WO1989002156A1 - OPTIMIZATION OF THE MICROSTRUCTURE OF SINTERED Fe-Nd-B MAGNETS - Google Patents

OPTIMIZATION OF THE MICROSTRUCTURE OF SINTERED Fe-Nd-B MAGNETS Download PDF

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Publication number
WO1989002156A1
WO1989002156A1 PCT/EP1988/000555 EP8800555W WO8902156A1 WO 1989002156 A1 WO1989002156 A1 WO 1989002156A1 EP 8800555 W EP8800555 W EP 8800555W WO 8902156 A1 WO8902156 A1 WO 8902156A1
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Prior art keywords
phase
magnets
sintered
composition
sintered magnet
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PCT/EP1988/000555
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German (de)
French (fr)
Inventor
Waldemar Draxler
Adolf Meller
Friedrich J. Esper
Klaus-Dieter Durst
Ernst Theo Henig
Helmut KRONMÜLLER
Günter Petzow
Gerhard Schneider
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Max-Planck-Gesellschaft Zur Förderung Der Wissensc
Robert Bosch Gmbh
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Publication of WO1989002156A1 publication Critical patent/WO1989002156A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—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

  • the invention relates to a sintered magnet based on Fe-Nd-B with improved properties and its manufacture.
  • Fe 14 Nd 2 B hereinafter referred to as referred to as the carrier of the magnetic properties
  • L phase An Nd-rich phase (consisting essentially of Nd, Nd 2 O 3 and pores) hereinafter referred to as L phase, which is liquid above 655 ° C and both good compression by liquid phase sintering, as well as a magnetic Decoupling of neighboring S grains causes and
  • Fe 4 NdB 4 hereinafter referred to as ⁇ phase, which is paramagnetic above 13 K and is therefore regarded as the main cause of the disadvantages explained above.
  • the volume fraction of the ⁇ phase is, for example, 5 to 8%, the fraction of the L phase is approximately 10% and the rest consists of the ferromagnetic 35 phase.
  • the object of the invention is therefore to improve the magnetic properties of sintered magnets of the Fe-Nd-B type and in particular to improve the coercive To improve the field strength as such and its temperature dependency and also to increase the remanence.
  • a sintered magnet based on Fe-Nd-B which is characterized in that its structure is free of Fe 4 NdB 4 grains ( ⁇ phase) which are larger than 0.5 ⁇ m and its composition at sintering temperature in the 2-phase area Fe 14 Nd 2 B and Nd-rich, liquid phase (L phase) above 655 ° C.
  • FIG. 1 shows this new phase diagram in the form of an isothermal section at 1060 ° C., the 2-phase region mentioned being shown in broken lines.
  • the composition of two-phase alloys must lie in the triangle that is spanned by the following points: Fe 82.3 Nd 11.8 B 5.9 , Fe 58.5 Nd 38 B 3.5 and Fe 60.5 Nd 27 B 12.5 .
  • Sintered magnets of this composition according to the invention are therefore preferred.
  • FIGS. 2a and 2b show the difference in the structure between the known magnets (2a) and the magnets (2b) according to the invention.
  • the composition of the magnet of FIG. 2a corresponds to the formula Fe 77 Nd 15 B 8 .
  • The is light, the ⁇ phase is gray, the L phase is shown in black.
  • the magnet of FIG. 2b corresponds to the composition Fe 75 Nd 18.5 B 6.5 .
  • the appearance of the gray ⁇ phase is no longer recognizable here.
  • This sintered magnet with the composition Fe 75 Nd 18.5 B 6.5 typically has the following properties at room temperature:
  • the sintered magnets according to the invention can also contain other elements alloyed.
  • one or more of the elements Co, Al, Dy, Tb and C can be present as alloy constituents in the amounts known from the literature in order to influence properties such as crystal anisotropy, Curie temperature and magnetic moment.
  • the sintered magnet according to the invention can preferably contain 0 to 20 at.% Co, 0 to 15 at.% Al, 0 to 20 at.% Dy, 0 to 20 at.% Tb and 0 to 12.5 at.% C included.
  • the general superiority of the 2-phase magnets according to the invention, even when alloying one or more of the above-mentioned additional elements, can be seen in FIG. 3, where the temperature dependence of the coercive field strength of 3 Fe-Nd-B base magnets according to the prior art without an additional element, or with the addition of Al or Dy is compared with the correspondingly composed magnets according to the invention.
  • the 3-phase magnets of the prior art have the composition Nd 15 Fe 77 B 8 , Nd 15 (Fe 75 Al 2 ) B 8 and
  • the corresponding 2-phase magnets according to the invention have the composition
  • the sintered magnets according to the invention are produced from a master alloy, for example from a composition of the pure components (purity 99% or better) in a manner known per se, by powder metallurgy.
  • the production is preferably carried out by applying a magnetic field perpendicular to the pressing direction to a powder mixture of the components, compressing the powder axially to form a green compact, and sintering the green compact in an inert gas atmosphere, preferably a noble gas atmosphere, at a temperature of 1040 to 1080 ° C and then at 500 up to 700 ° C.
  • a WC-Co vibration ball mill in an inert gas atmosphere is suitable for producing the powder mixture of the components.
  • the powder is aligned and then axially pressed by applying a magnetic field of preferably 0.4 to 0.6 T perpendicular to the pressing direction.
  • the pressing pressure is preferably 500 to 800 MPa, particularly preferably 450 to 550 MPa.
  • the sintering itself is preferably carried out in the range from 1050 to 1070 ° C. and then takes about 0.5 to 3 hours depending on the conditions used.
  • the final tempering which is generally carried out at 500 to 700 ° C and preferably at 550 to 650 ° C, usually takes 0.2 to 4 hours.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Hard Magnetic Materials (AREA)

Abstract

Sintered Fe-Nd-B magnets are characterized in that their microstructure is free from Fe4NdB4 grains (eta-phase) larger than 0.5 mum and their composition at the sintering temperature lies in the two-phase region of the Fe14Nd2B (PHI-phase) and the Nd-rich phase liquid above 655°C (L-phase).

Description

Optimierung der Gefügestruktur des Fe-Nd-B-Basis Sintermagneten Optimization of the structure of the Fe-Nd-B base sintered magnet
Die Erfindung betrifft einen Sintermagneten auf Basis Fe-Nd-B mit verbesserten Eigenschaften und seine Herstellung.The invention relates to a sintered magnet based on Fe-Nd-B with improved properties and its manufacture.
Seit M. Sagawa in J.Appl.Phys. 55, 2083 (1984) erstmals über ein neues Permanentmagnet-Material auf Basis Nd-Fe-B berichtet hat, wurden viele Untersuchungen vorgenommen, um die Eigenschaften dieses Materials weiterhin zu verbessern. Diese Versuche beruhten auf der Tatsache, daß Magnete vom Typ Fe-Nd-B, insbesondere Sintermagnete dieser Zusammensetzung, sich bei Raumtemperatur durch besonders hohe magnetische Kennwerte auszeichnen. Diesem Vorteil steht jedoch als Nachteil gegenüber, daß ihre Temperaturbeständigkeit, hauptsächlich die Temperaturbeständigkeit der Koerzitivfeldstär- ke HCJ unbefriedigend ist und die Anwendung dieser Magnete in temperaturbelasteten Maschinen verhindert. Für die technische Brauchbarkeit auf diesen Gebieten ist es daher erforderlich, diese Magnete so zu verbessern, daß sie bis 200 °C auch bei starken Gegenfeldern eingesetzt werden können.Since M. Sagawa in J.Appl.Phys. 55, 2083 (1984) for the first time reported a new permanent magnet material based on Nd-Fe-B, many investigations were carried out to further improve the properties of this material. These experiments were based on the fact that magnets of the Fe-Nd-B type, in particular sintered magnets of this composition, are distinguished by particularly high magnetic characteristics at room temperature. However, this advantage is offset by the disadvantage that their temperature resistance, mainly the temperature resistance of the coercive force H CJ, is unsatisfactory and prevents the use of these magnets in temperature-stressed machines. For the technical usability in these areas, it is therefore necessary to improve these magnets so that they can be used up to 200 ° C even with strong opposing fields.
Eine der wesentlichen Ursachen für die unbefriedigenden Eigenschaften, insbesondere die niedrige Koerzitivfeidstärke im Vergleich zu der theoretisch zu erwartenden, liegt in der Existenz nicht ferromagnetischer Gefügebestandteile. Sie verursachen hohe magnetische Streufelder, durch die eine Keimbildung von unmagnetischen Domänenin der Nachbarschaft dieser unmagnetischen Einflüsse erleichtert wird. Dieser Selbstentmagnetisierungseffekt wirkt sich bei steigender Temperatur immer stärker aus, da die intrinsische Koerzitivfeldstärke mit der Tempera tur stärker abnimmt als die Streufeldeffekte.One of the main reasons for the unsatisfactory properties, in particular the low coercive field strength in comparison to that which is to be expected theoretically, lies in the existence of non-ferromagnetic structural components. They cause high stray magnetic fields, which facilitate the nucleation of non-magnetic domains in the vicinity of these non-magnetic influences. This self-demagnetizing effect has an increasing effect with increasing temperature, since the intrinsic coercive field strength with the tempera decreases more than the stray field effects.
In herkömmlichen Sintermagneten mit beispielsweise der Zusammensetzung Fe77Nd15B8 treten hauptsächlich 3 Phasen auf, nämlichIn conventional sintered magnets, for example with the composition Fe 77 Nd 15 B 8 , there are mainly 3 phases, namely
1. Fe14Nd2B, nachstehend als
Figure imgf000004_0001
bezeichnet, als Träger der magnetischen Eigenschaften,1. Fe 14 Nd 2 B, hereinafter referred to as
Figure imgf000004_0001
referred to as the carrier of the magnetic properties,
2. eine Nd-reiche Phase (im wesentlichen aus Nd, Nd2O3 und Poren bestehend) im folgenden als L-Phase bezeichnet, die oberhalb 655°C flüssig ist und sowohl eine gute Verdichtung durch Flüssigphasen- sintern, als auch eine magnetische Entkopplung benachbarter S-Körner bewirkt und2. An Nd-rich phase (consisting essentially of Nd, Nd 2 O 3 and pores) hereinafter referred to as L phase, which is liquid above 655 ° C and both good compression by liquid phase sintering, as well as a magnetic Decoupling of neighboring S grains causes and
3. Fe4NdB4, im folgenden als η-Phase bezeichnet, die oberhalb 13 K paramagnetisch ist und daher als wesentliche Ursache für die oben erläuterten Nachteile angesehen wird.3. Fe 4 NdB 4 , hereinafter referred to as η phase, which is paramagnetic above 13 K and is therefore regarded as the main cause of the disadvantages explained above.
In einem typischen bekannten Magneten der angegebenen Art beträgt beispielsweise der Volumenanteil der η-Phase 5 bis 8 %, der Anteil der L-Phase etwa 10 % und der Rest besteht aus der ferromagnetisehen 35-Phase.In a typical known magnet of the type specified, the volume fraction of the η phase is, for example, 5 to 8%, the fraction of the L phase is approximately 10% and the rest consists of the ferromagnetic 35 phase.
Nach Ansicht der Fachwelt läßt sich die Bildung der unerwünschten. η-Phase bei der Herstellung von Fe-Nd-B- Magneten nicht verhindern, muß also als unvermeidbar in Kauf genommen werden (R.K. Mishra, J.Appl.Phys. 59, 2244 (1986)).According to experts, the formation of the undesirable. Do not prevent the η phase in the production of Fe-Nd-B magnets, so it must be accepted as inevitable (R.K. Mishra, J.Appl.Phys. 59, 2244 (1986)).
Der Erfindung liegt daher die Aufgabe zugrunde, die magnetischen Eigenschaften von Sintermagneten vom Fe-Nd-B-Typ zu verbessern und insbesondere die Koerzi- tivfeldstärke als solche und deren Temperaturabhängigkeit zu verbessern und auch die Remanenz zu steigern.The object of the invention is therefore to improve the magnetic properties of sintered magnets of the Fe-Nd-B type and in particular to improve the coercive To improve the field strength as such and its temperature dependency and also to increase the remanence.
Gelöst wird diese Aufgabe erfindungsgemäß durch einen Sintermagneten auf Basis Fe-Nd-B, der dadurch gekennzeichnet ist, daß sein Gefüge frei ist von Fe4NdB4-Körnern (η-Phase), die größer als 0,5 μm sind und seine Zusammensetzung bei Sintertemperatur im 2-Phasengebiet Fe14Nd2B
Figure imgf000005_0002
und Nd-reiche, oberhalb 655 °C flüssige Phase (L-Phase) liegt.This object is achieved according to the invention by a sintered magnet based on Fe-Nd-B, which is characterized in that its structure is free of Fe 4 NdB 4 grains (η phase) which are larger than 0.5 μm and its composition at sintering temperature in the 2-phase area Fe 14 Nd 2 B
Figure imgf000005_0002
and Nd-rich, liquid phase (L phase) above 655 ° C.
Durch das Fehlen größerer η-Körper im erfindungsgemäßen Sintermagneten gelingt es, die oben angegebenen magnetischen Eigenschaften wesentlich zu verbessern.The absence of larger η bodies in the sintered magnet according to the invention makes it possible to significantly improve the magnetic properties specified above.
Nach dem bisher bekannten ternären Phasendiagramm desFe-Nd-B-Systems (K.H.J. Buschow et al., Philips J.Res. 40, 230 (1985)) konnte ein 2-Phasen-Gebiet L +
Figure imgf000005_0001
bei Sintertemperatur nicht existieren. Nunmehr wurde jedoch überraschenderweise gefunden und hierauf beruht die Erfindung, daß tatsächlich ein 2-Phasen-Gebiet bei Sintertemperatur auftritt und es möglich ist, die Zuammensetzung für die Magnetlegierung so zu wählen, daß sie bei Sintertemperatur von etwa 1000 bis 1080 °C in diesem 2-Phasen-Gebiet liegt. Figur 1 zeigt dieses neue Phasendiagramm in Form eines isothermen Schnitts bei 1060°C, wobei das erwähnte 2-Phasen-Gebiet gestrichelt eingezeichnet ist. Bei einer Sintertemperatur von 1060°C müssen demzufolge zweiphasige Legierungen in ihrer Zusammensetzung in dem Dreieck liegen, das von folgenden Punkten aufgespannt wird: Fe82,3Nd11,8B5,9, Fe58,5Nd38B3,5 und Fe60,5Nd27B12,5.According to the previously known ternary phase diagram of the Fe-Nd-B system (KHJ Buschow et al., Philips J. Res. 40, 230 (1985)), a 2-phase region L +
Figure imgf000005_0001
do not exist at sintering temperature. However, it has now surprisingly been found that the invention is based on the fact that a 2-phase region actually occurs at the sintering temperature and that it is possible to choose the composition for the magnetic alloy so that it is at a sintering temperature of about 1000 to 1080 ° C. in this second -Phase area lies. FIG. 1 shows this new phase diagram in the form of an isothermal section at 1060 ° C., the 2-phase region mentioned being shown in broken lines. At a sintering temperature of 1060 ° C, the composition of two-phase alloys must lie in the triangle that is spanned by the following points: Fe 82.3 Nd 11.8 B 5.9 , Fe 58.5 Nd 38 B 3.5 and Fe 60.5 Nd 27 B 12.5 .
Erfindungsgemäße Sintermagnete dieser Zusammensetzung werden daher bevorzugt.Sintered magnets of this composition according to the invention are therefore preferred.
Erfindungsgemäße, im 2-Phasen-Gebiet bei Sintertempera- tur liegende Magnete bilden beim Abkühlen von der Sintertemperatur nur sehr kleine η-Körner im Gefüge. Durch das Fehlen der bisher unvermeidlichen großen r^-Körner werden die verbesserten Eigenschaften erzielt. Die Figuren 2a und 2b zeigen den Unterschied in der Gefügestruktur zwischen den bekannten Magneten (2a) und den erfindungsgemäßen Magneten (2b). Die Zusammensetzung des Magneten von Figur 2a entspricht der Formel Fe77Nd15B8. Die
Figure imgf000006_0001
ist hell, die η-Phase ist grau, die L-Phase ist schwarz wiedergegeben. Der Magnet von Figur 2b entspricht der Zusammensetzung Fe75Nd18,5B6,5. Hier ist das Auftreten der grauen η-Phase nicht mehr erkennbar. Dieser Sintermagnet der Zusammensetzung Fe75Nd18,5B6,5 weist bei Raumtemperatur typisch folgende Eigenschaften auf:Magnets according to the invention, located in the 2-phase region at the sintering temperature, form only very small η grains in the structure when they cool down from the sintering temperature. The lack of the previously inevitable large r ^ grains achieves the improved properties. FIGS. 2a and 2b show the difference in the structure between the known magnets (2a) and the magnets (2b) according to the invention. The composition of the magnet of FIG. 2a corresponds to the formula Fe 77 Nd 15 B 8 . The
Figure imgf000006_0001
is light, the η phase is gray, the L phase is shown in black. The magnet of FIG. 2b corresponds to the composition Fe 75 Nd 18.5 B 6.5 . The appearance of the gray η phase is no longer recognizable here. This sintered magnet with the composition Fe 75 Nd 18.5 B 6.5 typically has the following properties at room temperature:
Remanenz Br = 1,1 T Koerzitivfeldstärke HCJ = 1040 kA/m.Remanence B r = 1.1 T coercive field strength H CJ = 1040 kA / m.
Diese Werte sind typisch für die erfindungsgemäßen Sintermagneten und weichen von den für die oben angegebene spezielle Zusammensetzung in der Regel nicht mehr als 5 % nach oben und unten ab. Der besondere Vorteil der erfindungsgemäßen Sintermagnete liegt in einem wesentlich verbesserten Temperaturkoeffizienten der Koerzitivfeldstärke der magnetischen Polarisation HCJ. So liegt dieser Koeffizient bei den bekannten Magneten über -0,7 bis -0,9 %/K, bei den erfindungsgemäßen Magneten dagegen bei -0,5 %/K, wobei mit einer Abweichung von 0,1 %/K nach oben und unten gerechnet werden kann je nach Zusammensetzung.These values are typical of the sintered magnets according to the invention and generally do not deviate more than 5% up and down from the special composition specified for the above. The particular advantage of the sintered magnets according to the invention lies in a significantly improved temperature coefficient of the coercive field strength of the magnetic polarization H CJ . Thus, this coefficient is above -0.7 to -0.9% / K in the known magnets, but in the case of the magnets according to the invention it is -0.5% / K, with a deviation of 0.1% / K upwards and can be calculated below depending on the composition.
Die erfindungsgemäßen Sintermagnete können außer den essentiellen Bestandteilen Fe-Nd-B auch noch weitere Elemente zulegiert enthalten. Insbesondere kann als Legierungsbestandteil eines oder mehrere der Elemente Co, AI, Dy, Tb und C in den aus der Literatur bekannten Mengen vorliegen, um Eigenschaften wie Kristallanisotropie, Curie-Temperatur und magnetisches Moment zu beeinflussen. Bevorzugt kann der erfindungsgemäße Sintermagnet 0 bis 20 At.-% Co, 0 bis 15 At.-% AI, 0 bis 20 At.-% Dy, 0 bis 20 At.-% Tb und 0 bis 12,5 At.-% C enthalten.In addition to the essential components Fe-Nd-B, the sintered magnets according to the invention can also contain other elements alloyed. In particular, one or more of the elements Co, Al, Dy, Tb and C can be present as alloy constituents in the amounts known from the literature in order to influence properties such as crystal anisotropy, Curie temperature and magnetic moment. The sintered magnet according to the invention can preferably contain 0 to 20 at.% Co, 0 to 15 at.% Al, 0 to 20 at.% Dy, 0 to 20 at.% Tb and 0 to 12.5 at.% C included.
Die generelle Überlegenheit der erfindungsgemäßen 2-phasigen Magnete auch bei Zulegierung eines oder mehrerer der oben genannten zusätzlichen Elemente ist aus Figur 3 ersichtlich, wo die Temperaturabhängigkeit der Koerzitivfeldstärke von 3 Fe-Nd-B-Basismagnete nach dem Stand der Technik ohne Zusatzelement, bzw. mit Zusatz von AI oder Dy mit den entsprechend zusammengesetzten erfindungsgemäßen Magneten verglichen wird. Die 3-phasigen Magnete des Standes der .Technik haben die Zusammensetzung Nd15Fe77B8, Nd15(Fe75Al2)B8 undThe general superiority of the 2-phase magnets according to the invention, even when alloying one or more of the above-mentioned additional elements, can be seen in FIG. 3, where the temperature dependence of the coercive field strength of 3 Fe-Nd-B base magnets according to the prior art without an additional element, or with the addition of Al or Dy is compared with the correspondingly composed magnets according to the invention. The 3-phase magnets of the prior art have the composition Nd 15 Fe 77 B 8 , Nd 15 (Fe 75 Al 2 ) B 8 and
Nd13,5Dy1,5Fe77B8. Die entsprechenden erfindungsgemäßen 2-phasigen Magnete besitzen die ZusammensetzungNd 13.5 Dy 1.5 Fe 77 B 8 . The corresponding 2-phase magnets according to the invention have the composition
Nd18,5Fe75B6,5, Nd18,5(Fe73Al2)B6,5 Und Nd16,65Dy1,85Fe75B6,5. Die Herstellung der erfindungsgemäßen Sintermagneten erfolgt ausgehend von einer Vorlegierung, beispielsweise von einer Zusammensetzung der reinen Komponenten (Reinheit 99 % oder besser) in an sich bekannter Weise auf pulvermetallurgischem Wege. Bevorzugt wird die Herstellung durchgeführt, indem man an eine Pulvermischung der Komponenten ein Magnetfeld senkrecht zur Preßrichtung anlegt, das Pulver axial zu einem Grünling verpreßt und den Grünling in Inertgasatmosphäre, vorzugsweise Edelgasatmosphäre, bei einer Temperatur von 1040 bis 1080°C sintert und danach bei 500 bis 700°C anläßt.Nd 18.5 Fe 75 B 6.5 , Nd 18.5 (Fe 73 Al 2 ) B 6.5 and Nd 16.65 Dy 1.85 Fe 75 B 6.5 . The sintered magnets according to the invention are produced from a master alloy, for example from a composition of the pure components (purity 99% or better) in a manner known per se, by powder metallurgy. The production is preferably carried out by applying a magnetic field perpendicular to the pressing direction to a powder mixture of the components, compressing the powder axially to form a green compact, and sintering the green compact in an inert gas atmosphere, preferably a noble gas atmosphere, at a temperature of 1040 to 1080 ° C and then at 500 up to 700 ° C.
Für die Herstellung der Pulvermischung der Komponenten eignet sich beispielsweise eine WC-Co-Vibrationskugel- mühle- in Edelgasatmosphäre. Durch Anlegen eines Magnetfelds von vorzugsweise 0,4 bis 0,6 T senkrecht zur Preßrichtung wird das Pulver ausgerichtet und dann axial verpreßt. Der Preßdruck beträgt vorzugsweise 500 bis 800 MPa, besonders bevorzugt 450 bis 550 MPa.For example, a WC-Co vibration ball mill in an inert gas atmosphere is suitable for producing the powder mixture of the components. The powder is aligned and then axially pressed by applying a magnetic field of preferably 0.4 to 0.6 T perpendicular to the pressing direction. The pressing pressure is preferably 500 to 800 MPa, particularly preferably 450 to 550 MPa.
Das Sintern selbst erfolgt bevorzugt im Bereich 1050 bis 1070°C und dauert je nach den angewendeten Bedingungen dann etwa 0,5 bis 3 Stunden. Das abschließende Anlassen, welches im allgemeinen bei 500 bis 700°C und bevorzugt bei 550 bis 650°C durchgeführt wird, dauert in der Regel 0,2 bis 4 Stunden. The sintering itself is preferably carried out in the range from 1050 to 1070 ° C. and then takes about 0.5 to 3 hours depending on the conditions used. The final tempering, which is generally carried out at 500 to 700 ° C and preferably at 550 to 650 ° C, usually takes 0.2 to 4 hours.

Claims

P a t e n t a n s p r ü c h e Patent claims
1. Sintermagnete auf Basis Fe-Nd-B, d a d u r c h g e k e n n z e i c h n e t , daß ihr Gefüge frei ist von Fe4NdB4-Körnern (η-Phase) die größer als 0,5 μm sind und ihre Zusammensetzung bei Sintertemperatur im 2-Phasengebiet Fe14Nd2B
Figure imgf000009_0001
und Nd-reiche, oberhalb 655°C flüssige Phase (L-Phase) liegt.1. Sintered magnets based on Fe-Nd-B, characterized in that their structure is free of Fe 4 NdB 4 grains (η phase) which are larger than 0.5 μm and their composition at sintering temperature in the 2-phase region Fe 14 Nd 2 B
Figure imgf000009_0001
and Nd-rich, liquid phase (L phase) above 655 ° C.
2. Sintermagnete nach Anspruch 1, g e k e n n z e i c h n e t d u r c h Zusammensetzungen, die in dem Dreieck liegen, das von den Punkten Fe82,3Nd11,8B5,9, Fe58,5Nd38B3,5 und Fe60,5Nd27B12,5 aufgespannt .wird.2. Sintered magnet according to claim 1, characterized by compositions which lie in the triangle, of the points Fe 82.3 Nd 11.8 B 5.9 , Fe 58.5 Nd 38 B 3.5 and Fe 60.5 Nd 27 B 12.5 is clamped.
3. Sintermagnet nach Anspruch 1 und 2, g e k e n n z e i c h n e t d u r c h. die Zusammensetzung Fe75Nd18,5B6,5.3. Sintered magnet according to claim 1 and 2, characterized by . the composition Fe 75 Nd 18.5 B 6.5 .
4. Sintermagnet nach einem der Ansprüche 1 bis 3, g e k e n n z e i c h n e t d u r c h einen Temperaturkoeffizienten der Koerzitivfeldstärke der magnetischen Polarisation HCJ im Bereich von 10 bis 110°C bei -0,5 %/K.4. Sintered magnet according to one of claims 1 to 3, characterized by a temperature coefficient of the coercive field strength of the magnetic polarization H CJ in the range of 10 to 110 ° C at -0.5% / K.
5. Sintermagnet nach Anspruch 3, g e k e n n z e i c h n e t d u r c h eine Remanenz BR von 1,1 ± 5 % T und eine Koerzitivfeidstärke HCJ von 1040 ± 5 % kA/m bei Raumtemperatur. 5. Sintered magnet according to claim 3, characterized by a remanence B R of 1.1 ± 5% T and a coercive field strength H CJ of 1040 ± 5% kA / m at room temperature.
6. Sintermagnet nach einem der Ansprüche 1 bis 5, d a d u r c h g e k e n n z e i c h n e t , daß er wenigstens ein Element aus der Gruppe Co, AI, Dy, Tb und C enthält.6. sintered magnet according to one of claims 1 to 5, d a d u r c h g e k e n n z e i c h n e t that it contains at least one element from the group Co, Al, Dy, Tb and C.
7. Sintermagnet nach Anspruch 6, d a d u r c h g e k e n n z e i c h n e t , er 0 bis 20 At.-% Co, 0 bis 15 At.-% AI, 0 - 20 At.-% Dy, 0 bis 20 At.-% Tb und 0 bis 12,5 At.-% C enthält. 7. Sintered magnet according to claim 6, characterized in that it 0 to 20 at.% Co, 0 to 15 at.% Al, 0 to 20 at.% Dy, 0 to 20 at.% Tb and 0 to 12, Contains 5 at% C.
PCT/EP1988/000555 1987-09-02 1988-06-23 OPTIMIZATION OF THE MICROSTRUCTURE OF SINTERED Fe-Nd-B MAGNETS WO1989002156A1 (en)

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DEP3729361.3 1987-09-02
DE19873729361 DE3729361A1 (en) 1987-09-02 1987-09-02 OPTIMIZATION OF THE STRUCTURE OF THE FE-ND-B BASE SINTER MAGNET

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Publication number Priority date Publication date Assignee Title
EP0505348A1 (en) * 1991-03-18 1992-09-23 BÖHLER YBBSTALWERKE G.m.b.H. Permanent magnet material or sintered magnet and fabrication process

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4142160C1 (en) * 1991-12-20 1993-03-11 Heraeus Elektrochemie Gmbh, 6450 Hanau, De
DE19945943B4 (en) * 1999-09-24 2005-06-02 Vacuumschmelze Gmbh Borarme Nd-Fe-B alloy and process for its preparation

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Publication number Priority date Publication date Assignee Title
EP0177371A1 (en) * 1984-10-05 1986-04-09 Hitachi Metals, Ltd. Process for manufacturing a permanent magnet
EP0197712B1 (en) * 1985-03-28 1990-01-24 Kabushiki Kaisha Toshiba Rare earth-iron-boron-based permanent magnet

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
EP0177371A1 (en) * 1984-10-05 1986-04-09 Hitachi Metals, Ltd. Process for manufacturing a permanent magnet
EP0197712B1 (en) * 1985-03-28 1990-01-24 Kabushiki Kaisha Toshiba Rare earth-iron-boron-based permanent magnet

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0505348A1 (en) * 1991-03-18 1992-09-23 BÖHLER YBBSTALWERKE G.m.b.H. Permanent magnet material or sintered magnet and fabrication process

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CN1032262A (en) 1989-04-05

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