Alloy, magnetic core and method for manufacturing a tape from an alloy

Abstract

alloy that from Fe 100-a-b-e-d-x-y-z Cu a Note b M e T d Si x B y Z z and contains up to 1 atom% impurities, where M is Mo and / or Ta, T is one or more of the elements V, Cr, Co and Ni, and Z is one or more of the elements C, P and Ge, where a = 0.0 atom%, 0.0 atom% ≤ b < 2.0 atom%, 0.2 atom% ≤ c ≤ 3.0 atom%, 0.0 atom% ≤ d < 5.0 atom%, 12.0 atom% < x < 18.0 atom%, 5.0 atom% < y < 12.0 atom% and 0.0 atom% ≤ z < 2.0 atom%, and 2.1 atom% ≤ (b + c) ≤ 3.0 atom%, or Fe 74,7 C 0,8 Note 1,4 M1Si 15,5 B 6,6 , is formed in the shape of a band, a nanocrystalline structure in which at least 50 vol% of the grains have an average size smaller than 100 nm, a remanence relationship, J r / J s , < 0.02, where J r , the remanence polarization and J sthe saturation polarization is, and a coercive field strength, H c , exhibits less than 1% of the anisotropic field strength, H a , and / or is less than 10 A / m.

Description

[0001] The present invention relates to an alloy, in particular a soft magnetic alloy suitable for use as a magnetic core, a magnetic core and a method for producing a strip from an alloy.

[0002] Nanocrystalline alloys based on a composition of Fe 100-a-b-c-d-x-y-z Cu a Note b M c T a Si x B y Z z They can be used as magnetic cores in various applications. US 7,583,173 B2 discloses a wound magnetic core used, among other things, in a current transformer made of (Fe 1-a Nia) 100-x-y-z-α-β-ɣ Cu x Si y B z Note α M' β M'' ɣ consists of, where a ≤ 0, 3, 0, 6 ≤ x ≤ 1.5, 10 ≤ y ≤ 17, 5 ≤ z ≤ 14, 2 ≤ α ≤ 6, β ≤ 7, γ ≤ 8, M' is at least one of the elements V, Cr, Al and Zn and M'' is at least one of the elements C, Ge, P, Ga, Sb, In and Be.

[0003] EP 0 271 657 A2, JP H11 - 80 908 A, US 5 611 871 A and US 2008 / 0 196 795 A1 also disclose alloys with a composition based on this.

[0004] The publication by Herzer, G., Budinsky, V., and Polak, C. “Magnetic properties of FeCuNbSiB nanocrystallized by flash annealing under high tensile stress”, Physica Status Solidi B, Vol. 248, 2011, No. 10, pp. 2382–2388 describes the heat treatment of FeCuNbSiB alloys under tensile stress.

[0005] In applications for magnetic cores, low manufacturing costs are generally desirable. However, any cost reduction should ideally have no or only a minimal impact on the magnetic properties of the magnetic core.

[0006] The task is therefore to provide an alloy that has suitable magnetic properties for use as a magnetic core and that can be manufactured more cost-effectively.

[0007] This is resolved through the subject matter of the independent claims. Further developments are the subject matter of the respective dependent claims.

[0008] According to the invention, an alloy is specified which consists of Fe 100-a-b-e-d-x-y-z Cu a Note b M c T d Si x B y Z z and contains up to 1 atom% impurities. M is one or more of the elements Mo or Ta, T is one or more of the elements V, Cr, Co, or Ni, and Z is one or more of the elements C, P, or Ge, where a = 0.0 atom%, 0.0 atom% ≤ b < 2.0 atom%, 0.2 atom% ≤ c ≤ 3.0 atom%, 0.0 atom% ≤ d < 5.0 atom%, 12.0 atom% < x < 18.0 atom%, 5.0 atom% < y < 12.0 atom%, and 0.0 atom% ≤ z < 2.0 atom%. The sum of the elements Nb, Mo, and Ta (b + c) is 2.1 atom% ≤ (b + c) ≤ 3.0 atom%, or Fe 74,7 Cu 0,8 Note 1,4 Mo1S1 15,5 B 6,6The alloy is in the form of a ribbon and exhibits a nanocrystalline structure in which at least 50 vol% of the grains have an average size of less than 100 nm. The alloy also exhibits a remanence ratio, J r / J s , < 0.02, where J r the remanence polarization and J s the saturation polarization, and a coercive field strength, H c on, which are less than 1% of the anisotropic field strength, H a , and / or is less than 10 A / m.

[0009] The alloy thus has a composition with a niobium content of less than 2 atomic percent, as well as molybdenum (Mo) and / or tantalum (Ta), with the total content of Nb and / or Mo and / or Ta ranging between 2.1 and 3 atomic percent. This composition has the advantage of lower raw material costs compared to a composition with a higher niobium content, since niobium is a relatively expensive element. Furthermore, the coercive field strength is kept low due to the Mo and / or Ta content.

[0010] An increased coercive field strength leads to higher hysteresis losses, which negatively affects the remagnetization losses in the low frequency range.

[0011] Consequently, the low coercive field strength at lower raw material costs provided by the alloy according to the invention is advantageous in low-frequency applications.

[0012] The lower limit of the silicon content and the upper limit of the boron content of the alloy are set such that the alloy can be produced in strip form under tensile stress in a continuous furnace, achieving the aforementioned magnetic properties. Consequently, this manufacturing process allows the alloy to be supplied with the desired soft magnetic properties for magnetic core applications, despite the low niobium content.

[0013] The strip form not only allows for the production of the alloy under tensile stress in a continuous furnace, but also the fabrication of a magnetic core with any number of windings. Consequently, the size and magnetic properties of the magnetic core can be easily adapted to a specific application by selecting the appropriate number of windings. The nanocrystalline structure, with a grain size of less than 100 nm in at least 50% of the alloy by volume, results in low saturation magnetostriction and high saturation polarization. With suitable alloy selection, the tensile heat treatment yields a remanence ratio of less than 0.02 and a coercive field strength, H. c , which is less than 1% of the anisotropic field strength, Ha, and / or is below 10 A / m, preferably below 5 A / m.

[0014] In further embodiments, the alloy exhibits a magnetic hysteresis loop with a central linear part. Here, the central part of the hysteresis loop is defined as the part of the hysteresis loop that lies between the anisotropic field strength points that mark the transition to saturation.

[0015] A linear part of this central part of the hysteresis loop is described herein by a nonlinearity factor NL, where the nonlinearity factor is calculated as follows: NL=1002(δJauf+δJab) / Js where J auf the standard deviation of the magnetic polarization from a regression line through the ascending branch of the hysteresis loop between polarization values ​​of ± 75% of the saturation polarization J s is, and δJ abThe deviation of the magnetic polarization from a regression line through the descending branch of the hysteresis loop between polarization values ​​of ± 75% of the saturation polarization J s is.

[0016] In one embodiment, the alloy has a hysteresis loop with a nonlinearity factor NL, where NL < 0.5%.

[0017] This alloy is therefore particularly suitable for a magnetic core that has a reduced size and weight at lower raw material costs, while simultaneously possessing the desired soft magnetic properties for use as a magnetic core.

[0018] In one embodiment, the remanence ratio of the alloy is less than 0.01. The hysteresis loop of the alloy is therefore even more linear or flatter.

[0019] In one embodiment, the alloy further exhibits a permeability µ between 200 and 4000 or an anisotropic field strength H. a in the range between 250 A / m and 4000 A / m. The permeability, or the anisotropic field strength, can be primarily determined by selecting the tensile stress during heat treatment, whereby the anisotropic field strength is proportional and the permeability is inversely proportional to the applied tensile stress. In this embodiment, the tensile stress lies in the range between approximately 10 MPa (µ ∼ 4000, Ha ∼ 250 A / m) and approximately 250 MPa (µ ∼ 200, H). a ~ 5000 A / m). In one embodiment, the coercive field strength remains below 8 A / m even at high anisotropic field strengths.

[0020] The stated limits for permeability and anisotropic field strength are exemplary and not to be understood as restrictive. For example, by reducing the tensile stress to approximately 5 MPa, maximum permeabilities (minimal anisotropic field strengths) down to µ ∼ 10000 (Ha ∼ 100 A / m) can be achieved, and by increasing the tensile stress, minimum permeabilities (maximum anisotropic field strengths) down to µ ∼ 50 (Ha ∼ 20000 A / m) can be achieved.

[0021] The lower the permeability, the higher the electric currents can be through the windings of the magnetic core. without saturating the material. Likewise, for the same permeability, these currents can be higher the higher the saturation polarization, J. s, of the material. On the other hand, the inductance of the magnetic core increases with permeability and size. To build magnetic cores with simultaneously high inductance and high current tolerance, it is therefore advantageous to use alloys with higher saturation polarization. In one embodiment, the saturation polarization of J s = 1.22 T at a coercive field strength of less than 8 A / m, preferably less than 5 A / m. This can ultimately be used to reduce the size and weight of the core without any loss of performance.

[0022] The alloy can exhibit a saturation magnetostriction of less than 1 ppm. Alloys with a saturation magnetostriction below this threshold exhibit particularly good soft magnetic properties, even under internal stress. For higher permeabilities, it is advantageous to select alloys with lower saturation magnetostriction values.

[0023] In one embodiment, the alloy is niobium-free, i.e., b = 0. This embodiment has the advantage that raw material costs are reduced even further, since the element niobium is completely omitted.

[0024] In one embodiment, the alloy is copper-free, i.e., a = 0. In another embodiment, the alloy is niobium- and copper-free, i.e., a = 0 and b = 0.

[0025] In embodiments not according to the invention, the alloy is molybdenum-free and has a minimum tantalum content of 0.2 atomic percent and a minimum niobium content of 1.8 atomic percent. In one embodiment, the alloy is niobium-free and molybdenum-free and thus has a tantalum content between 2.1 atomic percent and 3 atomic percent.

[0026] In embodiments not according to the invention, the alloy is tantalum-free and the minimum molybdenum content is 0.2 atom% and the minimum niobium content is 1.8 atom%, or the minimum molybdenum content is 0.7 atom% and the minimum niobium content is 1.3 atom%, or the minimum molybdenum content is 1.0 atom% and the minimum niobium content is 1.0 atom%. In one embodiment, the alloy is niobium-free and tantalum-free and thus has a molybdenum content between 2.1 atom% and 3 atom%.

[0027] In another embodiment, the alloy is niobium-free and comprises a combination of molybdenum and tantalum. In another embodiment, the alloy comprises niobium, molybdenum, and tantalum.

[0028] The total content of niobium, molybdenum and tantalum is 2.1 atom% ≤ (b + c) ≤ 3.0 atom%.

[0029] In one embodiment, the upper limit of the content of the elements V, Cr, Co and / or Ni is limited to 0.0 atom% ≤ d < 2.0 atom%.

[0030] In one embodiment, the silicon content and the boron content are defined more precisely and are 14.0 atom% < x < 17.0 atom% and 5.5 atom% < y < 8.0 atom%.

[0031] As mentioned above, the alloy is in the form of a strip. This strip can generally have a thickness of 10 µm to 50 µm. However, very thin and very thick strips are more prone to cracking. For example, the surface roughness of strips with a thickness of less than approximately 17-18 µm can lead to holes where the strip, under tensile stress, can easily tear during heat treatment. With strip thicknesses above 24-25 µm, there is a risk of localized, brittle areas in the starting material where the strip can tear. Therefore, a strip thickness in the range of 18-22 µm is preferable for the aforementioned alloys. A particularly suitable strip should be free of holes and as smooth as possible, i.e., have a mean roughness value (roughness depth Ra) of less than 1 µm on both surfaces. The strip width can range from 0.5 to 100 mm.The probability of breakage during the heat treatment process, caused by notch effects, decreases significantly as the strip narrows. Therefore, strip widths of less than 30 mm, or even more advantageously less than 15 mm, are preferably used. For the exemplary embodiments, strips with a width of 6 mm and 10 mm were selected. The average strip thickness was approximately 18–22 µm. It should also be noted that the strip width and thickness decrease proportionally to the applied tensile stress during heat treatment. The relative decrease in strip width and thickness is 2–3% per 100 MPa of applied tensile stress.

[0032] In another embodiment, at least 70% by volume of the grains have an average size of less than 50 nm. This allows for a further improvement in the magnetic properties.

[0033] The alloy, in the form of a strip, is heat-treated under tensile stress to produce the desired magnetic properties. The alloy, i.e., the finished heat-treated strip, is thus also characterized by a microstructure resulting from this manufacturing process. In one embodiment, the crystallites have an average size of approximately 20–25 nm and a remanent rotation in the strip's longitudinal direction of approximately 0.02% to 0.5%, which is proportional to the tensile stress applied during heat treatment. For example, heat treatment under a tensile stress of 100 MPa results in an elongation of approximately 0.1%.

[0034] The magnetic properties of the alloy are influenced by the heat treatment parameters. In one embodiment, the strip is heat-treated continuously at a tempering temperature between 450°C and 750°C under a tensile stress of 10 MPa to 250 MPa for a dwell time of 2 seconds to 2 minutes. These tempering temperatures, tensile stresses, and dwell times enable the desired magnetic properties to be achieved for the alloy with a niobium content of less than 2 atomic percent, a molybdenum and / or tantalum content of 0.2 atomic percent to 3 atomic percent, and a total content of Nb, Mo, and Ta of 2.1 to 3.0 atomic percent.

[0035] A magnetic core made of an alloy according to one of the preceding embodiments is also specified. The magnetic core can have the shape of a wound strip, wherein, depending on the application, the strip can be wound in a plane or as a solenoid around a longitudinal axis to form the magnetic core.

[0036] The magnetic core tape can be additionally coated with an insulating layer to electrically isolate the windings of the magnetic core from each other. This layer can be, for example, a polymer or ceramic layer. The tape can be coated with the insulating layer before and / or after being wound into a magnetic core. This additional insulating layer is, however, optional.

[0037] In other embodiments, the tape has a natural insulating layer. During tape production, as well as during the heat treatment process, a thin layer of oxides, such as silicon oxides, only a few atoms thick, can form, providing sufficient electrical insulation for the tape layers in some applications.

[0038] The magnetic core according to one of the preceding embodiments can be used in various components. A power transformer, a current transformer, and a storage inductor with a magnetic core according to one of these embodiments are also described.

[0039] A method for producing a strip according to any one of claims 1 to 8 is also specified, comprising the following: A strip of an amorphous alloy with a composition consisting of Fe is provided. 100-a-b-e-d-x-y-z Cu a Note b M e T d Si x B y Z zand contains up to 1 atom% impurities, where M is one or more of the elements Mo, or Ta, T is one or more of the elements V, Cr, Co or Ni and Z is one or more of the elements C, P or Ge, where a = 0.0 atom%, 0.0 atom% ≤ b < 2.0 atom%, 0.2 atom% ≤ c ≤ 3.0 atom%, 0.0 atom% ≤ d < 5.0 atom%, 12.0 atom% < x < 18.0 atom%, 5.0 atom% < y < 12.0 atom% and 0.0 atom% ≤ z < 2.0 atom%, and 2.1 atom% ≤ (b + c) ≤ 3.0 atom%, or Fe 74,7 Cu 0,8 Note 1,4 Mo1Si 15,5 B 6,6 The strip is heat-treated under tensile stress between 450°C and 750°C to produce suitable magnetic properties for use as a magnetic core.

[0040] The heat treatment leads to the formation of a nanocrystalline structure in which at least 50 volume percent of the grains have an average size of less than 100 nm. In particular, this composition, with less than 2 atomic percent niobium and a molybdenum and / or tantalum content of 0.21 to 3 atomic percent, is produced by this process such that it exhibits a remanence ratio, J r / J s , < 0.02, where J r the remanence polarization and J s the saturation polarization, and a coercive field strength, H c exhibits less than 1% of the anisotropic field strength, H a , is and / or is less than 10 A / m.

[0041] The strip is heat-treated in a continuous furnace. Consequently, the strip is drawn through the furnace at a speed s. This speed s is set so that the residence time of the strip in a temperature zone of the furnace, where the temperature is within 5% of the temperature T, is between 2 seconds and 2 minutes. The time required to heat the strip to temperature T is of a comparable order of magnitude to the duration of the heat treatment itself. The same applies to the duration of the subsequent cooling. This residence time, within this tempering temperature range, results in the desired microstructure and magnetic properties.

[0042] The strip is drawn through the continuous furnace under a tensile stress between 5 MPa and 1000 MPa. This range of tensile stress is suitable for achieving the desired magnetic properties with the aforementioned compositions.

[0043] In further embodiments, the strip is heat-treated in a continuous process under a tensile stress of 10 MPa to 250 MPa or under a tensile stress of 250 MPa to 1000 MPa.

[0044] The tensile stress range determines the permeability range. Tensile stresses from 5 MPa to 1000 MPa result in permeabilities between 40 and 10000. Tensile stresses from 10 to 250 MPa result in permeabilities in the range of 200 to 4000. Tensile stresses above 250 up to approximately 1000 MPa are also achievable, resulting in flat loops with permeabilities in the range of approximately µ ∼ 50 ∼ 200, which are particularly desirable for storage inductors.

[0045] The desired magnetic properties can also depend on the tempering temperature T and can therefore be adjusted by selecting the tempering temperature. In one embodiment, the temperature T depends on the niobium content b according to the relationship (T x1+ 50°C) ≤ T ≤ (T x2 +30°C). T corresponds to x1 and T x2 the crystallization temperatures defined by the maximum heat of conversion, which are determined using standard thermal methods such as DSC (differential scanning calorimetry) at a heating rate of 10 K / min.

[0046] In another embodiment, a desired value of the anisotropic field strength, H, is used. a , or the permeability and / or a maximum value of a remanence ratio, J r / J s , of less than 0.02, and / or a maximum value of a coercive field strength, H c , which are less than 1% of the anisotropic field strength, H a , and / or less than 10 A / m, as well as a permissible deviation range for each of these values ​​is predetermined.

[0047] To achieve this value(s) along the length of the strip, its magnetic properties are continuously measured as it exits the continuous furnace. If deviations from the permissible ranges of magnetic properties are detected, the tension on the strip is adjusted accordingly to bring the measured magnetic properties back within the permissible ranges.

[0048] This embodiment reduces the variations in magnetic properties along the length of the strip, resulting in more homogeneous magnetic properties within a single magnetic core and / or less variation in the magnetic properties of multiple cores produced from a single strip. This improves the uniformity of the soft magnetic properties of the cores, particularly in commercial manufacturing.

[0049] Examples of implementation will now be explained in more detail using the following examples, tables and drawings. Fig. Figure 1 shows hysteresis loops of an alloy according to the invention, which is heat-treated under two different tensile stresses. Fig. Figure 2 shows magnetic properties for alloys with different Nb and Mo contents, produced at different tempering temperatures. Fig. Figure 3 shows magnetic properties for alloys produced under different tensile stresses, and Fig. Figure 4 shows a schematic view of a continuous furnace. Table 1 shows the magnetic properties for an alloy according to the invention as well as comparative examples. Table 2 shows further examples of alloys not in accordance with the invention and their magnetic properties. Table 3 shows crystallization temperatures T x1 and T x2(DSC 10K / min, peak) and tempering temperatures T for three alloys from Table 1.

[0050] Various alloys based on Fe 100-a-b-e-d-x-y-z Cu a Note b M c T d Si x B y Z z The base material is produced in the form of an amorphous ribbon. Typical ribbons have a width of 6 mm to 10 mm and a thickness of 17 µm to 25 µm. The amorphous ribbon can be produced with the desired composition, for example, using rapid solidification technology. These amorphous ribbons are then heat-treated to create a nanocrystalline structure and the desired magnetic properties.

[0051] It is desirable in alloys based on Fe 100-a-b-c-d-x-y-z Cu a Note b M c T d Si x B y Z z-to reduce the Nb content in order to lower raw material costs without excessively increasing the coercive field strength. It is hereby disclosed that this can be achieved by replacing Nb wholly or partially with Mo or Ta, wherein the total content of elements from the group Nb and / or Mo and / or Ta is at least 2.1 atomic%, and the niobium content is less than 2 atomic%.

[0052] Table 1 shows the saturation polarization measured in the manufacturing state, J s , as well as the values ​​of saturation magnetostriction, λs, nonlinearity, NL, and remanence ratio, J, measured after heat treatment under a tensile stress of 50±10 MPa r / J s , the coercive field strength, H c , the anisotropic field strength, H a , and the relative permeability, µ, of various alloy compositions. Composition values ​​are given in atomic percent.

[0053] The heat treatment is carried out under a tensile stress of 50 ± 10 MPa for a duration of 4 s for comparative examples (a) and (i) and for a duration of 6 s for comparative examples (ii), (iii), 1 to 7, 9 and 10 and for example 8 according to the invention, at the tempering temperature T specified in the table. Examples 1 to 10 in Table 1 all have a reduced Nb content of less than 2 atomic percent.

[0054] In comparative alloy examples 1, 2, and 3, Nb is completely replaced by varying molybdenum contents. For molybdenum contents greater than or equal to 2 atomic percent, the coercive field strength is below 8 A / m and decreases further with higher molybdenum contents.

[0055] In comparative alloy examples 4 and 5, Nb is completely replaced by different Ta contents. For Ta contents around 2 atomic percent, the coercive field strength with H c = 3 A / m, comparably small to the comparison examples, but with a larger magnetic saturation polarization J s .

[0056] One advantage of talc (Ta) and molybdenum (Mo) over nitrogen (Nb) is their greater availability on the global market. Ta also benefits from its superior effectiveness in reducing coercivity, particularly compared to Mo. However, a disadvantage is the high cost of Ta as a raw material. Consequently, efforts have focused on replacing Nb only partially, and where possible, with Mo.

[0057] In comparative alloy example 6, the majority of the Nb was replaced by Mo and Ta. Here too, the coercive field strength values ​​are comparable to the comparison examples, but again at a higher magnetic saturation polarization J. s .

[0058] In comparative alloy examples 7, 9, and 10, as well as in alloy example 8 according to the invention, Nb is partially replaced by Mo. Here, too, low coercive field strengths well below 10 A / m are obtained if the total content of Nb and Mo is at least 1.9 atomic percent. If the composition is at this lower limit, it is advantageous if the Nb content is slightly higher than the Mo content.

[0059] Table 2 shows further non-inventive alloy examples 11 and 12 and their magnetic properties after heat treatment of 6 s under a tensile stress of 50±10 MPa at the tempering temperature T given in the table.

[0060] The magnetic properties demonstrate that the addition of Mo and Ta is possible when the Nb content is greater than 2 atomic percent. For example, alloy example 11 shows that even a small addition of 0.2 atomic percent Mo, combined with a simultaneous reduction of the Nb content by 0.3 atomic percent, results in a light Hc -reduction compared to comparison example (a) of Table 1, where advantageously the saturation polarization J s is increased by approximately 15%. In alloy example 12, Nb is substituted by Ta, resulting in comparable magnetic properties to example (a) in Table 1, provided the alloy is heat-treated with a suitable tensile stress at a suitable tempering temperature.

[0061] Further examples are described in the Fig. 1, Fig. 2 and Fig. 3 revealed.

[0062] Fig. Figure 1 shows typical hysteresis loops as they result after heat treatment under tensile stress. Fig. Figure 1 shows quasi-static hysteresis loops of the alloy Fe according to the invention. 74,7 Cu 0,8 Note 1,4 Mo1S1 15,5 B 6,6 after a heat treatment of 6 s at 650°C with two different tensile stresses, where σa1 ~ 50 MPa and σa2∼140 MPa is.

[0063] Fig. Figure 1 further illustrates the definition of magnetic saturation polarization, J s , the anisotropic field strength, H a , the coercive field strength, H c , and the remanence polarization, J r For an alloy according to the invention, the coercive field strength at an anisotropic field, Ha, of approximately 1000 A / m should be less than 10 A / m, i.e., less than approximately 1% of Ha. Such small values ​​are difficult to measure when the hysteresis loop is fully driven (measurement accuracy approximately ± 1 A / m) and are therefore not possible. Fig. 1 is barely perceptible to the naked eye. Nevertheless, maintaining such small values ​​is advantageous for minimizing remagnetization losses.

[0064] A characteristic of a hysteresis loop is its linearity in the central part of the loop. A measure of this is a small remanence ratio J. r / J s .

[0065] Fig. Figure 2 shows saturation magnetostriction λs, the anisotropic field H a , the coercive field strength H c and the remanence ratio J r / J s as a function of the tempering temperature T for Fe 77,1-x- y Cu 0,8 Note x Mon y Si 15,5 B 6,6 with two different Nb contents and increasing Mo contents after a heat treatment of approximately 6 seconds under a tensile stress of approximately 50 MPa as a function of the tempering temperature T. These compositions are Fe 75,6 Cu 0,8 Nb1Mo 0,5 S1 15,5 B 6,6 , Fe 75,1 Cu 0,8 Nb1Mo1Si 15,5 B 6,6 , Fe 74,6 Cu 0,8 Nb1Mo 1,5 Si 15,5 B 6,6 , Fe 75,7 Cu 0,8 Note 1,4 Si 15,5 B 6,6 , Fe 75,2 Cu 0,8 Note 1,4 Mon 0,5 Si 15,5 B 6,6 and Fe 74,7 Cu 0,8 Note 1,4Mo1Si 15,5 B 6,6 .

[0066] The desired magnetic properties, i.e., a small saturation magnetostriction λs, a specific anisotropic field strength H a , a small coercive field H c and a small remanence ratio J r / J s These results occur within a specific tempering window characteristic of the respective alloy, which is defined by a minimum tempering temperature T1 and a maximum tempering temperature T2. This tempering range can be determined by a standard measurement of the crystallization temperatures T1 and T2. x1 and T x2 , e.g. by DSC (differential scanning calorimetry) to determine the tempering temperature T.

[0067] Table 3 shows crystallization temperatures T x1 and T x2 (DSC 10K / min, peak) and suitable tempering temperatures T for the alloy Fe 75,5-x-y Cu 0,8 Note 1,4 Mon x Si 15,5 B6,6 for tempering times of approximately 6 seconds. The example number corresponds to the alloy composition specified in Table 1. Table 3 shows an example of the corresponding relationship for the tempering time of approximately 6 seconds used here.

[0068] The results of the Fig. Figure 2 shows that the saturation magnetostriction and the anisotropy field strength behave approximately the same in all examples, while there are significant differences in the coercive field strength and the remanence ratio.

[0069] Fig.Figure 2, supplementing Table 1, reveals that alloys with a total (Nb + Mo) content greater than or equal to approximately 2 atomic percent (including 1.9 atomic percent) exhibit a coercive field strength significantly less than 10 A / m over a wide range of tempering temperatures. Alloys with a total (Nb + Mo) content greater than 2.3 atomic percent show even more favorable values ​​(H = A / m) over a wide range and are also less sensitive to the exact tempering temperature. In comparison, alloys with a (Nb + Mo) content typically exhibit a coercive field strength between 10 and 20 A / m and thus correspondingly high hysteresis losses. Furthermore, H changes c Here, the temperature is relatively strongly affected.

[0070] The preceding examples refer to a starting voltage. σa of approximately 50 MPa. Fig. Figure 3 shows the influence of this starting voltage on the magnet values.

[0071] Fig.3 shows relative permeability µ, anisotropy field H a , coercive field strength H c , Remanence ratio J r / J s and nonlinearity factor of the alloys Fe 75,7-y Cu 0,8 Note 1,4 Mon y Si 15,5 B 6,6 with y = 0.5 atom% and y = 1 atom% after heat treatment of 6 s at 640°C for Mo = 0.5 atom% and 650°C for Mo = 1 atom% in comparison with Fe 75,5 Cu1Nb 1,5 Mon x Si 15,5 B 6,5 during a heat treatment of 4 s at 610°C as a function of the tensile stress applied during the heat treatment σa.

[0072] Fig. 3 reveals that the anisotropy field H a The permeability increases proportionally to the tensile stress applied during heat treatment, while the permeability is inversely proportional to σ. a decreases. Ultimately, the starting tensile stress σ aThe permeability and anisotropic field strength are chosen such that a predetermined value is established. All the alloy examples shown behave approximately the same in this respect, while significant differences can be observed in the coercive field strength, and thus ultimately in the remagnetization losses. The alloys according to the invention exhibit even more favorable coercive field strength behavior, particularly at increased tensile stresses. For example, while the coercive field strength of an alloy with 1.5 atomic percent Nb decreases significantly with increasing tensile stress, a molybdenum addition of only 0.5 atomic percent reduces the tensile stress dependence of H. c and thus an improvement. The same applies to an addition of 1 atomic percent. which has a slightly more favorable effect. This is also evident with lower starting voltages, which are used if a small anisotropic field or permeabilities of around or greater than 2000 are to be set.

[0073] Fig. Figure 4 shows a schematic view of a device 1 suitable for producing the alloy with a composition according to one of the preceding embodiments in the form of a strip. The device 1 has a continuous furnace 2 with a temperature zone 3, wherein this temperature zone is set such that the temperature in the furnace in this zone is within 5°C of the tempering temperature T. The device 1 further has a spool 4 on which the amorphous alloy 5 is wound, and a receiving spool 6, which is inserted into the heat-treated strip 7. The strip 7 is drawn from the spool 4 through the continuous furnace 2 to the receiving spool 6 at a speed s. During this process, the strip 7 is under a tensile stress σ in the direction of travel from device 9 to device 10. a .

[0074] The device 1 further comprises a device 8 for continuously measuring the magnetic properties of the strip 6 after it has been heat-treated and drawn from the continuous furnace 2. In the area of ​​this device 8, the strip 7 is no longer under tensile stress. The measured magnetic properties can be used to determine the tensile stress σ. a , under which belt 7 is pulled through the continuous oven 2. This is to be adjusted using arrows 9 and 10 in the Fig. Figure 13 shows a schematic representation. By measuring the magnetic properties and continuously adjusting the tension, the uniformity of the magnetic properties over the length of the strip can be improved. Table 1 Nr Composition (at%) J s (T) T a (° C) l s (ppm) NL(%) J r / J s H c (A / m) H a (A / m) µ (a) Fe 74 Cu1Nb3Si 15.5 B 6.5 1.21 690 0.1 0.3 0.004 3 850 1130 (i) Fe 75.5 Cu1Nb 1.5 Yes 15.5 B 6.5 1.34 635 0.6 0.6 0.008 13 1180 890 (ii) Fe 75.7 With 0.8 Nb 1.4 And 15.5 B 6.6 1.36 625 0.4 0.7 0.011 11 1000 1085 (iii) Fe 75.6 With 0.8 Nb1Mo 0.5 And 15.5 B 6.6 1.37 625 -0.5 0.7 0.013 13 1000 1085 1 Fe 75.1 With 0.8 Mo2Si 15.5 B 6.6 1.30 625 0.5 0.2 0.010 7 1170 880 2 Fe 74.1 With 0.8 Si3Si 15.5 B 6.6 1.23 655 -0.06 0.5 0.006 6 1000 980 3 Fe 73.1 With 0.8 Mo4Si 15.5 B 6.6 1.14 640 0.2 0.07 0.003 3 1020 945 4 Fe 75.1 With 0.8 Ta2Si 15.5 B 6.6 1.31 640 0.3 0.10 0.003 3 1080 885 5 Fe 74.1 With 0.8 Ta3Si 15.5 B 6.6 1.23 640 0.4 0.07 0.002 2 1010 950 6 Fe 74.1 With 0.8 Nb1Mo1Ta1Si 15.5 B 6.6 1.24 640 0.2 0.09 0.004 4 990 965 7 Fe 74.6 With 0.8 Nb1Mo 1.5 And 15.5 B 6.6 1.27 650 0.4 0.3 0.004 4 930 1095 8 Fe 74.7 With 0.8 Nb 1.4 Mo1Si 15.5 B 6.6 1.28 650 -0.06 0.1 0.002 2 960 1060 9 Feb 75.2 Cu 0.8 No 1.4 Mo 0.5 Si 15.5 B 6.6 1.32 640 0.4 0.3 0.003 3 1000 1040 10 Fe 75.1 With 0.8 Nb1Mo1Si 15.5 B 6.6 1.31 625 0.6 0.3 0.005 6 1025 1020 (a) Comparative example (i), (ii), (iii), 1 to 7, 9 and 10 Comparative example (8) Example according to the invention Table 2 Nr Composition (at%) J s (T) T a (°C) l s (ppm) NL(%) J r / J s H c (A / m) H a (A / m) 11 11 Feb 74.2 Cu 0.8 No 2.7 Mo 0.2 Si 15.5 B 6.6 1.24 640 0.7 0.1 0.002 2 930 1025 12 Fe 74.0 With 0.8 Nb 2.2 Your 0.9 And 15.5 B 6.6 1.22 675 -0.1 0.1 0.003 4 970 980 Table 3 Nr Mo (at%) T x1 (°C) T x2 (°C) Starting temperatures T (ii) 0 488 645 from 540°C to 630°C 9 0.5 498 662 from 550°C to 650°C 8 1.0 505 678 from 550°C to 670°C

Claims

[1] alloy that from Fe 100-a-b-e-d-x-y-z Cu a Note b M e T d Si x B y Z z and contains up to 1 atom% impurities, where M is Mo and / or Ta, T is one or more of the elements V, Cr, Co and Ni, and Z is one or more of the elements C, P and Ge, where a = 0.0 atom%, 0.0 atom% ≤ b < 2.0 atom%, 0.2 atom% ≤ c ≤ 3.0 atom%, 0.0 atom% ≤ d < 5.0 atom%, 12.0 atom% < x < 18.0 atom%, 5.0 atom% < y < 12.0 atom% and 0.0 atom% ≤ z < 2.0 atom%, and 2.1 atom% ≤ (b + c) ≤ 3.0 atom%, or Fe 74,7 C 0,8 Note 1,4 M1Si 15,5 B 6,6 , is formed in the shape of a band, a nanocrystalline structure in which at least 50 vol% of the grains have an average size smaller than 100 nm, a remanence relationship, J r / J s , < 0.02, where J r , the remanence polarization and J sthe saturation polarization is, and a coercive field strength, H c , exhibits less than 1% of the anisotropic field strength, H a , and / or is less than 10 A / m. [2] Alloy according to claim 1, wherein the remanence ratio, J r / J s < 0.

01. [3] Alloy according to claim 1 or claim 2, wherein the alloy has a hysteresis loop and a nonlinearity factor NL, wherein NL < 0.5%, and NL=100 / 2(δJauf+δJab) / Js where δJ auf The deviation of the magnetic polarization from a regression line through the ascending branch of the hysteresis loop between polarization values ​​of ± 75% of the saturation polarization J s is, and δJ ab The deviation of the magnetic polarization from a regression line through the descending branch of the hysteresis loop between polarization values ​​of ± 75% of the saturation polarization J s is. [4] Alloy according to any one of claims 1 to 3, which furthermore has a permeability µ between 40 and 10000. [5] Alloy according to any one of claims 1 to 4, which furthermore has a saturation magnetostriction of less than 1 ppm. [6] Alloy according to any one of claims 1 to 5, which increases the saturation polarization J s ≥ 1.22T and the coercive field strength H c ≤ 8 A / m. [7] Alloy according to any one of claims 1 to 6, wherein 0.0 atom% ≤ d < 2.0 atom%. [8] Alloy according to any one of claims 1 to 7, wherein 14.0 atom% < x < 17.0 atom% and 5.5 atom% < y < 8.0 atom%. [9] Magnetic core made of an alloy according to any one of claims 1 to 8. [10] Magnetic core according to claim 9, having the shape of a wound band. [11] Magnetic core according to claim 9 or claim 10, wherein the tape has an oxide layer on the surface with a thickness of < 0.2 µm. [12] Magnetic core according to one of claims 9 to 11, wherein the tape is coated with an additional insulating layer. [13] Method for producing a strip of an alloy according to any one of claims 1 to 8, comprising the following: Providing a strip of an amorphous alloy with a composition consisting of Fe 100-a-b-c-d-x-y- z Cu a Note b M e T d Si x B y Z z and contains up to 1 atom% impurities, where M is Mo and / or Ta, T is one or more of the elements V, Cr, Co and Ni, and Z is one or more of the elements C, P and Ge, where a = 0.0 atom%, 0.0 atom% ≤ b < 2.0 atom%, 0.2 atom% ≤ c ≤ 3.0 atom%, 0.0 atom% ≤ d < 5.0 atom%, 12.0 atom% < x < 18.0 atom%, 5.0 atom% < y < 12.0 atom% and 0.0 atom% ≤ z < 2.0 atom%, and 2.1 atom% ≤ (b + c) ≤ 3.0 atom%, or Fe 74,7 Cu 0,8 Note 1,4 Mo1Si 15,5 B 6,6 , Heat treatment of the strip under tensile stress in a continuous process at a temperature T a , where 450°C ≤ T a ≤ 750°C the strip is heat-treated in a continuous oven, wherein the belt is pulled through the continuous furnace at a speed s, such that the residence time of the belt in a temperature zone of the continuous furnace with temperature T is a between 2 seconds and 2 minutes, and the strip is heat-treated continuously under a tensile stress of 5 MPa to 1000 MPa. [14] Method according to claim 13, wherein the strip is heat-treated continuously under a tensile stress of 10 MPa to 250 MPa. [15] Method according to claim 13, wherein the strip is heat-treated continuously under a tensile stress of 250 MPa to 1000 MPa. [16] Method according to any one of claims 13 to 15, wherein a desired value of the anisotropic field strength, Ha , or the permeability and / or a maximum value of a remanence ratio, J r / J s of less than 0.02, and / or a maximum value of a coercive field strength, H c , which is less than 1% of the anisotropy field strength, Ha, and / or less than 10 A / m, as well as a permissible deviation range for each of these values ​​are predetermined, and The magnetic properties of the strip are continuously measured as it leaves the continuous furnace, and If deviations from the permitted deviation ranges of the magnetic properties are detected, the tensile tension on the belt is adjusted accordingly to bring the measured values ​​of the magnetic properties back within the permitted deviation ranges.

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