US3790414A - As-CAST, RARE-EARTH-Co-Cu PERMANENT MAGNET MATERIAL - Google Patents

As-CAST, RARE-EARTH-Co-Cu PERMANENT MAGNET MATERIAL Download PDF

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US3790414A
US3790414A US00775651A US77565168A US3790414A US 3790414 A US3790414 A US 3790414A US 00775651 A US00775651 A US 00775651A US 77565168 A US77565168 A US 77565168A US 3790414 A US3790414 A US 3790414A
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mol percent
alloy
magnetic properties
mischmetal
permanent magnet
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US00775651A
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Y Tawara
H Senno
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/07—Alloys based on nickel or cobalt based on cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C28/00—Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00
    • 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
    • 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
    • H01F1/06—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 in the form of particles, e.g. powder

Definitions

  • ABSTRACT Permanent magnet material having a high coercive force and a high residual flux density is constituted by an alloy of cerium (15 to 20 mol percent), cobalt (52 to 77 mol percent) and copper (8 to 30 mol percent).
  • the cerium can be replaced by Ce-mischmetal in an amount providing the equivalent quantity of cerium.
  • the material has a novel microstructure. The material can be prepared by melting together the ingredient materials and fumace-cooling to room temperature. Superior results are obtained with specially scheduled heat-treatments including controlled cooling rates. It is not necessary to use fine particle magnet material.
  • This invention relates to a permanent magnet mateis a Ce-rich metal and is widely used in industry because of the lower cost than that of pure Ce metal.
  • the Ce-mischmetal contains, as a main ingredient, Ce, rare earth metals such as La, Pr and Nd rial characterized by a high coercive force and a 5 in a small amount, and other metals such as Fe, Mg and residual flux density and to a manufacturing method A] in a very small amount. thereof.
  • Ce-mischrnetal in the present specification, refers to It has been suggested that the alloy composed of a an alloy having a composition according to Table l.
  • rare earth metaland a transition metal such as YCo is a promising candidate for a fine particle magnet material. It has been a problem, however, how to make a fine and chemically stable particle of the material. In general, a mechanically crushed particle of the material is liable to be oxidized in air and the oxidation is accelerated by the coexistence of moisture even at room temperature. Therefore, it is desired to make a magnet of the material without using the pulverized form thereof.
  • An object of the invention is to provide a novel magnetic material characterized by a high coercive force and a high residual flux density.
  • a further object of the invention is to provide a permanent magnet material comprising Ce, Co and Cu.
  • a still further object of the invention is to provide a composition of the alloy consisting of Ce, Co and Cu,
  • a further object of the invention is to provide a permanent magnet material comprising Ce-mischmetal in-
  • FIG. I is a schematic drawing which shows a structure, enlarged by 200 times, of the alloy according to the present invention.
  • FIG. 2 shows the relation between the intrinsic coercive force in oersteds and the fineness of the fiber-like structure in microns, which is characteristic of the alloy of the present invention
  • FIG. 3 shows an example of cooling rate applicable to the method of manufacturing the magnet material of the invention
  • FIG. 4 is a graph showing the relation between the intrinsic coercive force and the aging timeaccording to one example of the invention.
  • an alloy which consists of proper amounts of Ce, C0 and Cu has excellent magnetic properties for use as a permanent magnet.
  • a novel composition of ferromagnetic alloy according to the invention comprises to mol percent of Ce, 52 to 77 mol percent of Co and 8 to mol percent of Cu. The 15 to 20 mol percent of Ce can be replaced by the less expensive Ce-mischmetal without impairing the magnetic properties.
  • the microstructure consists of a fiber-like structure as shown in FIG. 1.
  • the alloy body of the invention as heated is polished at one surface thereof with a suitable abrasive such as SiC powder or Cr O powder in a particle size of 0.5 to 10a in order that it may be provided with a flat surface.
  • a suitable abrasive such as SiC powder or Cr O powder in a particle size of 0.5 to 10a in order that it may be provided with a flat surface.
  • the surface is etched by a 12N HCl solution (aqueous) for several minutes at room temperature (15 to 30C).
  • the etched surface shows an etch pattern when observed microscopically as shown in FIG. I.
  • Said etch pattern is composed of many etch fibers 2,
  • a characteristic fineness defined as the average distance between two adjacent points 4 and 6 on a straight line 3 taken on the etch pattern, crossed by the etch fibers.
  • a characteristic fineness defined as the average distance between two adjacent points 4 and 6 on a straight line 3 taken on the etch pattern, crossed by the etch fibers.
  • the alloy having a fineness larger than 100a has a poor coercive force such as lower than 500 Oe regardless of the composition.
  • a coercive force higher than 2,000 Oe is obtained with an alloy having a fineness smaller than 20g.
  • FIG. 2 shows the relation between intrinsic coercive force and the fineness of the fiber-like structure of various specimens of the invention. It is clearly seen from FIG. 2 that the finer the structure the higher is the coercive force.
  • the alloy according to the present invention with the aforedescribed structure was crushed to a fine particle size and examined by X-ray powder diffractometry.
  • An example of the analysis for the alloy having a composition of 16.7 mol Ce, mol Co and 8.3 mol Cu is shown in Table 2.
  • Fe-Ka radiation generated in an X-ray tube working at an anode voltage of 35 kV and an anode current of 8 mA through a Mn filter was used as X-ray source.
  • the diffracted Xray from the specimen was counted by a conventional counter at a counting rate of 400 c/s and a scanning velocity of 1 /min. and recorded at a time constant of 2 sec.
  • the observed diffraction angles, 20, are listed in the first column ofTable 2. 1n the second column, is shown the line intensity. The interplanar spacings [d] corresponding to each line are shown in the third column. Some of the diffraction lines can be indexed as shown in the fourth column, assuming that the crystal phase has a CaCu -type structure which is well verified in the case of many RC compounds. The other lines, however, remain unexplained. The most intense ones among the unexplained lines appear at slightly lower angles than the main lines of (111) and (110). This looks like a splitting of the main line into two lines. Although the origin of these extra lines are unknown at present, it should be noted that these lines are characteristic of the alloy of the present invention.
  • the materials according to the present invention have a residual flux density higher than 3,500 G, a coercive force higher than 600 Oe, and a maximum energy product higher than 1.3 MG'Oe.
  • the best results are obtained with compositions consisting essentially of 17.1 to 17.4 mol percent of Ce, 64 to 72.6 mol percentgof Co and 10.3 to 18.57 mol percent of Cuin which the fine fiber-structure is easily formed. It is possible to replace Ce with Ce-mischmetal so that the amount of total rare earth elements in said Ce-mischmetal is equivalent to that of said Ce, without impairing the resultant magnetic properties.
  • the material of said optimal composition with a markedly developed fiberstructure has a residual flux density higher than 4,250 G, a coercive force higher than 1,500 Oe, and a maximum energy product higher than 4.0 MG'Oe.
  • the magnetic alloys according to the invention can be prepared by a conventional metallurgical method.
  • the ingredient metals are melted together in an alumina crucible in air at mmHg using a graphite heater, and the. molten alloy is furnace-cooled to room temperature.
  • the alloy thus prepared has a more or less developed fiber-structure.
  • the homogenizing treatment although not necessary, has a favorable effect on the magnetic properties.
  • An important feature of the process is the controlled colli ng after the homogenizing heat treatment in order to obtain superior magnetic properties.
  • the magnetic properties are highly dependent on the said cooling rate from 1,100C to 250C.
  • the cooling rate should be higher in a relatively high temperature region than in a relatively low temperature region.
  • the mostim portant process feature is the controlled colling from 1,000C to 650C of which the average rate should be 35 to 10C per minute.
  • the mixed ingredient metals are melted at a temperature higher than 1,200C, said melt is quenched to room temperature, for instance, in a metal mold cooled by a cooling means such as water, the quenched alloy is aged at a temperature of 400 to 650C for 20 minutes to 10 hours, and then the aged alloy is cooled to room temperature.
  • the qunch e d alloy exhibits a low c o ercive force value such as about 200 Oe.
  • the coercive force increases to value as high as 1,250 Oe during the aging period of 1 to 5 hours at a temperature of 400 to 650C.
  • An aging treatment below 400C requires too prolonged a period to obtain a sufficiently high coercive force value. In some cases. for a higher aging temperature, for example of 700C, the coercive force value decreases.
  • EXAMPLE 1 The alloy of 16.67 mol percent of Ce-mischmetal, 75.0 mol percent of Co and 8.33 mol percent of Cu was melted at 1,670C, maintained for 30 minutes at 1,000C, cooled to 400C according to the cooling curve shown in FIG. 3 and then rapidly cooled to room temperature. A sphere of about 3 mm in diameter was prepared frEjni tlie ingot. The demagnetizationcurve was measured by means of a conventinal vibrating specimen magnetometer. The magnetic properties were:
  • EXAMPLE 13 The alloy of 17.4 mol percent of Ce, 66.1 mol percent of Co and 16.5 mol percent of Cu was melted at 1,550C, maintained for 30 minutes at 1,000C, cooled to 400C at the average rate of 28C/min. between 1,000C and 650C and at the overall rate of l6.5C/min. and then rapidly cooled to room temperature.
  • the measurement of magnetic properties was carried out by the same method as in the previous examples. The magnetic properties were:
  • EXAMPLE 17 The alloy of 18.03 mol percent of Ce-mischmetal, 55.32 mol percent of Co and 26.65 mol percent of Cu was melted at 1,550C, and quenched in water. The measurement of magnetic properties was carried out by the same method as in the previous examples. The magnetic properties were:
  • EXAMPLE 23 The alloy of 18.03 mol percent Ce-mischmetal, 55,32 mol percent of Co and 26.65 mol percent of Cu which was prepared by melting the ingredient metals at 1,550C and quenching in water, was heated at 520C for various times.
  • the intrinsic coercive force ,H of thus-obtained alloy is plotted against the aging time in FIG. 4.
  • the intrinsic coercive force increased rapidly with increasing the aging time in the range from about 20 min. to 1 hour, and was followed by a gradual increase up to the aging time of about 8 hours, then by a gradual decrease with the aging time over 10 hours.
  • a permanent magnet comprising a composition of matter which consists essentially of to mol percent of at least one member selected from the group consisting of Ce and Ce-mischmetal, 52 to 77 mol percent of Co, and 8 to 30 mol percent of Cu, characterized in that the said magnet consists essentially of an as-cast body, the energy product of which is at least 1.3 million oersted-gauss.
  • a magnetic composition according to claim 1 consisting essentially of an alloy of 15.25 mol percent cerium mischmetal, 67.8 'mol percent C0 and 16.95 mol percent Cu.
  • a permanent magnet according to claim 3 wherein said alloy consists essentially of 17.1 to 17.43 mol percent of Ce, 64 to 72.6 mol percent of Co and 10.3 to 18.57 mol percent of Cu.
  • a permanent magnet according to claim 1 wherein said member is Ce-mischmetal.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Hard Magnetic Materials (AREA)
US00775651A 1967-11-15 1968-11-14 As-CAST, RARE-EARTH-Co-Cu PERMANENT MAGNET MATERIAL Expired - Lifetime US3790414A (en)

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Application Number Priority Date Filing Date Title
JP7437467 1967-11-15
JP1323368 1968-02-28
JP1815468 1968-03-18
JP1815268 1968-03-18
JP1815368 1968-03-18

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CA (1) CA942104A (de)
DE (1) DE1809535C3 (de)
FR (1) FR1604641A (de)
GB (1) GB1245460A (de)
NL (1) NL142812B (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3873379A (en) * 1972-07-12 1975-03-25 Hitachi Metals Ltd Method of producing rare earth-cobalt permanent magnet using special cooling rates
US3947295A (en) * 1973-02-09 1976-03-30 Matsushita Electric Industrial Co., Ltd. Hard magnetic material
US3950194A (en) * 1973-07-20 1976-04-13 Matsushita Electrical Industrial Co., Ltd. Permanent magnet materials
US4099995A (en) * 1974-07-31 1978-07-11 Bbc Brown, Boveri & Company, Ltd. Copper-hardened permanent-magnet alloy
US4131495A (en) * 1975-12-02 1978-12-26 Bbc Brown, Boveri & Company, Limited Permanent-magnet alloy
US4208225A (en) * 1975-05-05 1980-06-17 Les Fabriques D'assortiments Reunies Directionally solidified ductile magnetic alloys magnetically hardened by precipitation hardening

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH601481A5 (de) * 1975-05-05 1978-07-14 Far Fab Assortiments Reunies
DE3068420D1 (en) * 1979-04-12 1984-08-09 Far Fab Assortiments Reunies Ductile magnetic alloys, method of making same and magnetic body

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2813789A (en) * 1952-04-08 1957-11-19 Glaser Louis Permanent magnet alloys
US3102002A (en) * 1960-03-25 1963-08-27 Univ Pittsburgh Ferromagnetic materials prepared from lanthanons and transition metals
NL6608335A (de) * 1966-06-16 1967-12-18
US3421889A (en) * 1966-01-13 1969-01-14 Us Air Force Magnetic rare earth-cobalt alloys
US3424578A (en) * 1967-06-05 1969-01-28 Us Air Force Method of producing permanent magnets of rare earth metals containing co,or mixtures of co,fe and mn
US3501358A (en) * 1967-08-30 1970-03-17 Gen Electric Method of making permanent magnet material powders having superior magnetic characteristics
US3523836A (en) * 1967-01-21 1970-08-11 Philips Corp Permanent magnet constituted of fine particles of a compound m5r
US3560200A (en) * 1968-04-01 1971-02-02 Bell Telephone Labor Inc Permanent magnetic materials

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2813789A (en) * 1952-04-08 1957-11-19 Glaser Louis Permanent magnet alloys
US3102002A (en) * 1960-03-25 1963-08-27 Univ Pittsburgh Ferromagnetic materials prepared from lanthanons and transition metals
US3421889A (en) * 1966-01-13 1969-01-14 Us Air Force Magnetic rare earth-cobalt alloys
NL6608335A (de) * 1966-06-16 1967-12-18
US3546030A (en) * 1966-06-16 1970-12-08 Philips Corp Permanent magnets built up of m5r
US3523836A (en) * 1967-01-21 1970-08-11 Philips Corp Permanent magnet constituted of fine particles of a compound m5r
US3424578A (en) * 1967-06-05 1969-01-28 Us Air Force Method of producing permanent magnets of rare earth metals containing co,or mixtures of co,fe and mn
US3501358A (en) * 1967-08-30 1970-03-17 Gen Electric Method of making permanent magnet material powders having superior magnetic characteristics
US3560200A (en) * 1968-04-01 1971-02-02 Bell Telephone Labor Inc Permanent magnetic materials

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Strnat, K. et al., A Family of New Cobalt Base Permanent Magnet Materials, Journal of Applied Physics, Vol. 38, No. 3, March, 1967, pages 1001 and 1002. *
Velge, W. A. J. J. et al., Magnetic and Crystallographic Properties of Some Rare Earth Cobalt Compounds with CaZn Structure, Journal of Applied Physics, Vol. 39, No. 3, February, 1968, pages 1717 1720. *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3873379A (en) * 1972-07-12 1975-03-25 Hitachi Metals Ltd Method of producing rare earth-cobalt permanent magnet using special cooling rates
US3947295A (en) * 1973-02-09 1976-03-30 Matsushita Electric Industrial Co., Ltd. Hard magnetic material
US3950194A (en) * 1973-07-20 1976-04-13 Matsushita Electrical Industrial Co., Ltd. Permanent magnet materials
US4099995A (en) * 1974-07-31 1978-07-11 Bbc Brown, Boveri & Company, Ltd. Copper-hardened permanent-magnet alloy
US4208225A (en) * 1975-05-05 1980-06-17 Les Fabriques D'assortiments Reunies Directionally solidified ductile magnetic alloys magnetically hardened by precipitation hardening
US4131495A (en) * 1975-12-02 1978-12-26 Bbc Brown, Boveri & Company, Limited Permanent-magnet alloy

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NL6816336A (de) 1969-05-19
DE1809535B2 (de) 1972-12-14
GB1245460A (en) 1971-09-08
FR1604641A (de) 1972-01-03
CA942104A (en) 1974-02-19
DE1809535A1 (de) 1970-11-26
NL142812B (nl) 1974-07-15
DE1809535C3 (de) 1975-09-11

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