US3655463A - Sintered cobalt-rare earth intermetallic process using solid sintering additive - Google Patents

Sintered cobalt-rare earth intermetallic process using solid sintering additive Download PDF

Info

Publication number
US3655463A
US3655463A US33348A US3655463DA US3655463A US 3655463 A US3655463 A US 3655463A US 33348 A US33348 A US 33348A US 3655463D A US3655463D A US 3655463DA US 3655463 A US3655463 A US 3655463A
Authority
US
United States
Prior art keywords
rare earth
cobalt
alloy
percent
process according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US33348A
Other languages
English (en)
Inventor
Mark G Benz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Application granted granted Critical
Publication of US3655463A publication Critical patent/US3655463A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
    • H01F1/0557—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together sintered
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/0433—Nickel- or cobalt-based alloys
    • C22C1/0441—Alloys based on intermetallic compounds of the type rare earth - Co, Ni
    • 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

Definitions

  • ABSTRACT A process for preparing novel sintered cobalt-rare earth intermetallic products which can be magnetized to form permanent magnets having stable improved magnetic properties.
  • a particulate mixture is formed of a base CoR alloy and an additive CoR alloy, where R is a rare earth metal.
  • the base CoR alloy is one which, at sintering temperature, exists as a solid Co R intermetallic single phase.
  • the additive CoR alloy is richer in rare earth metal than the base CoR alloy, and at sintering temperature is solid.
  • the base and additive alloys, in particulate form, are each used in an amount to form a mixture which has a cobalt and rare earth metal content substantially corresponding to that of the final desired sintered product.
  • the mixture is pressed into compacts and sintered to the desired sintered product phase composition and density.
  • the final sintered product has a phase composition lying outside the Co R single phase on the rare earth richer side.
  • the final sintered product contains a major amount of the Co R solid intermetallic phase and-up to about 35 percent by weight of the product of a second solid CoR interrnetallic phase which is richer in rare earth content than the Co R phase.
  • the present invention relates generally to the art of permanent magnets and is more particularly concerned with 'novel sintered cobalt-rare earth intermetallic products having unique characteristics and with a sintering method for producing such products.
  • Permanent magnets i.e. hard magnetic materials such as the colbalt-rare earth intermetallic compounds, are of technological importance because they can maintain a high, constant magnetic flux in the absence of an exciting magnetic field or electrical current to bring about such a field.
  • Cobalt-rare earth intermetallic compounds exist in a variety of phases, but the Co R intermetallic single phase compounds (in each occurrence R designates a rare earth metal) have exhibited the best magnetic properties.
  • FIG. 1 is the cobalt-samarium phase diagram. It is assumed herein, that the phase diagram at 300 C., which is the lowest temperature shown in the figure, is substantially the same at room temperatures.
  • FIG. 2 is a chart bearing curves which illustrate the effect of samarium content on the magnetic properties of permanent magnets including one produced in accordance with the present invention.
  • the process of the present invention comprises the steps of forming a particulate mixture of a base cobalt-rare earth alloy and an additive cobalt-rare earth alloy, compacting the mixture to produce a green body, and sintering the green body to produce an ultimate sintered body containing a major amount of Co R and up to 35 percent of other cobalt-rare earth phases richer in rare earth content than Co R.
  • the base alloy is one which at sintering temperature exists as a solid C 11 intermetallic single phase where R is a rare earth metal.
  • the additive cobalt-rare earth alloy is richer in rare earth metal than the base alloy and at sintering temperature it is a solid.
  • the base and additive alloys, in particulate form, are each used in an amount to form a mixture which has a cobalt and rare earth metal content substantially corresponding to that of the final desired sintered product,
  • the mixture is pressed into compacts, preferably in an aligning magnetic field, and sintered to the desired sintered product phase composition and desired density.
  • the final sintered product has a composition lying outside the Co R single phase region on the rare earthrich side.
  • the final sintered product contains a major amount of the C0 R solid intermetallic phase and up to about 35 percent by weight of the product of a second CoR intermetallic phase which is richer in rare earth content than C0,,R phase.
  • the base cobalt-rare earth alloy used in the present process is one which at sintering temperature exists as a Co R single intermetallic phase. Since the Co R single phase may vary in composition, the base alloy may vary in composition which can be determined from the phase diagram for the particular cobalt-rare earth system, or empirically. For example, FIG. 1 shows that for the cobalt-samarium system, the base alloy at room temperature may vary in samarium content from about 32 to 36 percent by weight since this particular composition is single phase at sintering temperatures ranging from about 950 to l,200 C. Preferably, for simplicity, the base alloy at room temperature is a Co R intermetallic phase.
  • the additive cobalt-rare earth alloy is one which is richer in rare earth metal content than the base alloy, and at sintering temperature it is a solid. It may vary in composition which can be determined from the phase diagram for the particular cobalt-rare earth system or which can be determined empirically. For example, FIG. 1 shows that for the cobalt-samarium system, there is a solid phase containing samarium in an amount greater than about 36 percent by weight at a temperature ranging from 950 to l,200 C., which is a suitable sintering temperature range for Co-Sm in the present process.
  • the solid additive alloy for the cobalt-samarium system ranges in samarium content from about 36 to about 55 percent by weight of the additive, and at temperatures ranging from 950 to l,200 C., the solid additive alloy may range in samarium content from about 36 percent to about 45 percent by weight of the additive. Any additive alloy within these ranges would be a satisfactory additive alloy in the present process. If desired an additive alloy can be determined empirically by a number of methods, such as by means of a composition scan at the sintering temperature, i.e. heating samples of various additive alloy compositions to the desired sintering temperature to determine which is solid at sintering temperatures.
  • suitable additive CoR alloys fall within a general composition range, the preferred ones are comparatively low in rare earth metal content so that undesirable characteristics of the pure rare earth metal in the additive alloy are minimized.
  • pure samarium is both pyrophoric and very ductile and consequently difficult to crush and to blend with the base alloy since it has a tendency to separate out and fall to the bottom of the container.
  • an additive CoSm alloy of the present invention is substantially non-reactive at room temperature in air, it can be crushed by conventional techniques, and being slightly magnetic, it clings to the base alloy resulting in a substantially thorough stable mixture. The higher the cobalt content of the additive-alloy, the stronger are its magnetic properties and the more stable is the particulate mixture it forms with the base alloy.
  • the rare earth metals useful in forming the present cobaltrare earth alloys and intermetallic compounds are the 15 elements of the lanthanide series having atomic numbers 57 to 71 inclusive.
  • the element yttrium (atomic number 39) is commonly included in this group of metals and, in this specification, is considered a rare earth metal.
  • a plurality of rare earth metals can also be used to form the present desired cobalt-rare earth alloys or intermetallic compounds which, for example may be ternary, quartenary or which may contain an even greater number of rare earth metals as desired.
  • cobalt-rare earth alloys useful as base and additive alloys in the present invention are cobalt-cerium, cobalt-praseodymium, cobalt-neodymium, cobalt-promethium, cobalt-samarium, cobalt-europium, cobalt-gadolinium, cobalt-terbium, cobalt-dysprosium, cobalt-holmium, cobalterbium, cobalt-thulium, cobalt-ytterbium, cobalt-lutecium, cobalt-yttrium, cobalt-lanthanum and cobalt-misch metal.
  • Cerium misch metal is the most common alloy of the rare earth metals which contains the metals in the approximate ratio in which they occur in their most common naturally occurring ores.
  • specific ternary alloys include cobalt-samarium-cerium misch metal, cobalt-ceriumpraseodymium, cobalt-yttrium-praseodymium, and cobaltpraseodymium-misch metal.
  • the base and additive cobalt-rare earth alloys can be formed by a number of methods.
  • each can be prepared by arc-melting the cobalt and rare earth metal together in the proper amounts under a substantially inert atmosphere such as argon and allowing the melt to solidify.
  • the melt is cast into an ingot.
  • the solid base and additive alloys can be converted to particulate form in a conventional manner. Such conversion can be carried out in air at room temperature since the alloys are substantially non-reactive. For example, each alloy can be crushed by mortar and pestle and then pulverized to a finer form by jet milling.
  • the particle size of the base and additive cobalt-rare earth alloys used in forming the mixture of the present process may vary. Each can be in as finely divided a form as desired. For most applications, average particle size will range from about 1 micron or less to about 10 microns. Larger sized particles can be used, but as the particle size is increased, the maximum coercive force obtainable is lower because the coercive force generally varies inversely with particle size. In addition, the smaller the particle size, the lower is the sintering temperature which may be used.
  • the base and additive alloys are each used in an amount so that the resulting mixture has a cobalt and rare earth metal content substantially corresponding to that of the final desired sintered product phase composition.
  • the alloy additive should be used in an amount sufficient to promote sintering. This amount depends largely on the specific composition of the alloy additive and can be determined empirically, but generally, the additive alloy should be used in an amount of at least 0.5 percent by weight of the base-additive alloy mixture. Specifically, the larger the rare earth metal component of the additive alloy, the less is the amount of the additive alloy which need be used.
  • the final sintered product at sintering temperature, should have a phase composition lying outside the Co R single phase on the rare earth-rich side. Magnetization of such a product results in a permanent magnet with superior magnetic properties.
  • a final sintered product at sintering or room temperatures consists only of a single Co R inter-metallic phase, or if it contains a second cobalt-rare earth intermetallic phase of lesser rare earth content than the C0,,R phase, a permanent magnet of only inferior magnetic properties can be produced no matter how the magnetization step is carried out.
  • the final sintered product contains a major amount of the Co R solid intermetallic phase, generally at least about 65 percent by weight of the product, and up to about 35 percent by weight of the product of a second solid CoR intermetallic phase which is richer in rare earth metal content than the Co R phase. Traces of other cobalt-rare earth intermetallic phases, in most instances less than one percent by weight of the product, may also be present.
  • Sintered products having the highest energy products are those having the smallest content of the second CoR phase.
  • the preferred final sintered product therefore, is comprised predominantly of the Co R intermetallic phase, i.e.
  • a composition scan i.e. a series of runs at the same sintering temperature with proportionately varying mixtures of base and additive alloys, may be made to determine the specific sintered product composition which produces the best magnetic properties.
  • Detennination of the second CoR phase can be made by a number of techniques, such as for example, X-ray diffraction as well as standard metallographic analysis.
  • the magnetic properties obtainable decrease correspondingly. Furthermore, when the content of the Co R intermetallic phase is below about 65 percent by weight of the present sintered product, its permanent magnet properties are sharply reduced.
  • the base alloy is admixed with the additive alloy in any suitable manner to produce a substantially thorough particulate mixture.
  • the particulate mixture can then be compressed into a green body of the desired size and density by any of a number of techniques such as hydrostatic pressing or methods employing steel dies.
  • the mixture is compressed in the presence of an aligning magnetizing field to magnetically align the particles along their easy axis, or if desired, the mixture may be compressed after magnetically aligning the particles.
  • the greater the magnetic alignment of the particles the better are the resulting magnetic properties.
  • compression is carried out to produce a green body with as high a density as possible, since the higher its density, the greater the sintering rate. Green bodies having a density of about 40 percent of theoretical or higher are preferred.
  • the green body is sintered to produce a sintered body of desired density.
  • the green body is sintered to produce a sintered body wherein the pores are substantially non-interconnecting.
  • Such non-interconnectivity stabilizes the permanent magnet properties of the product because the interior of the sintered product or magnet is protected against exposure to the ambient atmosphere.
  • the sintering temperature used in the present process depends largely on the particular cobalt-rare earth mixture to be sintered, and to a lesser degree, on particle size.
  • the minimum sintering temperature must be sufficiently high for sintering to occur in a particular cobalt-rare earth system, i.e. it must be high enough to coalesce the component particles.
  • sintering is carried out so that the pores in the sintered product are substantially non-interconnecting.
  • the particles do not melt but undergo solid state diffusion, i.e., the motion of the atoms is sufficient at sintering temperatures so that diffusion occurs and the particles coalesce to the desired density.
  • a sintered body having a density or packing of at least about 87 percent of theoretical is generally one wherein the pores are substantially non-interconnecting. Such non-interconnectivity is determinable by standard metallographic techniques, as for example, by means of transmission electron micrographs of a cross-section of the sintered product.
  • the maximum sintering temperature is preferably one at which significant growth of the component particles or grains does not occur, since too large an increase in grain size deteriorates magnetic properties such as coercive force.
  • the green body is sintered in a substantially inert atmosphere such as argon, and upon completion of the sintering, it is preferably cooled to room temperatures in a substantially inert atmosphere.
  • the particular sintering temperature range can be determined empirically, as for example, carrying out a series of runs at successively higher sintering temperatures and then determining the magnetic properties of the sintered products.
  • a sintering temperature ranging from about 950 C. up to about l,200 C. is suitable with a sintering temperature of l,l00 C. being particularly satisfactory.
  • the density of the sintered product may vary. The particular density depends largely on the particular permanent magnet properties desired. Preferably, to obtain a product with substantially stable permanent magnet properties, the density of the sintered product should be one wherein the pores are substantially non-interconnecting and this occurs usually at a density or packing of about 87 percent. Generally, for a number of applications, the density may range from about percent to percent. For example, for low temperature applications, a sintered body having a density ranging down to about 80 percent may be satisfactory. The preferred density of the sintered product is one which is the highest obtainable without producing a growth in grain size which would deteriorate magnetic properties significantly, since the higher the density the better are the magnetic properties.
  • a density of at least about 87 percent of theoretical, i.e., of full density, and as high as about 96 percent of theoretical is preferred to produce permanent magnets with suitable magnetic properties which are substantially stable.
  • Standard metallographic examination, as for example, under a light microscope or an X-ray microprobe, of a polished crossosection of the sintered product of the present invention shows that its grains differ significantly in appearance from the original particles used in forming the green body. Specifically, the original particles have an angular rough surface structure. In contrast, substantially all of the grains of the present sintered product are rounded and have a smooth surface. The pores of the sintered product are preferably substantially non-interconnecting. Generally, for the sintered product to have good magnetic properties, the component grains of the bulk product should preferably not have an average size larger than about 30 microns.
  • the sintered product of the present invention is useful as a permanent magnet. Its permanent magnet properties can be significantly enhanced, however by subjecting it to a magnetizing field.
  • the resulting permanent magnet is substantially stable in air and has a wide variety of uses.
  • the permanent magnets of the present invention are useful in telephones, electric clocks, radios, television, and phonographs. They are also useful in portable appliances, such as electric toothbrushes and electric knives, and to operate automobile accessories.
  • the present permanent magnets can be used in such diverse applications as meters and instruments, magnetic separators, computers and microwave devices.
  • the sintered bulk product of the present invention can be crushed to a desired particle size preferably a power, which is particularly suitable for alignment and matrix bonding to give a stable permanent magnet.
  • the matrix material may vary widely and may be plastic, rubber or metal such as, for example, lead, tin, zinc, copper or aluminum.
  • the powdercontaining matrix can be cast, pressed or extruded to form the desired permanent magnet.
  • the aligning magnetizing field was used to magnetically align along the easy axis.
  • the sintering furnace was a ceramic tube.
  • All sintering was carried out in an inert atmosphere of purified argon and upon completion of the sintering, the sintered product was cooled in the same purified argon atmosphere.
  • Particle size was determined by a standard metallographic method.
  • the density of the green body as well as the sintered product is given as packing.
  • Packing is the relative density of the material, i.e., it is a percent of theoretical. Packing was determined by a standard method using the following equa- Normal coercive force H is the field strength at which the induction B becomes zero.
  • the maximum energy product (BI-1), represents the maximum product of the magnetic field H and the induction B determined on the demagnetization curve.
  • EXAMPLE 1 In this example the magnetic properties of sintered products 10 formed from three different cobalt-samarium mixtures were determined.
  • a base alloy melt and an additive alloy melt of cobaltsamarium were made under purified argon by arc-melting and cast into ingots.
  • the base alloy was formed from 33.3 weight I percent samarium and 66.7 weight percent cobalt.
  • the additive alloy was formed from 38.6 weight percent samarium and 61.4 weight percent cobalt.
  • Each ingot was initially crushed by means of mortar and pestle and then reduced by fluid energy jet milling to a powder ranging in size from approximately one to about 10 microns in diameter and having an average particle size of about 6 microns in diameter.
  • Portions of the particulate base and additive alloys were admixed by tumbling to prepare two mixtures. Specifically, for Run No. 1, 4.23 g. of the base alloy were admixed with 9.77 g. of the additive alloy to form a mixture composed of 63 percent by weight cobalt and 37 percent by weight samarium. For Run No. 2, 9.51 g. of the base alloy were admixed with 4.49 g. of the additive alloy to form a mixture composed of 65 percent by weight cobalt and percent by weight samarium. Since the additive alloy as well as the base alloy were substantially non-reactive in air and magnetic, both mixtures were stable. Standard wet chemical analysis of a portion of the mixture of Run No. 1 showed a content of 37 i 0.3 percent samarium and the same analysis of Run No. 2 showed a content of 35 i 0.3 percent samarium.
  • a bar was formed from each mixture. Specifically, a portion of each mixture was weighed, placed in a rubber tube and magnetically aligned therein by means of an aligning magnetizing field of kilo-oersteds provided by a superconducting coil. After magnetic alignment, the tube was evacuated to freeze the alignment and then it was pressed hydrostatically under a pressure of 200 K p.s.i. to form a green body in the shape of a bar.
  • the intrinsic coercive force H or H is the field strength at which the magnetization (8-11) or 417M is zero.
  • Run No. 1 of Table 1 illustrates the present invention and shows the significantly better magnetic properties produced by the present process.
  • Run Nos. 1 and 2 of Table Nun I show that sintering of the green body produces a sintered product which weighs the same as the green body indicating no loss in the cobalt and samarium components.
  • a comparison of the composition of Run No. l with those of Run Nos. 2 and 3 shows the criticality of sintering a cobalt-samarium mixture having a composition falling outside that covered by the single Co Sm intermetallic phase on the rare earth richer side.
  • the sintered bars of Run Nos. 1 and 2 were demagnetized using the specific magnetizing fields shown in FIG. 2 and their magnetization 41rM in such field was determined.
  • the abscissa of the graph is the magnetic field (H) in kilo-oersteds and the ordinate is magnetization 41rM in kilogauss.
  • H magnetic field
  • the ordinate magnetization 41rM in kilogauss.
  • the product as well as at room temperature is comprised of a major amount of the C0,,Sm single intermetallic phase, i.e., about 95 percent by weight of the product, and a minor amount of the Co Sm phase, i.e. about 5 percent by weight of the product.
  • FIG. 2 shows poor magnetic properties for the sintered product of Run No. 2 composed of 65 percent cobalt and 35 percent by weight samarium which according to FIG. 1 is the composition for a single Co Sm intermetallic phase.
  • the sintered product of each run of Table I was examined by standard metallographic analysis. Examination of a polished cross-section of each product was made under an X- ray microprobe and a light microscope and micrographs were made. In Run No. l, the pores of the sintered product were substantially non-interconnecting which is the characteristic that maintains its permanent magnet properties stable.
  • the Run No. 1 sintered product wascomposed of two phases, a major amount of one phase and a minor amount of a second phase with traces of a few other phases. Substantially all of the grains of this sintered product were rounded and had a smooth surface with the average grain size being about 7 microns. Standard wet chemical analysis of the product of Run No. 1 showed it to contain 37 percent by weight samarium.
  • a process for producing a sintered cobalt-rare earth intermetallic product containing a Co R intermetallic phase and a CoR intermetallic phase which is richer in rare earth metal content than said Co R intermetallic phase which comprises providing a particulate mixture of a base cobalt-rare earth metal alloy and an additive cobalt-rare earth metal alloy, said base alloy existing at sintering temperature as a solid C0,,R intermetallic phase and said additive CoR alloy being a solid at sintering temperature and being richer in rare earth metal content than said base alloy, said base alloy and said additive alloy each being used to form a mixture which has a cobalt and rare earth metal content substantially corresponding to that of the final sintered product with said additive C o R alloy being present in an amount of at least 0.5 percent by weight of said mixture, pressing said mixture into a green body, and sintering said green body in a substantially inert atmosphere to produce a sintered product having a density of at least about percent of theoretical and containing the Co R
  • said base cobaltrare earth alloy is a cobalt-samarium-cerium mischmetal alloy.
  • a process according to claim 1 wherein the particle size of said particulate mixture ranges from about I to 10 microns.
  • a process according to claim 1 which includes the steps of crushing said sintered product into particles, and bonding the resulting particles of sintered product to a matrix material.
  • a process according to claim 1 which includes the step of subjecting said sintered product to a magnetizing field to produce a magnetized sintered product.
  • a process according to claim 14 which includes the step of subjecting said bonded particles in said matrix material to a magnetizing field to magnetize said bonded particles.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Power Engineering (AREA)
  • Hard Magnetic Materials (AREA)
  • Powder Metallurgy (AREA)
US33348A 1970-04-30 1970-04-30 Sintered cobalt-rare earth intermetallic process using solid sintering additive Expired - Lifetime US3655463A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US3334870A 1970-04-30 1970-04-30

Publications (1)

Publication Number Publication Date
US3655463A true US3655463A (en) 1972-04-11

Family

ID=21869888

Family Applications (1)

Application Number Title Priority Date Filing Date
US33348A Expired - Lifetime US3655463A (en) 1970-04-30 1970-04-30 Sintered cobalt-rare earth intermetallic process using solid sintering additive

Country Status (6)

Country Link
US (1) US3655463A (https=)
JP (1) JPS5614731B1 (https=)
CA (1) CA929384A (https=)
DE (1) DE2121453B2 (https=)
GB (1) GB1347763A (https=)
NL (1) NL7105958A (https=)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3755007A (en) * 1971-04-01 1973-08-28 Gen Electric Stabilized permanent magnet comprising a sintered and quenched body of compacted cobalt-rare earth particles
DE2326960A1 (de) * 1972-06-22 1974-01-10 Gen Electric Wandler
US3816189A (en) * 1970-12-10 1974-06-11 Sermag Solid-state diffusion process for the manufacture of permanent magnet alloys of transition elements and metals of the rare-earth group
US3858308A (en) * 1973-06-22 1975-01-07 Bendix Corp Process for making a rotor assembly
US3892598A (en) * 1974-01-07 1975-07-01 Gen Electric Cobalt-rare earth magnets comprising sintered products bonded with solid cobalt-rare earth bonding agents
US3919003A (en) * 1971-12-17 1975-11-11 Gen Electric Sintered cobalt-rare earth intermetallic product
US3919001A (en) * 1974-03-04 1975-11-11 Crucible Inc Sintered rare-earth cobalt magnets comprising mischmetal plus cerium-free mischmetal
US3997371A (en) * 1973-11-12 1976-12-14 Hitachi Metals, Ltd. Permanent magnet
US4075042A (en) * 1973-11-16 1978-02-21 Raytheon Company Samarium-cobalt magnet with grain growth inhibited SmCo5 crystals
US4092184A (en) * 1975-10-08 1978-05-30 General Electric Company Method of preparing and installing cobalt-rare earth permanent magnets

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
US3425828A (en) * 1966-03-11 1969-02-04 Coast Metals Inc Production of cobalt strip and the like
US3546030A (en) * 1966-06-16 1970-12-08 Philips Corp Permanent magnets built up of m5r

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH519361A (de) * 1968-11-22 1972-02-29 Raytheon Co Verfahren zur Herstellung eines Permanentmagneten
NL6907499A (https=) * 1969-05-14 1970-11-17

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3425828A (en) * 1966-03-11 1969-02-04 Coast Metals Inc Production of cobalt strip and the like
US3546030A (en) * 1966-06-16 1970-12-08 Philips Corp Permanent magnets built up of 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

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Buschow, K. H. J., Intermetallic Compounds in the System Samarium Cobalt, Journal of the Less Common Metals, Vol. 14, No. 3, March, 1968, Pages 323 328. *
Westendorp, F. et al., Permanent Magnets with Energy Products of 20 Million Gauss Oersteds, Solid State Communications, 1969, Pages 639 640. *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3816189A (en) * 1970-12-10 1974-06-11 Sermag Solid-state diffusion process for the manufacture of permanent magnet alloys of transition elements and metals of the rare-earth group
US3755007A (en) * 1971-04-01 1973-08-28 Gen Electric Stabilized permanent magnet comprising a sintered and quenched body of compacted cobalt-rare earth particles
US3919003A (en) * 1971-12-17 1975-11-11 Gen Electric Sintered cobalt-rare earth intermetallic product
DE2326960A1 (de) * 1972-06-22 1974-01-10 Gen Electric Wandler
US3858308A (en) * 1973-06-22 1975-01-07 Bendix Corp Process for making a rotor assembly
US3997371A (en) * 1973-11-12 1976-12-14 Hitachi Metals, Ltd. Permanent magnet
US4075042A (en) * 1973-11-16 1978-02-21 Raytheon Company Samarium-cobalt magnet with grain growth inhibited SmCo5 crystals
US3892598A (en) * 1974-01-07 1975-07-01 Gen Electric Cobalt-rare earth magnets comprising sintered products bonded with solid cobalt-rare earth bonding agents
US3919001A (en) * 1974-03-04 1975-11-11 Crucible Inc Sintered rare-earth cobalt magnets comprising mischmetal plus cerium-free mischmetal
US4092184A (en) * 1975-10-08 1978-05-30 General Electric Company Method of preparing and installing cobalt-rare earth permanent magnets

Also Published As

Publication number Publication date
NL7105958A (https=) 1971-11-02
CA929384A (en) 1973-07-03
GB1347763A (en) 1974-02-27
DE2121453B2 (de) 1980-12-04
JPS5614731B1 (https=) 1981-04-06
DE2121453A1 (de) 1971-11-11

Similar Documents

Publication Publication Date Title
US3684593A (en) Heat-aged sintered cobalt-rare earth intermetallic product and process
US3655464A (en) Process of preparing a liquid sintered cobalt-rare earth intermetallic product
US3695945A (en) Method of producing a sintered cobalt-rare earth intermetallic product
US3655463A (en) Sintered cobalt-rare earth intermetallic process using solid sintering additive
JPS6325904A (ja) 永久磁石およびその製造方法並びに永久磁石製造用組成物
JPH07105289B2 (ja) 希土類永久磁石の製造方法
US3821035A (en) Sintered cobalt-neodymium-samarium intermetallic product and permanent magnets produced therefrom
US3682714A (en) Sintered cobalt-rare earth intermetallic product and permanent magnets produced therefrom
US3682716A (en) Sintered intermetallic product of cobalt,samarium and cerium mischmetal and permanent magnets produced therefrom
US3684591A (en) Sintered cobalt-rare earth intermetallic product including samarium and cerium and permanent magnets produced therefrom
EP0416098B1 (en) Magnetically anisotropic sintered magnets
US3919004A (en) Liquid sintered cobalt-rare earth intermetallic product
US4929275A (en) Magnetic alloy compositions and permanent magnets
JPS6181606A (ja) 希土類磁石の製造方法
EP0477810A2 (en) R-Fe-B type permanent magnet powder and bonded magnet therefrom
JP3222482B2 (ja) 永久磁石の製造方法
US3682715A (en) Sintered cobalt-rare earth intermetallic product including samarium and lanthanum and permanent magnets produced therefrom
US3755007A (en) Stabilized permanent magnet comprising a sintered and quenched body of compacted cobalt-rare earth particles
JPH0551656B2 (https=)
US3919003A (en) Sintered cobalt-rare earth intermetallic product
JPS6181603A (ja) 希土類磁石の製造方法
US3970484A (en) Sintering methods for cobalt-rare earth alloys
US4954186A (en) Rear earth-iron-boron permanent magnets containing aluminum
US4099995A (en) Copper-hardened permanent-magnet alloy
JPH0316762B2 (https=)