WO1995004996A1 - Sm2Fe17 ALLOY WITH Ta ADDITION AND THE PREPARATION PROCEDURE - Google Patents

Sm2Fe17 ALLOY WITH Ta ADDITION AND THE PREPARATION PROCEDURE Download PDF

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Publication number
WO1995004996A1
WO1995004996A1 PCT/SI1994/000014 SI9400014W WO9504996A1 WO 1995004996 A1 WO1995004996 A1 WO 1995004996A1 SI 9400014 W SI9400014 W SI 9400014W WO 9504996 A1 WO9504996 A1 WO 9504996A1
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WO
WIPO (PCT)
Prior art keywords
alloy
preparation
phase
sm2fe17
addition
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Application number
PCT/SI1994/000014
Other languages
French (fr)
Inventor
Boris Saje
BESENIC^¿AR Spomenka KOBE
Adrian Edwards Platts
Ivor Rex Harris
Original Assignee
Ins^¿Titut 'joz^¿Ef Stefan'
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.)
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Application filed by Ins^¿Titut 'joz^¿Ef Stefan' filed Critical Ins^¿Titut 'joz^¿Ef Stefan'
Priority to DE69402988T priority Critical patent/DE69402988T2/en
Priority to DK95907498.0T priority patent/DK0712532T3/en
Priority to EP95907498A priority patent/EP0712532B1/en
Publication of WO1995004996A1 publication Critical patent/WO1995004996A1/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
    • 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
    • H01F1/059—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and Va elements, e.g. Sm2Fe17N2
    • H01F1/0596—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and Va elements, e.g. Sm2Fe17N2 of rhombic or rhombohedral Th2Zn17 structure or hexagonal Th2Ni17 structure

Definitions

  • the invention relates to the Sm 2 Fe 17 alloy with Ta addition, and to the process for producing this alloy, which is suitable as the basic material for the preparation of permanent magnets based on nitrides of intermetallic compounds of rare earth and transition metals.
  • Nitrides of binary intermetallic compounds between rare earths in the following text designated as RE, and transition metals, in the following text designated as TM, thus Sm 2 Fe 17 N x , are new ferromagnetic materials, first discovered by Coey J. M. D. and Sun H., published in J. Mag. Magn. Mat. 87, (1990), L251 (1 ). The preparation of these materials is described in the European applications EP 369097, EP 453270, EP 538643, EP 493019 and Canadian applications CA 2040686, CA 2058283, .
  • Permanent magnets based on the Sm 2 Fe 17 N 3 -x ternary interstitial phase with a rhombohedral Th 2 Zn 17 - type structure are considered to be competitive with the well-known Nd-Fe-B based magnets.
  • the intrinsic properties of Sm 2 Fe 17 N 3 . x , where x is approximately 0.3, include a higher Curie temperature (Tc) for 100 to 200°C and anisotropy field (Ha), and a slightly lover magnetisation saturation (Ms).
  • Sm 2 Fe 17 binary phase which is used for production of the Sm 2 Fe 17 N 3 .
  • x interstitial ternary compound through a gas-phase interstitial modification process forms through a peritectic reaction between primary crystallised iron and Sm- rich liquid: L(liquid) + Fe -> Sm 2 Fe 17 .
  • Free iron especially, unless removed by a subsequent isothermal homogenization treatment, reduces the cdercivity of the Sm 2 Fe 17 nitride produced when used for permanent magnets.
  • the usual methods for creating an alloy without soft magnetic phases are either high temperature-long term annealing of the samarium-rich cast alloy (five days at 1050°C) or through the phase modification with the addition of a third alloying element (from the group of transition metals).
  • the phase relation can be influenced by the addition of the third element, which modifies the crystallization and prevents the primary crystallization of free iron and leads to a two phase structure consisting of Sm 2 Fe 1 7 phase and one paramagnetic intermediate Laves phase.
  • the elements Ti and Nb as elements which influence the phase relations, and is published in the open literature Reinch B., Grieb B., Henig E. T., Petzow G., IEEE Trans. Magn., 28, (1992), 2832 and Platts A. E., Harris I. R., Coey J. M. D., J. Alloys Comp., (1992), 251
  • the purpose and the aim of the invention relates to the Sm 2 Fe 17 alloy with Ta addition and to the process for producing this alloy with the corresponding properties.
  • the production of the alloy should be cheap and comparatively easy.
  • Tantalum forms a Pauli paramagnetic TaFe2 intermediate hexagonal Laves phase with iron, as described in the patent claims.
  • the preparation of as -cast alloy which contains a minimal quantity of free iron and other ferromagnetic phases is enabled.
  • the as -cast alloy is suitable for the nitrogenation procedure without any subsequent annealing process.
  • the nitrogenated alloy is suitable as a basic material for the preparation of a new generation of permanent magnets of Sm 2 Fe 17 N x type.
  • the alloy which contains a minimum quantity of free iron and other ferromagnetic phases, which diminish the hard magnetic coercivity of Sm 2 Fe 17 alloy, is produced.
  • the amount of soft magnetic phases is low enough that for the preparation of Sm 2 Fe 17 alloy suitable for the nitrogenation and production of Sm 2 Fe 17 N x , high temperature annealing can be avoided.
  • the alloy with the composition Sm 2 Fe 17 . x Ta x is produced by arc melting in an inert atmosphere of Ar purified with Ti as a getter.
  • Microstructural analysis shows phase compositional changes, which are dependent upon the increasing Ta content of the alloys of nominal composition Sm 2 Fe 17 . x Ta x .
  • Fig. 1 which shows the microstructure of the tantalum -free alloy, we can see the normal appearance of the as -cast state of the nominally stoichiometric Sm 2 Fe 17 alloy.
  • Dendrites of primary crystallised iron (black) are surrounded by peritecticaly formed Sm 2 Fe 17 phase (grey) with some Sm -rich phase which was identified as SmFe 2 (white).
  • microstructural morphology is typical for the as -cast alloy of stoichiometric composition with dendrites of primary recrystallised iron, surrounded by peritecticaly formed Sm 2 Fe 7 phase and partly with the Sm -rich phase, identified as SmFe 2 phase, detrimental for the magnetic properties and which can be removed by the known method of high temperature long term annealing.
  • Figure 2 shows the microstructure of the alloy with a nominal composition of 5 at.% of Ta. No iron dendrites are observed and the microstructure consists of a mixture of only Sm 2 Fe 17 (grey) and TaFe 2 (white) phases.
  • Fig.4 shows thermomagnetic curves normalised to the Curie temperature of the Sm 2 Fe 17 phase for the alloys with a) 1 % Ta, b) 2% Ta and c) 4% Ta. Thermomagnetic analysis also shows the increase in the Curie temperature as a function of the Ta concentration in the Sm 2 Fe 17 phase.
  • the invention relates to the preparation of the cast alloy with a minimum amount of free iron and/or other soft magnetic phases, which is suitable for further nitrogenation without high temperature long term annealing.
  • the as -cast alloy is suitable for the preparation of the Sm 2 Fe 17 . x Ta x N 3 . y compound.
  • the most important advantage of the invention is the cheaper preparation procedure of the alloy.
  • Ta addition is a new solution to the problem of the appearance of soft ferromagnetic phases which deteriorate the hard magnetic properties of the alloy.

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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

The process is provided for producing the Sm2Fe17 alloy with Ta addition, without expensive high temperature-long term annealing. As-cast alloy is suitable as the basic material for the preparation of permanent magnets based on nitrides of intermetallic compounds of rare earth and transition metals. The process is described for the as-cast alloy preparation with two phases present, Sm2Fe17 suitable for the nitrogenation to the hard magnetic Sm2Fe17N3-x phase and paramagnetic TaFe2 hexagonal phase. The phase modification is attained with the addition of a third alloying element. Ta substitutes Fe in the Sm2Fe17 nominal composition. The amount of iron or other ferromagnetic phases is lower than 0.5 wt.%. The invention relates to the preparation of the cast alloy with a minimum amount of free iron and/or other soft magnetic phases, which is suitable for further nitrogenation without high temperature long term annealing. The as-cast alloy is suitable for the preparation of the Sm2Fe17-xTaxN3-y compound.

Description

Sm2Fe17 ALLOY WITH Ta ADDITION AND THE PREPARATION PROCEDURE
The invention relates to the Sm2Fe17 alloy with Ta addition, and to the process for producing this alloy, which is suitable as the basic material for the preparation of permanent magnets based on nitrides of intermetallic compounds of rare earth and transition metals.
Nitrides of binary intermetallic compounds between rare earths, in the following text designated as RE, and transition metals, in the following text designated as TM, thus Sm2Fe17Nx, are new ferromagnetic materials, first discovered by Coey J. M. D. and Sun H., published in J. Mag. Magn. Mat. 87, (1990), L251 (1 ). The preparation of these materials is described in the European applications EP 369097, EP 453270, EP 538643, EP 493019 and Canadian applications CA 2040686, CA 2058283, .
Permanent magnets based on the Sm2Fe17N3-x ternary interstitial phase with a rhombohedral Th2Zn17 - type structure are considered to be competitive with the well-known Nd-Fe-B based magnets. The intrinsic properties of Sm2Fe17N3.x , where x is approximately 0.3, include a higher Curie temperature (Tc) for 100 to 200°C and anisotropy field (Ha), and a slightly lover magnetisation saturation (Ms). The compound where RE is Sm possesses these beneficial properties due to Sm, which is the only RE with a preferential vector of magnetisation in the direction of c -axis of the rhombohedral structure, which is the necessary condition for high magnetocrystal anisotropy. For comparison the magnetic properties of Nd2Fe14B and Sm2Fe17Nx are as follows:
Nd2Fe14B: Tc = 588 K, Ms = 1.60 T, Ha = 7.5 T (BH)max = 509 kJ/m3
Sm2Fe17Nx: Tc = 749 K, Ms = 1.55 T, Ha = 14 T, (BH)max = 472 kJ/m3 Unfortunately, Sm2Fe17 binary phase which is used for production of the Sm2Fe17N3.x interstitial ternary compound through a gas-phase interstitial modification process, forms through a peritectic reaction between primary crystallised iron and Sm- rich liquid: L(liquid) + Fe -> Sm2Fe17. This always leads to considerable amounts of free iron (up to 25 %.) and some SmFe2 or SmFe3 Sm-rich phases in the as cast state. Free iron especially, unless removed by a subsequent isothermal homogenization treatment, reduces the cdercivity of the Sm2Fe17 nitride produced when used for permanent magnets.
The usual methods for creating an alloy without soft magnetic phases are either high temperature-long term annealing of the samarium-rich cast alloy (five days at 1050°C) or through the phase modification with the addition of a third alloying element (from the group of transition metals). The phase relation can be influenced by the addition of the third element, which modifies the crystallization and prevents the primary crystallization of free iron and leads to a two phase structure consisting of Sm2Fe17 phase and one paramagnetic intermediate Laves phase. Up to the present, research work in this field was focused on the addition of the elements Ti and Nb as elements which influence the phase relations, and is published in the open literature Reinch B., Grieb B., Henig E. T., Petzow G., IEEE Trans. Magn., 28, (1992), 2832 and Platts A. E., Harris I. R., Coey J. M. D., J. Alloys Comp., (1992), 251
Of the other transition elements it was shown that Zr, Mo, Hf, V, Ti and Ta also form intermediate Laves phases of the AB2 - type. There were no data published or patented on the influence of these elements on the phase relationships in the system Sm-Fe-TM.
The technical problem of the preparation of a cast alloy without the formation of unfavourable secondary phases can be partially solved by high temperature-long term annealing of the samarium-rich as -cast alloy, which is an expensive process, or by influencing the phase modification by the addition of Nb or Ti.
The purpose and the aim of the invention relates to the Sm2Fe17 alloy with Ta addition and to the process for producing this alloy with the corresponding properties. The production of the alloy should be cheap and comparatively easy.
The technical problem of the preparation of the cast alloy without the formation of unfavourable secondary phases is solved in the invention by Ta addition and with the appropriate casting technique. Tantalum forms a Pauli paramagnetic TaFe2 intermediate hexagonal Laves phase with iron, as described in the patent claims.
By this invention the preparation of as -cast alloy which contains a minimal quantity of free iron and other ferromagnetic phases is enabled. The as -cast alloy is suitable for the nitrogenation procedure without any subsequent annealing process. As such, the nitrogenated alloy is suitable as a basic material for the preparation of a new generation of permanent magnets of Sm2Fe17Nx type.
The following example is meant to illustrate preffered embodiment of this invention.
The alloy which contains a minimum quantity of free iron and other ferromagnetic phases, which diminish the hard magnetic coercivity of Sm2Fe17 alloy, is produced. The amount of soft magnetic phases is low enough that for the preparation of Sm2Fe17 alloy suitable for the nitrogenation and production of Sm2Fe17Nx, high temperature annealing can be avoided.
By this invention the alloy with the composition Sm2Fe17.xTax is produced by arc melting in an inert atmosphere of Ar purified with Ti as a getter.
As -cast alloys were prepared by arc-melting of samples in a Ti purified Ar atmosphere using elemental Sm (99.99 %), Fe (99.99 %) and Ta (99.9%). The Ta addition is between 1 to 5 at.%. Excess Sm was added to the nominal composition of Sm2Fe17_xTax (10 to 30 at.%) to counterbalance Sm evaporation loses during melting. First Fe and Ta are melted and Sm is added later. The samples are remelted four times to improve macro and micro homogeneity. In some cases three times is sufficient and sometimes the melt has to be remelted several times additionally.
Microstructural analysis shows phase compositional changes, which are dependent upon the increasing Ta content of the alloys of nominal composition Sm2Fe17.xTax. From Fig. 1 , which shows the microstructure of the tantalum -free alloy, we can see the normal appearance of the as -cast state of the nominally stoichiometric Sm2Fe17 alloy. Dendrites of primary crystallised iron (black) are surrounded by peritecticaly formed Sm2Fe17 phase (grey) with some Sm -rich phase which was identified as SmFe2 (white). The microstructural morphology is typical for the as -cast alloy of stoichiometric composition with dendrites of primary recrystallised iron, surrounded by peritecticaly formed Sm2Fe 7 phase and partly with the Sm -rich phase, identified as SmFe2 phase, detrimental for the magnetic properties and which can be removed by the known method of high temperature long term annealing.
Figure 2 shows the microstructure of the alloy with a nominal composition of 5 at.% of Ta. No iron dendrites are observed and the microstructure consists of a mixture of only Sm2Fe17 (grey) and TaFe2 (white) phases.
Qualitative confirmation of the presence of the two phases Sm2Fe17 and TaFe2 in the as -cast alloy were confirmed by thermomagnetic analysis of the samples, which is normally used for Curie temperature determination of the extant phases.
The difference between the tantalum -free alloy and 5 at% Ta material is evident from Figure 3, where normalised temperature curves are shown for a) Ta -free alloy, b) alloy with 5 at.% Ta and c) TaFe2 alloy. For the Ta -free alloy three characteristic steps appeared on the M = f(T) curve, corresponding to the Curie temperatures of Sm2Fe17, SmFe2 and Fe respectively. The thermomagnetic curve of the 5 % Ta material shows only one large step, consistent with the Curie temperature of the Sm2Fe17 phase. A thermomagnetic scan of the TaFe2 phase shows the paramagnetic nature of the phase.
Fig.4 shows thermomagnetic curves normalised to the Curie temperature of the Sm2Fe17 phase for the alloys with a) 1 % Ta, b) 2% Ta and c) 4% Ta. Thermomagnetic analysis also shows the increase in the Curie temperature as a function of the Ta concentration in the Sm2Fe17 phase.
The invention relates to the preparation of the cast alloy with a minimum amount of free iron and/or other soft magnetic phases, which is suitable for further nitrogenation without high temperature long term annealing. The as -cast alloy is suitable for the preparation of the Sm2Fe17.xTaxN3.y compound. The most important advantage of the invention is the cheaper preparation procedure of the alloy. Ta addition is a new solution to the problem of the appearance of soft ferromagnetic phases which deteriorate the hard magnetic properties of the alloy.

Claims

Claims.
1. The Sm2Fe17 alloy with Ta addition characterized by the use of 1 at.% to 5 at. % of Ta and Sm and Fe as a basic material.
2. The process for producing the Sm2Fe17 alloy with Ta addition, characterized in that the alloying of Fe and Ta and further addition of 10 to 30 wt. % of Sm and that the alloy is at least remelted three times.
PCT/SI1994/000014 1993-08-06 1994-08-05 Sm2Fe17 ALLOY WITH Ta ADDITION AND THE PREPARATION PROCEDURE WO1995004996A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DE69402988T DE69402988T2 (en) 1993-08-06 1994-08-05 SmFeTa alloy with 4-5 at% Ta addition and its manufacturing process
DK95907498.0T DK0712532T3 (en) 1993-08-06 1994-08-05 SmFeTa alloy with 4-5 atom% Ta addition and process for preparing this alloy
EP95907498A EP0712532B1 (en) 1993-08-06 1994-08-05 SmFeTa alloy with 4-5 at% Ta addition and the process of its preperation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SIP-9300422 1993-08-06
SI9300422A SI9300422A (en) 1993-08-06 1993-08-06 Sm2fe17 alloy with ta addition and process for its preparation

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WO1995004996A1 true WO1995004996A1 (en) 1995-02-16

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EP (1) EP0712532B1 (en)
DE (1) DE69402988T2 (en)
DK (1) DK0712532T3 (en)
SI (1) SI9300422A (en)
WO (1) WO1995004996A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0827219A2 (en) * 1996-08-30 1998-03-04 Honda Giken Kogyo Kabushiki Kaisha Composite magnetostrictive material, and process for producing the same

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0344018A2 (en) * 1988-05-26 1989-11-29 Shin-Etsu Chemical Co., Ltd. Rare earth permanent magnet
JPH0525592A (en) * 1991-07-15 1993-02-02 Minebea Co Ltd Rare earth magnet material

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0344018A2 (en) * 1988-05-26 1989-11-29 Shin-Etsu Chemical Co., Ltd. Rare earth permanent magnet
JPH0525592A (en) * 1991-07-15 1993-02-02 Minebea Co Ltd Rare earth magnet material

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
A.E.PLATTZ ET AL, JOURNAL OF ALLOYS AND COMPOUNDS, vol. 185, 1992, AMSTERDAM NL, pages 251 - 258 *
B.SAJE ET AL, IEEE TRANSACTIONS ON MAGNETICS., vol. 30, no. 2, 2 March 1994 (1994-03-02), NEW YORK US, pages 690 - 692 *
BO-PING HU ET AL, JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, vol. 114, no. 1/2, August 1992 (1992-08-01), AMSTERDAM NL, pages 138 - 144 *
PATENT ABSTRACTS OF JAPAN vol. 17, no. 315 (C - 1071) 16 June 1993 (1993-06-16) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0827219A2 (en) * 1996-08-30 1998-03-04 Honda Giken Kogyo Kabushiki Kaisha Composite magnetostrictive material, and process for producing the same
EP0827219B1 (en) * 1996-08-30 2005-08-10 Honda Giken Kogyo Kabushiki Kaisha Composite magnetostrictive material, and process for producing the same

Also Published As

Publication number Publication date
DE69402988T2 (en) 1997-09-25
DE69402988D1 (en) 1997-06-05
SI9300422A (en) 1993-12-31
EP0712532B1 (en) 1997-05-02
EP0712532A1 (en) 1996-05-22
DK0712532T3 (en) 1997-11-03

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