EP0018942A1 - Alliages magnétiques ductiles, procédé pour leur fabrication et corps magnétique - Google Patents

Alliages magnétiques ductiles, procédé pour leur fabrication et corps magnétique Download PDF

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Publication number
EP0018942A1
EP0018942A1 EP19800810124 EP80810124A EP0018942A1 EP 0018942 A1 EP0018942 A1 EP 0018942A1 EP 19800810124 EP19800810124 EP 19800810124 EP 80810124 A EP80810124 A EP 80810124A EP 0018942 A1 EP0018942 A1 EP 0018942A1
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Prior art keywords
alloy
ductile
chromium
magnetic
phase
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EP19800810124
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German (de)
English (en)
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EP0018942B1 (fr
Inventor
Wilfried Kurz
Remi Glardon
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Comadur SA
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Les Fabriques dAssortiments Reunies SA FAR
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Priority claimed from US06/029,477 external-priority patent/US4279668A/en
Application filed by Les Fabriques dAssortiments Reunies SA FAR filed Critical Les Fabriques dAssortiments Reunies SA FAR
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • 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

  • the present invention relates to magnetic alloys and to a method of making same.
  • the invention relates to ternary magnetic alloys of the type consisting of rare-earth or rare-earth-like elements, cobalt and at least one metal selected from the group which consists of iron, nickel, aluminium, chromium, copper, molybdenum or manganese, which are adapted for realizing permanent magnets of improved mechanical properties, such as ductility and toughness in use or fabrication.
  • Ferromagnetic alloys of the cobalt/rare-earth type have a high energy product and for this reason have been widely used. At present they are generally fabricated by powder metallurgy, i.e. by sintering, high-pressure pressing or the like techniques.
  • the alloys generally have the formula TRCoy, where TR is a rare-earth element such as samarium (Sm), gadolinium (Gd), praseodymium (Pr), cerium (Ce), neodymium (Nd), holmium (Ho) or an element similar to a rare-earth such as lanthanum (La) or yttrium (Y) or a mixture of such elements.
  • TR is a rare-earth element such as samarium (Sm), gadolinium (Gd), praseodymium (Pr), cerium (Ce), neodymium (Nd), holmium (Ho) or an element similar to a rare-earth such as lanthanum (La) or yttrium (Y) or a mixture of such elements.
  • y varies between 5 and 8.5.
  • Alloys containing copper as well as TRCoy which are prepared by casting have also been proposed heretofore. These alloys are subjected to a magnetic hardening treatment but are also found to be very brittle and difficult to work, particularly by turning and similar machining operations.
  • Swiss patent Nr. 601 481 discloses magnetic alloys having the formula TR (CO,X)y wherein X is at least one metal selected from the groups comprising iron, nickel, copper, aluminium, molybdenum and manganese.
  • TR is present in an amount of 5 to 22,5 % (atomic) of the alloy, X varies between 5 and 65 % (atomic) of the alloy . and y lies between 3,5 and 10.
  • ductile fibres were obtained by an appropriate choice of composition together with the fabrication method using directed or directional solidification.
  • Another object of the invention is to provide magnets which are readily machined and yet retain the high magnetic-energy product B x H characteristic of rare-earth/cobalt magnets.
  • a magnetic alloy for making ductile permanent magnet by directional solidification has a ductile phase composed essentially of Co (or cobalt in combination with iron or chromium), which is dispersed in a magnetic matrix whose composition lies between TR (C O ,X) 5 and TR 2 (Co,X) 17 , the alloy consisting essentially of TR, cobalt and X, where TR is at least one element selected from the group which consists of samarium, gadolinium, praseodymium, cerium, neodymium, holmium, lanthanum and yttrium, X is at least one metal selected from the group comprising copper, iron, nickel, chromium, aluminium, molybdenum and manganese, TR is present in an amount of 10 to 15 at.
  • X is present in an amount of 10 to 40 at. % of the alloy and cobalt is present in an amount of 50 to 80 at. % of the alloy.
  • X includes iron and/or chromium in an amount of 0.1 to 10 % (atomic) of the alloy and, most advantageously, chromium in an amount of 1 to 5 % (atomic) of the alloy (inclusive).
  • the ternary composition is a composition represented by the shaded region A, B, C, D, (preferably A', B', C', D') of Fig. 5 and consists of 5 to 16.7 at % (atomic percent) of the rare-earth-type element TR, 5 to 50 at. % of at least one supplemental metal X selected from the group consisting of iron, nickel, aluminum, chromium, copper, molybdenum or manganese. X can also represent a combination of one or more of these metals. The balance is cobalt.
  • TR represents elements selected from the group which consists of Sm, Gd, Pr, Co, Nd, Ho, La and Y.
  • the percent compositions given are in atomic percent (at. X).
  • the magnetic properties cited hereunder are the saturation magnetization (Ms) and the coercive force (Hc).
  • Iron which also is included in component X also has a similar effect, but not so pronounced as Cr.
  • Useful magnets can however be made especially well when the Cr additions are made to alloy compositions already containing a certain proportion of Fe.
  • the reasons for the effectiveness of Cr as a dendrite former in these materials can be partially explained by the results obtained by microprobe analysis for the compositions of the phases present: the Cr appears to be preferentially incorporated into the ductile dendrite phase, leaving relatively little in the matrix phases to interfere with their (magnetic) hardenability.
  • the Fe is similary distributed preferentially into the ductile dendrites, though the effect is less pronounced as can be seen in Table 1.
  • the quantities of Cr required depend on the proportions of the components TR and X relative to the Co content as can be seen from the examples in Table 2 together with an indication of the magnetic hardening which can be achieved.
  • the incorporation of the Cr into the dendrite phase in the form --of a solid solution does not markedly affect the ductility of the phase, although the magnetic saturation can be substantially modified; Fe additions increasing the value, and Cr additions strongly reducing it.
  • the dendrites do not seem to have a major effect on the magnetic properties of the bulk material. They do however have secondary effects by reducing squarences of the hysteresis loop. The reduction of M S of the dendrites due to the Cr is therefore an advangage as the loop squareness is less deformed.
  • the magnetic properties of the matrix phases are also affected by the addition of Cr but the effects are only small as relatively little Cr is incorporated into the matrix phases.
  • the value of M S is slightly reduced, but most importantly there is very little effect on the hardenability (H ) as compared with that obtained in the Sm-Co-Cu materials without the dendrites. At the Cr concentration levels required to form the dendrites, the reactions responsible for the magnetic hardening appear undisturbed.
  • the alloy composition could be adjusted such that no TR (C O ,X) 5 compound is formed, the magnet then consisting only of ductile Co dendrites and the TR (Co,X) 17 phase.
  • TR (Co,X) 5 type phase is of considerable aid, and that the composition is advantageously adjusted such that approximately 5 - 30 % of the magnet consists of this phase. (The proportion is for the finished material, after heat-treatment; before heat treatment the volume fraction of this phase is rather higher).
  • the ordinate in fig. 1 represents the temperature T while the abscissa shows the content in atomic percent of TR, the vertical lines 1, 2 and 3 indicating respectively the compositions within the ambit of the present invention.
  • X may be one or more metals selected from the group which consists of iron, nickel, aluminum, chromium, copper, molybdenum and manganese.
  • the alloy should contain 0.1 to 10 % (atomic) iron and/or chromium with 0.1 to 5 % (atomic) chromium present in any event.
  • the most preferred composition contains 0.5 % to 5 % and more advantageously 1 to 5 % chromium (atomic).
  • a composite formed of a magnetic matrix TR (Co,X) 5 to 8.5 (y 5 to 8.5) together with a ductile phase (Co,X) in cellular or dendritic form.
  • An alloy is solidified along the line y (Fig. 1).
  • T represents the temperature and is plotted along the ordinate while the TR content, in atomic percent is plotted along the abscissa.
  • the lines 1, 2 and 3 represent the compounds TR 2 (Co;X) 17 , TR (C O ,X) 5 and TR 2 (Co,X) 7 .
  • Ductile dendrites 32 (fig. 3) are obtained in the magnetic matrix 31 from the system of fig. 1.
  • the solidification front 33 separates the liquid phase 34 from the solid phase 35.
  • the interfaces are shown at 36 and the distance between the dendritic fibres 37 is larger than in the previous case, e.g. about 50 microns.
  • the fiber length may exceed 100 microns and the diameter of the fibers may be 25 to 30 microns on the average.
  • a molten alloy of the composition y (fig. 2) will cool along the arrow to give a eutectic mixture of the matrix of TR 2 (Co,X) 17 and fibers or lamellae of another phase such as (Co,X).
  • X represents an element which can be substituted for cobalt such as iron, nickel, aluminium, copper, chromium, molybdenum and manganese for a mixture thereof such as iron and chromium with copper, or copper plus nickel, for example.
  • ductile fibers 11 (fig. 4) in a magnetic matrix 12 are obtained.
  • the solidification front 13 separates the liquid phase 14 from the solidifying phase 15.
  • At 16 are -shown the various interfaces between the two phases.
  • 17 represents the distance between the ductile fibers which can vary between 1 and 10 microns according to the speed of solidification.
  • the fiber length is a multiple of the distance between the fibers and the fibers may extend continuously throughout the body or in lengths upward of 100 microns.
  • a brittle body can be made tougher according to the invention, by the introduction of a second ductile phase, with its associated interphase boundaries in the material.
  • a composite body formed of two brittle phases is tougher than either of the phases taken alone and the mechanical properties of the composite body containing the two phases are improved. Even better properties can be obtained when one of the phases is a ductile phase which is associated with the brittle phase.
  • the workability of the body is improved by the double effect of the presence of a ductile phase and the existence of phase interfaces.
  • the mechanical and particularly the magnetic properties of the alloys according to the invention can be improved by controlling the solidification to give an oriental structure as described.
  • a directional-solidification furnace as described in U.S. patent 3,871,335 issued 13 March 1975 can be used to achieve this process.
  • Such a directional-solidification furnace may include a crucible which is moved at a predetermined speed relative to the heating elements just allowing the solidification conditions, the liquidus/ -solidus interface temperature gradient, solidification speed and the like to be established as is necessary to ensure the growth of the fiber phase.
  • the orientation is primarily important for obtaining the optimum magnetic properties.
  • Magnetic hardening in all cases is obtained by provoking precipitation as is conventional in the art.
  • the magnetic hardening can be carried out by subjecting the cast body to a solution treatment at a temperature above 900°C followed by precipitation by example at 400 0 to 700 o C for one to two hours.
  • a similar improvement in the mechanical properties and magnetic properties of a body can be obtained by casting the alloy in a mold which is cooled at the base, thereby carrying out directed solidification.
  • a structure similar to that in fig. 4 is obtained although the fibers may be partly or completely in cellular or dendritic form.
  • the alloys shown in fig. 1, e.g. of composition y a structure similar to that shown in fig. 3, although the dendrites may have secondary branches, is formed.
  • composition range in which magnetic alloys may be prepared according to the invention are represented by the shaded region A, B, C, D of fig. 5, the presence of the ductile dendrites depending on the detailed choice of the mixture for TR and X.
  • the cobalt content is plotted along the lower axis in atomic percent
  • the TR content is plotted along the right hand axis in atomic percent
  • the replacement metal X is plotted along the left hand axis in atomic percent.
  • the shaded diagram represents compositions between (Co+5 at.% TR) and Co 5 TR with between 10 and 40 at.% of the element X, where X is one or more of the elements iron, nickel, aluminum, copperm chromium, molybdenum and manganese.
  • TR is present in an amount of 10 to 15 atomic percent of the alloy
  • X constitutes 10 to 40 atomic percent of the alloy
  • cobalt 50 to 80 atomic percent of the alloy region A', B', C' and D' of fig. 5
  • composition ranges have TR constituted by Sm or Sm mixed with up to 40 % of Pr or Ce.
  • X is preferably a mixture of Cu, or Cu and Ni, together with Cr or Cr + Fe. Examples of such compositions are shown in tables 1 through 3.
  • the advantages of the magnets according to the present invention are numerous. They have high magnetic properties (BH max>10 MGOe, table 3) which are stable over long periods and under various environmental conditions. Their mechanical properties are superior to those of TR-cobalt magnets as are presently available, particularly with respect to their ability to be machined as proven by comparative tests. They can be machined by chip-removal methods, thereby allowing magnets of a wide range of shapes and sizes to be fabricated. They can be readily ground and hence given precision -dimensions. Their toughness in use is superior to commercial TR-cobalt magnets. Finally, it is possible to cast large pieces by the methods described above, since the improvement of the mechanical properties of the pieces allows them to be better able to resist the thermal stresses accurring on cooling.
  • the ductile phase is composed essentially of cobalt (and chromium or chromium + iron) and the composition of the magnetic matrix is represented between TR (Co,X) 5 to TR 2 (Co,X) 17 .
  • Fig. 6 shows, in photomicrograph form, the composite of the present invention in which the ductile cobalt dendrites can readily be distinguished from the brittle magnetic matrix.
  • the composite of the invention shows no evidence of cracking (composition corresponding to that of Example A I ) while a similar composition (modified to avoid dendrites but reproduce the matrix composition) without the formation of the ductile dendrites (fig. 8) shows heavy cracking.
  • Figs. 9 and 10 give the test results for these two alloys, showing the remarkable improvement resulting from the presence of the cobalt ductile dendrites. All of the compositions given have good magnetic properties as well.
  • test method was a three-point bend test effected on a notched square-section bar, in which the fracture surface is triangular as defined by the notches.
  • Fig. 9 is a test diagram on an alloy with ductile dendrites showing the charge (c) applied on the bar versus the displacement (d).
  • Fig. 10 is a similar test diagram for an alloy without ductile dendrites.
  • the directionally --solidified body has the same values for 4 ⁇ M s and Br of - 7.5 kGs.
  • the same body reduced to powder has the same value for Br but the values of 4 ⁇ M s in the first quadrant of the hysteresis loop are increased to - 9.0 kGs and in the second (technically important) quadrant, reduced by a similar amount due to the effect of the dendrites (see b. fig. 11)

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Power Engineering (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Hard Magnetic Materials (AREA)
EP19800810124 1979-04-12 1980-04-11 Alliages magnétiques ductiles, procédé pour leur fabrication et corps magnétique Expired EP0018942B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US29477 1979-04-12
US06/029,477 US4279668A (en) 1975-05-05 1979-04-12 Directionally solidified ductile magnetic alloy

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EP0018942A1 true EP0018942A1 (fr) 1980-11-12
EP0018942B1 EP0018942B1 (fr) 1984-07-04

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JP (1) JPS5613454A (fr)
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4824735A (en) * 1986-03-10 1989-04-25 Johnson Matthey Public Limited Company Casting transition metal alloy containing rare earth metal
WO2011011197A2 (fr) * 2009-07-20 2011-01-27 Borgwarner Inc. Turbocompresseur et roue de compresseur pour ce dernier
WO2013072899A1 (fr) * 2011-11-18 2013-05-23 Tubitak Alliage pour applications de formage d'acier à haute température

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60170127U (ja) * 1984-04-23 1985-11-11 服部　良助 ブラシ
JPS60170126U (ja) * 1984-04-23 1985-11-11 服部　良助 ブラシ
JPS6410227U (fr) * 1987-07-09 1989-01-19

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2017234A1 (de) * 1970-01-09 1971-07-15 Bbc Brown Boveri & Cie Verfahren zur Herstellung eines Dauermagneten
DE2143866A1 (de) * 1970-09-08 1972-03-09 Battelle Memorial Institute Verfahren zur Herstellung eines D auerm agnet Werkstoffes
CH529429A (de) * 1968-11-16 1972-10-15 Philips Nv Gegossener Dauermagnet
DE1809535C3 (de) * 1967-11-15 1975-09-11 Matsushita Electric Industrial Co. Ltd., Kadoma, Osaka (Japan) Dauermagnetlegierung und Verfahren zu ihrer Herstellung
DE2443071A1 (de) * 1974-07-31 1976-02-12 Bbc Brown Boveri & Cie Kupfergehaertete permanentmagnetische legierung
DE2507105A1 (de) * 1974-12-18 1976-07-01 Bbc Brown Boveri & Cie Permanentmagnetisches material mit samarium, kobalt, kupfer und eisen, verfahren zur herstellung und verwendung des materials
DE2558865A1 (de) * 1975-12-02 1977-06-16 Bbc Brown Boveri & Cie Dauermagnetlegierung
DE2727243A1 (de) * 1976-06-18 1977-12-29 Hitachi Metals Ltd Dauermagnetlegierung
DE2406782B2 (de) * 1973-02-09 1978-06-22 Matsushita Electric Industrial Co., Ltd., Kadoma, Osaka (Japan) Verwendung einer gesinterten hartmagnetischen Legierung
CH601481A5 (fr) * 1975-05-05 1978-07-14 Far Fab Assortiments Reunies

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1809535C3 (de) * 1967-11-15 1975-09-11 Matsushita Electric Industrial Co. Ltd., Kadoma, Osaka (Japan) Dauermagnetlegierung und Verfahren zu ihrer Herstellung
CH529429A (de) * 1968-11-16 1972-10-15 Philips Nv Gegossener Dauermagnet
DE2017234A1 (de) * 1970-01-09 1971-07-15 Bbc Brown Boveri & Cie Verfahren zur Herstellung eines Dauermagneten
DE2143866A1 (de) * 1970-09-08 1972-03-09 Battelle Memorial Institute Verfahren zur Herstellung eines D auerm agnet Werkstoffes
DE2406782B2 (de) * 1973-02-09 1978-06-22 Matsushita Electric Industrial Co., Ltd., Kadoma, Osaka (Japan) Verwendung einer gesinterten hartmagnetischen Legierung
DE2443071A1 (de) * 1974-07-31 1976-02-12 Bbc Brown Boveri & Cie Kupfergehaertete permanentmagnetische legierung
DE2507105A1 (de) * 1974-12-18 1976-07-01 Bbc Brown Boveri & Cie Permanentmagnetisches material mit samarium, kobalt, kupfer und eisen, verfahren zur herstellung und verwendung des materials
CH601481A5 (fr) * 1975-05-05 1978-07-14 Far Fab Assortiments Reunies
DE2558865A1 (de) * 1975-12-02 1977-06-16 Bbc Brown Boveri & Cie Dauermagnetlegierung
DE2727243A1 (de) * 1976-06-18 1977-12-29 Hitachi Metals Ltd Dauermagnetlegierung

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4824735A (en) * 1986-03-10 1989-04-25 Johnson Matthey Public Limited Company Casting transition metal alloy containing rare earth metal
WO2011011197A2 (fr) * 2009-07-20 2011-01-27 Borgwarner Inc. Turbocompresseur et roue de compresseur pour ce dernier
WO2011011197A3 (fr) * 2009-07-20 2011-04-21 Borgwarner Inc. Turbocompresseur et roue de compresseur pour ce dernier
CN102472162A (zh) * 2009-07-20 2012-05-23 博格华纳公司 涡轮增压器及用于其的压缩机叶轮
CN102472162B (zh) * 2009-07-20 2014-10-15 博格华纳公司 涡轮增压器及用于其的压缩机叶轮
US9366181B2 (en) 2009-07-20 2016-06-14 Borgwarner Inc. Turbocharger and compressor wheel therefor
WO2013072899A1 (fr) * 2011-11-18 2013-05-23 Tubitak Alliage pour applications de formage d'acier à haute température

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Publication number Publication date
DE3068420D1 (en) 1984-08-09
EP0018942B1 (fr) 1984-07-04
JPS5613454A (en) 1981-02-09

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