HK1058102B - Bulk stamped amorphous metal magnetic component - Google Patents

Description

Bulk stamped amorphous metal magnetic component

Technical Field

The present invention relates to amorphous metal magnetic components; and more particularly to a substantially three-dimensional bulk stamped 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

Magnetic Resonance Imaging (MRI) has become an important, non-invasive diagnostic tool in modern medicine. MRI systems typically include a magnetic field generating device. Many such magnetic field generating devices use permanent magnets or electromagnets as the source of magnetomotive force. Typically the magnetic field generating means further comprises a pair of pole faces defining a gap having a volume to be imaged within the gap.

Us patent 4672346 discloses a pole face having a solid construction and comprising a plate-like block made of magnetic material, such as carbon steel. Us patent 4818966 teaches that the magnetic flux generated by the pole pieces of the magnetic field generating device can be concentrated in the gap by making the peripheral portions of the pole pieces with laminated magnetic plates. Us patent 4827235 discloses a pole piece having a large saturation induction, soft magnetic properties and a resistivity of 20 μ Ω -cm or more. The soft magnetic materials taught for use in this patent include permalloy, silicon steel, amorphous magnetic alloys, ferrites, and magnetic composite materials.

Us patent 5124651 discloses a nuclear magnetic resonance scanner with a primary field magnet arrangement. The magnet assembly includes upper and lower iron pole pieces. Each pole piece comprises a plurality of narrow, elongated ferromagnetic rods aligned with their long axes parallel to the pole direction of the respective pole piece. The magnetic rods are made of a magnetically permeable alloy such as 1008 steel, soft iron, or the like. The magnetic bars are electrically isolated in the transverse direction by means of a non-conductive medium, so that the generation of eddy currents in the plane of the pole faces of the magnetic poles of the magnetic field arrangement is limited. U.S. patent 5283544 issued to Sakurai et al, 1994, 2, 1, discloses a magnetic field generating device for MRI. The apparatus includes a pair of pole pieces, which may be formed of a plurality of block-shaped pole piece members formed by laminating a plurality of non-oriented silicon steel plates.

Despite the many advantages of the above-mentioned patents, there remains a need in the art for improved pole pieces. This is because these pole pieces are important to improve the imaging capability and quality of the MRI system.

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 tiles for pole face magnets of MRI systems, 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, and thus conventional cutting and stamping processes result 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 causes durability concerns for 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 of the core in directing or focusing the 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 potential during operation of the device, mechanical stresses resulting from mechanical clamping or otherwise securing a bulk amorphous metal magnetic component, or internal stresses resulting from thermal expansion and/or from magnetic saturation of amorphous metal material.

Disclosure of Invention

The present invention provides a low loss bulk amorphous metal magnetic component comprising a plurality of similarly identical laminations stamped from ferromagnetic amorphous metal strips, the laminations being stacked and bonded together with an adhesive to form a polyhedrally shaped component, and

wherein the element, when excited at an excitation frequency "f", reaches 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/kilogram, hertz and tesla, respectively.

The invention also providesA method of 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. Magnetic elements constructed in accordance with the invention are excited to a peak magnetic induction value "B" at an excitation frequency "f_max"has a core loss at room temperature of less than" L ", where L is represented by the formula L ═ 0.0074f (B)_max)^1.3+0.000282f^1.5(B_max)^2.4The core loss, excitation frequency and peak magnetic induction values are given in watts/kg, hertz and tesla measurements, respectively. The magnetic component will have (i) a core loss of less than or about equal to 1 watt per kilogram of amorphous metal material when operated at a frequency of about 60Hz and a magnetic density of about 1.4T; (ii) (ii) a core loss of less than or about equal to 12 watts per kilogram of amorphous metal material when operated at a frequency of about 1000Hz and a magnetic density of about 1.0T, or (iii) a core loss of less than or about equal to 70 watts per kilogram of amorphous metal material when operated at a frequency of about 20000Hz and a magnetic density of about 0.30T.

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

The present invention also provides a method of constructing a bulk amorphous metal magnetic component. One embodiment of the method comprises the steps of: stamping a laminate of desired shape from a ferromagnetic amorphous metal strip stock, stacking the laminates to form a three-dimensional shape, applying and actuating a bonding device to bond the laminates to one another to form a component having sufficient mechanical integrity, and trimming the component to remove any excess adhesive to provide a suitable surface finish and final component dimensions. The method may further comprise a selective annealing step in order to improve the magnetic properties of the component. These steps can be performed in a variety of different sequences and using a variety of different techniques including those set forth below.

The present invention also relates to a bulk amorphous metal magnetic component formed by the above method. In particular, bulk amorphous metal magnetic components constructed in accordance with the present invention are particularly well suited for use as amorphous metal components, such as tiles (tiles) for pole face magnets of high performance MRI systems, television and video systems, and electron and ion beam systems. Bulk amorphous metal magnetic components constructed in accordance with the present invention are also useful in non-toroidal inductors such as C-cores, E-cores, and E/I-cores, where expressions C, E and E/I are used to illustrate the cross-sectional shape of the component. The advantages of the invention include: simplifying the manufacturing process, reducing manufacturing time, reducing stresses (e.g., magnetostriction-induced stresses) experienced during the manufacture of the bulk amorphous metal magnetic component, and optimizing the 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 stamped 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 stamped 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 shaped, bulk stamped amorphous metal magnetic component having oppositely disposed arcuate surfaces and constructed in accordance with the present invention;

figure 2A is a side view of a coil of ferromagnetic amorphous metal strip to be annealed and stamped and a ferromagnetic amorphous metal stack to be stacked arranged in accordance with the present invention;

FIG. 2B is a side view of a coil of ferromagnetic amorphous metal strip to be annealed, epoxy coated and stamped and a ferromagnetic amorphous metal laminate to be laminated, arranged in accordance with the present invention;

figure 2C is a side view of a roll of ferromagnetic amorphous metal strip arranged to be stamped and a stack of ferromagnetic amorphous metal layers arranged to be collected in accordance with the present invention;

figure 2D is a side view of a roll of ferromagnetic amorphous metal strip arranged to be stamped and a stack of ferromagnetic amorphous metal layers arranged to be stacked in accordance with the present invention; and

fig. 3 is a perspective view of a test apparatus for a bulk stamped amorphous metal magnetic component, comprising 4 components, each in the shape of a polyhedron with oppositely disposed arcuate surfaces, assembled into a substantially right circular annular cylinder.

Detailed Description

The present invention provides a low-loss bulk amorphous metal magnetic component of substantially polyhedral shape. Bulk amorphous metal magnetic components constructed in accordance with the present invention have a variety of three-dimensional (3D) 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 some embodiments include two oppositely disposed arcuate surfaces, thereby forming a generally 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 constructed 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.

Magnetic Resonance (MRI) imaging devices typically use pole pieces (also referred to as pole faces) as part of the magnetic field generating device. As is known in the art, such magnetic field generating means are used to provide a steady magnetic field and a time-varying magnetic field gradient superimposed on the steady magnetic field. In order to produce high quality high definition MRI images it is important that the steady magnetic field is homogeneous throughout the sample volume to be investigated and that the magnetic field gradients are well defined. The uniformity can be improved by using suitable pole pieces. The bulk amorphous metal magnetic component of the present invention is suitable for use in forming such pole faces.

Pole pieces for an MRI or other magnet system are adapted to shape and direct a magnetic flux generated by at least one magnetomotive force (mmf) source in a predetermined manner. The magnetomotive force source may comprise known magnetomotive force generating devices including permanent magnets and electromagnets, either normally conductive windings or superconducting windings. Each pole piece may include one or more bulk amorphous metal magnetic components as described herein.

It is desirable that the pole pieces have good dc magnetic properties, including high magnetic permeability and high saturation flux density. In order to improve clarity and have a higher operating flux density, the pole pieces are also required to have good ac magnetic properties. More specifically, it is desirable to minimize core losses in the pole pieces caused by the magnetic field of the time-varying gradient. Reducing the core loss advantageously improves the sharpness (definition) of the magnetic field gradient and enables the magnetic field gradient to change faster, thus enabling a reduction in imaging time without degrading image quality.

The earliest pole pieces were constructed of solid magnetic material such as carbon steel or high purity iron, commonly referred to in the art as amkote. They have good dc magnetic properties but have very high core losses in the presence of an ac magnetic field due to the presence of macroscopic eddy currents. Some improvement is obtained by constructing the pole pieces from laminated conventional steel sheets.

However, there is still a need for further improvement of pole pieces that not only have the desired dc magnetic properties, but also have greatly improved ac magnetic properties, the most important being lower core losses. As described below, the combination of the requirements of high flux density, high magnetic permeability and low core loss is achieved by using the magnetic components of the present invention to form the pole pieces.

Referring now in more detail to fig. 1A-1C, fig. 1A illustrates a bulk amorphous metal magnetic component 10 having a three-dimensional, substantially polyhedral shape. The magnetic component 10 is constructed of a stack 20 of a plurality of substantially identically shaped amorphous metal strip materials that are laminated together and annealed. The magnetic component depicted in fig. 1B has a three-dimensional, generally trapezoidal shape and is formed from a stack 20 of a plurality of substantially identically sized and shaped amorphous metal strip materials that are laminated together and annealed. The magnetic element shown in fig. 1C includes two oppositely disposed arcuate surfaces 12. The component 10 is constructed of a stack 20 of a plurality of substantially identically shaped amorphous metal strip materials 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 rectangular, square, or trapezoidal prism. Further, as shown in FIG. 1C, the element 10 may have at least one arcuate surface 12. And as shown may include two arcuate surfaces 12 disposed opposite each other.

A three-dimensional magnetic component 10 constructed in accordance with the present invention has low core losses. When excited to peak induction value B at excitation frequency f_max"the magnetic component has 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 loss, excitation frequency and peak magnetic induction values are measured in watts/kilogram, hertz and tesla, respectively. In another 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) having a 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)When operated at a frequency of about 20000 hertz and a flux density of about 0.30T, has a core loss of less than or equal to about 70 watts per kilogram of amorphous metal material. 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 stamped amorphous metal magnetic component of the present invention particularly well suited for use in high frequency excitation, such as excitation at a frequency 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 manufacturing a bulk stamped amorphous metal magnetic component. In one embodiment, the method comprises the steps of: stamping a laminate of a desired shape from a ferromagnetic amorphous metal strip stock, stacking the laminates to form a three-dimensionally shaped object, applying and actuating a bonding device to bond the laminates to one another to form a component having sufficient mechanical integrity, and trimming the component to remove any excess adhesive to provide a suitable surface finish and final component dimensions. The method may further comprise a selective annealing step in order to improve the magnetic properties of the component. These steps can be performed in a variety of different sequences and using a variety of different techniques, including those set forth below and apparent to those skilled in the art.

Historically, there have been 3 factors that combine to prevent the use of stamping as a method of manufacturing amorphous metal components. The first and earliest factor was the thinness of amorphous metal strip compared to conventional magnetic material strips such as non-oriented electrical steel. The use of thin materials means that more layers of lamination are required to construct a given shaped element. The use of thinner material also requires the use of smaller tool and die clearances in the stamping process.

In the second place, the first place is,amorphous metals are much harder than typical metal punch and die materials. The hardness of the iron-based amorphous metal is generally in excess of 1100kg/mm². In contrast, the hardness of the air-cooled, oil-quenched and water-quenched tool steels ranged from 800-². Thus, amorphous metals, due to their unique atomic structure and chemistry, have a hardness greater than that of conventional metal punch and die materials.

Third, amorphous metal may undergo severe deformation without cracking when forced between the punch and die during stamping before being stamped down. The deformation of the amorphous metal is caused by large local shear flows. The formation of a shear band can result in failure with little overall deformation when deformed under tension, such as when amorphous metal strip is drawn. Under tension, failure can occur at 1% or less elongation. However, when deformed in such a way that mechanical constraints prevent plastic instability, such as bending between the tool and die during stamping, multiple shear bands may form and undergo severe localized deformation. In this way of deformation, the elongation at failure can be locally more than 100%.

These latter two factors, the unusually high hardness plus severe deformation, combine to produce significant wear on the punch and die elements of the press when conventional stamping equipment, conventional tools and processes are used. Wear to the punch and die occurs through direct abrasion of the hard amorphous metal against the softer punch and die material during deformation prior to being blanked.

The present invention provides a method for minimizing wear on the punch and die during the stamping process. The method comprises the following steps: punch and die tools are made of carbide material, the tools are made in such a way that the separation between the punch and the die is small and uniform, and the stamping process is operated at a high strain rate. The carbide material for the punch and die tools should have a hardness of at least 1100kg/mm²Preferably has a hardness of more than 1300kg/mm²The hardness of (2). Carbide tools having a hardness equal to or greater than that of amorphous metal will prevent direct wear caused by amorphous metal during the stamping process, thus minimizing wear on the punch and die. The clearance between the punch and die should be less than 0.050mm (0.002 inch), and preferably less than 0.025mm (0.001 inch). The strain rate used during the stamping process should be that produced by at least one stroke per second and preferably 5 strokes per second. This range of stroke speeds corresponds approximately to at least 10 for 0.025mm (0.001 inch) thick amorphous metal strip⁵A deformation rate per second, preferably equal to 5X 10⁵Deformation rate per second. The small clearance between the punch and die used during the stamping process, combined with the high strain rate, limits the amount of mechanical deformation of the amorphous metal prior to blanking during the stamping process. Limiting the mechanical deformation of the amorphous metal that occurs within the die cavity will limit wear between the amorphous metal and the punch and die, thus minimizing wear of the punch and die.

The magnetic properties of 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. A magnetic field may optionally be applied to the strip during at least a portion of the heat treatment, for example at least during a cooling portion of the heat treatment.

The heat treatment of the amorphous metal used in the present invention may use any heating means which subjects the metal to the required thermal change process. Suitable heating means include: infrared heat sources, ovens, fluidized beds, and heat sinks maintained at high temperatures, resistive heating by passing an electric current through the metal strip, and inductive (RF) heating. The selection of the heating means may be made according to the sequence of required process steps described above.

Further, the heat treatment may be performed on the metal strip material prior to the stamping step, on discrete stacks after the stamping step but before the stacking step, or on a stack after the stacking step. The heat treatment may be performed prior to the stamping step, where the entire roll of material is subjected to a separate off-line batch process, preferably in an oven or fluidized bed, or in a continuous roll-to-roll process, where the metal strip from the feed roll is passed through a heating zone and received on the take-up roll. Alternatively, the heat treatment may be performed in-line, where the metal strip from the coil is passed continuously through a heating zone and thereafter into a press for subsequent stamping and stacking.

The heat treatment may also be performed on the discrete stacks after the stamping step and before the stacking step. In this embodiment, the laminate is preferably fed out of the press and placed directly on a conveyor belt which passes the laminate through a heating zone, whereby the laminate is subjected to a suitable time-temperature process.

In another embodiment, the heat treatment is performed after the discrete stacks are stacked in registration. Suitable heating means for annealing such a stack include ovens, fluidised beds and induction heating means.

A bonding means is used to bond a plurality of aligned stacks of amorphous metal material to one another, thereby enabling three-dimensional objects having sufficient structural integrity to be handled, used, or included in larger structures. There are a variety of suitable binders, including epoxies, varnishes, anaerobic adhesives, and Room Temperature Vulcanizing (RTV) silicone materials. The adhesive desirably has a low viscosity, low shrinkage, low elastic modulus, high peel strength, and high dielectric strength. The epoxy may be multi-part, the curing of which is initiated chemically, or single-part, the curing of which is initiated by heat or exposure to ultraviolet radiation. Suitable methods for applying the adhesive include dipping, spraying, brushing, and electrostatic deposition. Amorphous metal in the form of a strip or ribbon may also be coated with adhesive by passing it over a rod or roller that transfers the adhesive to the amorphous metal. The roller or bar having a textured surface, such as a gravure or wire-wound roller, is particularly effective for transferring a uniform coating of adhesive to amorphous metal. The adhesive may be applied to a separate layer of amorphous metal each time, either to the ribbon material prior to stamping or to the stack after stamping. Further, an adhesive applying device may be applied to the stacked laminated body after being stacked. In this case, the layers of the laminate are filled with a capillary flow of adhesive. The stack may be placed under vacuum, or under hydrostatic pressure, in order to be more effectively completely filled and still minimize the total volume of adhesive added, thus ensuring a high stacking factor.

A first embodiment of the invention is shown in figure 2A. A roll 30 of ferromagnetic amorphous metal strip material 32 is continuously passed through an annealing furnace 36 in which the strip temperature is raised to a value and held for a time sufficient to improve the magnetic properties of the strip. The strip material is then passed through an automatic high speed punch 38 between a punch 40 and an open-bottomed die 41. The punch is driven into the die, thereby forming the laminate 20 in the desired shape. The stack is then dropped or otherwise transferred to a magazine 48 and the punch 40 is retracted. Leaving a skeleton 33 of tape material 32 containing holes 34 formed after removal of the laminate 20. The skeleton 33 is collected on the take-up reel 31. After each press is completed, the strip 32 is marked to prepare the strip for the next press cycle. The strip material 32 may be fed into the press 38 either in a single layer or in multiple layers (not shown), or in multiple layers by multiple feeds or by being pre-rolled into multiple layers. The use of multiple layers of belt material 32 may advantageously reduce the number of strokes required to produce a given number of stacks. As the stamping process continues, a number of stacks 20 are collected in sufficient alignment in the magazine 48. After the desired number of stacks 20 have been punched and stacked in the magazine 48, the operation of the punch press 38 is interrupted. The desired number is either preselected or determined by the height of the stacks 20 stacked within the magazine 48. The magazine 48 is then removed from the press 38 for further processing. A low viscosity thermally activated epoxy (not shown) may be allowed to penetrate in the spaces between the stacks 20, the stacks 20 being held in alignment by the walls of the box 48. The epoxy is then cured by exposing the entire case 48 and the stack 20 contained therein to a heat source for a period of time to allow the epoxy to activate. The stack 10 of the stack 20 (see fig. 1A-1C) is now removed and the surface of the stack 10 is modified by removing any excess epoxy.

A second embodiment is shown in fig. 2B. A roll 30 of ferromagnetic amorphous metal strip material 32 is continuously passed through an annealing furnace 36 in which the strip temperature is raised to a value and held for a time sufficient to improve the magnetic properties of the strip 32. The tape 32 is then passed through an adhesive application device 50 comprising a gravure roll 52 on which is coated a low viscosity heat activated epoxy from within an adhesive reservoir 54. Thus, the epoxy is transferred from the roller 52 to the lower surface of the belt 32. The distance between the annealing oven 36 and the adhesive application device 50 is sufficient to allow the tape 32 to cool to at least below the thermal activation temperature of the epoxy during passage. In addition, a cooling device (not shown) may be used to achieve faster cooling of the ribbon 32 between the annealing lehr 36 and the coating device 50. The strip material 32 is then passed through an automatic high speed punch 38 between a punch 40 and an open-bottomed die 41. The punch is driven into the die, thereby forming the laminate 20 in the desired shape. The stack is then dropped or otherwise transferred to a magazine 48 and the punch 40 is retracted. Leaving a skeleton 33 of tape material 32 containing holes 34 formed after removal of the laminate 20. The skeleton 33 is collected on the take-up reel 31. After each press is completed, the strip 32 is marked to prepare the strip for the next press cycle. As the stamping process continues, a number of stacks 20 are collected in sufficient alignment in the magazine 48. After the desired number of stacks 20 have been punched and stacked in the magazine 48, the operation of the punch press 38 is interrupted. The desired number is either preselected or determined by the height of the stacks 20 stacked within the magazine 48. The magazine 48 is then removed from the press 38 for further processing. Additional low viscosity, thermally activated epoxy (not shown) may be allowed to penetrate in the spaces between the stacks 20, the stacks 20 being held in alignment by the walls of the box 48. The epoxy is then cured by exposing the entire case 48 and the stack 20 contained therein to a heat source for a period of time to allow the epoxy to activate. The stack 10 of the stack 20 (see fig. 1A-1C) is now removed and the surface of the stack 10 is modified by removing any excess epoxy.

A third embodiment is shown in fig. 2C. The ferromagnetic amorphous metal ribbon is first annealed in an inert gas oven (not shown) at a predetermined temperature and for a predetermined time sufficient to improve its magnetic properties without altering substantially the entire glassy microstructure. The heat treated metal strip 32 is fed from the coil 30 between the punch 40 and the open-bottomed die 41 of the automatic high-speed punch 38. The punch is driven into the die, thereby forming the laminate 20 in the desired shape. The stack 20 is now dropped or transported outside the die 41 to a collection device 49 and the punch 40 is retracted. The collection device 49 may be a conveyor belt, as shown in FIG. 2C, or may be a container for collecting the stack 20. Leaving a skeleton 33 of tape material 32 containing holes 34 formed after removal of the laminate 20. The skeleton 33 is collected on the take-up reel 31. After each press is completed, the strip 32 is marked to prepare the strip for the next press cycle. The stamping process is continued until a predetermined number of stacks 20 are collected in the container and the stamping cycle is then stopped. One side of each laminate 20 may then be manually coated with an anaerobic adhesive and the laminates stacked in an aligned state in an aligned fixture (not shown). The adhesive is allowed to cure and the stack 10 of stacks 20 is now removed from the alignment fixture and the surface of the stack 10 is finished by removing any excess epoxy.

Another embodiment is shown in fig. 2D. A roll 30 of ferromagnetic amorphous metal strip material 32 is continuously fed into an automated high speed punch 38 between a punch 40 and an open-bottomed die 41. The punch is driven into the die, thereby forming the laminate 20 in the desired shape. The stack 20 is now dropped or otherwise conveyed to a magazine 48 and the punch 40 is retracted. Leaving a skeleton 33 of tape material 32 containing holes 34 formed after removal of the laminate 20. The skeleton 33 is collected on the take-up reel 31. After each press is completed, the strip 32 is marked to prepare the strip for the next press cycle. The strip material 32 may be fed into the press 38 either in a single layer or in multiple layers (not shown), or in multiple layers by multiple feeds or by being pre-rolled into multiple layers. The use of multiple layers of belt material 32 may advantageously reduce the number of strokes required to produce a given number of stacks. The stamping process is continued and a number of stacks 20 are collected in sufficient alignment in the magazine 48. After the desired number of stacks 20 have been punched and stacked in the magazine 48, the operation of the punch press 38 is interrupted. The desired number is either preselected or determined by the height of the stacks 20 stacked within the magazine 48. The magazine 48 is then removed from the press 38 for further processing. In one method of implementation, the enclosure 48 and the stack 20 therein are placed in an inert gas oven (not shown) and annealed at a predetermined temperature and for a predetermined time sufficient to improve the magnetic properties thereof without altering substantially all of the glassy microstructure. The box and stack are then cooled to ambient temperature. A low viscosity thermally activated epoxy (not shown) may be allowed to penetrate in the spaces between the stacks 20, the stacks 20 being held in alignment by the walls of the box 48. The epoxy is then activated by placing the entire box 48 and the stack 20 therein in a curing oven for a sufficient time to effect curing of the epoxy. The stack 10 of the stack 20 (see fig. 1A-1C) is now removed and the surface of the stack 10 is modified by removing any excess epoxy.

Bulk amorphous metal magnetic components constructed in accordance with the present invention are particularly well suited for use as tiles for pole face magnets in high performance MRI systems, television and video systems, and electron beam and ion beam systems. The manufacture of the magnetic element is simplified and the manufacturing time is shortened. Reducing the stresses experienced during the manufacture of the bulk amorphous metal magnetic component and optimizing the performance of the final bulk amorphous metal magnetic component.

The bulk stamped 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_0-20Defining subscripts are atomic percentages wherein 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; with the proviso that: (i) up to 10 atomic percent of component M may be 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) up to 10 atomic percent of component (Y + Z) may be replaced by at least one of the non-metallic species In, Sn, Sb and Pb, and (iii) about 1 atomic percent of component (M + Y + Z) may be incidental impurities. The term "amorphous metal alloy" as used herein 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 those observed for liquid or inorganic oxide glasses.

Alloys suitable for use in the practice of the present invention are ferromagnetic at the temperatures at which the components are to be used. A ferromagnetic material is a material that has a strong long-range coupling and spatial arrangement of the magnetic moments of its constituent atoms at temperatures below a characteristic temperature of the material (commonly referred to as the curie temperature). Preferably, the Curie temperature of the material used in the device to be operated at room temperature is at least about 200 deg.C, more preferably at least about 375 deg.C. These devices may be operated at other temperatures, including as low as freezing or as high as possible, provided that the materials included therein have a suitable curie temperature.

As is known in the art, a ferromagnetic material is also characterized by its saturation induction, or equivalently, by its saturation flux density or magnetization. Alloys suitable for use in the present invention preferably have a saturation induction of at least about 1.2T, more preferably at least about 1.5T. The alloy also has a high electrical resistivity, preferably at least about 100 μ Ω -cm, and more preferably at least about 130 μ Ω -cm.

Amorphous metal alloys are commercially available in the form of generally continuous thin strips 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 strip composed of an iron-boron-silicon alloy is 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 amorphous metal strip having a composition consisting essentially of about 11 atomic percent boron and about 9 atomic percent silicon, with the balance being iron and incidental impurities. Such a ribbon having a saturation induction of about 1.56T and a resistivity of about 137 μ Ω -cm is sold by Honeywell international inc under the trademark METLAS alloy 2605 SA-1. Those skilled in the art will appreciate that embodiments of the present invention, which require continuous, automated feeding of ribbon stock through a punch press, may conveniently use amorphous metal, for example, supplied as a thin ribbon roll. Further, the invention may be practiced with other forms of stock and other feeding methods, including manually feeding shorter length belts or other shaped belts having a non-uniform width.

Systems comprising electromagnets with one or several pole face magnets are commonly used to generate a time-varying magnetic field in the gap of the electromagnet. The time-varying magnetic field may be entirely an 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 the electromagnet system, at least one pole face magnet is under a time-varying magnetic field. As a result, the pole face magnet is magnetized and demagnetized at each excitation period. Time-varying magnetic flux density or magnetic induction in a pole face magnet generates heat from core losses therein. In the case of a pole face composed of a plurality of bulk magnetic elements, the total loss is composed of two parts, one part being the core loss that would be generated within each element if it were under an ac flux waveform in isolation, and the other part being the loss due to eddy currents circulating in the path providing continuity of electricity between the elements.

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

It is believed in the prior art that eddy currents in pole pieces constructed from elongated ferromagnetic rods can be reduced by insulating the ferromagnetic rods from each other by inserting a non-conductive material. The present invention provides a further substantial reduction in overall losses because the use of the materials and construction methods taught by the present invention reduces the losses generated within each element based on the losses experienced by prior art elements made from other materials and construction methods.

Core loss, as is well known in the artLosses are the energy dissipation that occurs within a ferromagnetic material as the magnetization of the ferromagnetic material changes over time. The core loss of a given magnetic component is typically determined by cyclic excitation of the component. A time-varying magnetic field is applied to the element to produce a corresponding time-varying magnetic induction or flux density therein. In order to standardize the measurement, the excitation is generally selected such that the magnetic induction is at a frequency "f" and a peak value "B_max"downward varies sinusoidally with time. The core loss is then determined using known electrical measurement instruments and techniques. Core losses are generally expressed in watts of magnetic material per unit mass or per unit volume that is excited. It is well known in the art that core loss varies with f and B_maxMonotonically increasing. The most standard protocols for testing the core loss of soft magnetic materials used in components of pole face magnets, such as ASTM standards a912-93 and a927(a927M-94), require that a sample of the material be located in a substantially closed magnetic circuit, i.e. a configuration in which the closed magnetic field lines are completely contained within the volume of the sample. On the other hand, the magnetic material used in the components, such as the pole face magnets, is placed in an open magnetic circuit, i.e. an arrangement in which the magnetic field lines have to cross the air gap. Because of edge effects and non-uniformities of the magnetic field, a given material tested in an open circuit generally has a higher core loss, i.e., a higher wattage per unit mass or volume, than measurements in a closed circuit. The bulk magnetic component of the present invention has low core losses over a wide range of flux densities and frequencies, even in an open circuit configuration.

Without being bound by any theory, it is believed that the total core loss of the low-loss bulk amorphous metal component of the present invention consists of hysteresis losses and eddy current losses. Both contributions are peak magnetic induction B_maxAnd the excitation frequency f. The amount of each contribution depends in turn on external factors including the manufacturing method of the component and the thermal history of the materials used in the component. Prior art analyses of core loss for amorphous metals (see g.e.fish, j.appl.phys.57, 3569(1985) and g.e.fish et al, j., appl.phys.64, 5370(1998)) are generally limited to magnetic material in a closed magnetic circuitThe data obtained. The low hysteresis and eddy current losses seen in these analyses are due in part to the high resistivity of the amorphous metal.

Total core loss per unit mass L (B) of the bulk amorphous metal component of the present invention_maxF) can be determined substantially by a function of the form:

L(B_max，f)＝c₁f(B_max)ⁿ+c₂ f^q(B_max)^m

where the coefficients c1 and c2, and the indices n, m and q must be determined experimentally, since there is no known theory to be able to determine their values accurately. Using this formula enables the total core loss of the bulk amorphous metal component of the invention to be determined at any desired operating magnetic induction and excitation frequency. It has been found that the magnetic field in bulk amorphous metal components 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 the peak flux density in space and time approaching the flux density distribution measured in an actual bulk amorphous metal component. These techniques are capable of predicting with suitable accuracy the corresponding core loss of a given element in its operating configuration by using as input suitable experimental formulae that give the core loss of the material at spatially uniform flux densities.

The measurement of core loss for the magnetic component of the present invention can be measured using a number of methods known in the art. A method suitable for measuring the magnetic component of the present invention includes forming a magnetic circuit having the magnetic component of the present invention and a flux closure structure apparatus. In another approach, the magnetic circuit may comprise a plurality of magnetic elements of the present invention and a flux closure structure means in operation. Generally, the flux closure structure arrangement 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 detected. Preferably, said soft magnetic material has a magnetic density at least equal to the saturation of the component. The direction of such magnetic flux generally defines 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 follow the plane of the amorphous metal strip of the component 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. 3, there is shown one form of apparatus 60 for carrying out the above described testing method which does not require a flux closure structure apparatus. The apparatus 60 comprises 4 bulk stamped amorphous metal magnetic components 10 of the present invention. Each element 10 is a portion of a right circular cylinder having an arcuate surface 12 shaped as shown in figure 1C. Each element has a first opposing surface 66a and a second opposing surface 66 b. The elements 10 are arranged in a mating relationship to form a device 60 that is substantially in the shape of a right circular cylinder. The first opposed surface 66a of each element 10 is immediately adjacent to and aligned substantially parallel with the corresponding first opposed surface 66a of its adjacent element 10. Thus 4 sets of adjacent surfaces of the elements 10 define 4 equally spaced gaps 64 along the circumference of the device 60. The mating relationship of the components 10 may be secured by means of the tape 62. The device 60 forms a magnetic circuit having 4 magnetically permeable portions (each comprising one element 10) and 4 gaps 64. Two copper wire windings (not shown) are wound annularly by the device 60. An alternating current of suitable magnitude is passed through the first winding to provide a magnetomotive force which excites the device at the desired frequency and peak flux density. The magnetic field lines are substantially in the plane of the band 20 and in the circumferential direction. A voltage is induced in the second winding indicative of the time-varying magnetic flux density in each element 10. From the measured voltage and current values, the total core loss is determined using conventional electronics and is divided equally among the 4 elements 10.

For a more complete understanding of the present invention, examples are given below. Wherein specific techniques, conditions, materials, proportions and reported data are used to explain the principles and practice of the invention, they are by way of example only and are not intended to limit the scope of the invention.

Example 1

Preparation and electromagnetic testing of stamped amorphous metal arch elements

Fe₈₀B₁₁Si₉Ferromagnetic amorphous metal strip, approximately 60 mm wide and 0.022 mm thick, is stamped to form individual laminations, each having the shape of a 90 degree torus portion having an outer diameter of 100mm and an inner diameter of 75 mm. Approximately 500 laminations are stacked and aligned to form an arcuate portion of a 90 degree right circular cylinder having a height of 12.5mm, an outer diameter of 100mm and an inner diameter of 75mm as shown in figure 1C. The cylindrical part of the device was placed in a fixture and 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 device to ambient temperature. The cylindrical portion means is removed from the fixing means. The cylindrical part assembly was placed in a second fixture, vacuum impregnated with an epoxy resin solution and cured at 120 ℃ for about 4.5 hours. When fully cured, the cylinder part means is removed from the second fixture means. Obtained (a)The weight of the epoxy bonded amorphous metal cylindrical part arrangement was approximately 70 g. The above process was repeated so that a total of 4 such devices were formed. The 4 devices were placed and bundled in a mating relationship to form a substantially cylindrical test device with 4 equally spaced gaps as shown in fig. 3. The primary and secondary electrical windings are secured to the cylindrical test apparatus for electrical testing.

The test apparatus has a core loss of less than 1 watt per kilogram of amorphous metal material when operated at a frequency of about 60 hertz, a magnetic density of about 1.4T, less than 12 watts per kilogram of amorphous metal material when operated at a frequency of about 1000 hertz, a magnetic density of about 1.0T, and less than 70 watts per kilogram of amorphous metal material when operated at a frequency of about 20000 hertz, a magnetic density of about 0.30T. The low core loss of the element of the present invention makes it suitable for use in constructing pole faces.

Example 2

High frequency electromagnetic testing of stamped amorphous metal arch elements

A cylindrical test device having 4 stamped amorphous metal arcuate components as described in example 1 was prepared. Primary and secondary electrical windings are provided on the test device. Electrical tests were performed at 60, 1000, 5000, and 20000 hertz and different magnetic densities. Core loss values are compiled in tables 1, 2, 3 and 4 below. As shown in tables 3 and 4, the core loss is exceptionally low at excitation frequencies of 5000hz or higher. The magnetic component of the invention is thus particularly suitable for use in a pole face magnet of an MRI system.

TABLE 1

Core loss at 60Hz (W/kg)

	Material
						Magnetic flux density	Amorphous Fe80B11Si9(22μm)	Crystal Fe-3% Si (25 μm)	Crystalline Fe-3% Si (50 μm)	Crystalline Fe-3% Si (175 μm)	Crystalline Fe-3% Si (275 μm)
		National-ArnoldMagnetics Silectron	National-ArnoldMagnetics Silectron	National-ArnoldMagnetics Silectron	National-ArnoldMagnetics Silectron
						0.3T	0.10	0.2	0.1	0.1	0.06
0.7T	0.33	0.9	0.5	0.4	0.3
						0.8T		1.2	0.7	0.6	0.4
1.0T		1.9	1.0	0.8	0.6
						1.1T	0.59
1.2T		2.6	1.5	1.1	0.8
						1.3T	0.75
1.4T	0.85	3.3	1.9	1.5	1.1

TABLE 2

Core loss at 1000Hz (W/kg)

	Material
						Magnetic flux density	Amorphous Fe80B11Si9(22μm)	Crystal Fe-3% Si (25 μm)	Crystalline Fe-3% Si (50 μm)	Crystalline Fe-3% Si (175 μm)	Crystalline Fe-3% Si (275 μm)
		National-ArnoldMagnetics Silectron	National-ArnoldMagnetics Silectron	National-ArnoldMagnetics Silectron	National-ArnoldMagnetics Silectron
						0.3T	1.92	2.4	2.0	3.4	5.0
0.5T	4.27	6.6	5.5	8.8	12
						0.7T	6.94	13	9.0	18	24
0.9T	9.92	20	17	28	41
						1.0T	11.51	24	20	31	46
1.1T	13.46
						1.2T	15.77	33	28
1.3T	17.53
						1.4T	19.67	44	35

TABLE 3

Core loss at 5000Hz (W/kg)

	Material
					Magnetic flux density	Amorphous Fe80B11Si9(22μm)	Crystal Fe-3% Si (25 μm)	Crystalline Fe-3% Si (50 μm)	Crystalline Fe-3% Si (175 μm)
		National-ArnoldMagnetics Silectron	National-ArnoldMagnctics Silcctron	National-ArnoldMagnetics Silectron
					0.04T	0.25	0.33	0.33	1.3
0.06T	0.52	0.83	0.80	2.5
					0.08T	0.88	1.4	1.7	4.4
0.10T	1.35	2.2	2.1	6.6
					0.20T	5	8.8	8.6	24
0.30T	10	18.7	18.7	48

TABLE 4

Core loss at 20000Hz (W/kg)

	Material
					Magnetic flux density	Amorphous Fe80B11Si9(22μm)	Crystal Fe-3% Si (25 μm)	Crystalline Fe-3% Si (50 μm)	Crystalline Fe-3% Si (175 μm)
		National-ArnoldMagnetics Silectron	National-ArnoldMagnetics Silectron	National-ArnoldMagnetics Silectron
					0.04T	1.8	2.4	2.8	16
0.06T	3.7	5.5	7.0	33
					0.08T	6.1	9.9	12	53
0.10T	9.2	15	20	88
					0.20T	35	57	82
0.30T	70	130

Example 3

High frequency performance of low loss bulk amorphous metal magnetic component

The core loss data obtained in example 2 above was analyzed by a conventional nonlinear 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+c₂ f^q(B_max)^m.

suitable values for the coefficients c1, c2 and the indices n, m, and q are selected to provide an upper limit on the magnetic loss of the bulk amorphous metal magnetic component. Table 5 cites the losses measured by the element of example 2 and predicted by the above formula, in 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 2 is less than the corresponding loss predicted by the equation.

TABLE 5

Dot	Bmax(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

Having described the invention in detail, it will be understood that the invention is not necessarily limited to such detail, but is capable of numerous variations and modifications without departing from the spirit of the invention as defined in the appended claims.

Claims (8)

1. A low-loss bulk amorphous metal magnetic component comprising a plurality of identical laminations stamped from ferromagnetic amorphous metal strips, said laminations being stacked and bonded together with an adhesive to form a polyhedrally shaped part, and

wherein the element, when excited at an excitation frequency "f", reaches 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)^2.4Giving, said core losses, excitation frequency and peak magnetic inductionThe units of values are watts/kg, hertz and tesla, respectively.

2. A bulk amorphous metal magnetic component as recited by claim 1, wherein said ferromagnetic amorphous metal strip has the general formula M_70-85Y_5-20Z_0-20Defined composition, subscripts are atomic percentages, wherein 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; with the proviso that: (i) up to 10 atomic percent of component M may be 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, and (ii) up to 10 atomic percent of component (Y + Z) may be replaced by at least one of the non-metallic species In, Sn, Sb and Pb, and (iii) up to 1 atomic percent of component (M + Y + Z) may be incidental impurities.

3. A bulk amorphous metal magnetic component as recited by claim 2, wherein each of said ferromagnetic 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, with the proviso that the total content of B and Si is at least 15 atom percent.

4. A bulk amorphous metal magnetic component as recited by claim 3, wherein each of said ferromagnetic amorphous metal strips has the general formula Fe₈₀B₁₁Si₉Defined composition.

5. 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.

6. 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.

7. 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.

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