JPH0542497B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to ferromagnetic vitreous metal bodies consolidated from vitreous alloy powders. Amorphous metal alloys and articles made therefrom are disclosed in U.S. patent no.
It is described in Specification No. 3856513 (issued December 24, 1974). This specification teaches certain new alloy compositions that are obtained in an amorphous state and are superior to previously known crystalline alloys based on the same metal. These compositions can be easily quenched to an amorphous state and have desirable physical properties. Also, by atomizing the molten alloy to form droplets and quenching these droplets in a liquid such as water, chilled brine, or liquid nitrogen, particles with a particle size of about 10 to 250 μm can be produced. It is also stated that amorphous metal powders can be produced. It is known to produce magnetic articles by consolidating permalloy and other amorphous alloy powders. New applications requiring improved magnetic properties have simultaneously required efforts to develop alloys and consolidation methods that increase the strength and magnetic response of magnetic articles. The present invention provides an amorphous alloy powder that is particularly suitable for aggregation into objects with excellent strength and magnetic response. Furthermore, according to the invention, the aggregation of the vitreous metal powder is carried out using mechanical pressure and/or binders at elevated temperatures below the crystallization temperature of the substance. The present invention also teaches optimal powder dimensions and preferred alloy compositions, suitable binder materials, and post-processing heat treatments. Articles made according to the invention have low core loss and high magnetic permeability. Generally this kind of united magnetic glassy metal body has a frequency of 5kHz and an induction level
It has an initial relative permeability of at least about 70 at 0.1 Tesla. As used herein, the term "relative permeability" shall mean the ratio of the magnetic induction caused by a particular magnetic field in a medium to the magnetic induction caused by the same magnetic field in vacuum. The magnetic compact bodies of the present invention with high magnetic permeability are generally manufactured from powdered vitreous or amorphous alloys. A common method for producing metallic glass powders from alloys involves a quenching step of the molten alloy followed by a milling step. The manufacture of glassy alloys is covered by U.S. Patent No.
3856553 (Chien et al.). The resulting sheets, ribbons, tapes and wires are useful precursors for the materials described herein. Fine pulverization of these amorphous materials is performed as follows. An amorphous material in the form of a sheet, ribbon, wire or flake is heated above its embrittlement temperature but below its crystallization temperature and mechanically fractured. The resulting flakes and powders of various sizes are sieved to collect flakes and powders of desired size. Other methods for obtaining glassy metal alloy powders are shown in US Pat. No. 4,290,803 (Ray et al.). When starting from powder, powder consolidation is the first step to produce the object. The powder for binding is a fine powder (approximately 2~
(with a particle size in the range of 100 μm), coarse powder (with a particle size of 100 to 1000 μm), and flakes (with a particle size of 1000 μm to about 2 mm). These flakes and powders are hereinafter simply referred to as powders or powder particles. Consolidation is accomplished by compacting or adhesively bonding the vitreous metal alloy powder. If low permeability is desired, particle diameters of about 5-10 μm are used. To obtain high magnetic permeability, larger particle diameters of about 180 μm or more are used. Relatively high permeability (e.g. 5kHz and 0.1
A combination of tesla induction of the order of about 200) and excellent mechanical hardness (eg of the order of about 400 Kg/mm ² ) is achieved by the use of particles with a mesh size (US sieve) of about 80. The flake core uses larger particles with parallel planes. The properties in this case approach those of a lamellar core. For consolidation, the powder is placed in an evacuated can and hot rolled below the glass transition temperature of the alloy.
Alternatively, it can be hot isostatically pressed in an equilibrium state to form the desired shape. Additionally, the powders can be conventionally hot compacted below their glass transition temperature in vacuum or other protective atmosphere into any desired shape. Preferably, the powder is compacted at a pressure of at least 7 MPa and at a temperature of 85-95% of the glass transition temperature. High pressures and temperatures can also be used to obtain compacted amorphous shape densities near the theoretical maximum with short pressing times. Fe ₇₈ B ₁₃ Si ₉
The table shows the effect of time, temperature and pressure on compacted density for glassy alloys. The relative density will increase as the temperature increases to the glass transition temperature and as the pressure increases. By using high pressures and temperatures near the glass transition temperature, compression times can be reduced to a few seconds.

[Table] The powder can be mixed with a suitable organic binder (such as paraffin) and then cold pressed into the appropriate shape. Resins, such as phenol formaldehyde resins, as insulators and binders;
For example, Bakelite (trademark of Union Carbide Company) is used. Other suitable binders include synthetic resins, dry oils, distillation residues of oils or fats, solutions of gums or resins, and oxidized oil or wax compounds. Certain oxides such as SiO ₂ , MgO and B ₂ O ₃ can be mixed with powders and this mixture can be united under pressure at elevated temperatures below the glass transition temperature or crystallization temperature of the powders. . Certain acids, such as borates, can be mixed with the powder and the mixture consolidated under pressure at an elevated temperature below the glass transition or crystallization temperature of the powder. In this case, the acids decompose during coalescence into certain oxides (for example B ₂ O ₃ in the case of borates) and water (which evaporates during coalescence). The amount of binder is up to 30% by weight, preferably below 10% by weight for high permeability cores, more preferably between 0.1 and 30% by weight.
It is 4% by weight. . Such shaped alloys may have a density of at least 90% of the theoretical maximum. The compressed object is cured at a relatively low temperature below the glass transition temperature to give it greater strength,
It can then be ground to final dimensions. Preferred products from this method have a shape suitable for magnetic components. The curing process can be performed while simultaneously applying a magnetic field. Preferably, the curing process is carried out in the absence of oxygen. These processes are
Optimal heat treatment cycles are adapted to obtain products of desired magnetic and structural properties produced from glassy metal alloys. After compaction, the final product is ground to final dimensions. This process is suitable for machining large engineering equipment with simple geometries. Furthermore, if desired, the final product can be
Annealing can be done depending on the particular alloy used in the application at hand. The solid body has a density not less than about 60%, preferably 95%, of the as-formed alloy. Metallic glasses are molten alloy products that have been cooled to a rigid state without crystallization. This kind of metallic glass generally has the following properties: high hardness and scratch resistance, large vitreous surface smoothness, dimensional and shape stability, mechanical stiffness, strength,
ductility, high electrical resistance compared to related metals and their alloys, excellent magnetic flexibility (magnetic
softness) and an X-ray diffraction pattern. The word "alloy" is used here in its ordinary sense to denote a solid mixture of two or more metals (Condensed Chemical Dictionary).
Dictionary), 9th edition, Juan Norstrand Reinhold, Inc., New York, 1977).
These alloys further contain at least one non-metallic element. “glassy or
The terms "vitreous metal alloy", "metallic glass", and "amorphous metal alloy" are all considered equivalent when used herein. It has a composition consisting of M _a Mo _b Z _c , where M is Fe,
at least 1 of Ni and Co; Z is at least 1 of B, Si and C; a, b and c are atomic percent, a+b+c equals 100 and a is 78-
81.5, b is 4 or less, c is in the range 18-22. During compaction, each powder is subjected to a different degree of external stress. The external stress changes the magnetic properties of the powder if it is magnetostrictive. Therefore, it is desirable to consolidate powders with low saturation magnetostriction. This is especially true for cohesive materials for use at high frequencies. Saturation magnetostriction λ _s is related to the fractional change in length Δ/ that occurs in a magnetic material when going from a demagnetized state to a saturated ferromagnetic state. Magnetostriction (a unitless quantity) is often expressed in units of microstrain (ie, a microstrain is a fractional change in length of 1 ppm). The quantity λ _s is positive or negative and is determined depending on the material whose soft magnetism is strongly influenced by this quantity. The preferred absolute value of λ _s for powders is approximately 10×10 ^-6 (i.e.
10 ppm), which is the majority of glassy alloy powders based on cobalt and nickel, as well as Cr, Mo, W, V, with about 40 at.% iron.
Approximately 2 atomic % or less of at least one element selected from the group consisting of Nb, Ta, Ti, Zr and Hf, or approximately 40 to 88 atomic % of iron and Cr, Mo, W, V, Nb,
It is found in iron-based glassy alloy powders containing 2 atomic percent or more of at least one element selected from the group consisting of Ta, Ti, Zr, and Hf.
The most preferred value of λ _s for powders is near zero, or zero, which is achieved in cobalt-based vitreous alloy powders with iron to cobalt content ratios ranging from about 0.03 to about 0.13. If magnetostriction is not an important factor, as is the case in most low frequency applications (ie in the 50/60 Hz region), there is no need to consider these. Amorphous metal powder can be compressed into parts suitable for various uses, such as electromagnetic cores and pole pieces. Vitreous metal compacts have high magnetic permeability. These may have much less nickel than ordinary compression alloy bodies of comparable magnetic permeability.
The obtained core can be used as a transformer core or for other alternating current applications. The following examples and references are presented to provide a more complete understanding of the invention. The specific techniques, conditions, materials, proportions, and data reported to illustrate the principles and practice of the invention are illustrative and should not be construed as limiting the scope of the invention. Reference Example 1 An amorphous metal powder having a size of several millimeters or less was prepared from an alloy having a composition of Fe ₇₈ B ₁₃ Si ₉ .
These powders were sieved and those with different dimensions were sorted. The sieved powder was compressed into a toroid-like body with inner and outer diameters of approximately 3.2 cm and 4.2 cm, respectively, and a height of approximately 0.7 cm. The temperature and pressure of the unity were 350°C and 345MPa, respectively. The effect of powder size on the magnetism of as-formed and annealed toroids is summarized in a table. This table shows that larger powders tend to give better magnetism, with powder sizes between 180 μm and 1.4 mm being most preferred to obtain the best overall magnetism. For example, about 180μm~1.4mm
Annealed toroids made from powders with dimensions in the range of 20 to 30 kHz have magnetic permeabilities of over 200 and 70 at 5 kHz and 50 KHz, respectively.

[Table] Reference Example 2 In the table, it is recognized that the magnetic permeability μ(f) of the toroid decreases as the frequency f increases.
This is due to eddy current losses caused by conductivity between the powders. This electrical conductivity is significant since each powder particle is not insulated. In general, eddy current losses in metallic ferromagnetic materials increase with frequency, the dimensions of the material, and its conductivity. Therefore, reducing particle size and interpowder conductivity will reduce eddy current losses. of various dimensions to increase powder-to-powder electrical resistance (the opposite of conductivity).
The table summarizes the effect of 2% by weight of SiO ₂ mixed with Fe ₇₈ B ₁₃ Si ₉ powder on the magnetism of the united core.
For cores made from powders larger than 180μm, borate was used to investigate the effect of different insulation properties.
7.5% by weight was also used. Borate is boric acid;
Decomposes into boron oxide, providing an excellent binder and insulation between powder particles. As the results in the table show, the insulation provided by SiO ₂ , or boron oxide, was indeed effective in improving high frequency magnetism. However, what was unexpected was the result that larger powder sizes yielded better magnetism. For example, the magnetic permeability μ for a core made from insulating powder with dimensions of 180 μm or more at 50 kHz and 0.1 T induction is approximately 160. μ (50k
Hz, 0.1T) = 42. Therefore, the size of the insulating powder is preferably about 180 μm or more in order to achieve good magnetism in the compressed core of the present invention.

Reference Example 3 A number of cores were produced from powders of various sizes insulated with 2% by weight SiO ₂ or 7.5% by weight borate. Powders with dimensions below 75μm, and 180μm to 1.4mm
The table shows the range of magnetism obtained in cores manufactured from and annealed. The overall properties of cores made from larger powders were better than those made from smaller powders. It is noteworthy that a low core loss (L) of 10 W/Kg and a high permeability (μ) of 1000 at 5 kHz and 0.1 T were achieved in an Fe-based powder core with a saturation induction of about 1.3 Tesla. These values are compared to a commercially available
This should be compared to the μ (5kHz, 0.1T) of about 1000 and L of about 5W/Kg for Ni-Zn ferrite.

[Table] Example 1 The performance of a ferromagnetic material is greatly influenced by its magnetostriction (λ) and the magnitude of magnetochemical action. The amount of λ introduces additional magnetic anisotropic energy due to internal stresses. Compressing magnetic powders places each powder under a different degree of stress. If the powder is magnetostrictive, its external stress increases its coercivity and changes its remanence, thus affecting the AC properties of the core. The table summarizes the relationship between the magnetostriction value of a powder material and the AC characteristics of a core compressed from powder of the same size. This table clearly shows that powder cores with lower magnetostriction exhibit better magnetic properties. Therefore, a low magnetostriction of about 10×10 ^-6 or less is preferred, and the most preferred value of λ is approximately zero to obtain the best overall magnetism of the compressed core of the present invention.

[Table] Example 2 In order to further improve the magnetism of the compressed core of the present invention manufactured from the powder with low magnetostriction shown in the table,
4% by weight SiO ₂ and 4% by weight MgO were added to insulate the powder particles. The results are shown in the table. Comparing the table to table data, it is clear that the insulated low magnetostrictive powder core exhibits the best overall magnetic properties. Permeability (μ) at 5kHz and 0.1 Tesla
800 to 1600 is related to Ni−Zn, but μ is “~”
1000” or better.

[Table] Although the present invention has been described in considerable detail above, it is not necessary to adhere to these detailed descriptions, and it is obvious that various changes can be made to those skilled in the art, and all of these changes are within the scope of the claims. Included in the description.

Claims (1)

[Scope of Claim] 1. A ferromagnetic vitreous metal body consolidated from powders having a particle size of 180 μm to 1.4 mm and annealed in a magnetic field, the vitreous alloy having substantially the formula M _a Mo _b
Zc , where M is Fe, Ni and Co
Z is at least 1 of B, Si and C; a, b and c are atomic %, a+b+c is equal to 100, a is 78-81.5;
b is 4 or less, c is in the range 18-22, and 5k
A consolidated ferromagnetic vitreous metal body consisting of a vitreous alloy having an initial relative magnetic permeability of at least 650 at Hz and an induction of 0.1 Tesla. 2. The glassy alloy has the composition Fe ₄₀ Ni ₃₈ Mo ₄ B ₁₈ and has an initial relative permeability of about 650 and a core loss of about 22 W/Kg at 5 kHz and 0.1 Tesla induction. The ferromagnetic glassy metal body described above. 3. Claims in which the glassy alloy has a composition of Co _72.2 Fe _5.8 Mo ₂ B ₁₅ Si ₅ and has an initial relative permeability of at least 800 and a core loss of about 19 W/Kg at 5 kHz and 0.1 Tesla induction Ferromagnetic glassy metal body according to item 1. 4 A ferromagnetic glassy metal body agglomerated from powders with a particle size of 180 μm-1.4 mm and annealed in a magnetic field, the glassy alloy substantially having the formula M _a Mo _b
Zc , where M is Fe, Ni and Co
Z is at least 1 of B, Si and C; a, b and c are atomic %, and a
+b+c is equal to 100, a is 78-81.5, b is 4
Hereinafter, c is in the range 18-22; and consists of a glassy alloy with an initial relative magnetic permeability of at least 650 at 5 kHz and 0.1 Tesla induction, in combination with SiO ₂ , MgO and B ₂ O ₃ A bonded ferromagnetic glassy metal body mixed with a binder consisting of an oxide selected from the group consisting of: 5. The glassy alloy has a composition of Fe ₄ Ni ₃₈ Mo ₄ B ₁₈ and has an initial relative permeability of about 650 and a core loss of about 22 W/Kg at 5 kHz and 0.1 Tesla induction. The ferromagnetic glassy metal body described above. 6. A claim in which the glassy alloy has a composition of Co _72.2 , Fe _5.8 Mo ₂ B ₁₅ Si ₅ and has an initial relative permeability of at least 800 and a core loss of about 19 W/Kg at 5 kHz and 0.1 Tesla induction. Ferromagnetic glassy metal body according to scope 4.