US3730784A - Method of making manganese-aluminum-carbon ternary alloys for permanent magnets - Google Patents

Method of making manganese-aluminum-carbon ternary alloys for permanent magnets Download PDF

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US3730784A
US3730784A US00850307A US3730784DA US3730784A US 3730784 A US3730784 A US 3730784A US 00850307 A US00850307 A US 00850307A US 3730784D A US3730784D A US 3730784DA US 3730784 A US3730784 A US 3730784A
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alloys
aluminum
manganese
weight
temperature
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US00850307A
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H Yamamoto
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C28/00—Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00

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  • ABSTRACT OF THE DISCLOSURE Ternary alloys consisting essentially of, by weight, (a) 67 to 69% Mn, 29 to 32.0% Al, and 0.3 to 3.0% C, and (b) 70.0 to 72.5% Mn, 26.5 to 29.0% Al and 0.5 to 2.5% C, are prepared by heating the selected alloy composition to a temperature of about 1380 C. to form a melt, casting the melt in a mold to form an ingot, quenching the ingot from a temperature of 880 to 1250 C. and then isothermally tempering the quenched ingot at a temperature of 380 to 700 C.
  • the thus heat-treated alloys are suitable for use as permanent magnets with magnetic properties superior to those of binary alloys of similar manganese and aluminum contents.
  • the present invention relates to an entirely novel material for permanent magnets and more particularly to manganese-aluminum-carbon ternary alloys in which a suitable amount of carbon is added positively as a new and third element to the already known magnetic material of manganese-aluminum binary alloys.
  • the primary object of the present invention is to provide a method for making manganese-aluminum-carbon ternary alloys for permanent magnets, whose residual induction Br, coercive force H maximum energy product BI-I saturation magnetization 411-1 and others, are higher than those of the prior magnetic materials of manganese-aluminum binary alloys.
  • alloys in which carbon is added purposely as a third element to such manganese-aluminum alloys are so excellent that they have improved magnetic properties, have a high antioxidation property, have a widened composition range showing excellent magnetic properties and can be subjected to heat treatments under conditions which are not so severe as compared with prior conditions.
  • a method for making rnanganese-aluminum-carbon ternary alloys for extremely powerful permanent magnets comprising the steps of preparing a mixture essentially consisting of from 67.0 to 69.0% by weight metallic manganese, from 29.0 to 32.0% by weight metallic alu- 3,730,784 Patented May 1, 1973 minum and from 0.3 to 3% by weight carbon, or consisting of from 70.0 to 72.5% by weight metallic Mn, from 26.5 to 29.0% by weight Al and from 0.5 to 2.5 by weight C, heating to melt the mixture at a temperature range of 1260 to 1500 C.
  • FIG. 1 is a composition diagram of manganese-aluminum-carbon ternary system in which the portion surrounded by thick line shows a preferred composition range of the alloys according to the present invention.
  • FIGS. 2 to 6 are graphic representations of equivalent curves of saturation magnetization 41rI residual induction Br, coercive force He, intrinsic coercive force Hc, and maximum energy product EH of the inventive alloys as drawn on the composition diagram thereof, respectively.
  • Metallic manganese, metallic aluminum and carbon are weighed in various percentages to obtain mixtures of the three elements of various compositions.
  • the mixtures are charged into respective crucibles and are heated to melt in one or more of atmospheres selected from the group of inert gas, reducing gas and vacuum.
  • Melting temperatures for the mixtures vary depending on their compositions, but lie within a range of 1260 to 1500 C.
  • Preferred melting temperature is about 1380 C. and at this temperature the three elements are effectively alloyed.
  • the mixtures are heated up to about 800 C. in a vacuum and in a temperature range thereabove heated in an argon atmosphere.
  • the melts are cast into suitable molds or are cooled in the crucibles to obtain ingots of predetermined size.
  • the ingots may be subjected to forging, solution treatment or any other treatment, but this step is not necessarily required.
  • Table 1 below shows chemical compositions, as determined by chemical analysis, of thirty-three specimens selected from the ingots of the manganese-aluminum-carbon ternary alloys thus obtained.
  • FIG. 1 shows a composition diagram of the manganese-aluminum-carbon ternary alloys which are included in. the composition range within the line A-G-H-I-E-F.
  • TAB LE I-C'ontinued Percent by weight Some of these alloys show ferromagnetic properties as they are molten and as cast.
  • the specimens are subjected to water or oil quenching from a temperature of 1100 C.
  • the quenching temperature may desirably suitably be varied depending on the alloy compositions, but a quenching temperature range of 880 C. to 1250 C. is sufficient.
  • the quenched alloys are subjected to a second heat treatment or isothermal tempering in a temperature range of 380 C. to 760 C. for a suitable time of the order of from several minutes to several hundred hours.
  • a second heat treatment or isothermal tempering in a temperature range of 380 C. to 760 C. for a suitable time of the order of from several minutes to several hundred hours.
  • the purpose of the two heat treatments is to cause in the ternary alloys the transformation similar to that caused in the manganese-aluminum binary alloys. But the difference between there is that, in the ternary alloys of the present invention including therein carbon, allowable ranges of temperature and time in both of the first step and the second step heat treatments are far wider than in the case of the binary alloys. Temperature and time settings for the second heat treatment vary depending on the alloy composition, and magnetic properties obtained also greatly vary by a combination of temperature and time. Conditions for obtaining best magnetic properties with respect to the respective alloys are not common to all cases. Though it is difiicult to set up comprehensive conditions for all of the ternary alloys, the optimum conditions may, for example, be such as are shown in Table 2. As seen from Table 2, the tempering temperature for the ternary alloys is 500 to 650 C., preferably.
  • No. 3 alloy shows best magnetic properties when tempered for 3 hours at 600 C. or for 8 hours at 540 C.
  • No. 21 alloy shows a maximum energy product BH of 1.05 X 10 G-oe.
  • No. 21 alloy shows a maximum energy product BH of the same value when tempered for 35 minutes at 620 C.
  • No. 21 alloy how ever shows poor magnetic properties when tempered for 35 minutes at 500 C. and it has a poor BH value of 0.4 10 G-oe.
  • No. 29 alloy shows a poor BH value of 0.2 10 G-oe.
  • the just-mentioned alloy however shows a high BH value of 1.18 10. G-oe. under diiferent heat treatment conditions. In General, it seems that best results can be obtained at a higher tempering temperature and a longer time in case of the manganese rich alloys and at a lower tempering temperature and a shorter time in case of the manganese poor alloys.
  • Magnetic properties of the ternary alloys are as tabulated in Table 3 and, when shown in the form of equivalent curves on the ternary composition diagram are as depicted in FIGS. 2 to 6.
  • BH is greatly influenced by the percentages of manganese, aluminum and carbon in the ternary alloys.
  • Those alloys falling within a composition range of from 67 to 69% by weight manganese, from 29 to 32% by weight aluminum and from 0.3 to 3.0% by weight carbon and a composition range of from 70 to 72.5% by weight manganese, from 26.5 to 29% by weight aluminum and from 0.5 to 2.5% by weight carbon show especially excellent magnetic properties and they have a BH value of BH ZLOX l G-oe.
  • manganese-aluminum-carbon ternary alloys consisting of from 65.0 to 69.0% by weight manganese, from 31.0 to 34.0% by Weight aluminum, and less than 1.0% by Weight carbon, that is, the alloys having a composition falling within a portion surrounded by the line A-B-C-F in FIG. 1, have a BH value of the order of 1.05 10 G-oe.
  • manganese-aluminumcarbon ternary alloys consisting of from 65.0 to 68.0% by weight manganese, from 28.0 to 34.0% by weight aluminum and from 1.0 to 4.0% by weight carbon, that is, the alloys having a composition falling within a portion surrounded by the line C-D-E-F, have a BH value of the order of 1.26X 10 G-oe.
  • some of the manganese-aluminum-carbon ternary alloys consisting of from 68.0 to 74.0% by weight manganese, from 25.0 to 31.0% by weight aluminum and less than 4.0% by weight carbon, that is, the alloys having a composition falling within a portion surrounded by the line B-G-H-I-D-C, have a BH value of the order of 1.83 10 G-oe.
  • the manganese-aluminum-carbon ternary alloys according to the present invention have a very wide composition range in which they show a BH value of BH ZLOX l0 G-oe.
  • the manganese-aluminum binary alloys which generally have a BH value of the order of 0.5 to 0.6 10 G-oe., have a narrow composition range showing ferromagnetic properties and have a narrow allowable range of heat treatment for the purpose of obtaining ferromagnetic properties. It is quite apparent from the above experiments that the alloys obtained by the above-mentioned process provide a BH value of the order of BH gOJ X 10 G-oe.
  • Carbon may be added in any amount less than 4.0% by weight excluding zero since addition of carbon in a very small amount, for example, 0.02% by weight can efiectively improve the magnetic properties. Further, the magnetic properties of the inventive alloy would not be affected by the inclusion therein of impurity elements, other than manganese, aluminum and carbon, which may commonly be found in ordinary alloys. No variation in the magnetic properties was observed even with inclusion of certain impurity elements in an amount up to 2% by weight.
  • a method of making manganese-aluminum-carbon ternary alloys for a permanent magnet comprising the steps of 1) selecting an alloy composition which consists essentially of (a) 67.0 to 69.0% manganese by weight, 29.0 to 32.0% aluminum by weight and 0.3 to 3.0% carbon by weight or (b) 70.0 to 72.5 manganese by Weight, 26.5 to 29.0% aluminum by weight and 0.5 to 2.5 carbon by weight, (2) heating the selected alloy composition at a temperature of about 1380 C. to form a melt, (3) casting the melt into a mold to obtain an ingot, (4) quenching the ingot from a temperature of 880 to 1250 C., and (5) then isothermal tempering the ingot at a temperature of 380 to 760 C.
  • alloy composition consists essentially of 67.0 to 69.0% manganese by Weight, 29 to 32%) aluminum by Weight and 0.3 to 3% carbon by Weight.
  • alloy composition consists essentially of 70.0 to 72.5% manganese by Weight, 26.5 to 29.0% aluminum by weight and 0.5 to 2.5% carbon by weight.
  • heating step (2) is carried out in an atmosphere selected from the group consisting of an inert gas, a reducing gas and a vacuum.
  • tempering step (4) is carried out for a period of 1.0 to 6.0 hours.
  • heating step (2) is carried out in two stages, first under vacuum from room temperature to about 800 C., then in an argon atmosphere to a temperature of about 1380 C.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
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  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Hard Magnetic Materials (AREA)
US00850307A 1964-02-01 1969-07-28 Method of making manganese-aluminum-carbon ternary alloys for permanent magnets Expired - Lifetime US3730784A (en)

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JP565364 1964-02-01
JP1267964A JPS4121965B1 (ja) 1964-03-03 1964-03-03

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NL (1) NL6501185A (ja)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3976519A (en) * 1973-08-02 1976-08-24 Matsushita Electric Industrial Co., Ltd. Machinable anisotropic permanent magnets of Mn-Al-C alloys
US4023991A (en) * 1973-08-02 1977-05-17 Matsushita Electric Industrial Co., Ltd. Anisotropic permanent magnet of Mn-Al-C alloy
US4042429A (en) * 1973-10-03 1977-08-16 Matsushita Electric Industrial Co., Ltd. Magnetic alloys having wasp-waisted magnetic hysteresis loop
US4051706A (en) * 1974-07-11 1977-10-04 Matsushita Electric Industrial Co., Ltd. Method of making anisotropic permanent magnets of mn-al-c alloys
US4055732A (en) * 1974-12-02 1977-10-25 Matsushita Electric Industrial Company Limited Inboard type magnetic system for electro-dynamic transducer
US4133703A (en) * 1976-08-27 1979-01-09 Matsushita Electric Industrial Co., Ltd. Permanent magnetic Mn-Al-C alloy
US4312684A (en) * 1980-04-07 1982-01-26 General Motors Corporation Selective magnetization of manganese-aluminum alloys
US4342608A (en) * 1980-04-21 1982-08-03 Bell Telephone Laboratories, Incorporated Mn-Al Permanent magnets and their manufacture
CN110241342A (zh) * 2019-07-23 2019-09-17 四川兰德高科技产业有限公司 一种高锰含量铝锰中间合金及其制备方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2295131A1 (fr) * 1974-10-24 1976-07-16 Matsushita Electric Ind Co Ltd Alliages magnetiques a base de manganese, de carbone et d'aluminium, presentant des cycles d'hysteresis magnetique dits a taille de guepe

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE144584C (ja) *
US1750751A (en) * 1927-02-04 1930-03-18 Geyer Andre Aluminum alloy
US2797995A (en) * 1954-05-03 1957-07-02 Canadian Patents Dev Ferromagnetic non-ferrous alloys
DE1156240B (de) * 1958-09-30 1963-10-24 Philips Nv Verfahren zur Herstellung von Dauermagneten bzw. eines Dauermagnetwerkstoffes auf der Basis Mn-Al

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3976519A (en) * 1973-08-02 1976-08-24 Matsushita Electric Industrial Co., Ltd. Machinable anisotropic permanent magnets of Mn-Al-C alloys
US4023991A (en) * 1973-08-02 1977-05-17 Matsushita Electric Industrial Co., Ltd. Anisotropic permanent magnet of Mn-Al-C alloy
US4042429A (en) * 1973-10-03 1977-08-16 Matsushita Electric Industrial Co., Ltd. Magnetic alloys having wasp-waisted magnetic hysteresis loop
US4051706A (en) * 1974-07-11 1977-10-04 Matsushita Electric Industrial Co., Ltd. Method of making anisotropic permanent magnets of mn-al-c alloys
US4055732A (en) * 1974-12-02 1977-10-25 Matsushita Electric Industrial Company Limited Inboard type magnetic system for electro-dynamic transducer
US4133703A (en) * 1976-08-27 1979-01-09 Matsushita Electric Industrial Co., Ltd. Permanent magnetic Mn-Al-C alloy
US4312684A (en) * 1980-04-07 1982-01-26 General Motors Corporation Selective magnetization of manganese-aluminum alloys
US4342608A (en) * 1980-04-21 1982-08-03 Bell Telephone Laboratories, Incorporated Mn-Al Permanent magnets and their manufacture
CN110241342A (zh) * 2019-07-23 2019-09-17 四川兰德高科技产业有限公司 一种高锰含量铝锰中间合金及其制备方法

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GB1100973A (en) 1968-01-31
DE1483261B1 (de) 1974-06-06
DE1483261C2 (de) 1975-01-16
FR1428050A (fr) 1966-02-11

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