CA1181262A - Amorphous alloys for electromagnetic devices - Google Patents
Amorphous alloys for electromagnetic devicesInfo
- Publication number
- CA1181262A CA1181262A CA000386675A CA386675A CA1181262A CA 1181262 A CA1181262 A CA 1181262A CA 000386675 A CA000386675 A CA 000386675A CA 386675 A CA386675 A CA 386675A CA 1181262 A CA1181262 A CA 1181262A
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C45/00—Amorphous alloys
- C22C45/02—Amorphous alloys with iron as the major constituent
-
- 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
- H01F1/12—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 soft-magnetic materials
- H01F1/14—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 soft-magnetic materials metals or alloys
- H01F1/147—Alloys characterised by their composition
- H01F1/153—Amorphous metallic alloys, e.g. glassy metals
- H01F1/15341—Preparation processes therefor
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- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Dispersion Chemistry (AREA)
- Power Engineering (AREA)
- Soft Magnetic Materials (AREA)
- Powder Metallurgy (AREA)
Abstract
ABSTRACT
An iron based, boron containing magnetic alloy having at least 85 percent of its structure in the form of an amorphous metal matrix is annealed in the absence of a magnetic field at a temperature and for a time sufficient to induce precipitation therein of discrete particles of its constituents. The resulting alloy has decreased high frequency core losses and increased low field permeability; is particularly suited for high frequency applications.
An iron based, boron containing magnetic alloy having at least 85 percent of its structure in the form of an amorphous metal matrix is annealed in the absence of a magnetic field at a temperature and for a time sufficient to induce precipitation therein of discrete particles of its constituents. The resulting alloy has decreased high frequency core losses and increased low field permeability; is particularly suited for high frequency applications.
Description
DE _RIPTION
AMORPH~US ALI.OYS FOR ELECTROMAGNETIC DEVICES
BACKGROUND OF THE INVENTION
Field of the Invention The invention relates to iron-boron base amorphous me-tal alloy compositions and~ in particular, to amorphous alloys containing iron, boron, silicon and carbon having enhanced high frequency magnetic proper-ties.
Description of the Prior Art Investigations have demonstrated that it is possible to obtain solid amorphous materials from cer-tain metal alloy compositions. An amorphous materialsubstantially lacks any long range atomic order and is characterized by an X-ray diffraction profile consisting of broad intensity maxima. Such a profile is qualita-tively similar to the diffraction profile of a liquid or ordinary window glass. This is in contast to a crystalline material which produces a diffraction profile consisting of sharp, narrow intensity maxima.
These amorphous materials exist in a meta-stable state. Upon heating to a sufficiently high temperature, they crystallize with evolution of the heat of crysta].lization, and the X-ray diEfraction profile changes fr~m one having amorphous characteristics to one
AMORPH~US ALI.OYS FOR ELECTROMAGNETIC DEVICES
BACKGROUND OF THE INVENTION
Field of the Invention The invention relates to iron-boron base amorphous me-tal alloy compositions and~ in particular, to amorphous alloys containing iron, boron, silicon and carbon having enhanced high frequency magnetic proper-ties.
Description of the Prior Art Investigations have demonstrated that it is possible to obtain solid amorphous materials from cer-tain metal alloy compositions. An amorphous materialsubstantially lacks any long range atomic order and is characterized by an X-ray diffraction profile consisting of broad intensity maxima. Such a profile is qualita-tively similar to the diffraction profile of a liquid or ordinary window glass. This is in contast to a crystalline material which produces a diffraction profile consisting of sharp, narrow intensity maxima.
These amorphous materials exist in a meta-stable state. Upon heating to a sufficiently high temperature, they crystallize with evolution of the heat of crysta].lization, and the X-ray diEfraction profile changes fr~m one having amorphous characteristics to one
-2-having crystalline characteristics.
Novel amorphous metal alloys have been dis-closed by H.S. Chen and D.E. Polk in U.S. Pat. No.
Novel amorphous metal alloys have been dis-closed by H.S. Chen and D.E. Polk in U.S. Pat. No.
3,856,513, issued December 24, 1974. These arnorphous alloys have the formula MaYbZC where M is at least one metal selected from the group of iron, nickel, cobalt, chromium and vanadium, Y is at least one element selected from the group consistiny of phosphorus, boron and carbon, Z is at least one element selected from the group consisting of alurninum, antirnony, beryllium, germanium, indiurn, tin and silicon, "a" ranges from about 60 to 90 atom percent, 'Ib" ranges from about 10 to 30 atorn percent and l'cl' ranyes from about 0.1 to 15 atom percent. I'hese amorphous alloys have been found suit-able for a wide variety of applications in the form of ribbon, sheet, wire, powder, etc. The Chen and Polkpatent also discloses amorphous alloys having the formula TiXj, where T is at least one transition metal, X is at least one element selected from the group con-sisting of aluminum, antimony, beryllium, boron,germanium, carbon, indium, phosphorus, silicon and tin, "i" ranges frorn about 70 to 87 atom percent and "j"
ranges from about 13 to 30 atom percent. These amorphous alloys have been found suitable for wire applications.
At the time that the amorphous alloys des-cribed above were discovered, they evidenced magnetic properties that were superior to then known polycrystal-line alloys. Nevertheless, new applications requiring improved magnetic properties and higher thermal stability have necessitated efforts to develop addi-tional alloy compositions.
S~MMARY O~ T~IE INVENTION
In accordance with the present invention, there is provided an iron based boron containing mag-netic alloy having at least 85 percent of its structurein the form of an arnorphou~ rnetal matrix, the alloy is annealed at a temperature and for a time sufficient to induce precipitation of discrete particles of its induce precipitation of discrete partic~es of its constituents. Precipitated discrete particles of the alloy have an average size ranging from about .05~m to l~m and an average interparticle spacing of about l~m to about lO~m, and constitute an average volume fraction of the alloy of about .01 to .3. ~nnealing of the alloy is conducted in the presence of a magnetic field. ~owever, it has been found that excellent maynetic properties are obtained at reduced manufac-turing costs by annealing the alloy in the absence of amagnetic f.ield. Preferably, the alloy is composed of a cornposition having the formula FeaBbSicCd wherein "a", "b", "c", and "d" are atomic percentages ranging from about 74 to 84, 8 to 24, 0 to 16 and 0 to 3, respectively, with the proviso that the sum of "a", "b", "c" and "d" equals 100.
Further, the invention provides a method of enhancing magnetic properties of the alloy set forth above, which method comprises the steps of (a) quenching a melt of the alloy at a rate of about 105 to 106C/sec to form said alloy into continuous ribbon; (b) coating sald ribbon with an insulating layer such as magnesium oxide; (c) annealing said coated ribbon at a temperature and for a time sufficient to induce precipitation of discrete particles in the amorphous metal matrix thereof.
Alloys produced in accordance with the method of this invention are not more than 30 percent crystal-line and preferably not more than about 15 percent crystalline as determined by X-ray diffraction, electron diffraction, or transmission electron microscopy.
Alloys produced by the method of this inven-tion exhibit improved high frequency rnagnetic properties that rernain stable at temperatures up to about 150C.
As a result, the alloys are particularly suited for use in energy storage inductors, pulse transformers, trans-formers for switch mocle power supplies, current trans~
formers and the like.
B~IEF ~ESCRIPrrION O~' T~E DRAWING~
_ The invention will be more fully understood and further advantages will become apparent when refer-ence is made to the accompanying drawings, in which:
Fig. 1 is a graph showing the relationship between induction and magnetizing force for arnorphous alloys in which precipitated discrete crystalline par-ticles are absent;
Fig. 2 is a graph showing the relationship between ind~ction and rnagnetizing force for amorphous alloys oE the present invention containing an optimurn volume fraction of discrete particles;
Fig. 3 is a graph showing the relationship between induction and magentizing force for amorphous alloys of ~he invention containing a volume fraction of discrete particles larger than the optimurn amount; and Fig. 4 is a schematic representation of an alloy of the invention, showing the distribution of discrete particles therein.
DETAILED DESCRIPTION OF THE I~VENTION
The composition of the new iron based amorphous alloys, preferably consists essentially of 74 to 84 atom percent iron, 8 to 24 atom percent boron, O
to 16 atom percent silicon and O to 3 atom percent car-bon. Such compositions exhibit enhanced high frequency magnetic properties when annealed in accordance with the method of the invention. The improved magnetic proper-ties are evidenced by high rnagnetization, low core loss and low volt-ampere dernand. An especially preEerred composition within the foregoing ranges consists of 79 atom percent iron, 16 atom percent boron, 5 atom percent silicon and O atom percent carbon.
Alloys treated by the rnethod of the present invention are not more than 30 percent crystalline and preferably are about 15 percent crystalllne. ~ligh fre-c~uency rnagnetic properties are improved in alloys pos-sessing the preferred voluMe percent oE crystalline material. I'he volume percent of crystalline rnaterial is conveniently determined by X-ray diffraction, electron diffraction or transmission electron microscopy.
The amorphous metal alloys are formed by cool-ing a melt at a rate of about 105~ to 106C/sec. The purity of all materials is that found in normal commer-cial practice. A variety of techniques are available for fabricating splat-quenched foils and rapid-quenched continuous ribbons, wire, sheet, etc. Typically, a particular composition is selected, powders or granules of the requisite elements (or of materials that decom-pose to form the elements, such as ferroboron, ferro~
silicon, etc.) in the desired proportions are melted and hornogenized, and the molten alloy is rapidly quenched on a chill surface, such as a rotating cylinder.
The magnetic properties of the subject alloys can be enhanced by annealing the alloys. The method of annealing generally comprises heating the alloy to a temperature for a time to induce precipation of discrete crystalline particles within the amorphous rnetal matrix, such particles having an average size ranging from about .05 to 1 ~m, an average interparticle spacing of about 1 to 10 ~m and consti-tuting an average volume fraction of about .01 to .3%. The annealing step is typically conducted in the presence of a mag-netic field, the strength of which ranges from about1 Oersted (80 amperes per meter) to 10 Oersteds (800 amperes per meter). However, as noted hereinabove, excellent magnetic properties are obtained and manufac-turing costs are reduced by annealing the alloy in the absence of a magnetic Eield.
It has been discovered that in -the absence of discrete crystalline particles, amorphous alloys of this invention exhibit square d.c. B-H loops with hic3h rernnant maynetization (Br); as in Fiyure 1. Henceforth, square d.c. B-H loops will be referred to as r~pe A.
Square loop material will yield large power losses at high frequencies.
At the optimum level of discrete crystalline particle density, the d.c. s-H loop is sheared Witll substantially reduced Br, as in Figure 2. Henceforth, sheared d.c. B-H loops will be referred to as Type B.
Sheared loop material exhibits increased low field permeabilities and reduced core losses at high fre-quencies. Typically, the high frequency core loss of sheared loop Material is approximately one-half the loss of square loop material. Lower core loss results in less heat build-up in the core and permits the use of less core material at a higher induction level for a given operating temperature.
If the alloy is annealed to precipitate a volume fraction of discrete crystalline particles larger than the optimum amount, the d.c. B-H loop becomes flat with near zero Br, as shown in Figure 3.
~enceforth, flat d.c. B-~l loops will be referred to as Type C. The exciting power necessary to drive flat loop material is extremely large, reaching val~es up to ten times the exciting power of sheared or square loop material.
At high frequencies the dominant component of the total core loss is the eddy current loss, which decreases with the ferromagnetic domain size. By re-ducing the domain size, the high frequency core loss can 2S be minimized. It has been found that the domain size can be reduced by controlled precipitation of discrete ~-(Fe, Si) particles, which act as pinning points for the domain walls.
The extent to which core loss is minimized by controlled precipitation in accordance with the inven-tion depends upon the interparticle spacing, volume fraction of the discrete particles and particle size of the precipitated phase. Because the particles act as the pinning points for the domain walls, the domain size is controlled by the interparticle spacing. Gen-erally, the interparticle spacing should be of the same order of the domain size. Absent the presence of discrete particles, the domain size is too large, with the result that eddy current and core losses are excessive. ~owever, too small an interparticle spacin~3 results in very small domains and impedes the domain wall motion, raising the high frequency core loss.
Preferably the interparticle spaeing should range from about 2 to 6 ~m.
Similarly, the extent to which core loss is minimized depends upon the alloy's volume fraction of discrete ~-(Fe, Si) particles. When the volume fraction increases beyond 30~, the soft magnetic characteristics of the amorphous rnatrix begin to deteriorate and the erystalline ~-(Fe, Si) particles offer exeessive resis-tance to the domain wall motion. It has been found necessary to con-trol the volume fraction of the discrete crystalline particles within a range of about 1-30%.
The volume fraction is a function of the interparticle spacing and particle size. It has been found that the partiele size preferably ranges from about .1 to .5 ~m.
For arnorphous alloys eontaining about 78 to 82 20 atom percent iron, 10 to 16 atom percent boron, 3 to 10 atom percent silicon and 0 to 2 atorn percent carbon, torodial samples must be heated to temperatures between about 340C and 450C for times frorn about 15 minutes to 5 hours to induee the OptimuM distribution of discrete erystalline partieles. The specific time and tempera-ture is dependent on alloy composition and quench rate.
For iron boron base alloys such as Fe81B13 5S3 5C2 and Fe81B14S5, the discrete crystalline particles are star shaped, d- (Fe, Si) precipitates, as illustrated in Fic3ure 4. The precipitate si~e ranges from about 0.1 to 0.3 ~m. The preferred average interparticle spacing (d) ranges frorn about 1.0 to 10. ~m, corresponding to an optimum volume fraction oE about .01 to .15. To calcu-late interparticle spacing frorn election mlcrocJraphs, care must be taken to account for the projection of three diMensional arrays onto a two dimensional imac3e.
~ pplications wherein low core losses are par-ticularly advantageous include energy storage inductors, pulse transformers, transformers that switch mode power supplies, current transformers and the like.
As discussed above, alloys annealed by the method of the present invention exhibit improved magne-tic properties that are stable at temperatures up to about 150C. The temperature stability of the present alloys allows utilization thereof in high temperature applications.
When cores comprising the subject alloys are utilized in electroMagnetic devices, such as trans-formers, they evidence low power loss and low exciting power demand, thus resulting in more efficient operation of the electromagnetic device. The loss of energy in a magnetic core as the result of eddy currents, which circulate through the core, results in the dissipation of energy in the form of heat. Cores made from the subject alloys require less electrical energy for operation and produce less heat. In applications where cooling apparatus is required to cool the transformer cores, such as transformers in aircraft and large power transformers, an additional savings is realized since less cooling apparatus is required to remove the srnaller amount of heat generated by cores made from the subject alloys. In addition, the high magnetization and high efficiency of cores made from the sub~ect alloys result in cores of reduced weight for a given capacity rating.
The following examples are presented to provide a more complete understanding of the invention.
The specific techniques, conditions, materials, propor-tions and reported data set forth to illustrate the principles and practice of the invention are exemplary and should not be construed as limiting the scope of the invention.
EXAMPLE I
Toroidal test samples were prepared by winding approximately 0.030 kg of 0.025~ m wide alloy ribbon ofthe composltion Fe~lBl3 5Si3 5C2 on a steatite core having inside and outside diameters of 0.0397 m and 0.0445 m, respectively. The alloy was cast into ribbon by quenching the alloy on a chromium coated copper substrate. One hundred and fifty turns of high temperature magnetic wire were wound on the toroid to provide a d.c. circumferential field of up to 795.8 ampere/meter for annealing purposes. The samples were annealed in an inert gas atmosphere at temperatures from 365C to 430C for times from 30 minutes to 2 hours with the 795.8 A/m field applied during heating and cooling.
The average particle size, interparticle dis-tance and volume fraction were measured by transmission electron microscopy. These parameters plus the 50 kllz, 0.11 power loss and exciting power are set forth in Table I as a function of the annealing parameters 2~
TABLE I
Alloy: Fe81B13.ssi3.5C2 D.C. @50 kHz,.lT
B-H Inter-Anneal Loop Particle particle ~ol. Core Exciting Cycle. ~ Diameter Spacing Frac. Loss ~ower 2 hr @ 365C Type A No discrete particles 18 w/kg 44 VA/ky with a 795.8 A/m in the ~morphous ~trix c ircumferen-10 tial field 2 hr @ 390C '~ e B .2~m 3 ~m <15~ 6 w/kg 26 VA/kg with a 795.8 A/m circwnferen-tial field 30 min. @ Type C .3~m .5 ~m >30~ 18.4 270 V~/
15 430C with a w/kg kg 10 Oe circum-ferential field Example II
Toroidal test samples were prepared in accor-dance with the procedure set forth in Example I, except that the alloy was cast into ribbon by quenching the alloy on a Cu-Be substrate of higher conductivity than the substrate of Example I. The average particle size inter-particle distance, volume fraction, power loss and exciting power of the alloys are set forth in Table II.
mABLE~ I I
Alloy: Fe8113l3. sSi3. 5C2 B-E~ @50 kHz, . lT
D. C.Inter-Anneal l~cpParticle particle Volume Core Exciting Cycle pe Diameter Spacing Fraction Loss Power 2 hr @ 390C ~pe A No discrete particles in the 35 w/ 75 VA/kg with a 795.8 A/m amorphous matrix kg circwnferen-tial f ield 10 1 hr @ 410C '~pe B .211m 4 llm <15% 5 w/ 28 VA/kg with a 795.8 ~/m kg c ircumferen-tial field 30 min @ Type C .31~m >2 llm 30~ 16.6 287 VA/kg 430C with a -.51,m w/kg 15 398 A/m cir-cwnEerential f ield Toroidal test samples (hereafter designated Examples 3-4 were prepared in accordance with the same 20 procedure set forth in Example II except that the com-position of the alloy quenched into ribbon was Fe81B14 7 8 16 5 ' P Y
Power loss and exciting power values for these alloys at 50 kHz and .lT are set forth in Tables III and 25 IV as a function of annealing temperatures.
TABLE III
Alloy: Fe81Bl4Si5 D.C.
B-HInter- Volume @50 k~lz O.lT
Anneal Loop Particle particle Frac- CoreExciting 5 Cycle Type Diameter Spacing tion Loss Power 1 hr @ 400C r~rpe A No discrete particles in 25 w/kg 34 VA/kg with a 398 A/m the arnorphous matrix circwnferen-tial ~ield 30 min @ r~rpe B .2-.6 ~m >2 ~m <10% 12 w/kg 29 VA/kg 420C with a 398 A/m circum ferential field 30 min @ '~ype C .4-.7 ~m <.5 ~m >50% Could not be mea-450C with a sured as toroid 15 398 A/m circum- needed extremely ferential high exciting field power TABLE IV
Alloy Fe79B16Si5 D.C.
~-H Inter Vol~ne @ 50 kHz,O.lT
Anneal Loop Particle particle Frac- Core Exciting 5 Cycle T~pe Diameter Spacing tlon Loss Power 20 min @ 450C Type A no discre-te particles 23 w/kg 29 VA/kgwith a 398 A/m in the amorphous matrix circumferen-tial field 10 30 min @ Type B .3~m >3 ~m <5~ 9 w/kg 21 VA4kg 450C with a 398 A/m circw~
ferential field 15 1 hr @ 450C Type C .4~m >3~m >15% 8 w/kg 67 VA/kg with a 398 A/M
circwmferen-tial field Example III
Toroidal test samples of alloy Fe79B16Si5 were prepared in accordance with the procedure set forth in Example I, except that the alloy was cast into ribbon by quenching the alloy on a Cu-Be substrate of higher con-ductivity than the substrate of Example I. Also, unlike Examples I and II, test samples were annealed in the absence of a magnetic filed. Microstructural character-istics namely, the average particle size, inter-particle distance and volume fraction remained substantially the same as shown in Table IV. Power loss and exciting power values for the alloy at 50 KHz and .lT are set Eorth in Table V as a function of annealing conditions.
TABLE V
Alloy Fe79B16Si5 ~.C. B-H @50 kHz, .lT
Anneal Cycle Loop q~?e Core Loss Exciting Power -53 1/2 hr ~d 420C type A 20 W/kg 35 VA/kg
ranges from about 13 to 30 atom percent. These amorphous alloys have been found suitable for wire applications.
At the time that the amorphous alloys des-cribed above were discovered, they evidenced magnetic properties that were superior to then known polycrystal-line alloys. Nevertheless, new applications requiring improved magnetic properties and higher thermal stability have necessitated efforts to develop addi-tional alloy compositions.
S~MMARY O~ T~IE INVENTION
In accordance with the present invention, there is provided an iron based boron containing mag-netic alloy having at least 85 percent of its structurein the form of an arnorphou~ rnetal matrix, the alloy is annealed at a temperature and for a time sufficient to induce precipitation of discrete particles of its induce precipitation of discrete partic~es of its constituents. Precipitated discrete particles of the alloy have an average size ranging from about .05~m to l~m and an average interparticle spacing of about l~m to about lO~m, and constitute an average volume fraction of the alloy of about .01 to .3. ~nnealing of the alloy is conducted in the presence of a magnetic field. ~owever, it has been found that excellent maynetic properties are obtained at reduced manufac-turing costs by annealing the alloy in the absence of amagnetic f.ield. Preferably, the alloy is composed of a cornposition having the formula FeaBbSicCd wherein "a", "b", "c", and "d" are atomic percentages ranging from about 74 to 84, 8 to 24, 0 to 16 and 0 to 3, respectively, with the proviso that the sum of "a", "b", "c" and "d" equals 100.
Further, the invention provides a method of enhancing magnetic properties of the alloy set forth above, which method comprises the steps of (a) quenching a melt of the alloy at a rate of about 105 to 106C/sec to form said alloy into continuous ribbon; (b) coating sald ribbon with an insulating layer such as magnesium oxide; (c) annealing said coated ribbon at a temperature and for a time sufficient to induce precipitation of discrete particles in the amorphous metal matrix thereof.
Alloys produced in accordance with the method of this invention are not more than 30 percent crystal-line and preferably not more than about 15 percent crystalline as determined by X-ray diffraction, electron diffraction, or transmission electron microscopy.
Alloys produced by the method of this inven-tion exhibit improved high frequency rnagnetic properties that rernain stable at temperatures up to about 150C.
As a result, the alloys are particularly suited for use in energy storage inductors, pulse transformers, trans-formers for switch mocle power supplies, current trans~
formers and the like.
B~IEF ~ESCRIPrrION O~' T~E DRAWING~
_ The invention will be more fully understood and further advantages will become apparent when refer-ence is made to the accompanying drawings, in which:
Fig. 1 is a graph showing the relationship between induction and magnetizing force for arnorphous alloys in which precipitated discrete crystalline par-ticles are absent;
Fig. 2 is a graph showing the relationship between ind~ction and rnagnetizing force for amorphous alloys oE the present invention containing an optimurn volume fraction of discrete particles;
Fig. 3 is a graph showing the relationship between induction and magentizing force for amorphous alloys of ~he invention containing a volume fraction of discrete particles larger than the optimurn amount; and Fig. 4 is a schematic representation of an alloy of the invention, showing the distribution of discrete particles therein.
DETAILED DESCRIPTION OF THE I~VENTION
The composition of the new iron based amorphous alloys, preferably consists essentially of 74 to 84 atom percent iron, 8 to 24 atom percent boron, O
to 16 atom percent silicon and O to 3 atom percent car-bon. Such compositions exhibit enhanced high frequency magnetic properties when annealed in accordance with the method of the invention. The improved magnetic proper-ties are evidenced by high rnagnetization, low core loss and low volt-ampere dernand. An especially preEerred composition within the foregoing ranges consists of 79 atom percent iron, 16 atom percent boron, 5 atom percent silicon and O atom percent carbon.
Alloys treated by the rnethod of the present invention are not more than 30 percent crystalline and preferably are about 15 percent crystalllne. ~ligh fre-c~uency rnagnetic properties are improved in alloys pos-sessing the preferred voluMe percent oE crystalline material. I'he volume percent of crystalline rnaterial is conveniently determined by X-ray diffraction, electron diffraction or transmission electron microscopy.
The amorphous metal alloys are formed by cool-ing a melt at a rate of about 105~ to 106C/sec. The purity of all materials is that found in normal commer-cial practice. A variety of techniques are available for fabricating splat-quenched foils and rapid-quenched continuous ribbons, wire, sheet, etc. Typically, a particular composition is selected, powders or granules of the requisite elements (or of materials that decom-pose to form the elements, such as ferroboron, ferro~
silicon, etc.) in the desired proportions are melted and hornogenized, and the molten alloy is rapidly quenched on a chill surface, such as a rotating cylinder.
The magnetic properties of the subject alloys can be enhanced by annealing the alloys. The method of annealing generally comprises heating the alloy to a temperature for a time to induce precipation of discrete crystalline particles within the amorphous rnetal matrix, such particles having an average size ranging from about .05 to 1 ~m, an average interparticle spacing of about 1 to 10 ~m and consti-tuting an average volume fraction of about .01 to .3%. The annealing step is typically conducted in the presence of a mag-netic field, the strength of which ranges from about1 Oersted (80 amperes per meter) to 10 Oersteds (800 amperes per meter). However, as noted hereinabove, excellent magnetic properties are obtained and manufac-turing costs are reduced by annealing the alloy in the absence of a magnetic Eield.
It has been discovered that in -the absence of discrete crystalline particles, amorphous alloys of this invention exhibit square d.c. B-H loops with hic3h rernnant maynetization (Br); as in Fiyure 1. Henceforth, square d.c. B-H loops will be referred to as r~pe A.
Square loop material will yield large power losses at high frequencies.
At the optimum level of discrete crystalline particle density, the d.c. s-H loop is sheared Witll substantially reduced Br, as in Figure 2. Henceforth, sheared d.c. B-H loops will be referred to as Type B.
Sheared loop material exhibits increased low field permeabilities and reduced core losses at high fre-quencies. Typically, the high frequency core loss of sheared loop Material is approximately one-half the loss of square loop material. Lower core loss results in less heat build-up in the core and permits the use of less core material at a higher induction level for a given operating temperature.
If the alloy is annealed to precipitate a volume fraction of discrete crystalline particles larger than the optimum amount, the d.c. B-H loop becomes flat with near zero Br, as shown in Figure 3.
~enceforth, flat d.c. B-~l loops will be referred to as Type C. The exciting power necessary to drive flat loop material is extremely large, reaching val~es up to ten times the exciting power of sheared or square loop material.
At high frequencies the dominant component of the total core loss is the eddy current loss, which decreases with the ferromagnetic domain size. By re-ducing the domain size, the high frequency core loss can 2S be minimized. It has been found that the domain size can be reduced by controlled precipitation of discrete ~-(Fe, Si) particles, which act as pinning points for the domain walls.
The extent to which core loss is minimized by controlled precipitation in accordance with the inven-tion depends upon the interparticle spacing, volume fraction of the discrete particles and particle size of the precipitated phase. Because the particles act as the pinning points for the domain walls, the domain size is controlled by the interparticle spacing. Gen-erally, the interparticle spacing should be of the same order of the domain size. Absent the presence of discrete particles, the domain size is too large, with the result that eddy current and core losses are excessive. ~owever, too small an interparticle spacin~3 results in very small domains and impedes the domain wall motion, raising the high frequency core loss.
Preferably the interparticle spaeing should range from about 2 to 6 ~m.
Similarly, the extent to which core loss is minimized depends upon the alloy's volume fraction of discrete ~-(Fe, Si) particles. When the volume fraction increases beyond 30~, the soft magnetic characteristics of the amorphous rnatrix begin to deteriorate and the erystalline ~-(Fe, Si) particles offer exeessive resis-tance to the domain wall motion. It has been found necessary to con-trol the volume fraction of the discrete crystalline particles within a range of about 1-30%.
The volume fraction is a function of the interparticle spacing and particle size. It has been found that the partiele size preferably ranges from about .1 to .5 ~m.
For arnorphous alloys eontaining about 78 to 82 20 atom percent iron, 10 to 16 atom percent boron, 3 to 10 atom percent silicon and 0 to 2 atorn percent carbon, torodial samples must be heated to temperatures between about 340C and 450C for times frorn about 15 minutes to 5 hours to induee the OptimuM distribution of discrete erystalline partieles. The specific time and tempera-ture is dependent on alloy composition and quench rate.
For iron boron base alloys such as Fe81B13 5S3 5C2 and Fe81B14S5, the discrete crystalline particles are star shaped, d- (Fe, Si) precipitates, as illustrated in Fic3ure 4. The precipitate si~e ranges from about 0.1 to 0.3 ~m. The preferred average interparticle spacing (d) ranges frorn about 1.0 to 10. ~m, corresponding to an optimum volume fraction oE about .01 to .15. To calcu-late interparticle spacing frorn election mlcrocJraphs, care must be taken to account for the projection of three diMensional arrays onto a two dimensional imac3e.
~ pplications wherein low core losses are par-ticularly advantageous include energy storage inductors, pulse transformers, transformers that switch mode power supplies, current transformers and the like.
As discussed above, alloys annealed by the method of the present invention exhibit improved magne-tic properties that are stable at temperatures up to about 150C. The temperature stability of the present alloys allows utilization thereof in high temperature applications.
When cores comprising the subject alloys are utilized in electroMagnetic devices, such as trans-formers, they evidence low power loss and low exciting power demand, thus resulting in more efficient operation of the electromagnetic device. The loss of energy in a magnetic core as the result of eddy currents, which circulate through the core, results in the dissipation of energy in the form of heat. Cores made from the subject alloys require less electrical energy for operation and produce less heat. In applications where cooling apparatus is required to cool the transformer cores, such as transformers in aircraft and large power transformers, an additional savings is realized since less cooling apparatus is required to remove the srnaller amount of heat generated by cores made from the subject alloys. In addition, the high magnetization and high efficiency of cores made from the sub~ect alloys result in cores of reduced weight for a given capacity rating.
The following examples are presented to provide a more complete understanding of the invention.
The specific techniques, conditions, materials, propor-tions and reported data set forth to illustrate the principles and practice of the invention are exemplary and should not be construed as limiting the scope of the invention.
EXAMPLE I
Toroidal test samples were prepared by winding approximately 0.030 kg of 0.025~ m wide alloy ribbon ofthe composltion Fe~lBl3 5Si3 5C2 on a steatite core having inside and outside diameters of 0.0397 m and 0.0445 m, respectively. The alloy was cast into ribbon by quenching the alloy on a chromium coated copper substrate. One hundred and fifty turns of high temperature magnetic wire were wound on the toroid to provide a d.c. circumferential field of up to 795.8 ampere/meter for annealing purposes. The samples were annealed in an inert gas atmosphere at temperatures from 365C to 430C for times from 30 minutes to 2 hours with the 795.8 A/m field applied during heating and cooling.
The average particle size, interparticle dis-tance and volume fraction were measured by transmission electron microscopy. These parameters plus the 50 kllz, 0.11 power loss and exciting power are set forth in Table I as a function of the annealing parameters 2~
TABLE I
Alloy: Fe81B13.ssi3.5C2 D.C. @50 kHz,.lT
B-H Inter-Anneal Loop Particle particle ~ol. Core Exciting Cycle. ~ Diameter Spacing Frac. Loss ~ower 2 hr @ 365C Type A No discrete particles 18 w/kg 44 VA/ky with a 795.8 A/m in the ~morphous ~trix c ircumferen-10 tial field 2 hr @ 390C '~ e B .2~m 3 ~m <15~ 6 w/kg 26 VA/kg with a 795.8 A/m circwnferen-tial field 30 min. @ Type C .3~m .5 ~m >30~ 18.4 270 V~/
15 430C with a w/kg kg 10 Oe circum-ferential field Example II
Toroidal test samples were prepared in accor-dance with the procedure set forth in Example I, except that the alloy was cast into ribbon by quenching the alloy on a Cu-Be substrate of higher conductivity than the substrate of Example I. The average particle size inter-particle distance, volume fraction, power loss and exciting power of the alloys are set forth in Table II.
mABLE~ I I
Alloy: Fe8113l3. sSi3. 5C2 B-E~ @50 kHz, . lT
D. C.Inter-Anneal l~cpParticle particle Volume Core Exciting Cycle pe Diameter Spacing Fraction Loss Power 2 hr @ 390C ~pe A No discrete particles in the 35 w/ 75 VA/kg with a 795.8 A/m amorphous matrix kg circwnferen-tial f ield 10 1 hr @ 410C '~pe B .211m 4 llm <15% 5 w/ 28 VA/kg with a 795.8 ~/m kg c ircumferen-tial field 30 min @ Type C .31~m >2 llm 30~ 16.6 287 VA/kg 430C with a -.51,m w/kg 15 398 A/m cir-cwnEerential f ield Toroidal test samples (hereafter designated Examples 3-4 were prepared in accordance with the same 20 procedure set forth in Example II except that the com-position of the alloy quenched into ribbon was Fe81B14 7 8 16 5 ' P Y
Power loss and exciting power values for these alloys at 50 kHz and .lT are set forth in Tables III and 25 IV as a function of annealing temperatures.
TABLE III
Alloy: Fe81Bl4Si5 D.C.
B-HInter- Volume @50 k~lz O.lT
Anneal Loop Particle particle Frac- CoreExciting 5 Cycle Type Diameter Spacing tion Loss Power 1 hr @ 400C r~rpe A No discrete particles in 25 w/kg 34 VA/kg with a 398 A/m the arnorphous matrix circwnferen-tial ~ield 30 min @ r~rpe B .2-.6 ~m >2 ~m <10% 12 w/kg 29 VA/kg 420C with a 398 A/m circum ferential field 30 min @ '~ype C .4-.7 ~m <.5 ~m >50% Could not be mea-450C with a sured as toroid 15 398 A/m circum- needed extremely ferential high exciting field power TABLE IV
Alloy Fe79B16Si5 D.C.
~-H Inter Vol~ne @ 50 kHz,O.lT
Anneal Loop Particle particle Frac- Core Exciting 5 Cycle T~pe Diameter Spacing tlon Loss Power 20 min @ 450C Type A no discre-te particles 23 w/kg 29 VA/kgwith a 398 A/m in the amorphous matrix circumferen-tial field 10 30 min @ Type B .3~m >3 ~m <5~ 9 w/kg 21 VA4kg 450C with a 398 A/m circw~
ferential field 15 1 hr @ 450C Type C .4~m >3~m >15% 8 w/kg 67 VA/kg with a 398 A/M
circwmferen-tial field Example III
Toroidal test samples of alloy Fe79B16Si5 were prepared in accordance with the procedure set forth in Example I, except that the alloy was cast into ribbon by quenching the alloy on a Cu-Be substrate of higher con-ductivity than the substrate of Example I. Also, unlike Examples I and II, test samples were annealed in the absence of a magnetic filed. Microstructural character-istics namely, the average particle size, inter-particle distance and volume fraction remained substantially the same as shown in Table IV. Power loss and exciting power values for the alloy at 50 KHz and .lT are set Eorth in Table V as a function of annealing conditions.
TABLE V
Alloy Fe79B16Si5 ~.C. B-H @50 kHz, .lT
Anneal Cycle Loop q~?e Core Loss Exciting Power -53 1/2 hr ~d 420C type A 20 W/kg 35 VA/kg
4 hr @ 435C type B lO W/kg 20 VA/kg 3 1/2 hr @ 440C type C 13 W/kg 42 VA/kg Having thus described the invention in rather full detail, it will be understood that this 10 detail need not be strictly adhere(3 to but that various changes and modifications may suggest themselves to one skilled in the art, all falling within the scope of the invention as defined by the subjoined claims.
Claims (11)
1. An iron based boron containing magnetic alloy having at least 85 percent of its structure in the form of an amorphous metal matrix, said alloy having been annealed at a temperature and for a time sufficient to induce precipitation of discrete particles of its constituents in said amorphous metal matrix, said parti-cles having an average size ranging from about .05µm to 1µm and an average interparticle spacing of about 1µm to 10µm, and constitute an average volume fraction of said alloy of about .01 to .3.
2. An alloy as recited in claim 1, wherein said alloy has been annealed in the presence of a mag-netic field.
3. An alloy as recited in claim 1, wherein said alloy has been annealed in the absence of a mag-netic field.
4. An alloy as recited in claim 3, wherein said discrete particles constitute an average volume fraction of said alloy of about .01 to .15.
5. An alloy as recited in claim 3, wherein said discrete particles have an average particle size of about .1 to .5 µ m.
6. An alloy as recited in claim 3, wherein said average interparticle spacing of said discrete particles is about 2 to 6 µ m.
7. An alloy as recited in claim 3, said alloy consisting essentially of a composition having the formula FeaBbSicCd, wherein "a", "b", "c", and "d" an atomic percentages ranging from about 74 to 84, 8 to 24, 0 to 16 and 0 to 3, respectively, with the proviso that "a", "b", "c" and "d" equals 100.
8. An alloy as recited in claim 2, said alloy consisting essentially of a composition having the formula FeaBbSicCd, wherein "a", "b", "c", and "d" an atomic percentages ranging from about 74 to 84, 8 to 24, 0 to 16 and 0 to 3, respectively, with the proviso that "a", "b", "c" and "d" equals 100.
9. A method of enhancing the magnetic proper-ties of an iron based, boron containing magentic alloy having at least 85 percent of its structure in the form of an amorphous metal matrix, comprising the step of annealing said alloy at a temperature and for a time sufficient to induce precipitation of discrete particles in said amorphous metal matrix.
10. A method as recited in claim 9, wherein said annealing step is carried out in the absence of a magnetic field.
11. A method as recited in claim 9, wherein said annealing step is carried out in the presence of a magnetic field.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US19147580A | 1980-09-26 | 1980-09-26 | |
| US191,475 | 1980-09-26 | ||
| US06/286,918 US4409041A (en) | 1980-09-26 | 1981-07-29 | Amorphous alloys for electromagnetic devices |
| US286,918 | 1988-12-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1181262A true CA1181262A (en) | 1985-01-22 |
Family
ID=26887080
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000386675A Expired CA1181262A (en) | 1980-09-26 | 1981-09-25 | Amorphous alloys for electromagnetic devices |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4409041A (en) |
| EP (1) | EP0049770B1 (en) |
| KR (1) | KR890001340B1 (en) |
| AU (1) | AU551753B2 (en) |
| CA (1) | CA1181262A (en) |
| DE (1) | DE3175108D1 (en) |
| ES (1) | ES8206642A1 (en) |
Families Citing this family (29)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4889568A (en) * | 1980-09-26 | 1989-12-26 | Allied-Signal Inc. | Amorphous alloys for electromagnetic devices cross reference to related applications |
| US6296948B1 (en) | 1981-02-17 | 2001-10-02 | Ati Properties, Inc. | Amorphous metal alloy strip and method of making such strip |
| JPS6034620B2 (en) * | 1981-03-06 | 1985-08-09 | 新日本製鐵株式会社 | Amorphous alloy with extremely low iron loss and good thermal stability |
| DE3274562D1 (en) * | 1981-08-21 | 1987-01-15 | Allied Corp | Metallic glasses having a combination of high permeability, low coercivity, low ac core loss, low exciting power and high thermal stability |
| JPS5947352A (en) * | 1982-09-08 | 1984-03-17 | Alps Electric Co Ltd | Super-rapidly chilled alloy containing dispersed second phase particle |
| US4473413A (en) * | 1983-03-16 | 1984-09-25 | Allied Corporation | Amorphous alloys for electromagnetic devices |
| SE443264B (en) * | 1984-04-03 | 1986-02-17 | Hoeganaes Ab | Silica-containing stable powder for the production of sintered soft magnetic bodies |
| US5035755A (en) * | 1984-05-23 | 1991-07-30 | Allied-Signal Inc. | Amorphous metal alloys having enhanced AC magnetic properties at elevated temperatures |
| US4834814A (en) * | 1987-01-12 | 1989-05-30 | Allied-Signal Inc. | Metallic glasses having a combination of high permeability, low coercivity, low AC core loss, low exciting power and high thermal stability |
| US4759949A (en) * | 1987-07-23 | 1988-07-26 | Westinghouse Electric Corp. | Method of insulating ferromagnetic amorphous metal continuous strip |
| TW226034B (en) * | 1991-03-06 | 1994-07-01 | Allied Signal Inc | |
| JP3302031B2 (en) * | 1991-09-06 | 2002-07-15 | 健 増本 | Manufacturing method of high toughness and high strength amorphous alloy material |
| US5278377A (en) * | 1991-11-27 | 1994-01-11 | Minnesota Mining And Manufacturing Company | Electromagnetic radiation susceptor material employing ferromagnetic amorphous alloy particles |
| JP2954775B2 (en) * | 1992-02-14 | 1999-09-27 | ワイケイケイ株式会社 | High-strength rapidly solidified alloy consisting of fine crystal structure |
| JP2911673B2 (en) * | 1992-03-18 | 1999-06-23 | 健 増本 | High strength aluminum alloy |
| US6815063B1 (en) | 1996-11-16 | 2004-11-09 | Nanomagnetics, Ltd. | Magnetic fluid |
| GB2319253A (en) | 1996-11-16 | 1998-05-20 | Eric Leigh Mayes | Composition, for use in a device, comprising a magnetic layer of domain-separated magnetic particles |
| US6986942B1 (en) | 1996-11-16 | 2006-01-17 | Nanomagnetics Limited | Microwave absorbing structure |
| US6713173B2 (en) | 1996-11-16 | 2004-03-30 | Nanomagnetics Limited | Magnetizable device |
| US6960860B1 (en) * | 1998-06-18 | 2005-11-01 | Metglas, Inc. | Amorphous metal stator for a radial-flux electric motor |
| US8382821B2 (en) | 1998-12-03 | 2013-02-26 | Medinol Ltd. | Helical hybrid stent |
| US20040267349A1 (en) * | 2003-06-27 | 2004-12-30 | Kobi Richter | Amorphous metal alloy medical devices |
| US7541909B2 (en) * | 2002-02-08 | 2009-06-02 | Metglas, Inc. | Filter circuit having an Fe-based core |
| US6749695B2 (en) | 2002-02-08 | 2004-06-15 | Ronald J. Martis | Fe-based amorphous metal alloy having a linear BH loop |
| US9039755B2 (en) | 2003-06-27 | 2015-05-26 | Medinol Ltd. | Helical hybrid stent |
| US9155639B2 (en) | 2009-04-22 | 2015-10-13 | Medinol Ltd. | Helical hybrid stent |
| EP1853742B1 (en) * | 2005-02-17 | 2020-09-30 | Metglas, Inc. | Iron-based high saturation induction amorphous alloy, method to produce it and magnetic core |
| US20060180248A1 (en) | 2005-02-17 | 2006-08-17 | Metglas, Inc. | Iron-based high saturation induction amorphous alloy |
| JP4558664B2 (en) * | 2006-02-28 | 2010-10-06 | 株式会社日立産機システム | Amorphous transformer for power distribution |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3856513A (en) * | 1972-12-26 | 1974-12-24 | Allied Chem | Novel amorphous metals and amorphous metal articles |
| US4036638A (en) * | 1975-11-13 | 1977-07-19 | Allied Chemical Corporation | Binary amorphous alloys of iron or cobalt and boron |
| US4038073A (en) * | 1976-03-01 | 1977-07-26 | Allied Chemical Corporation | Near-zero magnetostrictive glassy metal alloys with high saturation induction |
| US4217135A (en) * | 1979-05-04 | 1980-08-12 | General Electric Company | Iron-boron-silicon ternary amorphous alloys |
| US4264358A (en) * | 1979-02-12 | 1981-04-28 | California Institute Of Technology | Semiconducting glasses with flux pinning inclusions |
| US4226619A (en) * | 1979-05-04 | 1980-10-07 | Electric Power Research Institute, Inc. | Amorphous alloy with high magnetic induction at room temperature |
| US4219355A (en) * | 1979-05-25 | 1980-08-26 | Allied Chemical Corporation | Iron-metalloid amorphous alloys for electromagnetic devices |
| US4249969A (en) * | 1979-12-10 | 1981-02-10 | Allied Chemical Corporation | Method of enhancing the magnetic properties of an Fea Bb Sic d amorphous alloy |
| US4298409A (en) * | 1979-12-10 | 1981-11-03 | Allied Chemical Corporation | Method for making iron-metalloid amorphous alloys for electromagnetic devices |
-
1981
- 1981-07-29 US US06/286,918 patent/US4409041A/en not_active Expired - Lifetime
- 1981-09-16 DE DE8181107315T patent/DE3175108D1/en not_active Expired
- 1981-09-16 EP EP81107315A patent/EP0049770B1/en not_active Expired
- 1981-09-22 AU AU75554/81A patent/AU551753B2/en not_active Expired
- 1981-09-24 KR KR1019810003573A patent/KR890001340B1/en active
- 1981-09-25 CA CA000386675A patent/CA1181262A/en not_active Expired
- 1981-09-26 ES ES505808A patent/ES8206642A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| KR830007873A (en) | 1983-11-07 |
| ES505808A0 (en) | 1982-09-01 |
| EP0049770A3 (en) | 1982-05-12 |
| EP0049770A2 (en) | 1982-04-21 |
| KR890001340B1 (en) | 1989-04-29 |
| US4409041A (en) | 1983-10-11 |
| AU7555481A (en) | 1982-04-01 |
| DE3175108D1 (en) | 1986-09-18 |
| EP0049770B1 (en) | 1986-08-13 |
| ES8206642A1 (en) | 1982-09-01 |
| AU551753B2 (en) | 1986-05-08 |
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