Soft magnetic material and method for manufacturing the same

Abstract

To provide a soft magnetic material in which both of a high saturation magnetic flux density and a low coercive force are achieved, and provide a manufacturing method of them.SOLUTION: A soft magnetic material is expressed by the following compositional formula: Fe100-x-y-z-wBxNiySizMw (in the formula, M is one or more inevitable elements selected from Nb, Mo, Ta, W, Co, and Sn, and x, y, z, and w satisfy 12≤x≤17, 1≤y≤3, 0<z≤1, and 0<w≤0.1 at an atom%). The soft magnetic material contains a α-Fe phase, the α-Fe phase contains a crystal of which a mean particle diameter is 30nm or less, the mean particle diameter of the crystal is a mean value of a projection area equivalent circle diameter of a crystal in a transmission electron microscope (TEM) image of a soft magnetic material that is thinned by an integrated ion beam (FIB). A ratio of a peak area of a (211) surface of a crystalline substance against area of a whole peak measured by a XRD of the α-Fe phase of a front surface of the soft magnetic material is 0.10 or more.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a soft magnetic material and a method for producing the same.

Background Art

[0002] In order to improve the performance of components such as motors and reactors, the soft magnetic material used for the core part of such components is required to achieve both high saturation magnetic flux density (high torque) and low coercive force (low loss).

[0003] Examples of soft magnetic materials having a high saturation magnetic flux density include electromagnetic steel sheets, Fe-based nanocrystalline soft magnetic materials, etc. An Fe-based nanocrystalline soft magnetic material refers to a soft magnetic material whose main component is Fe and in which nanocrystals are dispersed in the material.

[0004] For example, Patent Document 1 describes an Fe-based soft magnetic alloy represented by the general formula Fe x , e , c , a , , , y , 100-x-y , d , b , 100-a-b-c-d-e ,

[0005] Ni a M b B c M’ d M’’ e (where M represents one or more elements selected from Si, Ge, Ga, M’ represents Nb, Mo, W, Ta, Zr, Hf, Ti, M’’ represents one or more elements selected from V, Cr, Mn, Al. a, b, c, d, e represent atomic %, and satisfy 0.5≦a≦5, 0≦b≦10, 9≦c≦16, 1≦d≦6, 0≦e≦2, 16≦a + b + c + d + e≦25).

[0005] Patent Document 2 discloses preparing an alloy having a composition represented by the following Composition Formula 1 or Composition Formula ② and having an amorphous phase, and heating the alloy at a heating rate of 10°C / second or more, and holding it for 0 to 80 seconds at a temperature above the crystallization start temperature and below the Fe-B compound formation start temperature. The Composition Formula 1 is Fe 100-x-y B x M yand M is at least one element selected from Nb, Mo, Ta, W, Ni, Co, and Sn, and x and y satisfy 10 ≦ x ≦ 16 and 0 ≦ y ≦ 8 in atomic %, and the composition formula 2 is Fe 100-a-b-c B a Cu b M’ c and M’ is at least one element selected from Nb, Mo, Ta, W, Ni, and Co, and a, b, and c satisfy 10 ≦ a ≦ 16, 0 < b ≦ 2, and 0 ≦ c ≦ 8 in atomic %, and a manufacturing method of a soft magnetic material is described.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] As described above, for improving the performance of magnetic components such as motors and reactors, it is important to achieve both a high saturation magnetic flux density and a low coercive force of the soft magnetic material for the core part.

[0008] Fe-based nanocrystalline soft magnetic materials have a high saturation magnetic flux density because their main component is Fe. Fe-based nanocrystalline soft magnetic materials are obtained by heat-treating (also called "annealing") an alloy having an amorphous phase. If the Fe content in the amorphous alloy is high, a crystalline phase (α-Fe) is easily formed from the amorphous phase during heat treatment, and this crystalline phase is prone to grain growth and coarsening. Therefore, elements that suppress grain growth are added to the material. However, the Fe content in the material decreases by the amount of these elements added, so the saturation magnetic flux density of the material decreases. For these reasons, in soft magnetic materials, when the main component is Fe, it is difficult to maintain a high saturation magnetic flux density while suppressing the coarsening of the crystalline phase during heat treatment and maintaining low coercivity.

[0009] Therefore, the object of the present invention is to provide a soft magnetic material that achieves both high saturation magnetic flux density and low coercivity, and a method for manufacturing the same. [Means for solving the problem]

[0010] As a result of various investigations into means to solve the above-mentioned problems, the inventors of the present invention have found that by rapidly heat-treating an alloy having an amorphous phase in which Fe is the main component and Si is contained in an appropriate amount, an Fe-based nanocrystalline soft magnetic material having a high saturation magnetic flux density while maintaining low coercivity can be obtained, and have completed the present invention.

[0011] In other words, the gist of this invention is as follows: (1) The following chemical formula: Fe 100-x-y-z-w B x Ni y Si z M w(In the formula, M is one or more inevitable elements selected from Nb, Mo, Ta, W, Co, and Sn, and x, y, z, and w are in atomic %, satisfying 12 ≤ x ≤ 17, 1 ≤ y ≤ 3, 0 < z ≤ 1, 0 < w ≤ 0.1). A soft magnetic material, wherein the soft magnetic material contains an α-Fe phase, the α-Fe phase contains crystals with an average particle size of 30 nm or less, and the average particle size of the crystals is the average value of the equivalent diameter of the projected area of the crystals in the transmission electron microscope (TEM) image of the soft magnetic material thinned by focused ion beam (FIB). The ratio (crystalline (211) plane peak area / XRD peak total area) of the peak area of the crystalline (211) plane to the total area of the peaks measured by XRD of the α-Fe phase on the surface of the soft magnetic material is 0.10 or more. (2) The soft magnetic material according to (1), wherein 0.2 ≤ z ≤ 0.9. (3) The following composition formula: Fe 100-x-y-z-w B x Ni y Si z M w (In the formula, M is one or more inevitable elements selected from Nb, Mo, Ta, W, Co, and Sn, and x, y, z, and w are in atomic %, satisfying 12 ≤ x ≤ 17, 1 ≤ y ≤ 3, 0 < z ≤ 1, 0 < w ≤ 0.1). Preparing an alloy having the composition and having an amorphous phase, and rapidly heat-treating the alloy so that the reaching temperature of the alloy is in a temperature range not less than the crystal formation start temperature of the α-Fe phase and less than the Fe-B compound formation start temperature. (4) The manufacturing method according to (3), wherein in the rapid heat treatment, the reaching temperature of the alloy is 485°C to 5°C. (5) The manufacturing method according to (3) or (4), wherein in the rapid heat treatment, the heating rate of the alloy is 100°C / second to 415°C / second. (6) The manufacturing method according to any one of (3) to (5), wherein in the rapid heat treatment, the holding time of the alloy is 0 second to 80 seconds. (7) The manufacturing method according to any one of (3) to (6), wherein the rapid heat treatment is carried out by sandwiching the heated block of the alloy.

Advantages of the Invention

[0012] The present invention provides a soft magnetic material in which a high saturation magnetic flux density and a low coercive force are compatible, and a method for producing the same.

Brief Description of the Drawings

[0013] [Figure 1] It is a graph showing the relationship between the Si content and (A) the peak area ratio of the crystalline (211) plane, or (B) the saturation magnetic flux density for Example 5 and Comparative Examples 5 to 6. [Figure 2] It is a graph showing the relationship between the heat treatment temperature and the saturation magnetic flux density for Examples 1 to 7 and Comparative Examples 1 to 4. [Figure 3] It is a graph showing the relationship between the peak area ratio of the crystalline (211) plane and the saturation magnetic flux density for Examples 1 to 7 and Comparative Examples 1 to 4.

Modes for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail. In this specification, the features of the present invention will be described with reference to the drawings as appropriate. The soft magnetic material and the method for producing the same of the present invention are not limited to the following embodiments, and can be implemented in various forms with modifications, improvements, etc. that can be made by those skilled in the art without departing from the gist of the present invention.

[0015] In this specification and the like, a range expressed as "numerical value ~ numerical value" means a range including the said numerical values.

[0016] (Soft Magnetic Material) The soft magnetic material of the present invention is an Fe-based nanocrystalline soft magnetic material represented by the following compositional formula: Fe 100-x-y-z-w B x Ni y Si z M w (In the formula, M is one or more inevitable elements selected from Nb, Mo, Ta, W, Co, and Sn, and x, y, z, and w are in atomic%, satisfying 12 ≤ x ≤ 17, 1 ≤ y ≤ 3, 0 < z ≤ 1, 0 < w ≤ 0.1).

[0017] The composition of the amorphous alloy does not usually change during the manufacturing process of the soft magnetic material of the present invention. Therefore, the composition of the soft magnetic material of the present invention is the same as the composition of the amorphous alloy used in its manufacture.

[0018] In the soft magnetic material of the present invention, the main component is Fe, and the Fe content is 50 atomic percent or more of the total composition. Therefore, 100-xyzw, which indicates the Fe content, is 50 or more in atomic percent, and from the viewpoint of having a high saturation magnetic flux density, it is 80 or more in one embodiment and 85 or more in another embodiment.

[0019] x, which indicates the boron (B) content, is in atomic percent and ranges from 12 to 17, or 12 to 14 in one embodiment.

[0020] By including B within the aforementioned range in the soft magnetic material of the present invention, the Fe content is ensured, and the presence of B between the α-Fe crystals suppresses the growth of α-Fe crystal grains, thereby maintaining a low coercivity of the soft magnetic material.

[0021] The value y, which indicates the Ni content, is in atomic percent and ranges from 1 to 3, and in one embodiment from 1.5 to 2.5.

[0022] By including Ni within the aforementioned range in the soft magnetic material of the present invention, the magnitude of induced magnetic anisotropy can be controlled.

[0023] The Si content, represented by z, is in atomic percent and is in the range of greater than 0 and less than or equal to 1, with 0.2 to 0.9 in one embodiment and 0.5 to 0.9 in another embodiment.

[0024] By including Si within the aforementioned range in the soft magnetic material of the present invention, the peak area ratio of the (211) plane measured by XRD (X-Ray Diffraction) of the α-Fe phase on the surface of the soft magnetic material can be increased.

[0025] M, or w, which represents the content of unavoidable elements, is in atomic percent and is in the range of greater than 0 and less than or equal to 0.1, and in one embodiment, it is in the range of greater than 0 and less than or equal to 0.05. Unavoidable elements refer to impurities contained in raw materials, etc., whose inclusion cannot be avoided, or whose avoidance would lead to a significant increase in manufacturing costs.

[0026] By including unavoidable elements within the aforementioned range in the soft magnetic material of the present invention, it is possible to suppress the decrease in saturation magnetic flux density due to an increase in unavoidable elements.

[0027] Furthermore, in order to improve corrosion resistance, suppress grain growth, and increase the frequency of nucleation, the soft magnetic material of the present invention may contain one or more elements selected from the group consisting of, for example, Zr, Hf, Cu, Ag, Au, Zn, As, Sb, Bi, Y, and rare earth elements, within a range that does not significantly reduce the saturation magnetic flux density.

[0028] In the soft magnetic material of the present invention, the ratio of the peak area of ​​the crystalline (211) plane (crystalline (211) plane peak area) to the total peak area (total XRD peak area) measured by XRD of the α-Fe phase on the surface of the soft magnetic material (crystalline (211) plane peak area / total XRD peak area, hereinafter also referred to as the "crystalline (211) plane peak area ratio") is 0.10 or more, 0.100 or more in one embodiment, 0.102 or more in one embodiment, and 0.105 or more in one embodiment. The crystalline (211) plane peak area ratio is not limited, but is usually 0.13 or less, and 0.12 or less in one embodiment.

[0029] Here, as is well known in the art, the peaks measured by XRD of the α-Fe phase on the surface of the soft magnetic material include the (110), (200), (211), (220), and (310) planes. Furthermore, the (110) and (211) planes each have crystalline and amorphous peaks (halo peaks), respectively. Therefore, the crystalline (211) plane peak area ratio in this invention refers to the ratio of the peak area of ​​the crystalline (211) plane to the total area of ​​all peaks observed by XRD, namely the crystalline (110), amorphous (110), (200), crystalline (211), amorphous (211), (220), and (310) planes.

[0030] The crystalline (211) plane peak area ratio can be calculated as follows: (1) The X-ray diffraction pattern of the soft magnetic material is measured by XRD. (2) The obtained X-ray diffraction pattern is normalized by the peak of the (110) plane, which has the highest intensity. (3) For each peak, the background (BG) is linearly approximated by the average value of 10 points at each end of the following 2θ ranges: 30° to 60° for the (110) plane, 60° to 70° for the (200) plane, 70° to 92° for the (211) plane, 94° to 102° for the (220) plane, and 112° to 120° for the (310) plane. (4) For each peak after subtracting the background (BG), the crystalline and amorphous peaks are peak-fitted using a split Pearson VII function, and the areas of Kα1 and Kα2 for each peak are calculated. Note that in the soft magnetic material of the present invention, amorphous halo peaks are observed in the (110) and (211) planes. Therefore, crystalline Kα1 and Kα2 and amorphous Kα1 and Kα2 are observed in the (110) and (211) planes, respectively. (5) The crystalline (211) plane peak area ratio is calculated by dividing the peak area of ​​the Kα1 of the crystalline (211) plane by the sum of the peak areas of the Kα1 of each peak.

[0031] The fact that the crystalline (211) plane peak area ratio of the soft magnetic material of the present invention falls within the aforementioned range means that in the soft magnetic material of the present invention, there are crystal grains in which the (211) plane, which is a specific crystal plane of the α-Fe phase, has been anisotropically grown (the crystal orientation is aligned). Such crystal grains result in low coercivity (low loss) and high saturation magnetic flux density (high torque) of the soft magnetic material.

[0032] The soft magnetic material of the present invention contains α-Fe phase crystals in an amount of 30 volume% or more, and in one embodiment, 60 volume% or more, relative to the total volume of the soft magnetic material.

[0033] The average grain size of the α-Fe phase crystals contained in the soft magnetic material of the present invention is 30 nm or less. However, the average grain size of the α-Fe phase crystals is not limited, but is usually 10 nm or more. Here, the average grain size of the α-Fe phase crystals is calculated by (1) thinning the soft magnetic material with an integrated ion beam (FIB), (2) observing the thinned soft magnetic material sample with a transmission electron microscope (TEM), (3) randomly selecting any number of crystals (100 or more) from the α-Fe phase in the TEM image, (4) measuring the equivalent diameter of the projected area circle (Heywood diameter) of the selected crystals as the grain size, and (5) averaging the obtained grain sizes.

[0034] By having the average grain size of the α-Fe phase crystals contained in the soft magnetic material of the present invention be within the aforementioned range, high saturation magnetic flux density and low coercivity can be achieved in the soft magnetic material.

[0035] When the soft magnetic material of the present invention is in the form of a thin strip, the average thickness of the soft magnetic material of the present invention is not limited, but is usually 10 μm to 25 μm, and in one embodiment, 15 μm to 30 μm.

[0036] By setting the thickness of the soft magnetic material of the present invention within the aforementioned range, losses can be reduced.

[0037] The saturation magnetic flux density of the soft magnetic material of the present invention is typically 1.850T or higher, and in one embodiment, 1.855T or higher, for example, 1.850T to 1.900T, and in one embodiment, 1.855T to 1.900T.

[0038] The coercivity of the soft magnetic material of the present invention is typically 20 A / m or less, and in one embodiment, 12 A / m or less, for example, 5 A / m to 20 A / m, and in one embodiment, 7.0 A / m to 12 A / m.

[0039] The soft magnetic material of the present invention achieves both high saturation magnetic flux density and low coercivity, and can be used as a core for electronic components such as motors and reactors.

[0040] (Method for manufacturing soft magnetic materials) The soft magnetic material of the present invention can be manufactured by known methods in the art, for example, the method described in Japanese Patent Application Publication No. 2019-206746, except that the raw material alloy contains an appropriate amount of Si and the alloy is subjected to rapid heat treatment.

[0041] An example of a method for producing the soft magnetic material of the present invention is described below. (Preparation process for amorphous alloys) First, an alloy having an amorphous phase is prepared. As mentioned above, the alloy having an amorphous phase is a raw material for the soft magnetic material of the present invention, and its main component is Fe.

[0042] In this invention, "main component is Fe" means that the Fe content in the material is 50 atomic percent or more. "Alloy having an amorphous phase" means that the amorphous phase is present in an alloy at a concentration of 50 volume percent or more, and this is sometimes simply called an "amorphous alloy." The "alloy" can take the form of a thin strip, flake, granules, or bulk material.

[0043] From the viewpoint of obtaining a large number of fine crystalline phases through rapid heat treatment, the amorphous phase content in the amorphous alloy is 60% by volume or more in one embodiment and 85% by volume or more in another embodiment.

[0044] Amorphous alloys are obtained by rapidly cooling molten metal whose main component is Fe. B promotes the formation of the amorphous phase when the molten metal is rapidly cooled. When the B content (residual amount of B) of the amorphous alloy obtained by rapidly cooling molten metal is 12 atomic percent or more of the total composition, the amorphous phase can be made the main phase of the amorphous alloy. On the other hand, when the B content of the amorphous alloy is 17 atomic percent or less of the total composition, it is possible to ensure the amount of Fe necessary for a high saturation magnetic flux density while avoiding the formation of Fe-B compounds during the crystallization of the amorphous phase.

[0045] Amorphous alloys contain Ni. The presence of Ni in amorphous alloys allows for control over the magnitude of induced magnetic anisotropy. From the viewpoint of clearly demonstrating this effect, the Ni content should be 1 atomic percent or more of the total composition. On the other hand, if the Ni content is 3 atomic percent or less of the total composition, the other essential elements of amorphous alloys, Fe and B, will not be excessively deficient. As a result, soft magnetic materials obtained by rapid heat treatment of amorphous alloys can achieve both high saturation magnetic flux density and low coercivity.

[0046] In amorphous alloys, some of the B is replaced by Si.

[0047] Conventionally, Si is known to be the element responsible for amorphous formation, and that adding Si can raise the temperature at which Fe-B compounds with high crystalline magnetic anisotropy are formed, thereby enabling higher heat treatment temperatures. In this invention, we have found that by using an appropriate amount of Si, i.e., in the range of greater than 0 atomic% and less than or equal to 1 atomic% of the total composition, in one embodiment 0.2 atomic% to 0.9 atomic%, and in another embodiment 0.5 atomic% to 0.9 atomic%, we can promote anisotropic growth of the α-Fe phase crystal through heat treatment, that is, the growth of the (211) plane of the α-Fe phase crystal, and thereby achieve a high saturation magnetic flux density, unlike conventional teachings.

[0048] Furthermore, Si has the effect of reducing the viscosity of the molten metal, making it easier to discharge, and suppressing nozzle clogging.

[0049] In amorphous alloys, the composition formula contains one or more unavoidable elements selected from the group consisting of Nb, Mo, Ta, W, Co, and Sn.

[0050] Furthermore, amorphous alloys may contain one or more elements selected from the group consisting of, for example, Zr, Hf, Cu, Ag, Au, Zn, As, Sb, Bi, Y, and rare earth elements, in order to improve corrosion resistance, suppress grain growth, and increase the frequency of nucleation, provided that the saturation magnetic flux density is not significantly reduced.

[0051] Next, a method for manufacturing amorphous alloys will be described. There are no restrictions on the method of manufacturing amorphous alloys, as long as an amorphous alloy having the composition represented by the above-mentioned composition formula can be obtained. As mentioned above, alloys can exist in forms such as thin strips, flakes, granules, and bulk materials. A manufacturing method for amorphous alloys can be appropriately selected to obtain the desired form.

[0052] One method for producing amorphous alloys involves, for example, preparing an ingot beforehand that is compounded to have the composition of the amorphous alloy represented by the aforementioned composition formula, and then rapidly cooling the molten metal obtained by melting this ingot to obtain the amorphous alloy. If there are elements that are depleted during the melting of the ingot, an ingot with a composition that takes this depletion into account should be prepared. Furthermore, if the ingot is crushed and melted, it is preferable to perform a homogenization heat treatment on the ingot before crushing.

[0053] Conventional methods are acceptable for rapidly cooling the molten metal, such as the single-roll method using a cooling roll made of copper or a copper alloy. The peripheral speed of the cooling roll in the single-roll method can be the standard peripheral speed used when manufacturing amorphous alloys whose main component is Fe. For example, the peripheral speed of the cooling roll can usually be between 15 m / sec and 55 m / sec.

[0054] When molten metal is discharged onto a single roll, its temperature is typically 50°C to 300°C higher than the melting point of the ingot. There are no particular restrictions on the atmosphere when the molten metal is discharged, but from the viewpoint of reducing the inclusion of oxides and other contaminants in the amorphous alloy, an atmosphere such as an inert gas is preferred.

[0055] (Process for rapid heat treatment of amorphous alloys) Next, the amorphous alloy is subjected to rapid heat treatment. Rapid heat treatment means rapidly heating the amorphous alloy to a predetermined temperature range, holding it for a short time, and then rapidly cooling it. Specifically, the amorphous alloy is heated from a temperature above the α-Fe phase crystal formation initiation temperature, or in one embodiment, as described below, a temperature that is, for example, usually 100°C higher, in one embodiment 150°C higher, and in one embodiment 200°C higher than the α-Fe phase crystal formation initiation temperature, down to a temperature range below the Fe-B compound formation initiation temperature, at a heating rate of usually 100°C / second or more. It is then held in this temperature range for 0 to 80 seconds, and then cooled at a cooling rate of usually 100°C / second or more.

[0056] If the heating rate is typically 100°C / second or higher, the crystalline phase will not coarseen. From the viewpoint of avoiding crystalline phase coarsening, a faster heating rate is preferable, so the heating rate is 150°C / second or higher in one embodiment, and 325°C / second or higher in another embodiment. On the other hand, if the heating rate is too fast, the heat source for heating becomes too large, which is economically disadvantageous. From the viewpoint of the heat source, the heating rate is 415°C / second or lower in one embodiment. The heating rate may be the average rate from the start of heating to the start of holding. If the holding time is 0 seconds, the heating rate may be the average rate from the start of heating to the start of cooling. Alternatively, the heating rate may be the average rate within a specific temperature range, for example, between 100°C and 500°C.

[0057] If the holding time is 0 seconds or longer, a fine crystalline phase can be obtained from the amorphous phase. A holding time of 0 seconds means that the mixture is cooled immediately after rapid heating or the holding process is terminated. In one embodiment, the holding time is 3 seconds or longer. On the other hand, if the holding time is 80 seconds or less, the coarsening of the crystalline phase can be avoided. From the viewpoint of avoiding the coarsening of the crystalline phase, the holding time is 60 seconds or less in one embodiment and 10 seconds or less in another embodiment.

[0058] The heat treatment temperature (holding temperature) is usually above the crystal formation initiation temperature of the α-Fe phase. This temperature can convert the amorphous phase into a crystalline phase and stabilize the resulting nanocrystalline structure. On the other hand, if the holding temperature is above the Fe-B compound formation initiation temperature, the formation of Fe-B compounds causes strong crystalline magnetic anisotropy, resulting in increased coercivity. Therefore, by setting the holding temperature below the Fe-B compound formation initiation temperature, the crystalline phase can be refined without forming Fe-B compounds. Accordingly, the heat treatment temperature is usually above the crystal formation initiation temperature of the α-Fe phase. In one embodiment, as described below, it is in the temperature range from a temperature higher than the crystal formation initiation temperature of the α-Fe phase to a temperature lower than the Fe-B compound formation initiation temperature. In one embodiment, the heat treatment temperature is usually 485°C to 500°C. Note that the crystal formation initiation temperature of the α-Fe phase and the Fe-B compound formation initiation temperature may vary depending on the alloy system, but can be measured, for example, by DSC measurement. The heat treatment temperature is the temperature reached by the amorphous alloy through heat treatment.

[0059] The heating method is not particularly limited as long as it can heat the amorphous alloy at the heating rate described above.

[0060] When using a conventional atmosphere furnace, the heating rate and / or holding temperature of the furnace atmosphere can be higher than the desired heating rate and / or holding temperature for amorphous alloys.

[0061] When using an infrared furnace instead of a conventional atmospheric furnace, the time lag between the amount of heat input to the infrared heater and the amount of heat received by the amorphous alloy can be reduced. An infrared furnace is a furnace that rapidly heats the object to be heated by reflecting the light emitted by an infrared lamp with a concave surface.

[0062] Furthermore, the amorphous alloy may be rapidly heated and held by heat transfer between solids. For example, the amorphous alloy may be sandwiched between blocks that have already been heated to a desired holding temperature, thereby rapidly heating and holding the amorphous alloy.

[0063] If the cooling rate of the soft magnetic material is typically 100°C / second or higher, and in one embodiment between 100°C / second and 415°C / second, the crystalline phase will not become further coarser.

[0064] While not bound by theory, it is thought that the following phenomena occur within amorphous alloys when they are subjected to rapid heat treatment.

[0065] The amorphous alloy is rapidly heated to a temperature range above the α-Fe phase crystal formation initiation temperature and held at that temperature range for a short period. Therefore, it is believed that the coarsening of the microstructure of the crystalline phase is avoided, and the resulting crystalline phase is refined.

[0066] Here, the size of the microstructure depends on the heterogeneous nucleation rate, which in turn is governed by atomic transport and the size of the critical nucleus.

[0067] To refine the microstructure, it is necessary to increase the heterogeneous nucleation rate, and to increase the heterogeneous nucleation rate, it is necessary to increase atomic transport and reduce the size of the critical nucleus. To achieve these two conditions, it is effective to introduce a supercooled liquid region in an amorphous material. In the supercooled liquid region of an amorphous material, viscous flow is very large, so the strain energy due to nucleation in the supercooled liquid is much smaller than the strain energy due to nucleation in the amorphous material. Therefore, in the supercooled liquid region, many embryos become nuclei.

[0068] In conventional heat treatment (annealing), however, the heating rate is slow, causing amorphous crystallization to begin at relatively low temperatures. Consequently, at relatively low temperatures, the transition from solid to supercooled liquid is limited, and heterogeneous nucleation is also very limited.

[0069] In contrast, when heating is performed by rapid temperature increase as in the present invention, the crystal formation initiation temperature of the α-Fe phase in the amorphous alloy can be increased. In this case, the amorphous phase can maintain its amorphous state up to a high temperature at which the transition of the amorphous material to a supercooled liquid occurs actively. When the amorphous material transitions to a supercooled liquid, atomic transport increases, the size of the critical nucleus decreases, and the heterogeneous nucleation rate increases. As a result, the nucleation frequency also increases.

[0070] Therefore, by rapidly heating an amorphous alloy, high atomic transport can be achieved within the region where a supercooled liquid is generated, leading to active nucleation.

[0071] On the other hand, rapidly heating an amorphous alloy also increases the grain growth rate. In this invention, the holding time is short, which shortens the time for grain growth and suppresses grain growth.

[0072] Furthermore, during the crystallization process, if the thermal energy supplied to the amorphous alloy is insufficient (for example, if the heat treatment temperature is low), the diffusion of atoms within the amorphous alloy will be insufficient, and the heat treatment may end in an unstable state. In that case, for example, when the resulting soft magnetic material is used in a high-temperature environment, the thermal energy supplied from the environment may cause atomic movement within the material, changing the short-range structure of the material. As a result, the magnetic properties of the material may deteriorate, for example, the coercivity of the material may increase.

[0073] Therefore, alloys having an amorphous phase are heated to a temperature above the α-Fe phase crystal formation initiation temperature, and particularly to a temperature that is typically 100°C to 200°C higher than the α-Fe phase crystal formation initiation temperature, and in one embodiment to a temperature that is 100°C to 150°C higher. This allows for sufficient diffusion of atoms in the amorphous alloy, and even when the resulting soft magnetic material is used in a high-temperature environment, the movement of atoms (mainly B atoms) due to thermal energy added from the environment is suppressed, and as a result, the magnetic properties of the material, especially its coercivity, remain stable at a low level.

[0074] On the other hand, when the temperature of an amorphous alloy reaches the Fe-B compound formation initiation temperature, Fe-B compounds are formed. Because Fe-B compounds have high crystalline magnetic anisotropy, they increase coercivity.

[0075] Therefore, by heating amorphous alloys to a temperature below the Fe-B compound formation initiation temperature, the formation of Fe-B compounds can be suppressed, and their properties, particularly magnetic properties, can be well maintained. [Examples]

[0076] The following describes some embodiments of the present invention, but the present invention is not intended to be limited to those shown in these embodiments.

[0077] (Fabrication of amorphous alloys) The raw materials were weighed to achieve the composition shown in Table 1, and then arc-melted to produce ingots. Pure Fe, Fe-B alloy, and pure Ni were used as raw materials. In this process, the ingots were repeatedly melted and inverted (3 to 5 times) to ensure homogeneity.

[0078] Finely cut ingots were charged into the nozzle of a liquid quenching device (single-roll method) and melted by high-frequency heating under an inert atmosphere to obtain molten metal. The molten metal was then extruded onto a copper roll at a peripheral speed of 30 m / s to 70 m / s and rapidly cooled to obtain a 5 mm wide ribbon-shaped amorphous alloy. The extrusion temperature was set to the melting point + 50°C to 200°C. The quenching conditions were adjusted by setting the gap to 0.4 mm and controlling the chamber pressure and nozzle pressure so that the extrusion pressure was between 40 kPa and 80 kPa.

[0079] Regarding the amorphous alloy, its amorphous nature was confirmed by XRD prior to the heat treatment described below, and its composition was confirmed by ICP.

[0080] (Heat treatment of amorphous alloys) An amorphous alloy having the composition described in Table 1 was sandwiched between a heating plate (made of stainless steel) and a calcium silicate plate, with the amorphous alloy temperature heated to the heat treatment temperature described in Table 1, in the order of heating plate-amorphous alloy-calcium silicate plate. The alloy was heated for 3 seconds, and then rapidly cooled by removing it from the heating plate. This heating caused the amorphous phase in the amorphous alloy to crystallize, resulting in a sample of soft magnetic material. The heating rate was 100°C / second or higher, and the cooling rate was 100°C / second.

[0081] (Evaluation of the sample) XRD (instrument: Rigaku Smart LabII) analysis was performed on each heat-treated sample under the conditions described in Table 2, and the area ratio of each peak in the α-Fe phase was calculated. The area ratio of each peak was calculated according to the method described above. Subsequently, the coercivity and saturation magnetic flux density were measured for each heat-treated sample using a VSM (vibrating sample magnetometer)-P2H type-Helmholtz coil 2000e (manufactured by Toei Kogyo Co., Ltd.).

[0082] The results are shown in Table 1 and Figures 1-3. Figure 1 shows the relationship between Si content and (A) crystalline (211) plane peak area ratio or (B) saturation magnetic flux density for samples with a heat treatment temperature of 490°C (Example 5 and Comparative Examples 5-6). Figure 2 shows the relationship between heat treatment temperature and saturation magnetic flux density for samples with a Si content of 0.8 atomic% (Examples 1-7 and Comparative Examples 1-4). Figure 3 shows the relationship between crystalline (211) plane peak area ratio and saturation magnetic flux density for samples with a Si content of 0.8 atomic%.

[0083] [Table 1]

[0084] [Table 2]

[0085] In Table 1, amo represents the amorphous peak. From Table 1 and Figure 1, it was found that by incorporating an appropriate amount of Si, the crystalline (211) plane peak area ratio can be improved, thereby improving the saturation magnetization. Furthermore, from Table 1 and Figure 2, it was found that during the manufacturing of the soft magnetic material of the present invention, the crystalline (211) plane peak area ratio can be controlled by rapid heat treatment, particularly by the heat treatment temperature. Moreover, from Table 1 and Figure 3, it was found that in the soft magnetic material of the present invention, the saturation magnetization can be improved by increasing the crystalline (211) plane peak area ratio.

Claims

1. The following chemical formula: Fe １００－ｘ－ｙ－ｚ－ｗ B ｘ Yes ｙ Yes ｚ M ｗ (In the formula, M is one or more unavoidable elements selected from Nb, Mo, Ta, W, Co, and Sn, and x, y, z, and w satisfy the following atomic percentages: 12 ≤ x ≤ 17, 1 ≤ y ≤ 3, 0 < z ≤ 1, and 0 < w ≤ 0.1) A soft magnetic material represented by, The soft magnetic material contains an α-Fe phase, The α-Fe phase contains crystals with an average grain size of 30 nm or less. The average grain size of the crystal is the average value of the equivalent diameter of the projected area circle of the crystal in transmission electron microscope (TEM) images of soft magnetic material thinned using integrated ion beam (FIB). The ratio of the peak area of ​​the crystalline (211) plane to the total peak area measured by XRD of the α-Fe phase on the surface of the soft magnetic material is 0.10 or greater. Soft magnetic material.

2. The soft magnetic material according to claim 1, wherein 0.2 ≤ z ≤ 0.

9.

3. The following compositional formula: Fe １００－ｘ－ｙ－ｚ－ｗ B ｘ Ni ｙ Si ｚ M ｗ (In the formula, M is one or more unavoidable elements selected from Nb, Mo, Ta, W, Co, and Sn, and x, y, z, and w satisfy the following atomic percentages: 12 ≤ x ≤ 17, 1 ≤ y ≤ 3, 0 < z ≤ 1, and 0 < w ≤ 0.1) To prepare an alloy having a composition represented by and having an amorphous phase, The alloy is subjected to rapid heat treatment such that the temperature reached by the alloy is in a temperature range above the crystal formation initiation temperature of the α-Fe phase and below the Fe-B compound formation initiation temperature. A method for manufacturing soft magnetic materials, including

4. The manufacturing method according to claim 3, wherein the temperature reached by the alloy in the rapid heat treatment is 485°C to 500°C.

5. The manufacturing method according to claim 4, wherein in the rapid heat treatment, the heating rate of the alloy is 100°C / second to 415°C / second.

6. The manufacturing method according to claim 5, wherein the holding time of the alloy in the rapid heat treatment is 0 to 80 seconds.

7. The manufacturing method according to any one of claims 3 to 6, wherein the rapid heat treatment is carried out by sandwiching the alloy between heated blocks.

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