CA1273231A - Permanent magnet alloy - Google Patents
Permanent magnet alloyInfo
- Publication number
- CA1273231A CA1273231A CA000488736A CA488736A CA1273231A CA 1273231 A CA1273231 A CA 1273231A CA 000488736 A CA000488736 A CA 000488736A CA 488736 A CA488736 A CA 488736A CA 1273231 A CA1273231 A CA 1273231A
- Authority
- CA
- Canada
- Prior art keywords
- dysprosium
- alloy
- coercive force
- neodymium
- permanent magnet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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
- 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
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
Landscapes
- 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)
Abstract
ABSTRACT OF THE DISCLOSURE
A permanent magnet alloy consisting essentially of, in weight percent, 1 to 10 dysprosium, 20 to 37 neodymium, with the total dysprosium and neodymium content being within the range of 30 to 38, 0.8 to 1.33 boron and balance iron. This alloy is characterized by high resistance to demagnetization at elevated temperatures with the alloy content being of relatively low cost.
******
A permanent magnet alloy consisting essentially of, in weight percent, 1 to 10 dysprosium, 20 to 37 neodymium, with the total dysprosium and neodymium content being within the range of 30 to 38, 0.8 to 1.33 boron and balance iron. This alloy is characterized by high resistance to demagnetization at elevated temperatures with the alloy content being of relatively low cost.
******
Description
1 ~ 73 ~
Permanent magnet alloys used in the production of permanent magnets for use in electric motors, and particularly electric motors used in househol~ appliances and the like, are required to have good resistance to demagnetization at elevated temperatures ~or efficient motor operation. The temperatures involved in these motor applications are typically within the rang~
of 125 to 150C. To achieve high resistance to demagnetization good remanence (Br) and coercive force (HCi) values are required within this temperature range. It is further desired in applications such as permanent magnets used in electric motors for household and appliance applications that the alloy of the magnet be relatively low cost.
It is known that permanent magnet alloys of neodymium, iron, boron have remanence values sufficiently high for the purpos~
and these are relatively inexpensive alloys; however, at the typical service temperatures of 125 to 150C magnets of these alloys are characterized by a loss of coercive force to below the level suitable for the purpose. Coercive force is known to be increased by increasing the crystal anisotropy or the anisotropy field (HA), It is accordingly a primary object of the present invention to provide a low-cost permanent magnet alloy that may be used in the manufacture of magnets having high resistance to demagnetization at elevated temperatures within the range of 125 to 150C.
-~ A more specific object of the invention is to provide a ; permanent rnagnet alloy of low cost having a ~ood combination of both remanence and coercive force within the temperature range of 125 to 150C which increase in coercive force is achieved by an improved crystal anisotropy without decreasing remanence to below acceptable levels, ~ , 1;~73;~31 These and other objects of the invention, as well as a more complete understanding thereof, may be obtained from the following description, specific examples and drawing.
The single FIGURE of the drawing is a graph illustrating the effect of the dysprosium content of a magnet alloy on the coercive force.
The permanent Magnet alloy of the invention consists essentially or in weight percent 1 to 10 dysprosium, 20 to 37 neodymium, with the total dysprosium and neodymium content being within the range of 30 to 38, 0.8 to 1.33 boron and balance iron.
Preferably the dysprosium content is 2.5 to 6.5% and more preferred within the range of 3 to 6%. It is known generally that coercive force (HCi) is increased by increases in the crystal anisotropy (HA). It has been discovered, in accordance with the present inventivn, that generally with magnet alloys of iron and boron with a neodymium content of approximately 33% the HA in kilo oersteds is 150; with similar alloys having dysprosium as the rare earth element the HA values in kilo oersteds are approximately 314.
It may be seen, therefore, that by the use of dysprosium in rare earth, iron, boron alloys the crystal anisotropy is improved to in turn increase the coercive force. In addition, however, it has been determined that the use of dysprosium in alloys of this type decreases remanence (Br)~ -The following specific examples of the invention show with neodymium, iron, boron magnets the temperature effect on ioss of coercive force. Also, the examples demonstrate that coercive .orce in ma~net alloys of this type are increased by the addition of dsyprosium as a rare earth element. They also show that increased dysprosium above the limits of the invention decreases remanence values to below acceptable levels. Consequently, it is - ' ' '' - ' - 1 ~ 73 '~1 critical with regard to achieving a combination of good remanence and coercive force within the required temperature range of 125 to 150C to have the rare earth ele~ent content of the alloy comprise a combination of dysprosium and neodymium.
An alloy of Nd (33%) B (1%) Fe (66%) in weight percent was melted, crushed to about 1 to 10 micron particle size. The fine powder was oriented in a magnètic field and pressed. The pressed part was sintered over a temperature range of 1000C -1100C and cooled. The sintered rQagnet had the intrinsic coercive force at the indicated temperatures in Table I.
TABLE I
INTP~INSIC COERCIVE FORCE VARIATION WITH
TE~PERATURE FOR AN ALLOY CONTAINING NO DY
TemperatureIntrinsic Coercive (C) Force (Oe) 10,500 62 6,130 94 3,900 142 2,550 The remanence of the magnet varied from 12,100 Gauss ~o 10,738 Gauss from 20 to 145C. The loss of intrinsic coercive force to below 6,000 ~ersted at 94C makes this magnet not applicable for motors.
Dysprosium was added to NdFeB alloy maintaining the total rare earth content as 35.6% and 37.1%. Tables II and III
list the magnetic properties of the magnets.
~,~ 7~
TABLE II
INTRIi~SIC COERCIVE FORCE AND RE~ANENCE FOR
ALLOYS OF NdDyFeB WITH A TOTAL Dy+Nd = 35.6%
AT ROOM TEMPERATURE
Wt. % B Hc Dy (G~ _ (Oe~
1.8~ 11,200 9,600
Permanent magnet alloys used in the production of permanent magnets for use in electric motors, and particularly electric motors used in househol~ appliances and the like, are required to have good resistance to demagnetization at elevated temperatures ~or efficient motor operation. The temperatures involved in these motor applications are typically within the rang~
of 125 to 150C. To achieve high resistance to demagnetization good remanence (Br) and coercive force (HCi) values are required within this temperature range. It is further desired in applications such as permanent magnets used in electric motors for household and appliance applications that the alloy of the magnet be relatively low cost.
It is known that permanent magnet alloys of neodymium, iron, boron have remanence values sufficiently high for the purpos~
and these are relatively inexpensive alloys; however, at the typical service temperatures of 125 to 150C magnets of these alloys are characterized by a loss of coercive force to below the level suitable for the purpose. Coercive force is known to be increased by increasing the crystal anisotropy or the anisotropy field (HA), It is accordingly a primary object of the present invention to provide a low-cost permanent magnet alloy that may be used in the manufacture of magnets having high resistance to demagnetization at elevated temperatures within the range of 125 to 150C.
-~ A more specific object of the invention is to provide a ; permanent rnagnet alloy of low cost having a ~ood combination of both remanence and coercive force within the temperature range of 125 to 150C which increase in coercive force is achieved by an improved crystal anisotropy without decreasing remanence to below acceptable levels, ~ , 1;~73;~31 These and other objects of the invention, as well as a more complete understanding thereof, may be obtained from the following description, specific examples and drawing.
The single FIGURE of the drawing is a graph illustrating the effect of the dysprosium content of a magnet alloy on the coercive force.
The permanent Magnet alloy of the invention consists essentially or in weight percent 1 to 10 dysprosium, 20 to 37 neodymium, with the total dysprosium and neodymium content being within the range of 30 to 38, 0.8 to 1.33 boron and balance iron.
Preferably the dysprosium content is 2.5 to 6.5% and more preferred within the range of 3 to 6%. It is known generally that coercive force (HCi) is increased by increases in the crystal anisotropy (HA). It has been discovered, in accordance with the present inventivn, that generally with magnet alloys of iron and boron with a neodymium content of approximately 33% the HA in kilo oersteds is 150; with similar alloys having dysprosium as the rare earth element the HA values in kilo oersteds are approximately 314.
It may be seen, therefore, that by the use of dysprosium in rare earth, iron, boron alloys the crystal anisotropy is improved to in turn increase the coercive force. In addition, however, it has been determined that the use of dysprosium in alloys of this type decreases remanence (Br)~ -The following specific examples of the invention show with neodymium, iron, boron magnets the temperature effect on ioss of coercive force. Also, the examples demonstrate that coercive .orce in ma~net alloys of this type are increased by the addition of dsyprosium as a rare earth element. They also show that increased dysprosium above the limits of the invention decreases remanence values to below acceptable levels. Consequently, it is - ' ' '' - ' - 1 ~ 73 '~1 critical with regard to achieving a combination of good remanence and coercive force within the required temperature range of 125 to 150C to have the rare earth ele~ent content of the alloy comprise a combination of dysprosium and neodymium.
An alloy of Nd (33%) B (1%) Fe (66%) in weight percent was melted, crushed to about 1 to 10 micron particle size. The fine powder was oriented in a magnètic field and pressed. The pressed part was sintered over a temperature range of 1000C -1100C and cooled. The sintered rQagnet had the intrinsic coercive force at the indicated temperatures in Table I.
TABLE I
INTP~INSIC COERCIVE FORCE VARIATION WITH
TE~PERATURE FOR AN ALLOY CONTAINING NO DY
TemperatureIntrinsic Coercive (C) Force (Oe) 10,500 62 6,130 94 3,900 142 2,550 The remanence of the magnet varied from 12,100 Gauss ~o 10,738 Gauss from 20 to 145C. The loss of intrinsic coercive force to below 6,000 ~ersted at 94C makes this magnet not applicable for motors.
Dysprosium was added to NdFeB alloy maintaining the total rare earth content as 35.6% and 37.1%. Tables II and III
list the magnetic properties of the magnets.
~,~ 7~
TABLE II
INTRIi~SIC COERCIVE FORCE AND RE~ANENCE FOR
ALLOYS OF NdDyFeB WITH A TOTAL Dy+Nd = 35.6%
AT ROOM TEMPERATURE
Wt. % B Hc Dy (G~ _ (Oe~
1.8~ 11,200 9,600
2.97 11,650 15,830 4.10 11,700 18,800 ~.21 11,560 >20,000 6.32 11,000 >20,000 . 6.88 11,000 >20,000 7.44 11,200 >20,000 TABLE III
Dy + ;Id = 37.1%
Wt. ','c Br ~ci Dy (G) (Oe) 1.74 12,380 13,020 2.7~ 11,750 17,000
Dy + ;Id = 37.1%
Wt. ','c Br ~ci Dy (G) (Oe) 1.74 12,380 13,020 2.7~ 11,750 17,000
3.83 11,330 19,300
4.87 10,800 >20,000
5.92 11,300 >20,000
6.43 10,700 >20,000 As can be seen from Tables II and III and ~IG. 1 adding dysprosium increases the coercive force rapidly at room ternperature. The temperature dependence of the coercive force of a 3% Dy containing alloy and 6% Dy containing alloy is given in Table IV.
TABLE IV
COERCIVE FORCE DEPENDENCE ON TEMPERATURE
OF 3% ~1~ 6% Dy CO~TAINING MAGI~ET
3C/o Dy Containin~ Magnet 5TernperatureIntrinsic Coercive Force (C) (Oe) _ 16,100 69 11,100 87 9,500 140 5,200 6~b Dy Containing Magnet 20,000 78 15,900 106 12,750 147 8,400 As can be seen from Table IV, dysprosium addition in combination with neodymium permits utilization of these magnets at elevated temperatures. Increasing the dysprosiuM further results in a decrease in Br which makes the magnets not have enough flux at the required tempèrature for the intended applications. Table V shows the magnetic properties of a 10~o Dy containing magnet.
TABLE V
10% Dy CO~TAINING MAGNET
Br ~ci (G)__ (OE) g,goo >26,000
TABLE IV
COERCIVE FORCE DEPENDENCE ON TEMPERATURE
OF 3% ~1~ 6% Dy CO~TAINING MAGI~ET
3C/o Dy Containin~ Magnet 5TernperatureIntrinsic Coercive Force (C) (Oe) _ 16,100 69 11,100 87 9,500 140 5,200 6~b Dy Containing Magnet 20,000 78 15,900 106 12,750 147 8,400 As can be seen from Table IV, dysprosium addition in combination with neodymium permits utilization of these magnets at elevated temperatures. Increasing the dysprosiuM further results in a decrease in Br which makes the magnets not have enough flux at the required tempèrature for the intended applications. Table V shows the magnetic properties of a 10~o Dy containing magnet.
TABLE V
10% Dy CO~TAINING MAGNET
Br ~ci (G)__ (OE) g,goo >26,000
Claims
1. A permanent magnet alloy having good coercive force at elevated temperature consisting essentially of in weight percent 1 to 10 dysprosium, 30 to 37 neodymium, with the total dysprosium and neodymium content being within the range of 31 to 38, 0.8 to 1.33. boron and balance iron.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US67973984A | 1984-12-10 | 1984-12-10 | |
| US679,739 | 1984-12-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1273231A true CA1273231A (en) | 1990-08-28 |
Family
ID=24728160
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000488736A Expired - Fee Related CA1273231A (en) | 1984-12-10 | 1985-08-14 | Permanent magnet alloy |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0185439B1 (en) |
| JP (1) | JPS61139641A (en) |
| AT (1) | ATE43932T1 (en) |
| CA (1) | CA1273231A (en) |
| DE (1) | DE3570942D1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4837109A (en) * | 1986-07-21 | 1989-06-06 | Hitachi Metals, Ltd. | Method of producing neodymium-iron-boron permanent magnet |
| EP0277416A3 (en) * | 1987-02-04 | 1990-05-16 | Crucible Materials Corporation | Permanent magnet alloy for elevated temperature applications |
| JP2001332410A (en) * | 2000-05-22 | 2001-11-30 | Seiko Epson Corp | Magnet powder, its manufacturing method, and bond magnet |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES8504404A3 (en) * | 1981-06-16 | 1985-04-16 | Proyectos Magneticos S A Proma | Permanent magnet alloy |
| JPS59163802A (en) * | 1983-03-08 | 1984-09-14 | Sumitomo Special Metals Co Ltd | Permanent magnet material |
| EP0108474B2 (en) * | 1982-09-03 | 1995-06-21 | General Motors Corporation | RE-TM-B alloys, method for their production and permanent magnets containing such alloys |
| JPS59204209A (en) * | 1983-05-06 | 1984-11-19 | Sumitomo Special Metals Co Ltd | Isotropic permanent magnet and manufacture thereof |
| JPS59215460A (en) * | 1983-05-21 | 1984-12-05 | Sumitomo Special Metals Co Ltd | Permanent magnet material and its production |
-
1985
- 1985-08-14 CA CA000488736A patent/CA1273231A/en not_active Expired - Fee Related
- 1985-08-30 EP EP85306148A patent/EP0185439B1/en not_active Expired
- 1985-08-30 AT AT85306148T patent/ATE43932T1/en not_active IP Right Cessation
- 1985-08-30 DE DE8585306148T patent/DE3570942D1/en not_active Expired
- 1985-09-10 JP JP60198721A patent/JPS61139641A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| ATE43932T1 (en) | 1989-06-15 |
| EP0185439A1 (en) | 1986-06-25 |
| EP0185439B1 (en) | 1989-06-07 |
| DE3570942D1 (en) | 1989-07-13 |
| JPS61139641A (en) | 1986-06-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |