • the oxygen content in the powder which has a 10 ⁇ m mean grain size, is 700 ppm.
  • 20% adjusting alloy powder is blended with the main phase alloy powder.
  • the material powders are charged into a grinder such as a jet mill or the like to comminute them into about 3 ⁇ m grain sizes, and the resulting powder is filled into a rubber mold and is subjected to hydrostatic pressing at 2.5 T/cm 2 (245 MPa) by a hydrostatic press machine, after applying a pulse magnetic field of 60 kOe (4775 kA/m) instantaneously for orientation, thereby to obtain a molded body of 8 mm ⁇ 15mm ⁇ 10 mm.
  • the molded body is sintered at 1100°C in an Ar atmosphere for 3 hours, and annealed at 550°C for one hour. Magnetic characteristics of the resulting magnet are shown in Table 4.
  • Magnetic characteristics of the magnet obtained by blending 10 % adjusting alloy powder with the main phase alloy powder prepared in the Embodiment 1, and magnetizing by the same process as the Embodiment 6 are shown in Table 4.
  • the R 2 Fe 14 B main phase crystal size is about 50 ⁇ m in a short axial direction and about 500 ⁇ m in a long axial direction, the R-rich phase (50 ⁇ m) is locally present throughout. Some ⁇ -Fe of 5 to 10 ⁇ m grain size is present in the main phase.
  • 20 % adjusting alloy powder is blended with the main phase alloy powder, and charged into a grinder such as a jet mill or the like to pulverize into about 3 ⁇ m.
  • the resulting fine powder is oriented in the magnetic field of about 10 kOe (796 kA/m), and molded at about 1.5 T/cm 2 (about 150 MPa) pressure to obtain a molded body of 8 mm ⁇ 15 mm ⁇ 10 mm.
  • the molded body is sintered in an Ar atmosphere at 1100°C for 3 hours, and annealed at 550°C for one hour. Magnetic characteristics of the resulting magnet are also shown in Table 4.
  • the adjusting alloy powder is prepared by melting.
  • the resulting powder consists of 13.5 atomic % Nd, 0.1 atomic % Pr, 1.0 atomic % Dy, 6.7 atomic % B, 11.3 atomic % Co and Fe.
  • the oxygen content is about 800 ppm.
  • the crystal size of the R 2 (Fe, Co 14 )B phase is about 0.3 to 1.5 ⁇ m in a short axial direction and about 5 to 90 ⁇ m in a long axial direction, the R-rich phase and the R-Co phase being present finely surrounding the main phase.

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EP93308184A 1993-07-06 1993-10-14 R-Fe-B permanent magnet materials and process of producing the same Expired - Lifetime EP0633581B1 (en)

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JP19288693A JP3415208B2 (ja) 1993-07-06 1993-07-06 Ｒ−Ｆｅ−Ｂ系永久磁石材料の製造方法
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JP20719193A JP3151088B2 (ja) 1993-07-28 1993-07-28 Ｒ−Ｆｅ−Ｂ系永久磁石用原料粉末の製造方法及び原料粉末調整用合金粉末
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JP20719093A JP3151087B2 (ja) 1993-07-28 1993-07-28 Ｒ−Ｆｅ−Ｂ系永久磁石用原料粉末の製造方法及び原料粉末調整用合金粉末
JP5207192A JPH0745412A (ja) 1993-07-28 1993-07-28 Ｒ−Ｆｅ−Ｂ系永久磁石材料
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US5666635A (en) * 1994-10-07 1997-09-09 Sumitomo Special Metals Co., Ltd. Fabrication methods for R-Fe-B permanent magnets
US5858123A (en) * 1995-07-12 1999-01-12 Hitachi Metals, Ltd. Rare earth permanent magnet and method for producing the same
US6319335B1 (en) 1999-02-15 2001-11-20 Shin-Etsu Chemical Co., Ltd. Quenched thin ribbon of rare earth/iron/boron-based magnet alloy
DE60028659T2 (de) * 1999-06-08 2007-05-31 Shin-Etsu Chemical Co., Ltd. Dünnes Band einer dauermagnetischen Legierung auf Seltenerdbasis
US6527874B2 (en) 2000-07-10 2003-03-04 Sumitomo Special Metals Co., Ltd. Rare earth magnet and method for making same
RU2205294C2 (ru) * 2001-04-26 2003-05-27 Зинченко Сергей Васильевич Магнитный насос
KR100446193B1 (ko) * 2002-05-29 2004-08-30 주식회사 태평양금속 도전체 박막을 구비한 영구 자석 제조 방법 및 장치
US7618497B2 (en) * 2003-06-30 2009-11-17 Tdk Corporation R-T-B based rare earth permanent magnet and method for production thereof
JP4179973B2 (ja) * 2003-11-18 2008-11-12 Ｔｄｋ株式会社 焼結磁石の製造方法
JP4656323B2 (ja) 2006-04-14 2011-03-23 信越化学工業株式会社 希土類永久磁石材料の製造方法
US7955443B2 (en) * 2006-04-14 2011-06-07 Shin-Etsu Chemical Co., Ltd. Method for preparing rare earth permanent magnet material
CN100394518C (zh) * 2006-08-04 2008-06-11 北京工业大学 一种制备高矫顽力烧结稀土-铁-硼永磁材料的方法
KR101456841B1 (ko) * 2006-09-14 2014-11-03 가부시키가이샤 알박 영구자석 및 영구자석의 제조방법
WO2008062757A1 (fr) 2006-11-21 2008-05-29 Ulvac, Inc. Procédé de production d'un objet orienté, d'un objet moulé, et d'un objet fritté et procédé de production d'un aimant permanent
CN101563737B (zh) * 2006-12-21 2013-03-20 株式会社爱发科 永磁铁及永磁铁的制造方法
KR101373271B1 (ko) * 2006-12-21 2014-03-11 가부시키가이샤 알박 영구자석 및 영구자석의 제조방법
CN101393791B (zh) * 2007-09-21 2012-10-03 有研稀土新材料股份有限公司 一种各向异性粘结磁粉及其制备方法
CN101911226B (zh) * 2007-12-25 2013-07-24 株式会社爱发科 永磁体的制造方法
CN101872668B (zh) * 2009-04-23 2014-06-25 北京中科三环高技术股份有限公司 具有优良磁化特性的烧结钕铁硼稀土永磁体及其制造方法
CN102087917B (zh) * 2009-12-02 2014-06-25 北京中科三环高技术股份有限公司 一种辐射取向磁环或多极磁环的制备方法及其压制设备
JP5572673B2 (ja) 2011-07-08 2014-08-13 昭和電工株式会社 Ｒ−ｔ−ｂ系希土類焼結磁石用合金、ｒ−ｔ−ｂ系希土類焼結磁石用合金の製造方法、ｒ−ｔ−ｂ系希土類焼結磁石用合金材料、ｒ−ｔ−ｂ系希土類焼結磁石、ｒ−ｔ−ｂ系希土類焼結磁石の製造方法およびモーター
EP2745298B1 (en) 2011-08-17 2019-12-11 Regents of the University of Minnesota Technique and system for forming iron nitride permanent magnet
US9412505B2 (en) 2011-12-27 2016-08-09 Intermetallics Co., Ltd. NdFeB system sintered magnet
WO2013100010A1 (ja) 2011-12-27 2013-07-04 インターメタリックス株式会社 NdFeB系焼結磁石
JP6119548B2 (ja) * 2012-10-17 2017-04-26 信越化学工業株式会社 希土類焼結磁石の製造方法
CN103887028B (zh) 2012-12-24 2017-07-28 北京中科三环高技术股份有限公司 一种烧结钕铁硼磁体及其制造方法
JP6238444B2 (ja) 2013-01-07 2017-11-29 昭和電工株式会社 Ｒ−ｔ−ｂ系希土類焼結磁石、ｒ−ｔ−ｂ系希土類焼結磁石用合金およびその製造方法
US9715957B2 (en) 2013-02-07 2017-07-25 Regents Of The University Of Minnesota Iron nitride permanent magnet and technique for forming iron nitride permanent magnet
CA2916483C (en) 2013-06-27 2017-02-28 Regents Of The University Of Minnesota Iron nitride materials and magnets including iron nitride materials
BR112016022561A2 (pt) 2014-03-28 2017-08-15 Univ Minnesota Material magnético de nitreto de ferro incluindo nanopartículas revestidas
US9994949B2 (en) 2014-06-30 2018-06-12 Regents Of The University Of Minnesota Applied magnetic field synthesis and processing of iron nitride magnetic materials
KR20170039741A (ko) 2014-08-08 2017-04-11 리전츠 오브 더 유니버시티 오브 미네소타 다층 질화철 경자성 재료
AU2015301085A1 (en) 2014-08-08 2017-03-02 Regents Of The University Of Minnesota Forming iron nitride hard magnetic materials using chemical vapor deposition or liquid phase epitaxy
US10002694B2 (en) 2014-08-08 2018-06-19 Regents Of The University Of Minnesota Inductor including alpha″-Fe16Z2 or alpha″-Fe16(NxZ1-x)2, where Z includes at least one of C, B, or O
US10072356B2 (en) 2014-08-08 2018-09-11 Regents Of The University Of Minnesota Magnetic material including α″-Fe16(NxZ1-x)2 or a mixture of α″-Fe16Z2 and α″-Fe16N2, where Z includes at least one of C, B, or O
DE102016205243A1 (de) * 2016-03-30 2017-10-05 Thyssenkrupp Ag Vorrichtung und Verfahren zur Aufbereitung eines Probematerials
CN108481877B (zh) * 2018-03-10 2020-06-23 葛理想 电磁屏蔽用磁材的碎化处理工艺
US12018386B2 (en) 2019-10-11 2024-06-25 Regents Of The University Of Minnesota Magnetic material including α″-Fe16(NxZ1-x)2 or a mixture of α″-Fe16Z2 and α″-Fe16N2, where Z includes at least one of C, B, or O
JP7409285B2 (ja) * 2020-10-22 2024-01-09 トヨタ自動車株式会社 希土類磁石及びその製造方法
CN115747611B (zh) * 2022-10-13 2023-10-20 包头金山磁材有限公司 一种辅合金铸片和高剩磁高矫顽力钕铁硼永磁体及制备方法

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1316375C (en) * 1982-08-21 1993-04-20 Masato Sagawa Magnetic materials and permanent magnets
JPS62291901A (ja) * 1986-06-12 1987-12-18 Toshiba Corp 永久磁石
CN1051864C (zh) * 1986-08-04 2000-04-26 住友特殊金属株式会社 具有优异耐蚀性的稀土永磁体
GB2201426B (en) * 1987-02-27 1990-05-30 Philips Electronic Associated Improved method for the manufacture of rare earth transition metal alloy magnets
CN1012477B (zh) * 1987-08-19 1991-05-01 三菱金属株式会社 稀土-铁-硼磁体粉末及其制备方法
JPH01119001A (ja) * 1987-10-30 1989-05-11 Kubota Ltd 希土類含有永久磁石粉末の製造方法
JPH0529117A (ja) * 1990-10-22 1993-02-05 Kawasaki Steel Corp 希土類−遷移金属系異方性磁粉の製造方法
SU1760563A1 (ru) * 1990-12-14 1992-09-07 Центральный научно-исследовательский институт черной металлургии им.И.П.Бардина Способ получени заготовки посто нного магнита
EP0517179B1 (en) * 1991-06-04 1995-05-17 Shin-Etsu Chemical Co., Ltd. Method of making two phase Rare Earth permanent magnets
JP2782024B2 (ja) * 1992-01-29 1998-07-30 住友特殊金属株式会社 Ｒ−Ｆｅ−Ｂ系永久磁石用原料粉末の製造方法

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EP0633581A1 (en) 1995-01-11
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DE69318147D1 (de) 1998-05-28
KR950004295A (ko) 1995-02-17
RU2113742C1 (ru) 1998-06-20
TW272293B (enrdf_load_stackoverflow) 1996-03-11
CN1076115C (zh) 2001-12-12
DE69318147T2 (de) 1998-11-12

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