US2546047A - Sintered anisotropic alnico magnet - Google Patents
Sintered anisotropic alnico magnet Download PDFInfo
- Publication number
- US2546047A US2546047A US20842A US2084248A US2546047A US 2546047 A US2546047 A US 2546047A US 20842 A US20842 A US 20842A US 2084248 A US2084248 A US 2084248A US 2546047 A US2546047 A US 2546047A
- Authority
- US
- United States
- Prior art keywords
- per cent
- sintered
- zirconium
- alloy
- 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 - Lifetime
Links
Classifications
-
- 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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/922—Static electricity metal bleed-off metallic stock
- Y10S428/9265—Special properties
- Y10S428/928—Magnetic property
Definitions
- the present invention relates to sinteredianisotropic lk-lnico magnet alloys. It is particularly concerned with sinterel Alnico magnets containing zirconium, which magnets are prepared by powder metallurgy techniques and have BHmax values corresponding to those, or approaching those of the best cast Alnico magnets.
- Essentially isotropic permanent magnets of the type known as Alnico magnets contain iron, nickel and aluminum as basic or essential ingredients. It is well known or has been proposed to include other elements such as cobalt, copper, titanium, silicon, chromium, molybdenum, tungsten, manganese, sulphur, and others either for the purpose of modifying or enhancing the physical and/or magnetic properties of the alloys.
- Peak H oersteds 2,000 Peak B gauss 15,700 Coercive force He oersteds 5'75 Residual Br gauss 12,000 BHmax gauss-oersteds 4 .5 10
- a cast magnet possessing these excellent magnetic values consists of an alloy of about 8 per cent aluminum, 14 per cent nickel, 24 per cent cobalt, 3 per cent copper, balance substantially iron, the exceptional magnetic properties being obtained by heat treatment or coolin of the alloy in a magnetic field as described in the aboveor m) mentioned Jonas patent. Because of the exceptional magnetic qualities of this cast alloy and the known advantages of the powder metallurgy techniques numerous attempts have been made to duplicate its magnetic properties in a. :sintered magnet alloy.
- the present invention is based on the discovery that an anisotropic s'intered magnet can also be obtained by including additions of zirconium in the com-positions employed in making cast ani otropic magnets.
- the zirconium appears to perform the same function in the sintered alloys as does the titanium although, in general, only about half as much by weight of zirconium is re quired to obtain the same magnetic properties in the finished sintered alloy.
- zirconium in the sintered products appears to make the magnetic field treatment more efiec'tive in obtaining a high available energy product, which product is an accepted criterion for comparing permanent magnet alloys.
- zirconium in smaller amounts by weight than titanium it has been found that there is less tendency toward surface oxidation and distort-ion of the sintered material.
- the sintered magnets of the present invention are generally characterized by a zirconium content of at least .15 to about 1.25 per cent, generally from 0.3 to 1.0 per cent. While the invention is broadly applicable to the Various known anisotropic magnet alloys characterized by a cobalt content of 16 to 30 per cent, a nickel content of 11 to 20 per cent, and an aluminum content of 6 to 11 per cent, the preferred sintered magnets are those containing 7.5 to 9 per cent aluminum, 0.3 to 0.8 per cent zirconium, 22 to 26 per cent cobalt, 2 to 4 per cent copper, 13 to 15 per cent nickel, remainder substantially all iron except for incidental impurities. Small amounts of titanium may also be present in the sintered alloy in amounts not exceeding about 1.25 per cent, and when titanium is present it may function as a substitute for a part of the zirconium in the proportions of about 2 parts titanium for each part zirconium.
- the sintered products are prepared in the manner usually employed in making sintered Alnico magnets as described, for example, in Howe Patents 2,192,743 and 2,192,744.
- the source of zirconium may suitably be a foundation alloy of nickel-zirconium such as 50-50 nickel-zirconium alloy powder, while the foundation alloy of iron-aluminum, cobalt-aluminum, or nickel-aluminum can be used as a source of aluminum.
- the finely divided materials are mixed in the desired proportions, and pressed to the desired form or shape.
- the pressed products are sintered in a hydrogen atmosphere at temperatures of from 1000 to 1400 C. preferably at a temperature below but close to the melting point of the alloy.
- the time required for the sintering action will, of course, depend upon the furnace load and size of the pieces to be sintered.
- the sintered material can then be normalized by heating to an elevated temperature after which the sintered product is subjected to a further heat treatment in a magnetic field as described in the Jonas Patent 2,295,082 to make the sintered alloy magnetically anisotropic.
- the heat treatment in the magnetic field is preferably carried out by withdrawing the sintered alloy compacts from the sintering zone of the furnace at a temperature of about 1250 C. and controlling their cooling cycle in a magnetic field of proper field strength. Further low temperature treatments may be applied as described by Jonas.
- the resultant magnets usually exhibit a BHmax at least equal to 3.5 X 10 gauss-oersteds, a Br of at least 10,000 and Ho of at least 600.
- Typical magnetic properties of a sintered magnet having the preferred composition set forth hereinbefore include a Br of 10,600 gauss an E0 of 600 cers eds, and a BHmax of 4x10 These BHmax values are to be compared with values of 1.4 to
- the sintered alloy free of zirconium is characterized by a Br of 11,000 to 12,000 and He of 450 to 550 and BHmax of 2.0 to 3.0 10 whereas the sintered alloy containing an addition of .5 per cent zirconium has a slightly lower Br of 10,600, a somewhat higher He of 600, and a much higher BHmax of 4x10".
- An anisotropic sintered permanent magnet containing 7.5 to 9 per cent aluminum, 13 to 15 per cent nickel, 22 to 26 per cent cobalt, 2 to 4 per cent copper, 0.3 to 1.0 per cent zirconium, balance iron except for incidental impurities, said magnet having a BHmax in the principal direction at least equal to 3.5 10 I,
- An anisotropic sintered permanent magnet consisting of 8.5 per cent aluminum, 14 per cent nickel, 25 per cent cobalt, 3 per cent copper, 0.3 to 0.8 per cent zirconium, balance iron except for incidental impurities, said sintered magnet having a BHmX of at least 3.5 10
- An anisotropic sintered permanent magnet consisting of 8.5 per cent aluminum, 14 per cent nickel, 25 per cent cobalt, 3 per cent copper, 0.5 per cent zirconium, balance substantially all iron, said magnet having a Brim; of at least 3.5 10
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Hard Magnetic Materials (AREA)
Description
Patented Mar. 20, 1951 .SINTEKED ANISOTROPIC .ALNICO .MAGNET Robert J. Studders, Schenectady, 1 rassignor to General Electric Company, a corporation of New York No Drawing. Application April 13, 1948, Serial No. 20,842
B GIaimS. 1
The present invention relates to sinteredianisotropic lk-lnico magnet alloys. It is particularly concerned with sinterel Alnico magnets containing zirconium, which magnets are prepared by powder metallurgy techniques and have BHmax values corresponding to those, or approaching those of the best cast Alnico magnets. Essentially isotropic permanent magnets of the type known as Alnico magnets contain iron, nickel and aluminum as basic or essential ingredients. It is well known or has been proposed to include other elements such as cobalt, copper, titanium, silicon, chromium, molybdenum, tungsten, manganese, sulphur, and others either for the purpose of modifying or enhancing the physical and/or magnetic properties of the alloys. Many of these magnetic alloys have been produced in bothcast and sintered form, and prowided the proper procedures are followed in the manufacture of the sintered products to prevent oxidation of the aluminum and any other highly oxidizable elements, it has been found that for most of the alloys the sintered products exhibited the same or approximately the same magnetic properties as the cast products of the same composition.
Another known development in the Alnico mag- "net field was the discovery described more fully in Jonzas'iPatent 2295;082 that certain cast nickelal uminum-iron alloys having a cobalt content of 16 to 30 per cent, a nickel content of 12 to 20 per cent, and an aluminum content of 6 to 1.1 per cent Whenheat treated in a magnetic field would exhibit 'BHmx values in one direction (anisotrope) which was at least 50 per cent, and generally over 100 per cent, higher than that for the same alloy whose magnetic properties were substantially equal in all directions (isotrope). As a result of this development there is now commercially available cast Alnico magnets having approximately the following minimum magnetic properties:
Peak H oersteds 2,000 Peak B gauss 15,700 Coercive force He oersteds 5'75 Residual Br gauss 12,000 BHmax gauss-oersteds 4=.5 10
.A cast magnet possessing these excellent magnetic values consists of an alloy of about 8 per cent aluminum, 14 per cent nickel, 24 per cent cobalt, 3 per cent copper, balance substantially iron, the exceptional magnetic properties being obtained by heat treatment or coolin of the alloy in a magnetic field as described in the aboveor m) mentioned Jonas patent. Because of the exceptional magnetic qualities of this cast alloy and the known advantages of the powder metallurgy techniques numerous attempts have been made to duplicate its magnetic properties in a. :sintered magnet alloy.
Unlike the isotropic type of Alnico alloys, it was found that simple duplication of the chemical composition of the anisotropic type of alloy, as :described in the Jonas patent, in a :sintered product, did not result in a very satisfactory permanent magnet. There appears to be many other factors which influence the efiectiveness of the magnet c field treatment in imparting superior available energy products to the alloy.
'In my 'copending application, Serial No. 9,013, filed "February 17, 1948, and assigned to the same assi-gnee as the present invention, there are described anisotropic sintered magnets possessing high BHmax values, the sintered magnets containing titanium as an essential ingredient.
The present invention is based on the discovery that an anisotropic s'intered magnet can also be obtained by including additions of zirconium in the com-positions employed in making cast ani otropic magnets. The zirconium appears to perform the same function in the sintered alloys as does the titanium although, in general, only about half as much by weight of zirconium is re quired to obtain the same magnetic properties in the finished sintered alloy.
The presence of zirconium in the sintered products appears to make the magnetic field treatment more efiec'tive in obtaining a high available energy product, which product is an accepted criterion for comparing permanent magnet alloys. In addition, by using the zirconium in smaller amounts by weight than titanium to obtain a product having equivalent magnetic characteristics, it has been found that there is less tendency toward surface oxidation and distort-ion of the sintered material.
The sintered magnets of the present invention are generally characterized by a zirconium content of at least .15 to about 1.25 per cent, generally from 0.3 to 1.0 per cent. While the invention is broadly applicable to the Various known anisotropic magnet alloys characterized by a cobalt content of 16 to 30 per cent, a nickel content of 11 to 20 per cent, and an aluminum content of 6 to 11 per cent, the preferred sintered magnets are those containing 7.5 to 9 per cent aluminum, 0.3 to 0.8 per cent zirconium, 22 to 26 per cent cobalt, 2 to 4 per cent copper, 13 to 15 per cent nickel, remainder substantially all iron except for incidental impurities. Small amounts of titanium may also be present in the sintered alloy in amounts not exceeding about 1.25 per cent, and when titanium is present it may function as a substitute for a part of the zirconium in the proportions of about 2 parts titanium for each part zirconium.
Particularly good results have been obtained by employing 8.5 per cent aluminum, 0.5 per cent zirconium, 25 per cent cobalt, 3.25 per cent copper, 14 per cent nickel, balance iron. The sintered products are prepared in the manner usually employed in making sintered Alnico magnets as described, for example, in Howe Patents 2,192,743 and 2,192,744. The source of zirconium may suitably be a foundation alloy of nickel-zirconium such as 50-50 nickel-zirconium alloy powder, while the foundation alloy of iron-aluminum, cobalt-aluminum, or nickel-aluminum can be used as a source of aluminum. The finely divided materials are mixed in the desired proportions, and pressed to the desired form or shape. The pressed products are sintered in a hydrogen atmosphere at temperatures of from 1000 to 1400 C. preferably at a temperature below but close to the melting point of the alloy. The time required for the sintering action will, of course, depend upon the furnace load and size of the pieces to be sintered. The sintered material can then be normalized by heating to an elevated temperature after which the sintered product is subjected to a further heat treatment in a magnetic field as described in the Jonas Patent 2,295,082 to make the sintered alloy magnetically anisotropic. The heat treatment in the magnetic field is preferably carried out by withdrawing the sintered alloy compacts from the sintering zone of the furnace at a temperature of about 1250 C. and controlling their cooling cycle in a magnetic field of proper field strength. Further low temperature treatments may be applied as described by Jonas.
The resultant magnets usually exhibit a BHmax at least equal to 3.5 X 10 gauss-oersteds, a Br of at least 10,000 and Ho of at least 600. Typical magnetic properties of a sintered magnet having the preferred composition set forth hereinbefore include a Br of 10,600 gauss an E0 of 600 cers eds, and a BHmax of 4x10 These BHmax values are to be compared with values of 1.4 to
10x10 for the best commercially available sintered Alnico magnets and 4.5 to 6 10 for the best anisotropic cast Alnicos. The effect of the zirconium on the magnetic properties of the sintered material becomes clearly evident from a comparison of the magnetic characteristics of a heat-treated, sintered mixture of from 8 to 8.5 per cent aluminium, 24 per cent cobalt, 14 to 14.5 per cent nickel, 3.25 per cent copper, balance iron with the magnetic characteristics of a similarly prepared and heat treated sintered material of the same composition but containing in addition .5 per cent zirconium. The sintered alloy free of zirconium is characterized by a Br of 11,000 to 12,000 and He of 450 to 550 and BHmax of 2.0 to 3.0 10 whereas the sintered alloy containing an addition of .5 per cent zirconium has a slightly lower Br of 10,600, a somewhat higher He of 600, and a much higher BHmax of 4x10".
What I claim as new and desire to secure 'by Letters Patent of the United States, is:
1. An anisotropic sintered permanent magnet containing 7.5 to 9 per cent aluminum, 13 to 15 per cent nickel, 22 to 26 per cent cobalt, 2 to 4 per cent copper, 0.3 to 1.0 per cent zirconium, balance iron except for incidental impurities, said magnet having a BHmax in the principal direction at least equal to 3.5 10 I,
2. An anisotropic sintered permanent magnet consisting of 8.5 per cent aluminum, 14 per cent nickel, 25 per cent cobalt, 3 per cent copper, 0.3 to 0.8 per cent zirconium, balance iron except for incidental impurities, said sintered magnet having a BHmX of at least 3.5 10
3. An anisotropic sintered permanent magnet consisting of 8.5 per cent aluminum, 14 per cent nickel, 25 per cent cobalt, 3 per cent copper, 0.5 per cent zirconium, balance substantially all iron, said magnet having a Brim; of at least 3.5 10
ROBERT J. STUDDERS.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 2,096,670 Catherall Oct. 19, 1937 2,185,464 Howell Jan. 2, 1940 2,192,744 Howe Mar. 5, 1940 2,245,477 Jonas June 10, 1941 2,285,406 Bieber June 9, 1942 2,295,082 Jonas Sept. 8, 1942 2,384,450 Bieber Sept. 11, 1945 FOREIGN PATENTS Number Country 7 Date 439,543 Great Britain Dec. 9, 1935 522,731 Great Britain June 26, 1940
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US20842A US2546047A (en) | 1948-04-13 | 1948-04-13 | Sintered anisotropic alnico magnet |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US20842A US2546047A (en) | 1948-04-13 | 1948-04-13 | Sintered anisotropic alnico magnet |
Publications (1)
Publication Number | Publication Date |
---|---|
US2546047A true US2546047A (en) | 1951-03-20 |
Family
ID=21800895
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US20842A Expired - Lifetime US2546047A (en) | 1948-04-13 | 1948-04-13 | Sintered anisotropic alnico magnet |
Country Status (1)
Country | Link |
---|---|
US (1) | US2546047A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1109332B (en) * | 1955-01-07 | 1961-06-22 | Andrews Houseware Manufacturer | Work table in connection with a seat |
US4401482A (en) * | 1980-02-22 | 1983-08-30 | Bell Telephone Laboratories, Incorporated | Fe--Cr--Co Magnets by powder metallurgy processing |
US5520748A (en) * | 1993-07-27 | 1996-05-28 | Pohang Iron & Steel Co., Ltd. | Process for manufacturing Alnico system permanent magnet |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB439543A (en) * | 1935-05-28 | 1935-12-09 | Swift Levick & Sons Ltd | Improvements in or relating to permanent magnets and alloys therefor |
US2096670A (en) * | 1934-05-01 | 1937-10-19 | Catherall Alfred Cyril | Permanent magnet |
US2185464A (en) * | 1937-12-20 | 1940-01-02 | Frank Raffies | Alumino-thermic mix for making permanent magnets |
US2192744A (en) * | 1939-05-24 | 1940-03-05 | Gen Electric | Sintered permanent magnet |
GB522731A (en) * | 1938-12-07 | 1940-06-26 | Philips Nv | Improvements in or relating to permanent magnets and processes of treating alloys for such magnets |
US2245477A (en) * | 1936-03-17 | 1941-06-10 | Hartford Nat Bank & Trust Co | Permanent magnet and method of making same |
US2285406A (en) * | 1940-04-18 | 1942-06-09 | Int Nickel Co | Permanent magnet |
US2295082A (en) * | 1938-12-06 | 1942-09-08 | Hartford Nat Bank & Trust Co | Permanent magnet and method of making the same |
US2384450A (en) * | 1942-06-04 | 1945-09-11 | Int Nickel Co | Alloy for permanent magnets |
-
1948
- 1948-04-13 US US20842A patent/US2546047A/en not_active Expired - Lifetime
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2096670A (en) * | 1934-05-01 | 1937-10-19 | Catherall Alfred Cyril | Permanent magnet |
GB439543A (en) * | 1935-05-28 | 1935-12-09 | Swift Levick & Sons Ltd | Improvements in or relating to permanent magnets and alloys therefor |
US2245477A (en) * | 1936-03-17 | 1941-06-10 | Hartford Nat Bank & Trust Co | Permanent magnet and method of making same |
US2185464A (en) * | 1937-12-20 | 1940-01-02 | Frank Raffies | Alumino-thermic mix for making permanent magnets |
US2295082A (en) * | 1938-12-06 | 1942-09-08 | Hartford Nat Bank & Trust Co | Permanent magnet and method of making the same |
GB522731A (en) * | 1938-12-07 | 1940-06-26 | Philips Nv | Improvements in or relating to permanent magnets and processes of treating alloys for such magnets |
US2192744A (en) * | 1939-05-24 | 1940-03-05 | Gen Electric | Sintered permanent magnet |
US2285406A (en) * | 1940-04-18 | 1942-06-09 | Int Nickel Co | Permanent magnet |
US2384450A (en) * | 1942-06-04 | 1945-09-11 | Int Nickel Co | Alloy for permanent magnets |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1109332B (en) * | 1955-01-07 | 1961-06-22 | Andrews Houseware Manufacturer | Work table in connection with a seat |
US4401482A (en) * | 1980-02-22 | 1983-08-30 | Bell Telephone Laboratories, Incorporated | Fe--Cr--Co Magnets by powder metallurgy processing |
US5520748A (en) * | 1993-07-27 | 1996-05-28 | Pohang Iron & Steel Co., Ltd. | Process for manufacturing Alnico system permanent magnet |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2193768A (en) | Magnetic alloys | |
US2167240A (en) | Magnet material | |
JPH03501189A (en) | Sintered magnet based on Fe-Nd-B | |
US2694790A (en) | Sintered anisotropic permanent magnet | |
EP0049141B1 (en) | Iron-chromium-base spinodal decomposition-type magnetic (hard or semi-hard) alloy | |
US2546047A (en) | Sintered anisotropic alnico magnet | |
US3730784A (en) | Method of making manganese-aluminum-carbon ternary alloys for permanent magnets | |
JPS63104406A (en) | Manufacture of permanent magnet | |
KR920700818A (en) | Magnetic Alloy Composition and Permanent Magnets | |
US3024142A (en) | Magnetic alloys | |
US2499860A (en) | Production of permanent magnets and alloys therefor | |
US3009809A (en) | Sintering of iron-aluminum base powders | |
KR880013194A (en) | Permanent magnet and its manufacturing method | |
US4721538A (en) | Permanent magnet alloy | |
US2622050A (en) | Process for heat-treating cobalt-platinum magnets | |
US2797995A (en) | Ferromagnetic non-ferrous alloys | |
US3450580A (en) | Permanent magnets | |
US2384450A (en) | Alloy for permanent magnets | |
JPS6034632B2 (en) | Method for manufacturing rare earth-containing permanent magnets | |
US1968569A (en) | Permanent magnet and method of making it | |
DE2443071A1 (en) | COPPER-HARDENED PERMANENT MAGNETIC ALLOY | |
US2673310A (en) | Permanent magnet | |
US3188247A (en) | Use of the hexagonal phase of the compound (fe, co)2p in particle size permanent magnets | |
US3194654A (en) | Manganese aluminum alloy magnets | |
EP0138496B1 (en) | Samarium-cobalt magnet alloy |