EP0334445A1 - Hard magnetic material - Google Patents
Hard magnetic material Download PDFInfo
- Publication number
- EP0334445A1 EP0334445A1 EP89200693A EP89200693A EP0334445A1 EP 0334445 A1 EP0334445 A1 EP 0334445A1 EP 89200693 A EP89200693 A EP 89200693A EP 89200693 A EP89200693 A EP 89200693A EP 0334445 A1 EP0334445 A1 EP 0334445A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- hard magnetic
- magnetic material
- materials
- iron
- formula
- 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.)
- Withdrawn
Links
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
-
- 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
- H01F1/058—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IVa elements, e.g. Gd2Fe14C
Definitions
- the invention relates to a hard magnetic material comprising a rare earth metal, iron and carbon.
- the invention also relates to a magnet on the basis of hard magnetic material.
- a hard magnetic material of the type described in the opening paragraph is known from, inter alia , J. Appl. Phys. 61 3574-3576 (1987).
- the authors of the article classify the compound Nd2Fe14C described therein as not stable. Consequently, this material cannot be used as a starting material for a permanent magnet.
- a hard magnetic material which is further characterized in that the material contains a hard magnetic phase the composition of which corresponds to the formula RE2Fe 14-x Mn x C, wherein RE is at least one element selected from the group formed by Nd (Neodymium), Pr (Praseodymium), Ce (Cerium) and La (Lanthanum), and wherein 0.2 ⁇ x ⁇ 2. It has been found that the value of x cannto be selected randomly. The materials in which x is smaller than 0.2 were found to be insufficiently stable.
- the Curie temperature of the materials in which x is larger than 2 is about room temperature or below room temperature, which is problematic for the magnetic application of these materials.
- the Curie temperature can be raised by substituting a part of the iron present in the material with cobalt.
- the absence of B in the compounds according to the invention is an advantage because as a consequence thereof no toxic, volatile boroncompounds can be formed during the preparations of said compounds.
- the hard magnetic phase of the compounds according to the invention has a tetragonal crystal structure of the ThMn12 type, which is also the case with the known Nd2Fe14B.
- the Curie temperature (T c ) of the compounds according to the invention is between 300 and 550 K.
- the Curie temperature of compounds according to the invention having an identical rare earth metal is lower as the Mn content is higher.
- the hard magnetic materials according to the invention can be obtained in a customary way by melting together suitable starting materials in ratios corresponding to the compositional formula, after which they are subjected to an annealing treatment in a temperature range from 800° C - 950° C in a protective gas or a vacuum for two days; during which treatment recrystallization occurs.
- this stable material can also be prepared by melt spinning a composition with formula Nd2Fe14C, followed by an annealing treatment of the ribbon formed, during which treatment recrystallization occurs.
- Both known methods have the disadvantage that they are less suitable from an economical point of view.
- the hard magnetic properties of the compounds in accordance with the invention are comparable with those of materials on the basis of Nd2Fe14B.
- the magnetization measured at Nd2Fe 13.7 Mn 0.3 C powder at room temperature is approximately 100 Am2/kg.
- This value is comparable with the saturation magnetization which is measured at Nd2Fe14B powder at room temperature. It is noted that this value cannot be regarded as the saturation magnetization, since the material under consideration is magnetically very anisotropic.
- magnets in the form of shaped bodies can be manufactured from said materials in the usual manner.
Abstract
A hard magnetic material having the composition RE₂Fe14-xMnxC, wherein RE is at least one element selected from the group formed by Nd, Pr, Ce and La, and wherein 0.2 ≦ x ≦ 2.
Description
- The invention relates to a hard magnetic material comprising a rare earth metal, iron and carbon. The invention also relates to a magnet on the basis of hard magnetic material.
- A hard magnetic material of the type described in the opening paragraph is known from, inter alia, J. Appl. Phys. 61 3574-3576 (1987). The authors of the article classify the compound Nd₂Fe₁₄C described therein as not stable. Consequently, this material cannot be used as a starting material for a permanent magnet.
- It is an object of the invention to provide a hard magnetic material which comprises a rare earth metal (RE), iron and carbon, and which is stable. This object is achieved in accordance with the invention by a hard magnetic material which is further characterized in that the material contains a hard magnetic phase the composition of which corresponds to the formula
RE₂Fe14-xMnxC,
wherein RE is at least one element selected from the group formed by Nd (Neodymium), Pr (Praseodymium), Ce (Cerium) and La (Lanthanum), and wherein 0.2 ≦ x ≦ 2. It has been found that the value of x cannto be selected randomly. The materials in which x is smaller than 0.2 were found to be insufficiently stable. The Curie temperature of the materials in which x is larger than 2 is about room temperature or below room temperature, which is problematic for the magnetic application of these materials. In principle, the Curie temperature can be raised by substituting a part of the iron present in the material with cobalt. The absence of B in the compounds according to the invention is an advantage because as a consequence thereof no toxic, volatile boroncompounds can be formed during the preparations of said compounds. - In experiments it has further been established that the hard magnetic phase of the compounds according to the invention has a tetragonal crystal structure of the ThMn₁₂ type, which is also the case with the known Nd₂Fe₁₄B. As is shown in the Table below, the Curie temperature (Tc) of the compounds according to the invention is between 300 and 550 K. The Curie temperature of compounds according to the invention having an identical rare earth metal is lower as the Mn content is higher.
Table Compound Curie temperature (K) Nd₂Fe13.7Mn0.3C 505 Nd₂Fe13.5Mn0.5C 492 Nd₂Fe₁₃MnC 452 Nd₂Fe12.5Mn1.5C 400 Nd₂Fe₁₂Mn₂C 355 Pr₂Fe13.7Mn0.3C 481 Pr₂Fe13.5Mn0.5C 460 Pr₂Fe₁₃MnC 412 Pr₂Fe₁₂Mn₂C 306 - The hard magnetic materials according to the invention can be obtained in a customary way by melting together suitable starting materials in ratios corresponding to the compositional formula, after which they are subjected to an annealing treatment in a temperature range from 800° C - 950° C in a protective gas or a vacuum for two days; during which treatment recrystallization occurs.
- It is noted that in the experiments leading to the present invention it has become clear to Applicants that the manufacture of a stable material having a hard magnetic phase, the composition of which corresponds to the formula Nd₂Fe₁₄C, can be achieved in principle. This was attained by subjecting a casting of the compositional formula Nd₂Fe₁₄C to a prolonged annealing treatment within a narrow temperature range, preferably between 850 and 880° C, during which treatment recrystallization occurs. Applicants have reason to believe that in comparison with the known method the preparation of the material according to the invention requires a shorter annealing treatment for recrystallization in order to obtain the desired tetragonal structure. Moreover, in the case of the materials according to the invention, the annealing treatment can take place in a wider temperature range. On the other hand, this stable material can also be prepared by melt spinning a composition with formula Nd₂Fe₁₄C, followed by an annealing treatment of the ribbon formed, during which treatment recrystallization occurs. Both known methods have the disadvantage that they are less suitable from an economical point of view.
- The hard magnetic properties of the compounds in accordance with the invention are comparable with those of materials on the basis of Nd₂Fe₁₄B. For example, the magnetization measured at Nd₂Fe13.7Mn0.3C powder at room temperature is approximately 100 Am²/kg. This value is comparable with the saturation magnetization which is measured at Nd₂Fe₁₄B powder at room temperature. It is noted that this value cannot be regarded as the saturation magnetization, since the material under consideration is magnetically very anisotropic.
- After the materials obtained have been pulverized, magnets in the form of shaped bodies can be manufactured from said materials in the usual manner.
Claims (3)
1. A hard magnetic material comprising a rare earth metal, iron and carbon, characterized in that the material contains a hard magnetic phase the composition of which corresponds to the formula
RE₂Fe14-xMnxC
wherein RE is at least one element selected from the group formed by Nd (Neodymium), Pr (Praseodymium), Ce (Cerium) and La (Lanthanum), and wherein 0.2 ≦ x ≦ 2.
RE₂Fe14-xMnxC
wherein RE is at least one element selected from the group formed by Nd (Neodymium), Pr (Praseodymium), Ce (Cerium) and La (Lanthanum), and wherein 0.2 ≦ x ≦ 2.
2. A hard magnetic material as claimed in Claim 1, characterized in that a part of the iron present in the material is replaced by cobalt.
3. A permanent magnet on the basis of a hard magnetic material as claimed in Claim 1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8800739A NL8800739A (en) | 1988-03-24 | 1988-03-24 | HARDMAGNETIC MATERIAL. |
| NL8800739 | 1988-03-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0334445A1 true EP0334445A1 (en) | 1989-09-27 |
Family
ID=19851992
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP89200693A Withdrawn EP0334445A1 (en) | 1988-03-24 | 1989-03-20 | Hard magnetic material |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0334445A1 (en) |
| JP (1) | JPH028345A (en) |
| KR (1) | KR890015303A (en) |
| CN (1) | CN1036101A (en) |
| NL (1) | NL8800739A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5478411A (en) * | 1990-12-21 | 1995-12-26 | Provost, Fellows And Scholars Of The College Of The Holy And Undivided Trinity Of Queen Elizabeth Near Dublin | Magnetic materials and processes for their production |
-
1988
- 1988-03-24 NL NL8800739A patent/NL8800739A/en not_active Application Discontinuation
-
1989
- 1989-03-20 EP EP89200693A patent/EP0334445A1/en not_active Withdrawn
- 1989-03-20 CN CN89101680A patent/CN1036101A/en active Pending
- 1989-03-21 KR KR1019890003486A patent/KR890015303A/en not_active Application Discontinuation
- 1989-03-22 JP JP1067766A patent/JPH028345A/en active Pending
Non-Patent Citations (3)
| Title |
|---|
| JOURNAL OF APPLIED PHYSICS, vol. 52, no. 3, part II, March 1981, pages 2049-2051, American Institute of Physics, New York, US; K. HARDMAN et al.: "Magnetic structures of Y6(Fe1-xMnx)23 compounds" * |
| JOURNAL OF APPLIED PHYSICS, vol. 61, no. 8, 15th April 1987, pages 3574-3576, American Institute of Physics; N.C. LIU et al.: "High intrinsic coercivities in iron-rare earth-carbon-boron alloys through the carbide or boro-carbide Fe14R2X(X=BxC1-x)" * |
| MATERIALS LETTERS, vol. 4, nos. 8,9, August 1986, pages 377-380, Elsevier Science Publishers B.V., Amsterdam, NL; N.C. LIU et al.: "High coercivity permanent magnet materials based on iron-rare-earth-carbon alloys" * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5478411A (en) * | 1990-12-21 | 1995-12-26 | Provost, Fellows And Scholars Of The College Of The Holy And Undivided Trinity Of Queen Elizabeth Near Dublin | Magnetic materials and processes for their production |
Also Published As
| Publication number | Publication date |
|---|---|
| NL8800739A (en) | 1989-10-16 |
| KR890015303A (en) | 1989-10-28 |
| JPH028345A (en) | 1990-01-11 |
| CN1036101A (en) | 1989-10-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
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| AK | Designated contracting states |
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| 17P | Request for examination filed |
Effective date: 19900322 |
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| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN |
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| 18W | Application withdrawn |
Withdrawal date: 19910726 |
|
| R18W | Application withdrawn (corrected) |
Effective date: 19910726 |