WO1988004098A1 - Procede de production d'un aimant fritte anisotrope en metaux des terres rares-fer-bore a partir de paillettes trempees en alliage de metaux des terres rares-fer-bore en forme de rubans - Google Patents

Procede de production d'un aimant fritte anisotrope en metaux des terres rares-fer-bore a partir de paillettes trempees en alliage de metaux des terres rares-fer-bore en forme de rubans Download PDF

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Publication number
WO1988004098A1
WO1988004098A1 PCT/JP1987/000917 JP8700917W WO8804098A1 WO 1988004098 A1 WO1988004098 A1 WO 1988004098A1 JP 8700917 W JP8700917 W JP 8700917W WO 8804098 A1 WO8804098 A1 WO 8804098A1
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alloy
ribbon
flakes
rapidly
quenched
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PCT/JP1987/000917
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English (en)
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Tadakuni Sato
Yuichi Tachiya
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Tokin Corporation
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0611—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by a single casting wheel, e.g. for casting amorphous metal strips or wires
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
    • 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
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
    • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
    • B22F9/10—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying using centrifugal force
    • 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
    • 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 rare earth metal-transition metal-boron (R-T-B) permanent magnet with a high energy product and, in particular, to a method for producing such permanent magnets with anisotropy by sintering compact bodies of rapidly-quenched R-T-B alloy powder.
  • R-T-B rare earth metal-transition metal-boron
  • J. J. Croat proposed amorphous R-Fe-B (Nd and/or Pr is especially used for R) alloy having magnetic properties for permanent magnets as disclosed in JP-A-59064739 (Reference 2, which is corresponding to U.S. Patent applications Serial Nos. 414936 and 508266) and JP-A-60009852 (Reference 3, which is corresponding to U.S. Patent applications Serial Nos. 508266 and 544728).
  • References 2 and 3 disclose to use other transition metal elements in place of or in part of Fe. Those magnetic properties were considered to be caused by a microstructure where Nd 2 Fe, ,B magnetic crystal grains having a grain size of 20-400 nm were dispersed within an amorphous Fe phase.
  • the rapidly-quenched alloy ribbon is prepared by the continuous splat-quenching method which is disclosed in, for example, a paper entitled “Low-Field Magnetic Properties of Amorphous Alloys” written by Egami, Journal of The American Ceramic Society, Vol. 60, No. 3-4, Mar.-Apr. 1977, p.p. 128-133 (Reference 5).
  • a similar continuous splat-quenching method is disclosed as a "Melt Spinning" method in References 2 and 3. That is, R-T-B molten alloy is ejected through a small orifice onto an outer peripheral chill surface of a copper disk rotating at a high speed.
  • the molten alloy is rapidly quenched by the disk to form a rapidly-quenched ribbon. Then, a comparatively high cooling rate produces an amorphous alloy but a comparatively low cooling rate crystallises the metal.
  • the principal limiting factor for the rate of chill of a ribbon of alloy on the relatively cooler disc surface is its thickness. If the ribbon is too thick, the metal most remote from the chill surface will cool too slowly and crystallise in a magnetically soft state. If the alloy cools very quickly, the ribbon will have a microstructure that is somewhere between almost completely amorphous and very, very finely crystalline.
  • the amorphous alloy can provide only an isotropic magnet because of its crystallographically isotropy. This means that a high performance anisotropic permanent magnet cannot be obtained from the amorphous alloy.
  • Reference 6 also discloses that magnetic alignment was strongly enhanced by upsetting fully dense hot-pressed samples of crushed amorphous alloy. But the technique cannot yet provide an anisotropic permanent magnet having a satis actorily high energy product.
  • the hot-pressed magnet has a residual magnetic flux density Br of 7.9 kGauss, an intrinsic coercive force _H.-, of 16 kOe, and an energy product (BH)max of 13 MGOe.
  • JP-A-60089546 discloses a rapidly quenched R-Fe-B permanent magnet alloy with a high coercive force.
  • the alloy contains very fine composite structures less than 5 urn predominant of tetragonal crystal compositions and is crushed into powders having particle sizes of -100 Tyler mesh- (less than 300 urn) to produce a bonded magnet.
  • Reference 7 describes possibility of application of the crushed powders to a sintered magnet and a c-axis anisotropy appreciated by application of X-ray diffraction microscopy to a surface of the alloy, no anisotropic sintered permanent magnet is disclosed.
  • the R-Fe-B alloy tends to be oxidized in production of the magnet, because the R-Fe-B alloy ingot comprises the magnetic crystalline phase of the chemical compound R-F -i .B and the R-rich solid solution phase and because the solid solution phase is very active to oxygen. Further, the solid solution phase is difficult to be uniformly ground into particles. Accordingly, it is difficult to produce an anti-corrosion anisotropic sintered magnet having a high energy product.
  • the present invention is directed to a method for producing a rare earth-transition metal-boron (R-T-B) sintered magnet by preparing an R-T-B alloy powder containing R_ , 4 B crystal grains, putting the powder in a magnetic field and compacting the powder into a compact body of a desired shape, and sintering the compact body at a sintering temperature thereby to produce the sintered magnet.
  • R-T-B rare earth-transition metal-boron
  • the R-T-B alloy powder is a rapidly quenched alloy powder produced by steps of preparing the R-T-B alloy in a molten state, rapidly quenching the molten R-T-B alloy to form ribbons and/or ribbon-like flakes, each ribbon and/or flake having a thickness and containing the crystal grains uniformly dispersed in the ribbon and/or flake, the crystal grains having an average grain size, and crushing and grounding the ribbons and/or flakes into a powder of an average particle size of a value less than the thickness, each particle of the powder containing the crystal grains extending in a direction, to thereby enable the powder to be magnetically aligned in the magnetic field.
  • Each ribbon and/or flake desirably has a thickness of 20-500 urn (preferably 50-500 x ) , and the crystal grains have an average grain size of 10 um or less (preferably 1-10 u ) .
  • the crushed and ground powder has an average particle size of 0.3-15 um (preferably 1.5-3 um) .
  • the sintering is desired to be carried out so that said crystal grains are grown to have a grain size of 7-30 um.
  • the R-T-B alloy powder consists, by weight, of R 28.0-65.0 %, and the balance of T and B.
  • the transition metal elements T in the R-T-B alloy may be Fe and Co represented by Fe, Co , x being 0.35 or less.
  • the ribbons and/or flakes can be produced by the continuous splat-quenching method, that is, the molten R-T-B alloy is ejected through a small orifice onto an outer peripheral chill surface of a quenching disk rotating at a predetermined speed, and the ejected molten alloy is thereby rapidly cooled into the rapidly-quenched ribbons and/or ribbon-like flakes.
  • the molten alloy is sprayed or atomized onto a cooling plate to form flat ribbon-like flakes.
  • the molten alloy is rapidly quenched on opposite sides of the ribbon or flake but at quenching start times offset from each other.
  • the rapidly-quenched powder can be subjected to a heat treatment at a temperature of 650-950 °C.
  • Fig. 1 is a graph showing magnetic properties of sintered magnets in Example 1 together with average particle sizes of used powders
  • Fig. 2 is a graph showing magnetic properties of sintered magnets in Example 4 together with thickness of ra idly-quenched ribbons;
  • Fig. 3 is a graph showing magnetic properties of sintered magnets- in Example 5 together with average grain sizes of crystals in rapidly-quenched ribbons;
  • Fig. 4 is a graph showing magnetic properties of sintered magnets in Example 10 together with R contents in rapidly-quenched alloys
  • Fig. 5 is a graph showing magnetic properties of sintered magnets in Example 13 together with cobalt contents in transition metal elements
  • Fig. 6 is a graph showing magnetic properties of sintered magnets in Example 16 together with average grain sizes of crystals in sintered bodies
  • Fig. 7 is a graph showing magnetic properties of sintered magnets in Example 19 together with heat treated temperatures for rapidly-quenched alloy ribbons;
  • Fig. 8 is a sectional view of a device for preparing a rapidly-quenched ribbon which is used in Example 22;
  • Fig. 9 is a side view of a device for preparing rapidly-quenched flakes which is used in Examples 23-25;
  • Fig. 9a is an enlarged view of a part in a circle A in Fig. 9;
  • Fig. 10 is a graph showing magnetic properties of sintered magnets in Example 23 together with thickness of rapidly-quenched alloys
  • Fig. 11 is a sectional view of a device for preparing rapidly-quenched flakes which is used in examples 26 to 29;
  • Figs. 12a, 12b, and 12c show microstructures of an ingot, a granule, and a flake prepared in Example 26;
  • the present invention was made on the following novel facts observed by the present inventors. That is, the inventors found out that the magnetic crystal of R 2 14 B such as Nd 2 Fe, 4 B had a predominant grain growing direction in the C-plane of the crystal. Further, the C-plane of the crystal in the rapidly-quenched R-T-B alloy ribbon tends to orient in a direction parallel to the main surface of the ribbon when the crystal is grown in a grain size 5 um or less. When the crystal grain grows larger than 5 um, the crystal grows in a needle-like form and the C-plane of the crystal has an orientation in a.direction perpendicular to the main surface of the ribbon.
  • the rapidly-quenched alloy ribbon has a high anisotropy when crystals are uniformly grown to have a generally equal and comparatively large grain size. Then, it will be noted that a powder obtained by grounding the rapidly-quenched anisotropic alloy ribbon can be magnetically aligned in a magnetic field so that an anisotropic sintered magnet can be produced through magnetic aligning, pressing, and sintering steps.
  • the present inventors further found out that orientations of adjacent crystal grains were generally equal, even if orientations were different between crystal grains distant from one another in the direction of thickness of the ribbon.
  • the present invention attempts to make an R-T-B alloy powder with a high anisotropy by grounding the rapidly-quenched alloy ribbon into a powder having an average particle size of a value less than the thickness of the ribbon, thereby to obtain a powder of separated particles, each particle containing crystal grains with C-planes generally extending in one direction.
  • the ground powder can be magnetically aligned and compacted into a desired shape which is sintered into an anisotropic sintered magnet with a high energy product.
  • An ingot of an alloy consisting of R 35.0 wt%, B 0.9 wt%, and substantially balance of Fe was prepared by the induction melting in argon gas atmosphere.
  • Starting materials used for R, B, and Fe were Nd of a purity factor of 97% including other rare earth metal elements mainly Ce and Pr, ferroboron containing B 20 wt%, and electrolytic iron, respectively.
  • the ingot was again melted by the induction melting in argon gas.
  • the molten alloy was ejected through a small orifice on to an outer chill surface of a copper disk rotating at a chill surface moving speed of 15 m/sec to produce a rapidly-quenched alloy ribbon having a width of 5 mm and a thickness of about 100 um.
  • the ribbon showed fine R ? Fe ⁇ B crystal grains dispersed in the ribbon and having an average grain size of 0.1 um.
  • the ribbon was crushed and ground by means of a ball mill to produce seven molding powders having average particle sizes of 0.5 um, 1.5 um, 3.0 um, 5.0 um, 10.0 um, 15.0 um, and 30.0 um, respectively.
  • the magnet was measured as to magnetic properties, that is, residual magnetic flux density Br, coercive force T iHt_-., and maximum energy-* product (BH)max
  • the measured properties are shown in Fig. 1 in relation to the average particle sizes of the molding powders.
  • (BH)max is larger than 16 MGOe for the average particle size smaller than 15 ⁇ which is considerably smaller than the size of the ribbon thickness.
  • (BH)mantonx drone is increased for the average particle size smaller than 10 um and is further increased for 5 um or less average particle size.
  • Example 2 There is no lower limit for the average particle size of the molding powder, but 0.3 um or more is desired in practical use.
  • Example 2
  • An alloy ingot consisting of R 40 wt%, B 1.0 wt%, and the balance of Fe was made in the similar manner as in Example 1.
  • a start material of R consisted of cerium didymium consisting of Ce 5 wt%, Pr 15 wt%, and the substantially balance of Nd and.an addition of 5 at% Dy.
  • Ferroboron and electrolytic iron were also used for start materials of B and Fe.
  • the R2_Fe1,4.B crystal grains dispersed in the ribbon had an average grain size of about 0.01 um.
  • the ribbon was crushed and ground into two powders having average particle sizes of 2.0 um and 20.0 um, respectively.
  • Example 2 Using Nd of a purity factor 97 % (including Pr, Ce and other rare earth metals), ferroboron, electrolytic iron, electrolytic cobalt, and aluminium of a purity factor of 99.9 %, an ingot was prepared in the similar manner as in Example 1.
  • the ingot consisted of R 40.0 wt%, B 0.9 wt%, and the balance of Fe__Co 20 Al 3 .
  • Rapidly-quenched ribbon-like flakes were obtained from the ingot by the continuous splat-quenching method similar to the method in Example 1 but using a quenching disk rotating at a chill surface speed of 5 m/sec
  • Each flake had a width of about 5 mm and a thickness of about 150 u .
  • An average size of crystal grains dispersed in each flake was about 0.5 um. These flakes were crushed and ground into two powders having average particle sizes of 2.5 um and 20.0 ⁇ m, respectively.
  • the magnetic properties of the magnet made from powder of 2.5 um particle size is superior to another magnet made from the 20.0 um particle size powder.
  • an R-T-B alloy ingot was also prepared in the similar manner as in Example 1. Amount of the start materials was adjusted so that the ingot consisted of R 32.0 wt%, B 1.0 wt%, and the balance of Fe. Seven rapidly-quenched ribbons were prepared from the alloy by the continuous splat-quenching method similar to that in Example 1 at different chill surface speeds within a range over about 2-50 m/sec, respectively. The seven ribbons had different width within a size range of 1-15 mm and different thickness sizes of 10 vim, 20 ⁇ m, 50 ⁇ m, 100 ⁇ m, 200 ⁇ x ⁇ . r 500 and 1000 lim, respectively.
  • Each alloy ribbon contains R ⁇ Fe.. 4 B crystal grains dispersed therein; 2) The crystal grains have sizes of 3 ⁇ m or less for each ribbon having a thickness of 200 um or less, and 10 um or less for each ribbon having a thickness of 500 um or less, while the ribbon having
  • each crystal grain of a size of 5 um or less has a C-plane generally oriented in a direction parallel to a main surface of the ribbon, while each crystal grown larger than 5 um size is in a needle like crystal and has a C-plane extending in a direction perpendicular to the main surface of the ribbon.
  • the compact body was sintered by holding at a temperature of 1,080 C in vacuum for one hour and in argon gas for next succeeding one hour, and then was quenched.
  • the sintered body was aged at 630 °C for 2 hours in argon gas. Thereafter, a magnetic field of 30 kOe was applied to the sintered body to form a magnet. Magnetic properties of the magnet was measured.
  • Fig. 2 shows the measured magnetic properties of the magnet in connection with ribbon thickness size of the powder used for the ' magnet.
  • an alloy ingot was prepared to consist of R 30.0 wt%, B 1.1 wt%, and the balance of Fe. Then, ribbons and/or ribbon-like flakes were obtained from the alloy ingot by the similar continuous splat-quenching method in use of a steel quenching disk. The width and the thickness of the ribbon or flakes were controlled over a range of about 1-10 mm and a range of about 10-500 um, respectively, by changing the chill surface moving speed over a range of about 1-60 m/sec.
  • Some of the obtained ribbons were amorphous alloy for higher chill surface speeds and the remaining ribbons and flakes contain the crystal grains having an average grain size of 0.001-10 ⁇ m, while crystals contained in individual ribbon or flake has a small grain size distribution.
  • the measured data of the magnets made from the individual powders are shown in Fig. 3 together with average crystal grain sizes in the powders.
  • An alloy ingot was used from the similar starting materials by the similar producing method as in Example 2.
  • the alloy ingot consisted of R 35.0 wt%, B 0.9 wt%, and the balance of Fe.
  • Two alloy ribbons were prepared by the method similar to that in Example 4 but at different chill surface speeds.
  • the two ribbons have width sizes of about 2 mm and 10 mm and thickness sizes of 15 ⁇ m and 100 um for the chill surface speeds of 50 m/sec and 10 m/sec, respectively.
  • Crystal grains in the 15 ⁇ m thick ribbon were measured smaller than a submicron meter in size and C-planes of some grains were merely observed to be oriented in parallel to the main surface of the ribbon. While the other ribbon having the thickness of 100 um contained crystal grains of about 2 um or less, C-planes of which were mostly oriented in parallel direction to the main surface of the ribbon.
  • the magnet made from the 100 um thickness ribbon has more excellent magnetic properties than the other magnet made from the 15 um thickness ribbon.
  • An alloy ingot consisting of R 40.0 wt%, B 1.0 5 wt%, and the balance of Fe was prepared in the manner as in Example 6. Then, an alloy ribbon having a width of about 3 um and a thickness of about 60 u was made by the continuous splat-quenching method using a steel quenching disk in a similar manner as in Example 5.
  • - j O magnet was obtained from the alloy ribbon by the similar steps in Example 5 but using ' 1,050 C and 650 °C for the sintering and aging temperatures. The magnetic properties of the magnet is shown in Table 4.
  • Example 3 Using the similar starting materials in Example 3, an alloy ingot was prepared in the similar manner. 0 The alloy ingot consisted of R 40.0 wt%, B 1.1 wt%, and the balance of Fe_ 7 Co 2n Al_, From the ingot, two ribbons with thickness sizes of about 15 um and 100 ⁇ m, respectively, were made by the similar manner as in Example 6. Two magnets were produced from these ribbons 5 in the similar steps as in Example 4 but using a sintering temperature of 1030 C and an aging condition of 650 °C for one hour.
  • Example 9 In the similar manner as in Example 8, an alloy ingot was prepared which consisted of R 40.0 wt%, B 0.9 wt%, and the balance of Fe__Co 2Q Al 3 . Then, an alloy ribbon with a width of about 3 mm and a thickness of about 60 ⁇ m was produced from the ingot by the similar method as in Example 7. From the alloy ribbon, a magnet was made in the similar manner as in Example 5 but using a sintering temperature of 1,050 C and an aging temperature of 630 C. The obtained magnet has magnetic properties as shown in Table 6. Table 6
  • Example 2 Using the similar starting materials as in Example 1, nine alloy ingots were produced in the manner as described in Example 1. Those nine ingots contains the same amount of B 1.0 wt%, different amounts of R in a range of 27.5-65.0 wt%, and the balance of Fe. From these nine ingots, nine rapidly-quenched alloys were 5 made by the continuous splat-quenching method using a steel quenching disk rotating a different chill surface moving speeds over a range of 10-20 m/sec. The rapidly-quenched alloys had a width of about 5 mm with thickness ranging over about 50-100 um in dependence of
  • each alloy contained fine crystal grains of an average grain size of about 0.2 um. Some of the alloys were lengthy ribbons and the remaining ones were ribbon-like flakes.
  • the sintered bodies were magnetized by application of a magnetic field of about 30 kOe to form nine magnets, which were subjected to measurement of magnetic properties.
  • Example 11 An alloy ingot consisting of R 40.0 wt%, B- 0.9 wt%, and the balance of Fe was prepared in the similar manner as described in Example 2. From the alloy ingot, an alloy ribbon was produced by the similar method as in Example 10 using a steel quenching disk rotating a chill surface speed of 30 m/sec. The alloy ribbon has a width of about 2 mm and a thickness of about 50 um. Crystal grains contained in the ribbon was confirmed to have an average grain size of about 0.01 um. The ribbon was processed in the similar steps as in Example 10 to produce a magnet but using 1,020 °C for the sintering temperature. Table 7 shows the magnetic properties of the magnet.
  • Example 3 In a similar manner as in Example 3, an alloy ingot consisting of R 40.0 wt%, B 1.0 wt%, and the balance of Fe was prepared. The ingot was processed by the similar continuous splat-quenching method using a steel quenching disk as in Example 10 but using a chill surface speed of 5 m/sec and ribbon-like flakes was obtained each having a width of about 5 mm and a thickness of about 150 um. Each flake was observed to contain crystal grains having an average grain size of about 0.5 um.
  • the flakes were also processed in the similar steps as described in Example 10 but using 1,030 C as the sintering temperature and a magnet was obtained which had magnetic properties as shown in Table 8.
  • the compacted bodies were processed in the similar manner as described in Example 5 but using a sintering temperature of 1,060 C to produce magnets. Magnetic properties were measured and shown in Fig. 5.
  • Two alloy ingots were prepared in the similar manner as described in Example 13.
  • One of the ingots consisted of R 40.0 wt%, B 1.0 wt%, and the balance of Fe as T (transition metal), while the other one consisted of R 40.0 wt%, B 1.0 wt%, and the balance of Feg_Co, Q as T (transition metals).
  • rapidly-quenched alloys each having a width of about 3 mm and a thickness of about 30 u were produced by the similar continuous splat-quenching method.
  • Each of rapidly-quenched alloys was confirmed to contain fine crystal grains of an average grain size.
  • Two magnets were made from these rapidly-quenched alloys, respectively, in the similar manner as described in the Example 13 but using 1,020 °C as the sintering temperature while aging being carried out for one hour.
  • Table 10 teaches us that addition of cobalt improves Br and (BH)max.
  • An alloy ingot consisting of R 32 wt%, B 1.1 wt% and the balance of Fe was made in the similar manner as in Example 1. From the alloy ingot, a ribbon was prepared by the similar continuous splat-quenching method using a copper quenching disk at a chill moving surface speed of 10 m/sec. The ribbon had a width of about 5-10 mm and a thickness of about 50-100 um, and contained crystal grains of average grain size of 0.3
  • the ribbon was crushed and ground into powder of an average particle size of 2.5 um and then compacted into a compact body by pressing force of 2 ton.f/cm 2
  • the compacted body was sintered at a temperature of 1,000-1,120 C in vacuum for one hour and in argon gas for another one hour.
  • the resultant sintered body had a saturated sintered density and contained crystal grains of an average grain size of 5-30 ⁇ m dependent on the sintering temperature.
  • the sintered body was aged at a temperature of 650 °C in argon gas for two hours, and then magnetized by a magnetic field of 30 kOe. The magnet was subjected to measurement of the magnetic properties.
  • Example 17 From the alloy ingot made in Example 11, an alloy ribbon was prepared by the continuous splat-quenching method similar to that in Example 16. The chill surface speed was about 15 m/sec and the obtained ribbon had a width of about 5 mm and a thickness of about 50 um. Crystal grains in the ribbon were about 0.1 um in the average grain size.
  • Two compacted bodies were formed from the powder by the similar manner as in Example 16, and were sintered at different temperatures of 980 °C and 1,050 C, respectively, and thereafter aged in the similar manner as in Example 16.
  • Those sintered bodies had a full sintered density and grown crystal grains which were about 6 um and 15 um in the average grain size for the sintering temperatures of 980 °C and 1,050 °C, respectively.
  • the sintered and aged bodies were magnetized similar to Example 16 and magnetic properties were measured. The measured data are shown in Table 11.
  • Example 3 an ingot consisting of R 35.0 wt%, B 1.0 wt%, and the balance of Fe__B 20 Al., was made. Then, an alloy ribbon was prepared from the ingot using a quenching disk rotating at the chill surface speed of 5 m/sec. The width and thickness of the ribbon were about 10 mm and about 200 um, respectively, and an average grain size of crystals in the ribbon was about 0.5 um.
  • Example 17 Two compacted bodies were formed in the manner similar to that in Example 17 and were sintered at temperatures of 1,000 °C and 1,080 °C, respectively.
  • the resultant sintered bodies had grown crystals of average grain sizes of 6 um and 15 um, respectively.
  • the sintered bodies were aged, and magnetized similar to Example 17. The magnetic properties are shown in Table 12. Table 12
  • Example 19 In the similar manner as in Example 1, an alloy ingot consisting of R 33.0 wt%, B 1.0 wt%, and the balance of Fe, was prepared and rapidly-quenched alloys ribbon were produced by the similar continuous splat-quenching method using a quenching copper disk rotating at the chill surface speed of 10 m/sec. Each of the ribbons had a width of 5 mm and a thickness of 50 um.
  • the ribbon had Nd 2 Fe, 4 B crystals of grain sizes of 1 um or less dispersed therein with C-planes of the crystals being mainly oriented in a parallel direction of the main surface of the ribbon.
  • the free surface farthest from the chill surface had crystals of large grain size with a high crystal orientation in comparison with the rapidly cooled surface impinging the chill surface.
  • Those ribbons were heat treated at 600 °C, 700 °C, 800 °C, 900 °C and 1,000 °C for two hours. respectively, and were crushed and ground into powders, respectively, with an average particle size of about 3 um.
  • Fig. 7 teaches us that heat treatment at 650 C or more considerably improves the Br and (BH)
  • Example 2 An ingot consisting of R 35.0 wt%, B 0.9 wt%, and the balance of Fe was prepared in the similar manner as described in Example 2. From the ingot, two rapidly-quenched alloy ribbons were prepared in the similar manner as in Example 19. Those ribbons contained crystals of grain sizes of 2 um or less with crystal orientation in the parallel direction to the main surface of the ribbon. One of the ribbons was heat treated at 800 °C in argon gas for one hour.
  • An alloy ingot consisting of R 40.0 wt%, B 1.1 wt%, and the balance of Fe 7 _Co 2Q Al 3 was prepared in the similar manner as described in Example 3. From the ingot, two rapidly-quenched ribbons were prepared by the continuous splat-quenching method as described in Example 19. Those ribbons had Nd 2 (FeCoAl) , 4 B crystals of grain sizes of 3 um or less with C-planes mainly oriented in the parallel direction to the main surface of the ribbon.
  • One of the ribbons was heat treated at 800 °C in argon gas for one hour.
  • the heat treated and no heat treated ribbons were crushed and ground into powders and were formed into sintered magnets, respectively, in the similar manner as described in Example 19, but using the sintering temperature of 1,050 C.
  • Table 14 The magnetic properties of the resultant magnets are shown in Table 14. Table 14 also teaches us that the heat treatment considerably improves the magnetic properties.
  • Example 2 In the similar manner as described in Example 1, an alloy ingot was made which consisted of R 34.0 wt%, B 1,0 wt%, and the balance of Fe. From the ingot, two rapidly-quenched alloy ribbons having a width of about 5 mm and a thickness of about 50 um were prepared by the similar continuous splat-quenching method using a copper quenching disk rotating at the chill surface speed of about 10 m/sec. One of the ribbon was exposed in a magnetic field during being rapidly cooled.
  • Fig. 8 shows a device used for preparing the ribbon with application of the magnetic field. The device comprises a melting tube 21 made of, for example, quartz, in which the alloy ingot is melted in a molten state.
  • the melting tube 21 has a small orifice 22 through which the molten alloy 23 is ejected onto a quenching disk 24 of iron.
  • a quenching disk 24 of iron On the opposite sides of the quenching disk 24, .
  • two hollow disk-shaped cases 25 and 25' are mounted which are made of non-magnetic steel and have rotating shafts 26 and 26' on a common central axis thereof.
  • the cases 25 and 25' fixedly contain disk-shaped permanent magnets 27 and 27* which are magnetized in a thickness direction and have the same magnetic pole surfaces adjacent to the opposite surfaces of the quenching disk, respectively. Accordingly, the flux from the both magnets 27 and 27' radially flows at the outer peripheral surface of the iron quenching disk 24.
  • a samarium cobalt magnet of a disk shape which had a diameter of 20 cm and a thickness of 2.5 cm with a surface flux density of 1 kGauss.
  • An iron disk having a diameter of 21 cm and a thickness of 2.0 cm was used for the quenching disk 24.
  • a magnetic field was observed about 3 kOe.
  • the molten alloy 23 was ejected through the orifice 22 onto the outer peripheral surface of the quenching disk 24 and the ribbon was produced. Accordingly, the ribbon was exposed in the radial magnetic field on the disk 24 so that the magnetic field was applied to the ribbon in the thickness direction during the ribbon being cooled. While, the other ribbon was prepared by the device shown in Fig. 8 but the magnets 27 and 27' were replaced by non-magnetic disks. Therefore, the other ribbon was not applied with any magnetic field. Those ribbons were observed by the X-ray diffraction microanalysis to have fine crystal grains of several micron meters or less. The ribbon applied with the magnetic field has many crystals of C-plane oriented in the parallel direction to the main surface of the ribbon in comparison with the other ribbon applied with no magnetic field.
  • the device comprises a melting tube 31 of, for example, quartz having a small orifice 32.
  • a melting tube 31 of, for example, quartz having a small orifice 32.
  • An alloy 33 is melted.
  • a quenching disk 34 is disposed under the orifice 32 so that the molten alloy 33 is ejected through the orifice 32 onto a chill surface of the quenching disk 34 which is rotated at a predetermined speed.
  • the chill surface of the quenching disk 34 is formed with a plurality of projections 35 defining grooves 36 between adjacent two projections 35 as shown at an enlarged sectional view in Fig. 9a.
  • projections 35 were formed at an repetition interval of 1 mm with a radial size of 0.5 mm.
  • a circular cooling plate 37 with a rotating shaft 38 is disposed at a side of the quenching disk 34 to have a main surface facing the chill surface of the quenching disk 34.
  • Example 23 In the similar manner as described in Example 1, an ingot was prepared which consisted of R 32.0 wt%, B 1.0 wt%, and the balance of Fe. From the ingot, rapidly-quenched alloy ribbons were prepared in the similar continuous splat-quenching method as in Example 1. In the case, the chill surface moving speed was changed within a range over about 2-80 m/sec so that the ribbons had widths of about 0.5-15 mm and thickness sizes of 10, 20, 50, 100, 200, 500, and 1,000 im, respectively.
  • rapidly-quenched alloy flakes were prepared from the ingot using the device as shown in Fig. 9.
  • a plurality of lots of flakes were prepared by changing the chill surface speed within a range over about 2-100 m/sec and therefore, resultant flakes have different widths 0.5-10 mm and thickness sizes of about 7-1,000 um in dependence on the different chill surface speeds.
  • Those compacted bodies were sintered in the similar condition as in Example 4 and were aged at a temperature of 650 °C for one hour. Thereafter, the sintered bodies were applied with a magnetic field of 30 kOe to form magnets.
  • the magnetic properties of the resultant magnets are shown in Fig. 10 together with the thickness sizes of the flakes made by spraying and ribbons by continuous splat-quenching method. It will be noted that the magnets using flakes made by spraying have improved magnetic properties in comparison with the magnets made from the continuous splat-quenched ribbons for the thickness sizes of 500 um or less. Further, it is noted that use of the flakes of 7 um or more provides a considerably excellent Br and
  • Example 6 From the ingot prepared in Example 6, a lot of generally circular flakes were prepared by the use of the device as shown in Fig. 9. Each flake had a thickness of 15 um and a diameter of 1 mm, and contained crystals having grain sizes of about 1 um or less.
  • Example 16 From the flakes, a magnet was prepared in the similar manner as described in Example 6. The magnetic properties of the resultant magnet are shown in Table 16 together with those of the magnet made from ribbon having 15 um thickness in Example 6.
  • Example 6 has a considerably improved magnetic properties comparing with Example 6.
  • Example 25 Using the ingot prepared in Example 8, a lot of flakes each having a thickness of 15 um and a diameter of 1 mm were prepared in the similar manner as in Example 24. From the flakes, a magnet was produced in the similar manner as described in Example 8. The magnetic properties of the resultant magnet are shown in Table 17 together with those of the sample made from 15 ⁇ m ribbon in Example 8. The present example clearly has an improved magnetic properties.
  • a device shown in Fig. 11 comprises a melting tube 41 of quartz and a spray nozzle 42 mounted at a lower portion of the melting tube 41.
  • An alloy is melted in the melting tube 41 in a molten state.
  • the molten alloy 43 is sprayed through the spray nozzle 42 in an atomized particles P by application of compressed argon gas Ar into the spraying nozzle 42.
  • This method is well known in the prior art as an atomizing method for preparing an amorphous alloy wherein the atomized particles are cooled in circular small balls or granules.
  • a cooling plate 44 of such as copper is disposed under the nozzle 42 and is rotated.
  • the atomized particles P impinge onto the main surface of the cooling plate 44 and deformed and cooled into small flat flakes F.
  • An alloy ingot consisting of R 30.0 wt%, B 1.0 wt%, and the balance of Fe was prepared using the similar starting materials and a similar melting method as in Example 1.
  • the ingot was formed with a thickness of about 10 mm by the use of a mould having a water cooling system.
  • a lot of granules or small balls were prepared from the alloy ingot by the known atomizing method. Each of the granules had a particle size of about 0.2 mm.
  • the ingot comprises predominant phases (shown in white, for example, at A in the figure) of large grown crystal grains of Nd 2 Fe 14 B, iron grains phases (shown by small white areas, for example, at B in the figure) precipitated in the predominant phase, and Nd rich crystal phases (shown in black, for example, at C in the figure) dispersed between the predominant phases.
  • the granule comprises a predominant phases (shown by white areas, for example, at A in the figure) of 2 Fe, 4 B crystals having grain sizes of about 5 um, a small amount of iron phases (shown by small white areas, for example, at B in the figure) dispersed in the predominant phases, and Nd rich phases (shown in black, for example, at C in the figure) dispersed between the predominant phases.
  • a predominant phases shown by white areas, for example, at A in the figure
  • iron phases shown by small white areas, for example, at B in the figure
  • Nd rich phases shown in black, for example, at C in the figure
  • the flake comprises predominant phases of needle-like crystals of Nd_Fe, 4 B and Nd rich phases at interfaces of the crystals.
  • the C-planes of the crystals are generally oriented in a direction perpendicular to the main surface of the flake.
  • the ingot, the lot of granules, and the lot of flakes were crushed and ground into respective powders having an average particle size of about 3.0 u .
  • Fig. 13 The magnetic properties of the resultant magnets are shown in Fig. 13 in connection with different production methods of alloy powders together with different sintering temperatures. It will be understood from Fig. 13 that magnets made from the flake powder are superior in the magnetic properties to magnets made from the other powders although the magnets made from the granule powder also have better properties than the magnets made from the ingot powder.
  • Example 27
  • a lot of granules having particle sizes of about 50 um and a lot of flakes having diameters of about 50 um and thickness of about 30 um were prepared from the ingot by the known gas atomizing method and the method using the device as shown in Fig. 11, respectively.
  • These granules and flakes comprised a microstructure of Ne 2 Fe 14 B crystal grains of sizes of 3 um or less and Nd rich phases at interfaces between the crystals. Further, it was confirmed by X-ray diffraction microanalysis that C-planes of the crystals in each flake were almost uniformly oriented in the direction parallel to the main surface of the flake. Those granules and flakes were crushed and ground into powders of an average particle size of 4 um, respectively, and were compacted to form compact bodies, respectively, in the similar manner as described in Example 26. The resultant compacted bodies were sintered at 1,080 °C in vacuum for one hour and in argon gas for succeeding one hour and quenched.
  • the sintered bodies were aged at 650 °C for five hours and then magnetized in the magnetic field of 25 kOe.
  • the magnetic properties of those resultant magnets are shown in Table 18. Although the magnets made from the granular powder have an excellent magnetic properties, the other magnets made from the flakes are superior to them. Table 18
  • Example 2 An ingot was prepared in the similar manner as described in Example 2.
  • the ingot comprised R 31.5 wt%, B 0.9 wt%, and the balance of Fe. From the ingot, a lot of granules having diameter about 0.1 mm and a lot of flakes each having a diameter of about 0.3 mm and a thickness of about 50 um in the manner similar to Example 27.
  • the granules and the flakes were crushed and ground into powders having an average particle size of about 3.5 um and were compacted into compact bodies, respectively, in the similar manner as in Example 26. Those compact bodies were similarly sintered at 1,060 C and were quenched. The resultant sintered bodies were aged at 650 °C for three hours and thereafter were magnetized in a magnetic field of 25 kOe.
  • An ingot consisting of R 32.0 wt%, B 1.1 wt%, and the balance of F __-Co 20 A 1 3 was prepared in the similar manner as described in Example 3.
  • a lot of granules having a diameter of about 0.1 mm and a lot of flakes each having a diameter of about 0.3 mm and a thickness of about 50 um were prepared in the similar manner as described in Example 28.
  • Magnets were produced from those granules and flakes, respectively, in the similar manner as described in Example 28.
  • the magnetic properties of the resultant magnets are shown in Table 20.
  • rapidly-quenched alloy ribbon is prepared with crystals having improved uniform orientation and grain size and therefore can provide sintered magnets with further improved magnetic properties.
  • a device for preparing the improved rapidly-quenched alloy ribbon comprises a melting tube 51 of, for example, quartz having a small orifice 52 on its bottom portion. An alloy is melted in the melting tube 51 in the molten state shown at 53. Un-der the orifice 52, a quenching disk 54 is disposed so that the molten alloy 53 is ejected onto an outer peripheral chill surface of the quenching disk 54 through the orifice 52. Another cooling disk 55 is disposed adjacent to the quenching disk 54 so that it has an outer peripheral surface spaced by a small gap from the chill surface. Both of the disks 54 and 55 rotate in opposite direction to each other but with a rotating speed.
  • the molten alloy ejected from the orifice 52 onto the chill surface of the disk 54 is formed into a ribbon form and thereafter a free surface of the ribbon 56 comes into contact with the outer surface of disk 55. Accordingly, the free surface of the ribbon 56 is also rapidly quenched by the disk 55 but delayed from the opposite surface impinging the disk 54.
  • a method using two quenching disks is well known for forming amorphous alloy ribbon (which will be referred to as "a double chill disk method” hereinafter) wherein, referring to Fig. 14, the molten alloy 53 is directly ejected into a small gap between two disks 54 and 55 so that the the molten alloy is rapidly quenched from the both sides at the same time.
  • the continuous splat-quenching method using a single quenching disk as disclosed in References 2, 3, and 5 will be referred to as "a single chill disk method”.
  • the device shown in Fig. 14 uses two disks similar to the double disk method but the molten alloy comes into contact with the two disks at not the same time but different times. Therefore, the method using the device shown in Fig. 14 will be referred to as "a modified double chill disk method".
  • Ribbon A was made from the ingot by the use of the device shown in Fig. 14 with steel disks 54 and 55 rotating at a surface moving speed of 10 m/sec. This ribbon will be referred to as ribbon A. Ribbon A had a width of about 10 mm and a thickness of about 100 um.
  • ribbon A a surface cooled by the first disk 54 shows very fine crystals of grain sizes from submicron orders to 3 u which are not almost oriented while the other surface cooled by the other disk 55 and intermediate region between the both surfaces showing crystals of grain sizes from 1 u to 3 um and almost oriented uniformly.
  • a surface cooled by the disk shows very fine crystals of grain sizes from submicron orders to 3 um which are not almost oriented while the other free surface and an intermediate region between both surfaces having large crystals of 1-5 um such as needle like crystals which are almost oriented uniformly.
  • the opposite surfaces shows very fine crystals of grain sizes from submicron orders to 3 um which are not almost oriented uniformly while the intermediate region between both surfaces having crystals which are slightly oriented uniformly.
  • Ribbons A, B, and C were crushed and ground into powders having an average particle size of about 3 um, respectively and then, compacted into compact bodies,
  • the magnet made from ribbon B has an improved magnetic properties in comparison with magnet made from ribbon C but the magnet made from ribbon A is superior to the magnets made from the ribbons B and C.
  • Example 30 From an ingot prepared in Example 30, rapidly-quenched alloy ribbons A and B were prepared by the modified double chill disk and the double chill disk methods, respectively.
  • a disk surface moving speed was about 2 m/sec and therefore each ribbon A and B had a width of about 10 mm and a thickness of about 500 u .
  • Magnets were prepared from those ribbons A and B in the similar manner as described in Example 30 but using the sintering temperature of 1,050 °C.
  • ribbons A and B were prepared by the modified double chill disk and the double chill disk methods and then magnets were produced from ribbons A and B, respectively, in the similar manner as described in Example 31.
  • the magnetic properties of the resultant magnets are shown in Table 23. Table 23
  • Example 3 In the method as described in Example 3, an ingot was prepared which consisted of R 40.0 wt%, B 1.1 wt%, and the balance of Fe__Co 2Q Al 3 .
  • Ribbons A and B were prepared from the ingot by the modified double chill disk method and the double chill disk method and then magnets were produced from ribbons A and B, respectively, in the similar manner as described in Example 31.
  • the magnetic properties of the magnets are shown in Table 24.
  • the present invention has been described in connection with examples wherein Nd is mainly used for rare earth metal elements, but the present invention is applied to magnets using other rare earth metal elements for R. Further, other transition metal elements than Co and Ni can be used together with Fe.

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Abstract

Procédé de production d'un aimant fritté anisotrope en métaux des terres rares-fer-bore (R-Fe-B) à partir de pailletttes en alliage de R-Fe-B en forme de rubans, où chaque paillette présente une épaisseur comprise entre 20 et 500 mum et contient des grains cristallins de R2Fe14B dispersés dans la paillette et présentant une taille moyenne égale ou inférieure à 10 mum. Les paillettes sont moulues de manière à obtenir une poudre présentant une taille particulaire moyenne inférieure à la valeur de l'épaisseur des paillettes. La poudre est alignée magnétiquement et compactée en un flan qui est ensuite fritté. On obtient ainsi un aimant fritté anisotrope à énergie élevée et présentant une excellente caractéristique anti-corrosion. Les paillettes en forme de ruban sont préparées par un procédé de trempe en continu. Dans une variante, les paillettes peuvent être préparées en pulvérisant l'alliage de R-Fe-B en fusion sous la forme de particules et en refroidissant les particules sur une plaque de refroidissement de manière à obtenir de minuscules fragments plats.
PCT/JP1987/000917 1986-11-26 1987-11-26 Procede de production d'un aimant fritte anisotrope en metaux des terres rares-fer-bore a partir de paillettes trempees en alliage de metaux des terres rares-fer-bore en forme de rubans WO1988004098A1 (fr)

Applications Claiming Priority (14)

Application Number Priority Date Filing Date Title
JP27964586 1986-11-26
JP61/279645 1986-11-26
JP61/285757 1986-11-29
JP28575786 1986-11-29
JP1259087 1987-01-23
JP62/12590 1987-01-23
JP62/16040 1987-01-28
JP1604087 1987-01-28
JP62/67943 1987-03-24
JP6794387 1987-03-24
JP62/79016 1987-03-31
JP7901687 1987-03-31
JP18359787 1987-07-24
JP62/183597 1987-07-24

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1017065A4 (fr) * 1996-10-18 2000-07-05 Sumitomo Spec Metals Aimant en feuille presentant une structure microcristalline, son procede de fabrication et procede de fabrication d'une poudre magnetique permanente isotrope
EP1018751A1 (fr) * 1997-02-14 2000-07-12 Sumitomo Special Metals Company Limited Aimant sous forme de mince plaquette a structure microcristalline
US6386269B1 (en) 1997-02-06 2002-05-14 Sumitomo Special Metals Co., Ltd. Method of manufacturing thin plate magnet having microcrystalline structure
EP1740734A2 (fr) * 2004-04-28 2007-01-10 The Nanosteel Company Feuille d'acier nanocristalline

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0197712B1 (fr) * 1985-03-28 1990-01-24 Kabushiki Kaisha Toshiba Aimant permanent à base de terre rare, de fer et de bore

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0197712B1 (fr) * 1985-03-28 1990-01-24 Kabushiki Kaisha Toshiba Aimant permanent à base de terre rare, de fer et de bore

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1017065A4 (fr) * 1996-10-18 2000-07-05 Sumitomo Spec Metals Aimant en feuille presentant une structure microcristalline, son procede de fabrication et procede de fabrication d'une poudre magnetique permanente isotrope
EP1017065A1 (fr) * 1996-10-18 2000-07-05 Sumitomo Special Metals Company Limited Aimant en feuille presentant une structure microcristalline, son procede de fabrication et procede de fabrication d'une poudre magnetique permanente isotrope
US6386269B1 (en) 1997-02-06 2002-05-14 Sumitomo Special Metals Co., Ltd. Method of manufacturing thin plate magnet having microcrystalline structure
EP1018751A1 (fr) * 1997-02-14 2000-07-12 Sumitomo Special Metals Company Limited Aimant sous forme de mince plaquette a structure microcristalline
EP1018751A4 (fr) * 1997-02-14 2000-07-19 Sumitomo Spec Metals Aimant sous forme de mince plaquette a structure microcristalline
EP1740734A2 (fr) * 2004-04-28 2007-01-10 The Nanosteel Company Feuille d'acier nanocristalline
EP1740734A4 (fr) * 2004-04-28 2008-05-07 Nanosteel Co Feuille d'acier nanocristalline

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