EP0249973B1 - Dauermagnet-Material und Verfahren zur Herstellung - Google Patents

Dauermagnet-Material und Verfahren zur Herstellung Download PDF

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EP0249973B1
EP0249973B1 EP87108724A EP87108724A EP0249973B1 EP 0249973 B1 EP0249973 B1 EP 0249973B1 EP 87108724 A EP87108724 A EP 87108724A EP 87108724 A EP87108724 A EP 87108724A EP 0249973 B1 EP0249973 B1 EP 0249973B1
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magnetic
powder
cementing
bulk
metallic
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French (fr)
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EP0249973A1 (de
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Kinya Sasaki
Etsuo Otsuki
Tsutomu Otsuka
Teruhiko Fujiwara
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Tokin Corp
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Tokin Corp
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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
    • 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
    • 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
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/09—Mixtures of metallic powders
    • 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

Definitions

  • This invention relates to a permanent magnet material of a bulk shape and, in particular, to an iron-rare earth metal-boron (R-Fe-B) permanent magnet material with a high coercive force.
  • R-Fe-B iron-rare earth metal-boron
  • Permanent magnets have been used in various applications such as electromechanical apparatus.
  • a possible approach has been directed to a novel intermetallic compound of transition metal (T) and rare earth metal (R) instead of the Sm-Co intermetallic compound.
  • J. J. Croat proposed amorphous (Nd and/or Pr)-Fe-B alloy having magnetic properties for a permanent magnet as disclosed in JP-A-60009852. Those magnetic properties were considered to be caused by a microstructure where Nd2Fe14B particles having a perticle size of 20-30 nm were dispersed within an amorphous Fe phase. Reference is further made to R. K. Mishra: J. Magnetism and Magnetic Materials 54-57 (1986) 450.
  • the amorphous alloy can provide only an isotropic magnet because of its crystallographically isotropy. This means that a high performance permanent magnet cannot be obtained from the amorphous alloy.
  • the R-Fe-B sintered magnet has a problem in considerably low corrosion resistance.
  • a magnetic body with a high coercive force for a permanent magnet which consists essentially of a metallic cementing phase and magnetic crystalline particles uniformly dispersed within the metal cementing phase.
  • the cementing phase is 10% or less by volume of the magnetic body and comprises at least one element selected from a first metallic group of Al, Zn, Sn, Cu, Pb, S, In, Ga, Ge, and Te.
  • the magnetic crystalline particles is substantially balance of the volume of the magnetic body and is a composition represented by a chemical formula R2T14B, where R is at least one element selected from Y and rare earth metals, T being transition metals and comprising Fe 50-100 at% in the transition metals.
  • Each of the magnetic particles is embedded in the cementing phase to form an interface therebetween.
  • the cementing phase is inert to oxygen in comparison with Nd and has, therefore, a good corrosion resistance.
  • the cementing phase may comprise an intermetallic compound of at least one of the first metallic group and at least one selected from a second metallic group of R, T, and B.
  • the present invention further provides a method for producing a magnetic body with a high coercive force for a permanent magnet.
  • the method comprises steps of: preparing an ingot of R-T-B magnetic alloy comprising a magnetic intermetallic compound represented by a chemical formula of R2T14B, where R is at least one element selected from Y and rare earth metals, T being transition metals but comprising Fe 50-100 at% in the transition metals; pulverizing and milling the ingot to thereby prepare a magnetic powder; preparing a metallic cementing powder comprising at least one element selected from a first metallic group of Al, Zn, Sn, Cu, Pb, S, In, Ga, Ge, and Te; mixing the metallic cementing powder of 10% or less by volume and the magnetic powder of substantially balance to prepare a mixed powder; and forming a bulk-shape body of the mixed powder at an elevated temperature.
  • the bulk-shape body forming step comprises steps of; compacting the mixed powder under influence of a grain aligning magnetic field into a compact body of a predetermined shape; and sintering the compact body at a temperature lower than a peritectic reaction temperature of the magnetic powder but higher than a melting temperature of the metallic cementing powder to thereby produce, as the bulk-shape body, a sintered body.
  • the sintered body may be subjected to a heat treatment at a temperature, preferably, 300-900 °C for improving the magnetic properties of the sintered body.
  • the bulk-shape body forming step may be hot compaction process for hot compacting the mixed powder into the bulk-shape body at an elevated temperature lower than 1,100 °C but higher than a melting temperature of the metallic cementing powder.
  • the hot compaction process is a hot-pressing process and alternatively a hot-extrusion process.
  • the present invention attempts to provide a permanent magnet material with a high coercive force and a corrosion resistance by making the material to have a microstructure as shown in Fig. 1 where magnetic particles of stoichiometric intermetallic compound of Nd2Fe14B are dispersed within a metallic cementing phase.
  • the metallic cementing phase is composed of metallic elements and/or an intermetallic compound or compounds, which are inert to oxygen in comparison with Nd.
  • Nd2Fe14B powder and metallic cementing powder are separately prepared and those powder are mixed.
  • the mixed powder is sintered or hot-formed at an elevated temperature into a bulk-shape body so that the cementing powder forms a cementing phase to cement the magnetic particles together.
  • the metallic element or elements are selected to be ones each having a melting point lower than a peritectic temperature of the intermetallic compound of Nd2Fe14B, and the elevated temperature is also selected lower than the peritectic temperature but higher than the melting point of the cementing powder. Therefore, only the cementing powder melts to form the cementing phase by the sintering process or hot compaction process while the intermetallic compound of the magnetic powder is not melted but dispersed within the cementing phase.
  • Nd is active to oxygen if they do not form any intermetallic compound together or with other metallic element or elements. Therefore, it is desired that the cementing phase includes no Nd.
  • Nd and/or Fe diffuse from the magnetic powder into the cementing phase so that the intermetallic compound of Nd2Fe14B is decomposed.
  • Nd and Fe are included in the cementing powder in the form of an intermetallic compound or compounds with other metallic element or elements.
  • the magnetic powder is prepared as an alloy powder including Nd and Fe in addition to the intermetallic compound of Nd2Fe14B.
  • Nd and Fe are present in the cementing phase of the produced body.
  • Nd forms an intermetallic compound with the other metallic element or elements. Accordingly, the cementing phase is also excellent in corrosion resistance.
  • both of the former and the latter can be employed.
  • a comparatively low temperature is used in the hot compaction process, the latter is employed because intermetallic compound of Nd and Fe with the other metallic element is apt to have a melting temperature higher than the temperature for hot compaction.
  • the amount of the cementing powder is limited at maximum 10 % by volume of the mixed powder, because when the cementing powder exceeds 10 vol%, the amount of the magnetic powder is insufficient to obtain a high remanence.
  • the intermetallic compound of Nd2Fe14B has a high residual magnetic flux density but has not a coercive force sufficient for a permanent magnet.
  • An ingot of an intermetallic magnetic alloy represented by Nd13Fe81B6 was prepared by the induction melting in argon gas atmosphere. Purity factors of used start materials of Nd, Fe (electrolytic iron), and B were 98%, 99.9%, and 99.5% or more, respectively.
  • the ingot was pulverized by a crusher to have a particle size below 24 mesh (Tyler) and, thereafter, finely divided by a ball mill into a fine magnetic powder having an average particle size of 3 ⁇ m.
  • Each metallic powder was mixed with the fine magnetic powder to form mixed powder.
  • Each metal was adjusted at 58 by volume of the mixed powder.
  • Zn, Al, S, In, Ga, Ge, Sn, Te, Cu, and Pb were, by weight, 5%, 2%, 2%, 5%, 4%, 4%, 5%, 4%, 6%, and 7% in the mixed powders, respectively.
  • each mixed powder was hot-pressed into a desired bulk-shape body under a pressing stress of 1,000 Kg.f/cm2 at a temperature of 600°C within argon gas atmosphere for 15 minutes.
  • Table 1 teaches that the samples Nos. 1-10 according to an embodiment of this invention are superior to comparing samples Nos. 11 and 12 according to the known production method in the magnetic properties, especially, the maximum energy product (BH)max.
  • a fine magnetic powder of Nd13Fe81B6 was prepared and was mixed with metal powders (each having an average particle size of 20-30 um ) of Zn 5wt%, Al 2wt%, S 2wt%, In 5wt%, Ga 4wt%, Ge 4wt%, Sn 5wt%, Te 4wt%, Cu 6wt%, and Pb 7wt%, respectively, in the similar manner as described in Example 1.
  • Each mixed powder was compacted into a compact body of a desired bulk-shape by application of a pressing force of 1.5 ton.f/cm2 under influence of a grain aligning magnetic field of 25 KOe.
  • the compact body was hot-pressed at 600°C by pressing stress of 1,000 Kg.f/cm2 within vacuum for 15 minutes.
  • Each hot-pressed body was subjected to measurement of density and magnetic properties. The measured data are shown as sample Nos. 13-22 in table 2.
  • alloy ingots of (Nd15Fe77B7)95Al5 and Nd14Fe81B6 were produced and were finely ground into powders. Those powders were compacted into compact bodies of a desired bulk shape and were hot-pressed in the similar manner. Densities and magnetic properties of those hot-pressed bodies are shown as sample Nos. 23 and 24 in Table 2.
  • sample Nos. 13-22 according to embodiments of the present invention are superior in the magnetic properties to not only comparing samples of Nos 23 and 24 according to the known producing method but also samples of Nos. 1-10 in Table 1 according to embodiments of the present invention.
  • Nd2Fe14B magnetic alloy ingot was prepared and was pulverized to have a particle size below 24 mesh (Tyler).
  • start materials of Nd having a purity factor of 98% or more
  • Fe having a purity factor of 99.9% or more
  • Al having a purity factor of 99.9%
  • Both of the powders were blended with each other at various mixing ratios so that Nd30Fe40Al30 powder is 0-15% by volume of the blended powder.
  • Each blended powder was finely ground into a powder of an average particle size of about 4 ⁇ m.
  • the finely ground powder was compacted into a compact body of a desired bulk-shape by application compacting stress of 1.5 ton.f/cm2 under influence of a grain aligning magnetic field of 20 KOe.
  • the compact body was sintered in vacuum at 1,000-1,150 °C for 2 hours.
  • the sintered body was heat treated at 500-900 °C for one hour.
  • Density d, residual magnetic flux density Br, coercive force I H C , and (BH)max of the sintered body after heat treatment were measured are are illustrated in Fig. 2 for various volume percents of Nd30Fe40Al30 in the sintered body.
  • Fig. 2 the maximum magnetic properties are obtained at 5 vol% of Nd30Fe40Al30 content.
  • the magnetic properties are shown as a sample No. 25 in Table 3.
  • the table also has properties of a comparing sample No. 26 which was a sintered Nd14Fe80B6 alloy produced from the alloy ingot through milling, compacting in the aligning magnetic field, sintering, and heat treating steps according to a conventional powder metallurgy.
  • sample No.25 according to the present invention has a considerably excellent magnetic properties in comparison with sample No. 26 according to the conventional process.
  • the sintered body of sample No. 25 was cross-sectioned and polished.
  • the microstructure in the polished surface was observed by a Scanning Electron Microscope (SEM).
  • SEM Scanning Electron Microscope
  • the magnetic crystalline particles (being black) of Nd2Fe14B are covered with, or embedded in, a cementing phase (being white) of Nd30Fe40Al30.
  • This example teaches us that magnetic properties of sintered Nd2Fe14B magnet can be considerably improved by covering and cementing the Nd2Fe14B particles with the Nd(Fe, Al)3 matrix or the cementing phase.
  • Fig. 2 shows that the magnetic properties gradually decrease along increase of the cementing phase from 5 vol% through 8 vol%. It is considered that this is because of decrease of the amount of the magnetic particles.
  • Nd2Fe14B alloy powder and Nd30Fe40Al30 alloy powder produced through the similar steps as described in Example 3 were blended with each other so that Nd30Fe40Al30 powder was 5% of volume of the blended powder.
  • the blended powder was compacted to a desired bulk shape in the grain aligning magnetic field of 20 KOe by application of compacting force of 1.5 ton.f/cm2 and produced a green compact body.
  • the green compact body was subjected to a hot compaction by hot-pressing the green compact at 800 °C in argon gas atmosphere by 1,000 Kg.f/cm2 for 15 minutes.
  • Density and magnetic properties of the hot-pressed body were measured and are described with sample number of No. 27 in Table 5.
  • sample No. 28 is a sample produced from a Nd14Fe80B6 powder through the similar compacting and hot-pressing steps.
  • Nd2Fe14B magnetic alloy powder with an average particle size of 3 ⁇ m was prepared in the similar manner as described in Example 1. While, NdCu2 powder for the cementing phase material having similar particle size was also produced in a similar producing method. Both powders were mixed with each other so that the amount of NdCu2 powder was about 10% by volume in the mixture, and the mixture was uniformly mixed in a ball mill. The mixture was compacted into a bulk shape by application of compacting stress of 1.5 ton.f/cm2 in the grain aligning magnetic field of 20 KOe. The compacted body was sintered in vacuum at 1,100-1,130 °C for 2 hours. The sintered body was heat-treated in argon gas atmosphere at 600-800 °C for one hour.
  • the magnetic properties of the sintered body as sample No. 29 are shown in Table 6 together with its density.
  • No. 29 sample was then cross-sectioned and polished.
  • the microstructure of the cross-section was observed by use of an optical microscope.
  • the observed microstructure is illustrated in Fig. 4.
  • Nd2Fe14B magnetic particle is shown in white and the NdCu2 cementing phase is shown in black.
  • the cementing phase comprises two intermetallic compounds I and II.
  • Compound I is represented by NdCu
  • Compound II is represented by Nd(Cu, Fe)2.
  • each magnetic particle (shown in white in Fig. 4) is cemented and covered with the cementing phase (black in Fig. 4).
  • the mixture was hot-pressed in argon gas atmosphere at 900 °C by application of pressing stress of 1,000 Kg.f/cm2 for 15 minutes.
  • Table 8 shows density and magnetic properties of the hot-pressed body as sample No. 30. Table 8 teaches us that excellent magnetic properties are obtained.
  • Nd2Fe14B magnetic powder similar to Example 5 was prepared. While, Nd25 .4 Cu52 .2 Zn22 .4 powder for the cementing phase was prepared in the similar manner as the magnetic powder. Both of the powders were blended with each other so that the amount of the Nd25 .4 Cu52 .2 Zn22 .4 powder was about 10% by volume of the blended powder. The blended powder was uniformly mixed in ball mill. The mixture was hot-pressed into a body of a desired shape in argon gas at 600 °C by pressing stress of 1,000 Kg.f/cm2 for 15 minutes.
  • a molten alloy of Nd34Fe65B was prepared in the similar way as in Example 1.
  • a powder less than 250 (Tyler) mesh was prepared from each of the molten alloys by atomization. Then, Nd16Fe18B6 magnetic powder was divided by ball mill into average particle size of about 3 ⁇ m. Each powder of Pb-Sn alloys A and B was blended with the magnetic powder and was mixed in ball mill. The amount of each of alloy A and B was 5% by volume of each mixture.
  • Each powder mixture was compacted into a compact body of a bulk shape in the aligning magnetic field of 20 KOe by compacting stress of 1.5 ton.f/cm2.
  • the compact body was sintered in vacuum at 1,000-1,150 °C for 2 hours.
  • the sintered body was heat-treated at 500-900 °C for one hour and was thereafter subjected to measurement of density and magnetic properties.
  • Fig. 5 shows the microstructure of No. 32 sample.
  • the magnetic particles are illustrated in white and the cementing phase is black.
  • the magnetic particle phase consists of the intermetallic compound of Nd2Fe14B. While, Nd and Fe is present in both of the cementing phase. I and II are analysed data at different portions of the cementing phase of the sintered body.
  • the cementing phase is constituted of an intermetallic compound of Nd(Pb, Fe, Sn) where a part of Pb in NdPb is replaced by Fe and Sn. While, the cementing phase in No. 33 sample is composed of an intermetallic compound of Nd(Sn, Fe, Pb) where a part of Sn in NdSn compound is replaced by Fe and Pb.
  • Nd and Fe diffuse from Nd-Fe-B particles into Pb-Sn phase so that each Nd-Fe-B particle becomes a stoichiometric intermetallic compound R2Fe14B which has ferromagnetism.
  • each magnetic particle comprises not only the intermetallic compound of Nd2Fe14B but also non-magnetic phase.
  • the powder mixtures prepared in Example 8 were compacted into green compact bodies in the aligning magnetic field of 20 KOe by compacting stress of 1.5 ton.f/cm2.
  • Each green compact body was hot-pressed in argon gas at 750 °C under application of a pressure 1,000 Kg.f/cm2 for 20 minutes. Thereafter, the hot-pressed body was heat-treated in argon gas at 600 °C for 30 minutes.
  • Nd2Fe14B magnetic alloy powder similar to Example 3 was prepared.
  • Nd-Fe-Pb-Sn alloy powders C, D, and E in Table 14 were produced from start materials of Nd (purity of 98 % or more), Fe (purity of 99.9% or more), Pb (purity of 99.9%), and Sn (purity of 99.9%).
  • Each powder of C-E was prepared to have an average particle size of 3 ⁇ m.
  • Each powder mixture was compacted into a compact body in the aligning magnetic field of 20 KOe by compacting force of 1.5 ton.f/cm2, and the compact body was sintered in vacuum at 1,000-1,150 °C for 2 hours. The sintered body was further heat-treated at 500-900 °C.
  • Table 15 indicates density and magnetic properties of each sintered and heat-treated body as samples Nos. 36, 37, and 38 which use Nd-Fe-Pb-Sn alloys C, D, and E, respectively.
  • Nos. 36-38 samples are nearly equal to them in the magnetic properties but have a reduced Nd content which is active to oxygen. Accordingly, Nos. 36-38 samples are superior to Nos. 32 and 33 samples in the corrosion resistance and especially during production and storage of powder materials.
  • Example 10 Each mixture obtained in Example 10 was compacted into a green compact in the aligning magnetic field of 25 KOe by pressing stress of 1.5 ton.f/cm2.
  • the green compact was hot-pressed in argon gas at 800 °C by pressing stress of 1.0 ton.f/cm2 for 20 minutes.
  • the hot-pressed body was heat-treated in argon gas atmosphere at 600 °C for 30 minutes.
  • Table 17 shows density and magnetic properties of each hot-pressed body after heat-treated as samples Nos. 39, 40, and 41.
  • Nos. 39 and 40 samples have magnetic properties equally to Nos. 34 and 35 samples but have a reduced amount of Nd.
  • a humidity test was carried out onto the test pieces under a test condition of a temperature of 60 °C and a humidity of 90% for 100 hours.
  • Test pieces of each sample were coated with surface coatings by electrolytic Ni plating, phosphate treating, and anti-corrosion resin coating, respectively.
  • the electrolytic Ni plating was carried out after Cu plating coating of 3-5 ⁇ m thickness was previously formed.
  • the phosphate treating was performed using a conventional phosphate solution.
  • epoxy resin was dissolved in an organic solvent and then sprayed onto test pieces. Thereafter, epoxy resin coating was formed by heating at 150 °C.
  • test pieces were subjected to salt spray corrosion test under a condition where salt water solution (5% NaCl) was sprayed onto the test pieces at 35 °C for 48 hours during which surface change of each test piece was observed. When the test completed, magnetic properties of each test were measured.
  • salt water solution 5% NaCl
  • Added amounts of Zn, Sn, and Al powders were selected to be 5% by volume of respective powder mixtures.
  • Each powder mixture was compacted in the aligning magnetic field of 25 KOe by pressing stress of 1.5 ton.f/cm2 and formed a green compact of a desired bulk shape.
  • the green compact was heated at 700 °C and then coated with glass coating by depositing glass powder onto the surface of the green compact.
  • the glass coated green compact was inserted in a extrusion mould and was moulded into a desired shape by extrusion.
  • each of Nos. 45 and 46 samples is a hot-pressed body produced from the alloy ingot through pulverizing, compacting, and extruding steps.
  • Magnetic materials according to the present invention can be produced by hot extrusion and has excellent magnetic properties in comparison with one produced from the alloy ingot.
  • Example 12 Each of green compact obtained in Example 12 was hot-pressed in argon gas atmosphere at 700 °C by pressing stress of 1,000 Kg.f/cm2 for 15 minutes.
  • the hot-pressed body was heat-treated in argon at 600 °C for 10 minutes.
  • Fig. 7 illustrates measured coercive force to variation of heat-treating temperature. Fig. 7 shows that the effective temperature is 300-900 °C.
  • Fig. 8 shows residual magnetic flux density Br and coercive force I H C to variation of heat-treating time period. It will be noted from Fig. 8 that the heat treatment for about 10 minutes is most effective for improvement of the magnetic properties.
  • Al11Zn89 powder and Al83Cu17 powder were produced from starting materials having purity of 98% or more. Each powder has an averaged particle size of 1-10 ⁇ m.
  • Example 2 Each powder and the Nd13Fe81B6 magnetic powder obtained in Example 2 were mixed with each other at a mixing ratio of 5 to 95 by volume (which means 4.4 wt% for Al11Zn89 and 2.4 wt% for Nd13Fe81B6) in a ball mill.
  • the mixture was compacted to a green compact in the aligning magnetic field of 25 KOe by pressing stress of 1.5 ton.f/cm2.
  • the green compact was hot-pressed in argon gas atmosphere at 600 °C by pressing stress of 1,000 Kg.f/cm2 for 15 minutes.
  • the magnetic properties of hot-pressed body of sample Nos. 50 and 51 are described in Table 23.
  • Al66Fe34 powder, Al25Ni75 powder, Al20Co80 powder, and Al75Cr25 powder were used in place of Al11Zn89 powder and Al83Cu17 powder in Example 14, and a green compact was produced from a mixture of each powder and Nd13Fe81B6 magnetic powder in similar manner as described in Example 14. The green compact was hot-pressed similarly, but for 10 minutes.
  • Magnetic properties of the hot-pressed body was excellent similarly as in Example 14 and is shown in Table 24 with sample numbers Nos. 52-55 for alloy powders used.

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Claims (15)

1. Magnetischer Körper mit einer hohen Koerzitivkraft für einen Permanentmagneten, der im wesentlichen aus einer metallischen Zementphase und gleichmäßig in der metallischen Zementphase verteilten magnetischen kristallinen Teilchen besteht, wobei die Zementphase 10 % oder weniger im Volumen des magnetischen Körpers darstellt und mindestens ein Element aufweist, das aus einer ersten Metallgruppe aus Al, Zn, Sn, Cu, Pb, S, In, Ga, Ge und Te ausgewählt ist, die magnetischen kristallinen Teilchen das Volumen des magnetischen Körpers im wesentlichen ausgleichen und von einer Zusammensetzung sind, die durch eine chemische Formel R₂T₁₄B dargestellt ist, worin R ein aus Y und seltenen Erdmetallen ausgewähltes Element ist, T Übergangsmetalle sind und Fe bei 50 - 100 % in dem Übergangsmetall aufweisen und jedes der magnetischen Teilchen in der Zementphase zum Bilden einer Grenzfläche dazwischen eingebettet ist.
2. Magnetischer Körper nach Anspruch 1, wobei die Zementphase eine intermetallische Verbindung aus mindestens einem der ersten metallischen Gruppe und mindestens einem aus einer zweiten metallischen Gruppe aus R, T und B ausgewählten aufweist.
3. Verfahren zum Erzeugen eines magnetischen Körpers mit einer hohen Koerzitivkraft für einen Permanentmagneten mit den Schritten:
   Vorbereiten eines Rohblockes aus einer R-T-B-Magnetlegierung, die eine magnetische intermetallische Verbindung aufweist, die durch eine chemische Formel R₂T₁₄B dargestellt wird, wobei R mindestens ein Element ist, das aus Y und seltenen Erdmetallen ausgewählt ist, B ein Übergangsmetall ist, aber Fe bei 50 - 100 % in dem Übergangsmetall aufweist;
   Pulverisieren und Zermahlen des Rohbarrens zum dadurch Vorbereiten eines magnetischen Pulvers;
   Vorbereiten eines metallischen Zementpulvers, das mindestens ein Element aufweist, das aus einer ersten Metallgruppe aus Al, Zn, Sn, Cu, Pb, S, In, Ga, Ge und Te ausgewählt ist;
   Mischen eines metallischen Zementpulvers von 10 % oder weniger im Volumen und des magnetischen Pulvers zum im wesentlichen Ausgleichen zum Vorbereiten eines gemischten Pulvers und
   Bilden eines bulkförmigen Körpers des gemischen Pulvers bei einer erhöhten Temperatur.
4. Verfahren nach Anspruch 3, wobei der Schritt des Bildens des bulkförmigen Körpers aufweist:
   Verdichten des gemischten Pulvers unter Einfluß eines kornausrichtenden Magnetfeldes in einen verdichteten Körper einer vorbestimmten Form und
   Sintern des verdichteten Körpers bei einer Temperatur, die niedriger ist als eine peritektische Reaktionstemperatur des magnetischen Pulvers, aber höher als eine Schmelztemperatur des metallischen Zementpulvers ist zum dadurch Erzeugen als der bulkförmige Körper eines gesinterten Körpers.
5. Verfahren nach Anspruch 4, bei dem der R-T-B-Rohbarren aus der intermetallischen Verbindung von R₂T₁₄B besteht und das metallische Zementpulver eine intermetallische Verbindung aus mindestens einem Element aufweist, das aus der ersten Metallgruppe gewählt ist, und eines, das aus einer zweiten Metallgruppe aus R, T und B ausgewählt ist.
6. Verfahren nach Anspruch 5, mit dem weiteren Schritt des Aussetzens des gesinterten Körpers einer Wärmebehandlung zum Verbessern der magnetischen Eigenschaften des gesinterten Körpers.
7. Verfahren nach Anspruch 6, bei dem die Wärmebehandlung bei 300 - 900 °C ausgeführt wird.
8. Verfahren nach Anspruch 3, bei dem der Schritt des Bildens des bulkförmigen Körpers ein warmer Verdichtungsvorgang zum warmen Verdichten des gemischten Pulvers in den bulkförmigen Körper bei einer erhöhten Temperatur niedriger als 1100 °C, aber höher als eine Schmelztemperatur des metallischen Zementpulvers ist.
9. Verfahren nach Anspruch 8, bei dem der warme Verdichtungsvorgang ein warmer Preßvorgang zum warm Pressen des gemischten Pulvers in den bulkförmigen Körper unter einem Druck von 5 - 5000 kp/cm² ist.
10. Verfahren nach Anspruch 9, wobei der Schritt des Bildens des bulkförmigen Körpers weiter einen Schritt des vorherigen Verdichtens des gemischten Pulvers zum Bilden eines Grünlings aufweist und der Grünling dann dem Warm-Pressen-Vorgang ausgesetzt wird.
11. Verfahren nach Anspruch 10, bei dem der Verdichtungsschritt in einem ausrichtenden Magnetfeld durchgeführt wird.
12. Verfahren nach Anspruch 8, bei dem der Warm-VerdichtungsVorgang die Schritte des Verdichtens des gemischten Pulvers zum Bilden eines Grünlings, Erwärmen des Grünlings bei der erhöhten Temperatur und dann Aussetzen des erwärmten Grünlings einem Extrudieren zum dadurch Erzeugen als dem bulkförmigen Körper eines extrudierten Körpers aufweist.
13. Verfahren nach Anspruch 12, bei dem der Grünling mit einem wärmeisolierenden Material vor dem Extrudieren beschichtet wird.
14. Verfahren nach Anspruch 8, das weiter einen Schritt des Unterwerfens des bulkförmigen Körpers einer Wärmebehandlung zum Verbessern seiner magnetischen Eigenschaften aufweist.
15. Verfahren nach Anspruch 14, bei dem die Wärmebehandlung bei 300 - 900 °C durchgeführt wird.
EP87108724A 1986-06-16 1987-06-16 Dauermagnet-Material und Verfahren zur Herstellung Expired - Lifetime EP0249973B1 (de)

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JP139650/86 1986-06-16
JP13965086 1986-06-16
JP8902887A JPS63114939A (ja) 1986-04-11 1987-04-11 Ｒ↓２ｔ↓１↓４ｂ系複合型磁石材料とその製造方法
JP89028/87 1987-04-11

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DE4027598C2 (de) * 1990-06-30 1997-09-11 Vacuumschmelze Gmbh Dauermagnet des Typs SE-Fe-B und Verfahren zu seiner Herstellung
US5354354A (en) * 1991-10-22 1994-10-11 Th. Goldschmidt Ag Method for producing single-phase, incongruently melting intermetallic phases
CN1044940C (zh) * 1992-08-13 1999-09-01 Ybm麦格奈克斯公司 基于钕铁硼的生产永久磁铁的方法
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