HK1063529B - Bulk amorphous metal magnetic component - Google Patents

Description

Bulk amorphous metal magnetic component

Cross Reference to Related Applications

This application is a continuation-in-part patent application entitled "Bulk Amorphous Metal Magnetic Components" having serial number 09/186914, filed on 6.11.1998.

Technical Field

The present invention relates to amorphous metal magnetic components; and more particularly to a substantially three-dimensional bulk amorphous metal magnetic component for use in large electronic devices such as magnetic resonance imaging systems, television and video systems, and electron and ion beam systems.

Background

Although amorphous metals provide superior magnetic properties compared to non-oriented electrical steels, they have long been considered unsuitable for use in bulk magnetic components, such as the pieces of pole face magnets used in magnetic resonance imaging systems (MRI), due to certain physical properties of amorphous metals and corresponding manufacturing limitations. For example, amorphous metals are thinner and harder than non-oriented silicon steel, thus resulting in faster wear of manufacturing tools and dies. The resulting increase in tooling and manufacturing costs makes the fabrication of bulk amorphous metal magnetic components using this technique commercially impractical. The thin thickness of amorphous metal also increases the number of laminations in the assembled component, which further increases the cost of the amorphous metal magnetic component.

Amorphous metal is generally provided in thin continuous strips having a uniform width. Amorphous metals, however, are very hard materials, which make them very difficult to cut and form, and become very brittle once annealed to peak magnetic properties. This makes the construction of bulk amorphous metal magnetic components difficult and expensive using conventional methods. The brittleness of amorphous metal also raises concerns about the durability of bulk amorphous metal magnetic components, such as in MRI system applications.

Another problem with bulk amorphous metal magnetic components is that when amorphous metal material is subjected to physical stress, its magnetic permeability is reduced. This reduced permeability may be very related to the strength of the stress placed on the amorphous metal material. When a bulk amorphous metal magnetic component is stressed, the efficiency with which the core directs or focuses magnetic flux is reduced, resulting in higher magnetic losses, increased heating, and thus reduced power. Due to the magnetostrictive nature of amorphous metal, this sensitivity to stress may be caused by stresses resulting from magnetic forces during operation of the device, mechanical stresses resulting from mechanical clamping or otherwise securing a bulk amorphous metal magnetic component, or expansion due to thermal expansion and/or magnetic saturation of amorphous metal material.

Disclosure of Invention

A low-loss bulk amorphous metal magnetic component is provided having the shape of a polyhedron and formed of a plurality of layers of amorphous metal strips. The present invention also provides a method for fabricating a bulk amorphous metal magnetic component. The magnetic elements can operate in the frequency range of 50Hz-20000Hz and have improved performance characteristics when compared to silicon steel magnetic elements operating in the same frequency range.

More specifically, in accordance with the present invention, a bulk amorphous metal magnetic component comprising a plurality of identically shaped amorphous metal strips stacked together and cured with a vacuum impregnated epoxy resin to form a polyhedral shaped component cut from the stacked strips or wound core has a core loss less than L when operating at an excitation frequency f to a peak magnetic induction Bmax, where L is 0.0074f (B) where L is given by the formula L ═ 0.0074f (B)_max)^1.3+0.000282f^1.5(B_max)^2.4Giving the unit of the core loss, the excitation frequency and the peak magnetic induction valueRespectively per kilogram watts, hertz and tesla.

Preferably, the magnetic component will have (i) a core loss of less than or equal to 1 watt per kilogram of amorphous metal material when operated at a frequency of 60Hz and a magnetic density of 1.4T; (ii) (ii) a core loss of less than or equal to 12 watts per kilogram of amorphous metal material when operated at a frequency of 1000Hz and a magnetic density of 1.0T, or (iii) a core loss of less than or equal to 70 watts per kilogram of amorphous metal material when operated at a frequency of 20000Hz and a magnetic density of 0.30T.

In a first embodiment of the present invention, a bulk amorphous metal magnetic component includes a plurality of strips of substantially identically shaped amorphous metal material laminated together to form a part having the shape of a polyhedron.

The present invention also provides a method for constructing a bulk amorphous metal magnetic component comprising the steps of:

(a) providing a plurality of strips of amorphous metal strip material in a stack;

(b) annealing the laminate;

(c) vacuum impregnating the laminate with an epoxy resin and curing the resin impregnated laminate;

(d) cutting the stack at a predetermined length to provide a plurality of polyhedral magnetic elements having a predetermined three-dimensional geometry,

when excited at an excitation frequency f to a peak magnetic induction value B_maxThen, the core loss is less than L, wherein L is represented by the formula L ═ 0.0074f (B)_max)^1.3+0.000282f^1.5(B_max)^2.4The units of core loss, excitation frequency and peak magnetic induction are given in watts per kilogram, hertz and tesla, respectively.

Amorphous metal strip material may be cut into a plurality of cut strips having a predetermined length. The cut strips are stacked into a stackAnd annealed to enhance the magnetic properties of the material and optionally convert the initial glassy structure to a nanocrystalline structure. The annealed laminated rod is impregnated and cured in an epoxy resin. Preferred amorphous metal materials have the general formula Fe₈₀B₁₁Si₉Defined composition.

In a second embodiment of the method, amorphous metal strip material is wound about a mandrel to form a generally rectangular core having generally rounded corners. The substantially rectangular core is then annealed to enhance the magnetic properties of the material and, optionally, to convert the initial glassy structure to a nano-scale crystalline structure, and the core is then impregnated with an epoxy resin and cured. The short sides of the rectangular core are then cut to form two magnetic elements having a predetermined three-dimensional geometry approximating the size and shape of the short sides of the substantially rectangular core. Rounded corners are removed from the long sides of the substantially rectangular core and the long sides of the substantially rectangular core are cut to form a plurality of polyhedral magnetic elements having a predetermined three-dimensional geometry. Preferred amorphous metal materials have the general formula Fe₈₀B₁₁Si₉Defined composition.

The present invention also relates to a bulk amorphous metal magnetic component constructed in accordance with the above-described method.

Bulk amorphous metal magnetic components constructed in accordance with the present invention are particularly well suited for use as pieces of pole face magnets in high performance MRI systems; television and video systems; and electron beam and ion beam systems. Advantages of the present invention include simplified manufacturing processes and reduced manufacturing time, reduced stresses (e.g., magnetostriction) encountered during the manufacture of the bulk amorphous metal magnetic component, and optimized performance of the resulting bulk amorphous metal magnetic component.

Drawings

A more complete understanding of the present invention and the advantages thereof may be acquired by referring to the following detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings, in which like reference numbers indicate like elements throughout the figures; wherein:

fig. 1A is a perspective view of a bulk amorphous metal magnetic component formed in accordance with the present invention and having a substantially rectangular polyhedron shape;

fig. 1B is a perspective view of a bulk amorphous metal magnetic component formed in accordance with the present invention and having a substantially trapezoidal polyhedron shape;

fig. 1C is a perspective view of a polyhedral bulk amorphous metal magnetic component having oppositely disposed arcuate surfaces and constructed in accordance with the present invention;

FIG. 2 is a side view of a roll of amorphous metal strips secured for cutting and stacking in accordance with the present invention;

FIG. 3 is a perspective view of an amorphous metal bar showing tangent lines for producing a plurality of substantially trapezoidal magnetic elements in accordance with the present invention;

FIG. 4 is a side view of a roll of amorphous metal strip wound on a mandrel to form a substantially rectangular core in accordance with the present invention; and

fig. 5 is a perspective view of a substantially rectangular amorphous metal core made in accordance with the present invention.

Detailed Description

The present invention provides a low-loss bulk amorphous metal magnetic component of substantially polyhedral shape having a variety of geometries, including but not limited to rectangular, square, and trapezoidal prismatic. Additionally, any of the geometries discussed above may include at least one arcuate surface, and preferably two oppositely disposed arcuate surfaces, to form a curved or arcuate bulk amorphous metal magnetic component. In addition, in accordance with the present invention, the entire magnetic device, such as a pole face magnet, may be formed into a bulk amorphous metal magnetic component. These devices may have a unitary construction or may be made up of several parts that can be brought together to form a unitary component. Alternatively, a device may be a composite structure composed entirely of amorphous metal components or a combination of amorphous metal components and other magnetic materials.

Referring now in detail to the drawings, fig. 1A illustrates a bulk amorphous metal magnetic component 10 having a three-dimensional, substantially polyhedral shape. Magnetic component 10 includes a plurality of substantially identically shaped amorphous metal strip material layers 20 that are laminated together and annealed. The magnetic component depicted in fig. 1B has a three-dimensional, generally trapezoidal shape and includes a plurality of layers 20 of substantially equal size and shape amorphous metal strip material that are laminated together and annealed. The magnetic element shown in fig. 1C includes two oppositely disposed arcuate surfaces 12. Element 10 is formed from a plurality of substantially identically shaped layers 20 of amorphous metal strip material that are laminated together and annealed.

The bulk amorphous metal magnetic component 10 of the present invention is a generally three-dimensional polyhedron and may be a rectangular, square, or trapezoidal prism. Further, as shown in FIG. 1C, the element 10 may have at least one arcuate surface 12. In a preferred embodiment, two arcuate surfaces 12 are provided and are disposed opposite each other.

Constructed according to the invention and excited to a peak induction value B at an excitation frequency f_maxHas a core loss at room temperature that is less than L, where L is given by: l ═ 0.0074f (B)_max)^1.3+0.000282f^1.5(B_max)^2.4The core losses, excitation frequency and peak magnetic induction values are measured in watts per kilogram, hertz and tesla, respectively. In a preferred embodiment, the magnetic component (i) has a core loss of less than or equal to about 1 watt per kilogram of amorphous metal material when operated at a frequency of about 60 hertz and a flux density of about 1.4T; (ii) when in largeA core loss of less than or equal to about 12 watts per kilogram of amorphous metal material when operated at a frequency of about 1000 hertz and a flux density of about 1.0T; or (iii) has a core loss of less than or equal to about 70 watts per kilogram of amorphous metal material when operated at a frequency of about 20000 hertz and a flux density of about 0.30T. The reduced core losses of the element of the invention advantageously improve the efficiency of an electrical device comprising said element.

The low core losses make the bulk amorphous metal magnetic component of the present invention particularly well suited for use in high frequency excitation, such as excitation at frequencies of at least about 100 Hz. The high core losses inherent in conventional steels at high frequencies make them unsuitable for use in devices requiring high frequency excitation. These core loss performance values are applicable to the various embodiments of the present invention regardless of the particular geometry of the bulk amorphous metal magnetic component.

The present invention also provides a method for fabricating a bulk amorphous metal magnetic component. As shown in fig. 2, a roll of amorphous metal strip material 30 is cut into a plurality of strips 20 of the same shape and size by a cutting tool 40. The strips 20 are stacked to form stacked amorphous metal strip material rods 50. The rod 50 is annealed, impregnated with epoxy and cured. The bar 50 may be cut along line 52 shown in fig. 3 into generally rectangular, square, or trapezoidal prism shaped components. The element 10 may further include at least one arcuate surface 12, as shown in FIG. 1C.

In a second embodiment of the present invention, a substantially rectangularly wound core 70 is formed by winding one amorphous metal strip 22 or a group of amorphous metal strips 22 around a substantially rectangular mandrel 60 as shown in fig. 4 and 5. The height of the short side 74 of the core 70 is preferably approximately equal to the desired length of the finished bulk amorphous metal magnetic component 10. The core 70 is annealed, impregnated with epoxy and cured. Two elements 10 can be formed by cutting the short sides 74, leaving radiused corners 76 connected to the long sides 78a, 78 b. Additional magnetic elements 10 may be formed by removing the rounded corners 76 from the long sides 78a, 78b and cutting the long sides 78a, 78b at a plurality of locations indicated by the dashed lines 72. In the example shown in fig. 5, bulk amorphous metal magnetic component 10 has a substantially rectangular shape, although other shapes, such as shapes having at least one trapezoidal or square surface, may be formed by the present invention.

Bulk amorphous metal magnetic component 10 of the present invention may also be cut from stacked amorphous metal bar 50 or from a core of wound amorphous metal bar using a variety of cutting techniques. The element 10 may be cut from the rod 50 or core 70 using a cutting blade or wheel. Furthermore, the element 10 can be cut with a discharge machine or a water jet.

Bulk amorphous metal magnetic components constructed in accordance with the present invention are particularly suitable for use as pieces of pole face magnets in high performance MRI systems, television and video systems, and electron beam and ion beam systems. Fabrication of the magnetic component is simplified and manufacturing time is reduced, stresses otherwise encountered during fabrication of the bulk amorphous metal magnetic component are reduced, and performance of the final bulk amorphous metal magnetic component is optimized.

The bulk amorphous metal magnetic component 10 of the present invention may be fabricated using a number of amorphous metal alloys. Generally, alloys suitable for use in the magnetic component 10 constructed in accordance with the present invention are of the general formula M_70-85Y_5-20Z_0-20The subscripts are defined as atomic percentages where M is at least one of Fe, Ni, and Co, Y is at least one of B, C, and P, and Z is at least one of Si, Al, and Ge, wherein (i) up to 10 atomic percent of component M can be replaced by at least one of the metal species Ti, V, Cr, Mn, Cu, Zr, Nb, Mo, Ta, Hf, Ag, Au, Pd, Pt, and W, and (ii) up to 10 atomic percent of component (Y + Z) can be replaced by at least one of the non-metal species In, Sn, Sb, and Pb. As used herein, the term "amorphous metal alloy" refers to a metal alloy that is substantially free of any long range order (order) characterized by X-ray diffraction intensity maxima qualitatively similar to observations made for liquid or inorganic oxide glassesTo the maximum value.

Amorphous metal alloys suitable for use in the present invention are commercially available in the form of generally continuous thin strips or ribbons having a width of up to 20 cm or more and a thickness of about 20-25 microns. These alloys have a glassy microstructure throughout substantially (e.g., at least about 80% by volume of the material has an amorphous structure). Preferably, substantially 100% of the material of the alloy has an amorphous structure. The volume percent of the amorphous structure may be determined by methods known in the art, such as X-ray, neutron or electron diffraction, transmission electron microscopy, or differential scanning calorimetry. An alloy in which M is iron, Y is boron, and Z is silicon can achieve the highest induction value at low cost. For this reason, amorphous metal strips composed of an iron-boron-silicon alloy are preferred. More specifically, such alloys are preferred: it contains at least 70 atomic percent Fe, at least 5 atomic percent B, and at least 5 atomic percent Si, with the proviso that: the total amount of B and Si is at least 15 atomic percent. Most preferred is an amorphous metal strip having a composition consisting essentially of about 11 atomic percent boron and about 9 atomic percent silicon, with the remainder being iron and incidental impurities. Such a strip is sold by Honeywell International Inc. under the trademark METLAS alloy 2605 SA-1.

The magnetic properties of the amorphous metal strip designated for use in the component 10 of the present invention may be enhanced by heat treatment at a temperature and for a time sufficient to provide the desired enhancement without altering substantially the entire glassy microstructure of the strip. Optionally, a magnetic field may be applied to the strip during at least a portion of the heat treatment, at least preferably during the cooling portion.

The magnetic properties of certain amorphous alloys suitable for use in the component 10 can be greatly improved by heat treating the alloy so as to form a nanocrystalline microstructure. These microstructures are characterized by the presence of a high density of particles having a size of less than about 100 nm, preferably less than about 50 nm, and most preferably less than about 10-20 nm. The particles preferably occupy at least 50% of the volume of the iron-based alloy. These preferred materials have low core loss and low magnetostriction. The latter property makes the material less susceptible to degradation of magnetic properties due to stresses generated during manufacture and/or operation of the component 10. The heat treatment required to produce a nanocrystalline structure in a given alloy must be performed at a higher temperature or for a longer period of time than the heat treatment performed to maintain substantially all of the glassy microstructure therein. The terms amorphous metal and amorphous alloy as used herein also include materials that initially have a substantially fully glassy microstructure and subsequently are converted by heat treatment or other processing to a material having a nano-scale crystalline microstructure. Amorphous alloys that can be heat treated to form a nanocrystalline microstructure are also commonly referred to simply as nanocrystalline alloys. The method of the present invention enables the nanocrystalline alloy to be formed into the desired geometry of the final bulk magnetic component. This method of formation is conveniently carried out while still maintaining its cast, ductile, substantially amorphous form prior to the heat treatment of the material to form the more brittle and more difficult to handle nano-scale crystalline structure.

Two preferred alloys capable of greatly enhancing their magnetic properties by forming nanocrystalline microstructures are given by the following general formula, where the subscripts are atomic percentages.

A first preferred nanocrystalline alloy is Fe_{100-u-x-y-z-w}R_uT_xQ_yB_zSi_wWherein R is at least one of Ni and Co, T is at least one of Ti, Zr, Hf, V, Nb, Ta, Mo, and W, Q is at least one of Cu, Ag, Au, Pd, and Pt, u ranges from about 0 to about 10, x ranges from about 3 to about 12, y ranges from about 0 to about 4, z ranges from about 5 to about 12, and W ranges from about 0 to about 8. Thereafter, the alloy is heat treated to form therein a nanocrystalline microstructure having a high saturation induction (e.g., at least 1.5T), low core loss, and low saturation magnetizationTelescoping (e.g. having an absolute value less than 4 x 10^-6Magnetostriction of (1). Such alloys are particularly useful in situations where component size must be minimized or for pole face magnets requiring high air gap flux.

A second preferred nanocrystalline alloy is Fe_{100-u-x-y-z-w}R_uT_xQ_yB_zSi_wWherein R is at least one of Ni and Co, T is at least one of Ti, Zr, Hf, V, Nb, Ta, Mo, and W, Q is at least one of Cu, Ag, Au, Pd, and Pt, u ranges from about 0 to about 10, x ranges from about 1 to about 5, y ranges from about 0 to about 3, z ranges from about 5 to about 12, and W ranges from about 8 to about 18. Thereafter, the alloy is heat treated to form therein a nanocrystalline microstructure having a saturation induction of at least about 1.0T, particularly low core loss, and low saturation magnetostriction (e.g., having an absolute value of less than 4 x 10)^-6). Such alloys are particularly useful for components that are excited at very high frequencies (e.g., requiring excitation frequencies higher than 1000 hertz).

Electromagnetic systems comprising magnets with one or several pole faces are generally systems for generating a time-varying magnetic field in the air gap of an electromagnet. The time-varying magnetic field may be a purely alternating magnetic field, i.e. a magnetic field whose time average is 0. Alternatively, the time-varying magnetic field may have a non-zero time average value, commonly referred to as the dc component of the magnetic field. In such an electromagnetic system, at least one of the pole face magnets is subjected to a time-varying magnetic field, with the result that the pole face magnet is magnetized and demagnetized with each excitation cycle. Time-varying magnetic flux density or magnetic induction in a pole face magnet causes heat generation due to core loss in the core.

Bulk amorphous metal magnetic components are capable of being magnetized and demagnetized more efficiently than components fabricated from other ferrous magnetic metals. When used as a pole magnet, the bulk amorphous metal magnetic component generates less heat when magnetized at the same magnetic induction and frequency as compared to components fabricated from other ferrous magnetic metals. Further, the iron-based amorphous metal preferably used in the present invention has a much larger saturation induction than other low-loss soft magnetic materials such as permalloy, which is generally 0.6 to 0.9T. Thus, when compared to components fabricated from other ferrous magnetic metals, the bulk amorphous metal magnetic component may be designed to operate under the following conditions: 1) low operating temperature; 2) higher magnetic induction, thus can reduce volume and weight; or 3) higher frequencies to reduce volume and weight, or to enable superior signal resolution.

As is well known in the art, core loss is a dissipation of energy that occurs in a ferromagnetic material as its magnetization changes over time. The core loss of a given magnetic element is typically determined by periodically energizing the element. The elements are provided with a time-varying magnetic field, thereby generating a corresponding time-varying magnetic induction or flux density therein. For the purpose of standardizing the measurement, the excitation is generally selected such that the magnetic induction varies with time in a sinusoidal manner at a frequency f and has a peak value B_max. The core loss is then determined using known electronic measurement instruments and techniques. Core loss is typically reported in watts of excited magnetic material per unit mass or volume. It is known in the art that core loss with f and B_maxMonotonically increasing. Most standard protocols for detecting core losses of soft magnetic materials used in components of pole face magnets, such as ASTM standards a912-93 and a927(a927M-94), require a sample of said materials to be located in a substantially closed magnetic circuit, which is a structure in which closed magnetic field lines are completely contained within the volume of said sample. On the other hand, magnetic materials used in, for example, pole face magnets are located in a magnetic open circuit, i.e. a structure in which the magnetic field lines have to cross an air gap. Due to edge effects of the magnetic field and non-uniformity of the magnetic field, a given material tested in an open circuit generally has a higher core loss, i.e., higher wattage per unit mass or volume, than when measured in a closed circuit. Bulk amorphous metal magnetic component of the present invention exhibits wide magnetic field even in an open circuit configurationLow core losses are still present in the pass density and frequency range.

Without being bound by any theory, it is believed that the total core loss of the low-loss bulk amorphous metal magnetic component of the present invention consists of hysteresis losses and eddy current losses. They are all peak magnetic induction B_maxAnd excitation frequency f. Prior art analyses of core loss for amorphous metals (see g.e.fish.j.appl.phys.57, 3569(1985) and g.e.fish et, appl.phys.64, 5370(1998)) are generally limited to data obtained for magnetic material in a closed magnetic circuit.

Total core loss per unit mass, L (B), of bulk amorphous metal magnetic components of the present invention_max. f) Can be determined essentially by a function of the form:

L(B_max，f)＝c₁f(B_max)ⁿ+C₂f^q(B_max)^m

where the coefficients c1 and c2, and the indices n, m and q must be determined experimentally, there is no known theory to be able to determine their values accurately. The total core loss of the bulk amorphous metal magnetic component of the present invention at any desired operating magnetic induction and excitation frequency can be determined using this equation. Generally, it is generally found that the magnetic field in a bulk amorphous metal magnetic component of a particular geometry is not uniform in space. Finite element modeling techniques, such as are known in the art, can provide estimates of the change in space and time of the peak flux density near the flux density distribution measured in an actual bulk amorphous metal magnetic component. These techniques can be used as suitable experimental formulae giving the core loss of a material at a spatially uniform flux density, which are able to predict with a suitable accuracy the corresponding core loss of a given element in its operating configuration.

The measurement of core loss for the magnetic component of the present invention can be performed using a number of methods known in the art. A method that is particularly suitable for measuring the magnetic elements of the present invention is described below. The method includes forming a magnetic circuit having the magnetic component and flux closure structure apparatus of the present invention. Alternatively, the magnetic circuit may comprise a plurality of magnetic elements of the invention and a flux closure structure arrangement. The flux closure structure means preferably comprises a soft magnetic material having a high magnetic permeability and a saturation flux density at least equal to the flux density of the magnetic element to be sensed. Preferably, the soft magnetic material has a saturation flux density at least equal to the saturation flux density of the component. The direction of the magnetic flux substantially defines the first and second opposing surfaces of the component along which the component is to be sensed. The magnetic field lines enter the element in a direction substantially perpendicular to the plane of the first opposing surface. The magnetic field lines generally enter along the plane of the amorphous metal strip and exit through the second, opposite surface. The flux closure structure means generally comprises a flux closure magnetic element which is preferably constructed in accordance with the present invention, but may be constructed in other ways using materials known in the art. The flux-closing magnetic element also has first and second opposed surfaces through which magnetic flux lines enter and exit in a direction substantially perpendicular to the surfaces. The size and shape of the opposing surfaces of the flux closure magnetic elements are substantially the same as the size and shape of the respective surfaces of the magnetic elements that mate with the flux closure elements during actual testing. The flux-closing magnetic element is in mating relationship with the magnetic element of the present invention with the first and second surfaces abutting and substantially abutting the first and second surfaces, respectively, of the magnetic element of the present invention. The magnetic potential is provided by inputting a current in a first winding surrounding the magnetic element or flux closure element of the present invention. The resulting flux density is determined by the voltage induced in the second winding around the magnetic component under test according to faraday's law. The applied magnetic field is determined by the magnetic potential and ampere's law. Core losses are then calculated from the applied magnetic field and the resulting magnetic flux density using conventional methods.

Referring to fig. 5, there is shown an element 10 whose core loss can be readily determined by the test method described below. The long side 78b of the core 70 is used as the magnetic component 10 for core loss testing. The remainder of the core 70 acts as a flux closure means and is substantially C-shaped and includes 4 rounded corners 76, short sides 74 and long sides 78 a. Each slit 72 is optionally split into rounded corners 76, short sides 74 and long sides 78 a. Preferably, only slits are formed that separate the long side 78b from the rest of the core 70. The cut surface formed by cutting core 70 to remove long side 78b defines the opposing surface of the magnetic elements and the opposing surface of the flux closure magnetic elements. In performing the test, the long side 78b and the corresponding surface defined by the slit are brought into parallel and close contact. The surface of the long side 78b is substantially the same size and shape as the surface of the flux closure magnetic element. Two copper wire windings (not shown) encircle the long side 78 b. An alternating current of suitable magnitude is passed through the first winding to provide a magnetic potential that excites the long side 78b at the desired frequency and peak magnetic flux density. The flux lines at the long side 78b and in the flux-closure magnetic element travel substantially in the plane of the strip 22 and in the circumferential direction. A voltage is induced in the second winding that represents a flux density that varies over time. The core loss is determined from the measured voltage and current values using conventional electronics.

For a more complete understanding of the present invention, examples are given below. The specific techniques, conditions, materials, proportions and reported data set forth herein are illustrative of the principles and practice of the invention, which are exemplary only, and are not to be construed as limiting the scope of the invention.

Example 1

Preparation and electromagnetic testing of amorphous metal rectangular prisms

Fe about 60 mm wide and 0.022 mm thick₈₀B₁₁Si₉A layer of amorphous metal material is wound around a rectangular mandrel or reel having dimensions of about 25 mm x 90 mm. Amorphous metal material is wound about 800 turns around a mandrel or reel to form a rectangular core form having internal dimensions of about 25 mm by 90 mm and a cumulative thickness of about 20 mm. The core/bobbin assembly was annealed in nitrogen. The annealing comprises the following steps: 1) the device was heated to 365 ℃; 2) holding at a temperature of about 365 ℃ for about 2 hours; and 3) cooling the apparatusBut to ambient temperature. Removing said rectangular, wound, amorphous metal core from said core/reel assembly. The iron core is vacuum impregnated with an epoxy resin solution. The reel is reset and the reassembled, impregnated core/reel assembly is cured at 120 ℃ for approximately 4.5 hours. When fully cured, the core is removed again from the core/reel assembly. The resulting rectangular, wound, epoxy bonded amorphous metal core weighed approximately 2100 grams.

A rectangular prism (approximately 800 layers) 60 mm long, 40 mm wide, 20 mm thick was cut from an epoxy bonded amorphous metal core using a 1.5 mm thick cutting blade. The cut surfaces of the rectangular prisms and the remaining portion of the core were etched in an aqueous nitric acid solution and washed with an aqueous ammonium hydroxide solution. The remaining portion of the core was etched in an aqueous nitric acid solution and washed with an aqueous ammonium hydroxide solution. The rectangular prism and the rest of the core are then reassembled into the shape of the complete cut core. The primary and secondary coils are secured to the remainder of the core. The cut cores were electrically tested at room temperature and 60, 1000, 5000 and 20000 hertz and compared to the class values of other magnetic materials of similar test structure [ National Arnold magnets, 17030 Muskrat Avenue, Adelanto, CA 92301(1995) ]. The results obtained are compiled in tables 1, 2, 3 and 4 below.

TABLE 1

Core loss at 60Hz (W/kg)

TABLE 2

Core loss at 1000Hz (W/kg)

TABLE 3

Core loss at 5000Hz (W/kg)

TABLE 4

Core loss at 20000Hz (W/kg)

As shown by the data in tables 3 and 4, the core loss is particularly low at excitation frequencies of 5000hz or higher. The magnetic component of the present invention is thus particularly suitable for use in a pole face magnet.

Example 2

Preparation of amorphous Metal trapezoidal prism

Fe approximately 48 mm wide and 0.022 mm thick₈₀B₁₁Si₉The amorphous metal strip is cut to a length of about 300 mm. Approximately 3800 layers of cut amorphous metal material strips were stacked to form a rod approximately 48 mm wide and 300 mm long, building up to a thickness of approximately 96 mm. The rods were annealed in nitrogen. The annealing comprises the following steps: 1) heating the rod to 365 ℃; 2) holding at a temperature of about 365 ℃ for about 2 hours; and 3) cooling the device to ambient temperature. The rods were vacuum impregnated with an epoxy resin solution and cured at 120 ℃ for approximately 4.5 hours. What is needed isThe resulting stacked, epoxy bonded amorphous metal rods weighed approximately 9000 grams.

Trapezoidal prisms were cut from stacked, epoxy bonded amorphous metal rods using a 1.5 mm thick cutting blade. The trapezoidal surfaces of the prisms had bases of 52 and 62 mm and a height of 48 mm. The thickness of the trapezoidal prism was 96 mm (3800 layers). The cut surfaces of the trapezoidal prisms and the remaining portion of the core were etched in an aqueous nitric acid solution and washed with an aqueous ammonium hydroxide solution.

The trapezoidal prism has a core loss of less than 11.5W/kg when excited to a peak magnetic induction of 1.0T at 1000 hz.

Example 3

Preparation of a polyhedral bulk amorphous metal magnetic component having an arcuate cross-section

Fe about 50 mm wide and 0.022 mm thick₈₀B₁₁Si₉Amorphous metal strip is cut to a length of about 300 mm. Approximately 3800 layers of cut amorphous metal material tape were stacked to form a rod approximately 50 mm wide and 300 mm long, building up to a thickness of approximately 96 mm. The rods were annealed in nitrogen. The annealing comprises the following steps: 1) heating the rod to 365 ℃; 2) held at a temperature of about 365 for about 2 hours; and 3) cooling the rod to ambient temperature. The rods were vacuum impregnated with an epoxy resin solution and cured at 120 ℃ for approximately 4.5 hours. The resulting stacked, epoxy bonded amorphous metal rods weighed approximately 9200 grams.

Stacked, epoxy bonded amorphous metal rods are cut into three-dimensional arcuate blocks using discharge cutting. The outer diameter of the block is approximately 96 mm. The inner diameter is about 13 mm. The arc length is approximately 90 degrees. The thickness of the block is approximately 96 mm.

Fe about 20 mm wide and 0.022 mm thick₈₀B₁₁Si₉Amorphous metal is wound around a mandrel or reel having an outer diameter of about 19 mm. Around said mandrel or rollThe amorphous metal material strip was shaft wound approximately 1200 turns to form an annular core having an inner diameter of approximately 19 mm and an outer diameter of approximately 48 mm. The cumulative thickness of the core is approximately 29 mm. The core is annealed in nitrogen. The annealing comprises the following steps: 1) heating the rod to 365 ℃; 2) holding at a temperature of about 365 ℃ for about 2 hours; and 3) cooling the core to ambient temperature. The core was vacuum impregnated with an epoxy resin solution and cured at 120 c for about 4.5 hours. The resulting stacked, epoxy bonded amorphous metal core weighed approximately 71 grams.

A wound, epoxy-bonded amorphous metal core is cut with a water jet to form a semi-toroidal three-dimensional shaped object. The semi-annular body has an inner diameter of about 19 mm, an outer diameter of about 48 mm and a thickness of about 20 mm.

The cut surfaces of the polyhedral bulk amorphous metal elements were etched in aqueous nitric acid and washed with aqueous ammonium hydroxide.

Each of the polyhedral bulk amorphous metal magnetic components has a core loss of less than 11.5W/kg when excited to a peak magnetic induction of 1.0T at 1000 hz.

Example 4

High frequency performance of low loss bulk amorphous metal magnetic component

The core loss data obtained in example 1 above was analyzed by a conventional non-linear regression method. Is determined by Fe₈₀B₁₁Si₉The core loss of a low-loss bulk amorphous metal magnetic component formed of amorphous metal strip is defined essentially by the function:

L(B_max，f)＝c₁f(B_max)ⁿ+C₂f^q(B_max)^m

suitable values for the coefficients c1, c2 and the indices n, m and q are selected to determine the bulk amorphous metal magnetic elementThe upper limit of the magnetic loss of the piece. Table 5 refers to the measured loss of the example 1 element and the loss predicted by the above equation in units of watts per kilogram. As f (Hz) and B_maxThe predicted loss utilization coefficient c1 of the function of (T) is 0.0074, c2 is 0.000282, the index n is 1.3, m is 2.4, and q is 1.5. The measured loss for the bulk amorphous metal magnetic component of example 1 is less than the corresponding loss predicted by the equation.

TABLE 5

Dot	B(Tesla)	Frequency (Hz)	Measured core loss (W/kg)	Predicted core loss (W/kg)
					1	0.3	60	0.1	0.10
2	0.7	60	0.33	0.33
					3	1.1	60	0.59	0.67
4	1.3	60	0.75	0.87
					5	1.4	60	0.85	0.98
6	0.3	1000	1.92	2.04
					7	0.5	1000	4.27	4.69
8	0.7	1000	6.94	8.44
					9	0.9	1000	9.92	13.38
10	1	1000	11.51	16.32
					11	1.1	1000	13.46	19.59
12	1.2	1000	15.77	23.19
					13	1.3	1000	17.53	27.15
14	1.4	1000	19.67	31.46
					15	0.04	5000	0.25	0.61
16	0.06	5000	0.52	1.07
					17	0.08	5000	0.88	1.62
18	0.1	5000	1.35	2.25
					19	0.2	5000	5	6.66
20	0.3	5000	10	13.28
					21	0.04	20000	1.8	2.61
22	0.06	20000	3.7	4.75
					23	0.08	20000	6.1	7.41
24	0.1	20000	9.2	10.59
					25	0.2	20000	35	35.02
26	0.3	20000	70	75.29

Example 5

Preparation of nano-scale crystal alloy rectangular prism

About 25 mm wide and 0.018 mm thick Fe_73.5Cu₁Nb₃B₉Si_13.5Amorphous metal strip is cut to a length of about 300 mm. Approximately 1200 layers of cut amorphous metal strips were stacked to form rods approximately 25 mm wide and 300 mm long, building up to a thickness of approximately 25 mm. The rods were annealed in nitrogen. The annealing is carried out according to the following steps: 1) heating the rod to 580 ℃; 2) holding at a temperature of about 580 ℃ for about 1 hour; and 3) cooling the rodTo ambient temperature. The rods were vacuum impregnated with an epoxy resin solution and cured at 120 ℃ for approximately 4.5 hours. The resulting stacked, epoxy bonded amorphous metal rods weighed approximately 1200 grams.

The stacked epoxy impregnated amorphous metal rods were cut into rectangular prisms using a 1.5 mm thick cutting blade. The prism surfaces are approximately 25 mm wide and 50 mm long. The rectangular prisms were 25 mm thick (1200 layers). The cut surfaces of the rectangular prisms were etched in an aqueous nitric acid solution and washed with an aqueous ammonium hydroxide solution.

The rectangular prism has a core loss of less than 11.5W/kg when excited to a peak magnetic induction of 1.0T at 1000 hz.

Having described the invention in detail, it will be understood that the invention is not necessarily limited to those details, since various changes and modifications may be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims (26)

1. Bulk amorphous metal magnetic component comprising a plurality of identically shaped amorphous metal strips stacked together and cured with a vacuum-impregnated epoxy resin to form a polyhedral shaped part cut from the stacked strips or wound core, which achieves a peak magnetic induction B when operated at an excitation frequency f_maxThen has a core loss less than L, where L is represented by the formula L0.0074 f (B)_max)^1.0+0.000282f^1.5(B_max)^2.4Given that the core loses, excitesMagnetic frequency and peak induction values are in units of watts per kilogram, hertz, and tesla, respectively.

2. A bulk amorphous metal magnetic component as recited by claim 1, said amorphous metal strip having the general formula M_70～85Y_5～20Z_0～20Defined composition, the subscripts being atomic percent, wherein M is at least one of Fe, Ni and Co, Y is at least one of B, C and P and the content of C and P is at most 5 atomic percent, Z is at least one of Si, Al and Ge and the content of Al and Ge is at most 5 atomic percent, wherein (i) at most 10 atomic percent of component M is replaced by at least one of the metallic species Ti, V, Cr, Mn, Cu, Zr, Nb, Mo, Ta, Hf, Ag, Au, Pd, Pt and W, (ii) at most 10 atomic percent of component (Y + Z) is replaced by at least one of the non-metallic species In, Sn, Sb and Pb, and (iii) at most 1 atomic percent of component (M + Y + Z) is an incidental impurity.

3. A bulk amorphous metal magnetic component as recited by claim 2, wherein each of said amorphous metal strips has a composition containing at least 70 atom percent Fe, at least 5 atom percent B, and at least 5 atom percent Si, wherein the combined B and Si content is at least 15 atom percent.

4. A bulk amorphous metal magnetic component as recited by claim 3, wherein each amorphous metal strip has a general formula of Fe₈₀B₁₁Si₉The composition defined.

5. A bulk amorphous metal magnetic component as recited by claim 2, wherein said amorphous metal strip has a nanocrystalline microstructure formed by heat treatment.

6. Bulk amorphous gold according to claim 5A magnetic component, wherein each amorphous metal strip has a general formula of Fe_{100-u-x-y-z-w}R_uT_xQ_yB_zSi_wWherein R is at least one of Ni and Co, T is at least one of Ti, Zr, Hf, V, Nb, Ta, Mo, and W, Q is at least one of Cu, Ag, Au, Pd, and Pt, u ranges from 0 to 10, x ranges from 3 to 12, y ranges from 0 to 4, z ranges from 5 to 12, and W ranges from 0 to less than 8.

7. A bulk amorphous metal magnetic component as recited by claim 5, wherein each said amorphous metal strip has a general formula of Fe_{100-u-x-y-z-w}R_uT_xQ_yB_zSi_wA defined composition, wherein R is at least one of Ni and Co, T is at least one of Ti, Zr, Hf, V, Nb, Ta, Mo, and W, Q is at least one of Cu, Ag, Au, Pd, and Pt, u ranges from 0 to 10, x ranges from 1 to 5, y ranges from 0 to 3, z ranges from 5 to 12, and W ranges from 8 to 18.

8. A bulk amorphous metal magnetic component as recited by claim 1, wherein said component has the shape of a three-dimensional polyhedron with at least one rectangular cross-section.

9. A bulk amorphous metal magnetic component as recited by claim 1, wherein said component has the shape of a three-dimensional polyhedron with at least one trapezoidal cross-section.

10. A bulk amorphous metal magnetic component as recited by claim 1, wherein said component has the shape of a three-dimensional polyhedron with at least one square cross-section.

11. A bulk amorphous metal magnetic component as recited by claim 1, wherein said component includes at least one arcuate surface.

12. A bulk amorphous metal magnetic component as recited by claim 1, wherein said component has a core loss of less than or equal to 1 watt per kilogram of amorphous metal material when operated at a frequency of 60hz and a flux density of 1.4T.

13. A bulk amorphous metal magnetic component as recited by claim 1, wherein said component has a core loss of less than or equal to 12 watts per kilogram of amorphous metal material when operated at a frequency of 1000 hertz and a flux density of 1.0T.

14. A bulk amorphous metal magnetic component as recited by claim 1, wherein said component has a core loss of less than or equal to 70 watts per kilogram of amorphous metal material when operated at a frequency of 20000 hertz and a flux density of 0.30T.

15. A method for constructing a bulk amorphous metal magnetic component comprising the steps of:

(a) providing a plurality of strips of amorphous metal strip material in a stack;

(b) annealing the laminate;

(c) vacuum impregnating the laminate with an epoxy resin and curing the resin impregnated laminate;

(d) cutting the stack at a predetermined length to provide a plurality of polyhedral magnetic elements having a predetermined three-dimensional geometry,

when excited at an excitation frequency f to a peak magnetic induction value B_maxThen, the core loss is less than L, wherein L is represented by the formula L ═ 0.0074f (B)_max)^1.3+0.000282 f^1.5(B_max)^2.4The units of core loss, excitation frequency and peak magnetic induction are given in watts per kilogram, hertz and tesla, respectively.

16. The method of claim 15, wherein the laminate is in the form of a stacked rod comprising a plurality of strips cut to predetermined lengths.

17. The method of claim 15, wherein the laminate is in the form of a wound rectangular core having rounded corners.

18. The method of claim 15, wherein step (a) comprises cutting the amorphous metal strip material using a cutting blade, a cutting wheel, a water jet, or a discharge machine.

19. The method of claim 15, wherein each of said cut strips has the formula M_70～85Y_5～20Z_0～20Defined composition, the subscripts being atomic percentages, wherein M is at least one of Fe, Ni and Co, Y is at least one of B, C and P and the content of C and P is at most 5 atomic percentages, Z is at least one of Si, Al and Ge and the content of Al and Ge is at most 5 atomic percentages, wherein (i) at most 10 atomic percentages of component M are replaced by at least one of the metallic species Ti, V, Cr, Mn, Cu, Zr, Nb, Mo, Ta, Hf, Ag, Au, Pd, Pt and W, (ii) at most 10 atomic percentages of component (Y + Z) are replaced by at least one of the non-metallic species In, Sn, Sb and Pb, and (iii) at most 1 atomic percentage of component (M + Y + Z) is an incidental impurity.

20. The method of claim 19 wherein each of said amorphous metal strips has the general formula Fe₈₀B₁₁Si₉The composition defined.

21. The method of claim 15, wherein the element has a three-dimensional polyhedral shape with at least one rectangular cross-section.

22. A method as recited by claim 15, wherein said bulk amorphous metal magnetic component has the shape of a three-dimensional polyhedron with at least one trapezoidal cross-section.

23. The method of claim 15, wherein the element has a three-dimensional polyhedral shape with at least one square cross-section.

24. The method of claim 15, wherein the element has a three-dimensional polyhedral shape with at least one arcuate cross-section.

25. A method as recited by claim 15, wherein said bulk amorphous metal magnetic component has a general formula M_70～85Y_5～20Z_0～20Defined composition, the subscripts being atomic percentages, wherein M is at least one of Fe, Ni and Co, Y is at least one of B, C and P and the content of C and P is at most 5 atomic percentages, Z is at least one of Si, Al and Ge and the content of Al and Ge is at most 5 atomic percentages, wherein (i) at most 10 atomic percentages of component M are replaced by at least one of the metallic species Ti, V, Cr, Mn, Cu, Zr, Nb, Mo, Ta, Hf, Ag, Au, Pd, Pt and W, (ii) at most 10 atomic percentages of component (Y + Z) are replaced by at least one of the non-metallic species In, Sn, Sb and Pb, and (iii) at most 1 atomic percentage of component (M + Y + Z) is an incidental impurity.

26. The method of claim 25, wherein the epoxy is a solution of epoxy vacuum impregnated into the core.