Iron-based amorphous soft magnetic alloy with high saturation magnetic flux density and low loss and preparation method of iron-based amorphous soft magnetic alloy

Abstract

The invention relates to an iron-based amorphous soft magnetic alloy with high saturation magnetic flux density and low loss and a preparation method thereof, the composition of the iron-based amorphous soft magnetic alloy meets the molecular formula: FeaNibSicBd, a, b, c and d respectively represent atomic percentages of corresponding alloy elements, and meet the following conditions: 76 < = a < = 80, 1 < = b < = 8, 3 < = c < = 11, 7 < = d < = 15, a + b < = 83, and a + b + c + d = 100. The invention further provides a preparation method of the iron-based amorphous soft magnetic alloy. The alloy disclosed by the invention not only has excellent soft magnetic properties of high saturation magnetic flux density and low loss, but also has large amorphous forming ability and excellent bending resistance, and is low in production cost. By combining the step-by-step magnetic field heat treatment method disclosed by the invention, the saturation magnetic flux density of the prepared iron-based amorphous soft magnetic alloy reaches 1.66 to 1.68 T, the coercive force is as low as 1.4 to 2.1 A / m, the effective magnetic conductivity is 7900 to 12600, the loss under 1.0 T / 50 Hz is 0.022 to 0.034 W / kg, and the loss under 1.3 T / 50 Hz is 0.081 to 0.122 W / kg. The iron-based amorphous soft magnetic alloy can be used for manufacturing an iron core material of a power transformer.

Description

Technical Field

[0001] The present invention relates to a high saturation magnetic flux density and low loss iron-based amorphous soft magnetic alloy and a preparation method thereof, belonging to the technical field of amorphous soft magnetic materials. Background Art

[0002] Iron-based amorphous soft magnetic alloys have a unique atomic structure with long-range disorder and short-range order, which endows them with properties superior to those of crystalline soft magnetic materials, such as high saturation magnetic flux density, low coercivity, and low core loss. Moreover, their forming process is simple, so they are widely used in power electronic devices such as distribution transformers, medium-frequency power transformers and inverters, and high-power switching power supplies. However, the saturation magnetic flux density of the currently widely used iron-based amorphous soft magnetic alloys is still significantly lower than that of silicon steel, and the no-load loss of amorphous transformer cores is still relatively large. Developing amorphous soft magnetic alloys with high saturation magnetic flux density and low loss is of great significance for realizing the miniaturization, energy saving, and high efficiency of power electronic devices. Researchers have carried out a number of studies on developing high saturation magnetic flux density and low loss iron-based amorphous soft magnetic alloys by means of composition design and process optimization, and have made a series of progress.

[0003] Adding Co element to iron-based amorphous alloys is regarded as an effective way to improve the saturation magnetic flux density. The most typical example is Metglas 2605Co(Fe 67 Co 18 B 14 Si 1 ) alloy [IEEE Transactions on Magnetics 1988, 24: 621-630], but this alloy contains 18% Co atoms and is expensive, so it cannot be used in industrial magnetic products.

[0004] US Patent No. US4226619 discloses an amorphous Fe-B-C alloy. The typical composition Fe 86 B 7 C 7 alloy has a saturation magnetic flux density exceeding 1.7T. However, its coercivity is as high as 9.5A / m, its amorphous forming ability is poor, and the as-quenched strip is fragile, so it cannot be actually popularized and applied.

[0005] Chinese Patent No. CN1721563A discloses an Fe-Si-B-C alloy named HB1. The saturation magnetic flux density of this alloy reaches 1.60 - 1.66T, but in the preparation process, carburizing is used, which undoubtedly increases the production cost and reduces the controllability of product quality.

[0006] Chinese Patent No. CN1721567A discloses an iron-based amorphous alloy strip and a magnetic core formed therefrom. The chemical composition of the alloy is Fe a Si b Bc M x or Fe a Si b B c C d M x where M is Cr or Ni, a is 78 to 86 atomic %, b is 0.001 to 5 atomic %, c is 7 to 20 atomic %, x is 0.01 to 5 atomic %, and d is 0.001 to 4 atomic %, and (a + b + c + x) or (a + b + c + d + x) is 100. The saturation magnetic flux density is 1.61 - 1.67 T, and the core loss at 1.3 T / 50 Hz is 0.2 - 0.31 W / kg. However, in this alloy, the Si content is relatively low. In specific embodiments, the upper limit of the Si content is only 2%, resulting in a significant decrease in thermal stability and a significant increase in alloy loss.

[0007] Chinese Patent CN1356403A discloses a high-iron-content Fe-Si-B-C-P amorphous alloy. The iron content of the alloy is between 82 - 90%, its saturation magnetic flux density is as high as 1.74 - 1.76 T, the loss at 1.3 T / 50 Hz is 0.091 - 0.118 W / kg, and the heat treatment temperature range is relatively wide. However, this alloy overemphasizes performance and ignores the limitation of the amorphous formation ability. The amorphous formation ability of its typical composition alloy is limited, and it is impossible to prepare a completely amorphous sample with conventional rapid quenching strip-making equipment.

[0008] Chinese Patent CN101840764A discloses an iron-based amorphous soft magnetic alloy with low cost and high saturation magnetic induction intensity. The chemical composition of the alloy is Fe a Si b B c P d C e M f where M is at least one of S, Sb, Mn, Al, Ti, Sn, and W. The preferred composition has a relatively high Si content, exceeding 5%, and a low amorphous formation ability. In addition, in the examples of this patent, the saturation magnetic flux densities of different alloys with similar compositions vary greatly, indicating poor repeatability in the preparation process of this component alloy, resulting in a large difference in the amorphous proportion among different alloy samples with similar compositions.

[0009] Chinese Patent CN102787282A discloses an iron-based amorphous thin strip with high saturation magnetic flux density and low iron loss and its preparation method. The chemical composition of the alloy is Fe a Si b B c C d O e, the preferred composition of the alloy has a saturation magnetic flux density as high as 1.65 - 1.72 T, a coercive force of 1.5 - 1.7 A / m, and a loss of 0.18 - 0.25 W / kg at 1.4 T / 50 Hz. However, during its preparation process, it is necessary to strictly control the gas flow rates of CO 2 and CH 4 to control the O-rich layer on the alloy roll-attached surface and the free surface, which increases the process complexity and difficulty and restricts the industrialization of this type of alloy.

[0010] Chinese Patent CN108396263A discloses an iron-based amorphous soft magnetic alloy with high saturation magnetic induction intensity, its preparation method and application. The chemical composition of the alloy is Fe a Si b B c Ga d . The alloy composition adopts a simple component design, and it is proposed to use Ga to entirely replace the metalloid elements in the traditional FeSiB amorphous alloy to improve the saturation magnetic flux density of the amorphous material. In addition, its heat treatment process is simple and only requires stress relief annealing treatment, and it has a relatively wide annealing temperature range (about 90 °C). However, the optimal performance saturation magnetic flux density of its examples still does not exceed 1.6 T, and Ga is quite expensive, and the high cost severely restricts the mass production of this alloy material.

[0011] Chinese Patent CN108018504A discloses an iron-based amorphous alloy. The chemical composition of the alloy is Fe a Si b B c RE d , where RE is one or more of La, Ce, Nd, and Yb. The saturation magnetic flux density of this alloy is 1.63 - 1.67 T, the loss at 1.3 T / 50 Hz is 0.134 - 0.157 W / kg, and the loss at 1.4 T / 50 Hz is 0.18 - 0.289 W / kg. However, the lower Si content in its preferred composition reduces the formability and thermal stability of the amorphous strip, and greatly improves the requirements for the strip-making process of the alloy. In addition, in the examples and comparative examples of this patent, for alloys with similar compositions, the trace rare earth element differences lead to a significant deterioration of the loss. This rare earth addition strategy is difficult to balance the magnetic properties and process adaptability, restricting its application and promotion.

[0012] Chinese Patent CN107267889A discloses an iron-based amorphous alloy with low stress sensitivity and its preparation method. The chemical composition of the alloy is Fe a B b Si cThe saturation magnetic flux density of this alloy is 1.60 - 1.63 T, the loss at 1.35 T / 50 Hz is 0.09 - 0.10 W / kg, and the loss at 1.4 T / 50 Hz is 0.115 - 0.145 W / kg. At the same time, it has low stress sensitivity, which is beneficial to improving the anti - sudden - short - circuit ability of amorphous transformers. However, for alloy compositions with a saturation magnetic flux density ≥1.62 T, the amorphous limit ribbon thickness decreases from 82 μm to 65 μm, the amorphous formation ability is greatly reduced, and the saturation magnetic flux density is still relatively low and needs to be further improved.

[0013] Chinese Patent CN109830352A discloses an Fe - Si - B - based amorphous soft magnetic alloy and its preparation method. The chemical composition of the alloy is Fe 84-x Ni x Si a B b , where 0 < x ≤ 5, a is 3 - 6, and a + b = 16. The saturation magnetic flux density of this alloy is 1.63 - 1.71 T, and the coercivity is 14.2 - 24.1 A / m. However, the coercivity of this alloy is relatively large, which affects the comprehensive soft magnetic properties. In addition, its amorphous formation ability is poor, and a relatively high rapid quenching rate for ribbon making (>50 m / s) is required, which undoubtedly increases the difficulty and cost of the preparation process and limits the large - scale production of this type of alloy.

[0014] The above - mentioned patents have improved the soft magnetic properties of amorphous alloys to varying degrees by adjusting the alloy composition and preparation process, but generally ignored two obvious problems: the difficulty of the preparation process and the amorphous formation ability of the alloy system. Therefore, on the basis of low cost and simple preparation process, developing an Fe - based amorphous soft magnetic alloy with high saturation magnetic flux density, low loss, and large amorphous formation ability has important scientific significance and practical value. Summary of the Invention

[0015] Object of the Invention: The object of the present invention is to provide an Fe - based amorphous soft magnetic alloy with both high saturation magnetic flux density and low loss. While having excellent soft magnetic properties and large amorphous formation ability, this amorphous alloy also has the advantage of low raw material cost. The present invention also provides a preparation method for this amorphous soft magnetic alloy. Through step - by - step magnetic field heat treatment of the alloy ribbon, the optimization of the magnetic properties of the Fe - based amorphous alloy is achieved.

[0016] Technical Solution: The composition of the Fe - based amorphous soft magnetic alloy of the present invention satisfies the molecular formula: Fe a Ni b Si c B d, where a, b, c, and d respectively represent the atomic percentages of the corresponding alloying elements, and satisfy the following conditions: 76 ≤ a ≤ 80, 1 ≤ b ≤ 8, 3 ≤ c ≤ 11, 7 ≤ d ≤ 15, a + b ≤ 83, and a + b + c + d = 100.

[0017] Furthermore, in the said molecular formula, the atomic percentage content of Ni is preferably 1 ≤ b ≤ 5, the atomic percentage content of Si is preferably 4 ≤ c ≤ 10, the atomic percentage content of B is preferably 8 ≤ d ≤ 14, and the atomic percentage content of Fe and Ni is preferably a + b ≤ 82.

[0018] In the above technical solution, the saturation magnetic flux density of the iron-based amorphous soft magnetic alloy reaches 1.66 - 1.68 T, the coercive force is as low as 1.4 - 2.1 A / m, the effective magnetic permeability is 7900 - 12600, the loss at 1.0 T / 50 Hz is 0.022 - 0.034 W / kg, and the loss at 1.3 T / 50 Hz is 0.081 - 0.122 W / kg.

[0019] On the other hand, the present invention provides a preparation method of the above-mentioned iron-based amorphous soft magnetic alloy, comprising the following steps:

[0020] Step 1, weigh and mix the Fe, Ni, Si, and B in the alloy components according to the alloy composition molecular formula Fe a Ni b Si c B d , wherein the purity of each raw material is greater than 99%;

[0021] Step 2, load the raw materials prepared in Step 1 into an induction melting furnace, and carry out induction melting in an inert gas atmosphere, and obtain a homogeneous master alloy ingot after cooling;

[0022] Step 3, prepare continuous amorphous alloy strips from the said master alloy ingot through a melt spinning and quenching equipment;

[0023] Step 4, carry out stepwise magnetic field heat treatment on the said amorphous alloy strips under vacuum conditions or in an inert atmosphere to obtain an iron-based amorphous soft magnetic alloy.

[0024] Preferably, in the said Step 3, the process parameters for preparing the amorphous alloy strips are: injection pressure 0.01 - 0.03 MPa, injection temperature 1150 - 1200 °C, and the surface linear velocity of the copper roller 15 - 35 m / s.

[0025] In the above technical solution, the width of the prepared continuous amorphous alloy strips is 1.2 - 1.5 mm, the thickness is 18 - 51 μm, and the density is 7.4 - 7.6 g / cm 3 .

[0026] Further, in the step 4, the method of stepwise magnetic field heat treatment is as follows:

[0027] In the first stage, the amorphous alloy strip is heated from room temperature to a first temperature and then held for insulation. After the insulation ends, it is water-quenched and cooled to room temperature.

[0028] In the second stage, the amorphous alloy strip is heated from room temperature to a second temperature again and then held for insulation, while a longitudinal magnetic field is applied. After the insulation ends, it is water-quenched and cooled to room temperature; wherein the first temperature is greater than the second temperature.

[0029] Further, the first temperature is 360 - 420 °C, and the second temperature is 250 - 350 °C.

[0030] Further, the magnetic field strength is 500 - 1500 Oe.

[0031] As a preferred embodiment, in step 4, the method of stepwise magnetic field heat treatment is as follows:

[0032] In the first stage, the amorphous alloy strip is heated from room temperature to 360 - 420 °C and held for 1 - 20 min, and then water-quenched and cooled to room temperature.

[0033] In the second stage, when the heat treatment environment reaches 250 - 350 °C, the amorphous alloy strip is pushed into the heat treatment environment, while a longitudinal magnetic field is applied, and the magnetic field strength is 500 - 1500 Oe. The amorphous alloy strip is heated from room temperature to 250 - 350 °C and held for 1 - 20 min, and then water-quenched and cooled to room temperature.

[0034] In the above technical solution, the stepwise magnetic field heat treatment method enables the iron-based amorphous soft magnetic alloy to have regular magnetic domains, and regulates the orientation arrangement of its magnetic domains along the magnetic field direction. The magnetic domain width exceeds 480 μm, the domain walls are straight and smooth, and the magnetization mechanism is dominated by uniform domain wall displacement.

[0035] The alloy prepared by the present invention has a large amorphous formation ability and excellent anti-bending performance. The supercooling degree of the alloy reaches 90 - 170 °C. An iron-based amorphous alloy strip with a width of 142 mm can be prepared using industrial raw materials, and it has good toughness after heat treatment at a temperature as high as 360 °C for 10 min, and can be repeatedly folded at 180° without breaking.

[0036] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages:

[0037] 1. The iron-based amorphous alloy provided by the present invention has a large amorphous formation ability. Using the single-roll rapid quenching method, the critical thickness of the strip for preparing a completely amorphous alloy is ≥51 μm, and the critical copper roll rotation speed is as low as 15 m / s. Moreover, using the planar flow casting method, an amorphous wide strip with a width of 142 mm can be prepared.

[0038] 2. The iron-based amorphous alloy provided by the present invention has a low Curie temperature, a fast stress release rate during the heat treatment process, a short heat treatment time, a low temperature, and the heat-treated sample has excellent anti-bending performance, and can maintain 180° repeated folding without breaking when obtaining excellent soft magnetic properties.

[0039] 3. By the strategy of replacing metalloid elements with trace Ni elements to increase the content of ferromagnetic elements, the present invention significantly improves the saturation magnetic flux density of the alloy on the premise of ensuring the amorphous formation ability. And it does not contain precious metals / oxidizable elements such as Co, Nb, Zr, Mo, Y, etc. Adding trace Ni elements reduces the raw material cost.

[0040] 4. The iron-based amorphous alloy provided by the present invention has excellent and controllable comprehensive soft magnetic properties. The saturation magnetic flux density reaches 1.66 - 1.68 T, the coercivity is as low as 1.4 - 2.1 A / m, the effective magnetic permeability is 7900 - 12600, the loss at 1.0 T / 50 Hz is 0.022 - 0.034 W / kg, the loss at 1.3 T / 50 Hz is 0.081 - 0.122 W / kg, and the power frequency loss is significantly lower than 0.152 W / kg of the METGLAS2605HB1 (saturation magnetic flux density 1.67 T) amorphous soft magnetic alloy.

[0041] 5. The preparation method provided by the present invention, especially the step-by-step magnetic field heat treatment method, has a simple process, wide applicability, a lower heat treatment temperature, and has the advantages of reducing production energy consumption and cost and improving production efficiency, and has broad application prospects. Description of the Drawings

[0042] Figure 1 X-ray diffraction patterns of strip materials with different thicknesses prepared from the representative components of the examples and the components of Comparative Example 1;

[0043] Figure 2 DSC curves of the melting and solidification processes of the amorphous alloys of the representative components of the examples and Comparative Example 1;

[0044] Figure 3 Curves of the loss varying with the magnetic flux density of the alloy samples after ordinary heat treatment at the optimal heat treatment temperature for the representative components of the examples and Comparative Example 1 under the condition of 50 Hz frequency;

[0045] Figure 4 Curves of the loss varying with the magnetic flux density of the alloy samples after step-by-step magnetic field heat treatment for the representative components of the examples of the present invention and Comparative Example 1 under the condition of 50 Hz frequency;

[0046] Figure 5 Magnetic domain structure diagram of the alloy sample of Comparative Example 1 after ordinary heat treatment at the optimal annealing temperature;

[0047] Figure 6 Magnetic domain structure diagram of the alloy sample after ordinary heat treatment at the optimal annealing temperature in Example 3;

[0048] Figure 7 Magnetic domain structure diagram of the alloy sample after step - by - step magnetic field heat treatment in Example 3;

[0049] Figure 8 Physical drawing of the strip after bending 180° after heat treatment for Comparative Example 1 and Examples 1 and 3;

[0050] Figure 9 Physical drawing of the 142 - mm - wide iron - based amorphous alloy strip prepared by the planar flow casting method. Detailed implementation mode

[0051] To further illustrate the content of the present invention, the present invention will be described in detail below in conjunction with the drawings and examples.

[0052] The iron - based amorphous soft magnetic alloy described in the present invention satisfies the molecular formula: Fe a Ni b Si c B d , where a, b, c, and d respectively represent the atomic percentages of the corresponding alloying elements: 76 ≤ a ≤ 80, 1 ≤ b ≤ 8, 3 ≤ c ≤ 11, 7 ≤ d ≤ 15, a + b ≤ 83 and a + b + c + d = 100.

[0053] In the composition of the iron - based amorphous soft magnetic alloy of the present invention, Fe is a ferromagnetic element, which can improve the saturation magnetic flux density of the alloy; Ni is a ferromagnetic element, which can not only improve the amorphous formation ability of the alloy, increase the saturation magnetic flux density, but also has a small saturation magnetostriction coefficient, which can effectively reduce the loss. The addition of Ni element can also increase the Poisson's ratio of the alloy, thereby improving the anti - bending performance; Si and B are amorphous - forming elements, which can effectively improve the amorphous formation ability of the alloy and improve its soft magnetic properties.

[0054] Generally, the atomic percentage content a of Fe is 76 ≤ a ≤ 80. The atomic percentage content b of Ni is 1 ≤ b ≤ 8, preferably 1 ≤ b ≤ 5. The atomic percentage content c of Si is 3 ≤ c ≤ 11, preferably 4 ≤ c ≤ 10. The atomic percentage content d of B is 7 ≤ d ≤ 15, preferably 8 ≤ d ≤ 14. The atomic percentage content of Fe and Ni is a + b ≤ 83, preferably a + b ≤ 82.

[0055] This iron - based amorphous soft magnetic alloy is prepared by the step - by - step magnetic field heat treatment method, realizing the optimization of the soft magnetic properties of the iron - based amorphous alloy.

[0056] Example 1

[0057] Prepare an alloy with the molecular formula Fe 78 Ni1 Si 8 B 13 Iron-based amorphous soft magnetic alloy of:

[0058] Step 1: Weigh and proportion raw materials of Fe, Ni, Si, and B with a purity greater than 99% according to the alloy composition molecular formula Fe 78 Ni 1 Si 8 B 13 to obtain 25 g of a mixed material.

[0059] Step 2: Load the mixed material prepared in Step 1 into the crucible of an induction melting furnace and melt it in an argon atmosphere. After cooling, a homogeneous master alloy ingot is obtained;

[0060] Step 3: Use a melt spinning equipment. After crushing the master alloy ingot obtained in Step 2, appropriately load it into a quartz tube with a nozzle at the bottom. Fix the quartz tube in the induction coil, adjust the vertical position of the quartz tube to control the distance between the tube orifice and the roll surface at 0.2 mm. After pumping the chamber to a high vacuum, fill it with an appropriate amount of protective gas (high-purity argon) with a pressure difference of 0.02 MPa. Set the surface linear velocity of the copper roll at 30 m / s, turn on the heating current. Wait until the solenoid heats and melts the master alloy to quickly reach the molten state, then turn off the heating power. When the alloy melt cools to 1150 °C, press the ejection button, and use the pressure difference between the inside of the quartz tube and the chamber to quickly spray the molten alloy liquid onto the surface of the rapidly rotating copper roll for rapid cooling, to prepare a continuous amorphous alloy strip with a width of 1.5 mm and a thickness of 29 - 32 μm;

[0061] Step 4: Cut 60 mm from the amorphous strip prepared in Step 3 and load it into a quartz tube matching the tube annealing furnace. Pump the high vacuum to 5×10 -3 Pa; when the temperature of the tube furnace reaches the preset value (within the temperature range of 360 - 420 °C, with each interval of 20 °C as a holding temperature, determine the optimal holding temperature according to the minimum coercivity of the alloy), push the quartz tube into the tube furnace for insulation for 10 min, and finally water quench to room temperature to obtain a structurally relaxed iron-based amorphous alloy.

[0062] Step 5: Cut 60 mm from the amorphous strip prepared in Step 3 and load it into a quartz tube matching the tube annealing furnace. Pump the high vacuum to 5×10 -3Pa; After the temperature of the tube furnace reaches the preset value (within the temperature range of 360 - 420 °C, with each interval of 20 °C as a heat preservation temperature), push the quartz tube into the tube furnace for heat preservation for 10 min, and then quench and cool it to room temperature; then reset the temperature of the tube furnace. When the temperature of the tube furnace reaches 300 °C, push the quartz tube into the tube furnace again, and apply an external magnetic field at the same time. The magnetic field direction is parallel to the strip direction, and the magnetic field intensity is 1000 Oe. Keep it for 10 min, and finally water quench and cool it to room temperature to obtain the iron-based amorphous alloy after step-by-step magnetic field heat treatment.

[0063] Step 6 is the same as step 3, except that by adjusting the surface linear velocity of the copper roller, different thicknesses of amorphous ribbons are prepared by changing the cooling rate, and the XRD is used to analyze the microstructure of the ribbons. The maximum thickness of the fully amorphous alloy ribbon obtained is the critical thickness of amorphous formation for the corresponding composition.

[0064] Example 2

[0065] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 1 Si 9 B 12 by referring to the method of Example 1.

[0066] Example 3

[0067] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 2 Si 7 B 13 by referring to the method of Example 1.

[0068] Example 4

[0069] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 2 Si 8 B 12 by referring to the method of Example 1.

[0070] Example 5

[0071] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 2 Si 9 B 11 by referring to the method of Example 1.

[0072] Example 6

[0073] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 3 Si 6 B 13 by referring to the method of Example 1.

[0074] Example 7

[0075] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 3 Si 7 B 12 by referring to the method of Example 1.

[0076] Example 8

[0077] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 3 Si 8 B 11 by referring to the method of Example 1.

[0078] Example 9

[0079] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 3 Si 9 B 10 by referring to the method of Example 1.

[0080] Example 10

[0081] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 4 Si 5 B 13 by referring to the method of Example 1.

[0082] Example 11

[0083] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 4 Si 6 B 12 by referring to the method of Example 1.

[0084] Example 12

[0085] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 4 Si 7 B 11 by referring to the method of Example 1.

[0086] Example 13

[0087] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 4 Si 8 B 10 by referring to the method of Example 1.

[0088] Example 14

[0089] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 4 Si 9 B 9 by referring to the method of Example 1.

[0090] Example 15

[0091] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Ni 4 Si 4 B 14 by referring to the method of Example 1.

[0092] Example 16

[0093] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 76 Ni 5 Si 5 B 14 by referring to the method of Example 1.

[0094] Example 17

[0095] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 80 Ni 2 Si 10 B 8 by referring to the method of Example 1.

[0096] Example 18

[0097] The composition of the iron-based amorphous soft magnetic alloy prepared in this example is the same as that of Example 3. During the preparation process, change the process parameters for preparing the amorphous alloy strip in Step 3 to: injection pressure 0.01 MPa, injection temperature 1150 °C, and linear velocity of the copper roller surface 15 m / s; change the heat treatment conditions of the stepwise magnetic field in the second stage of Step 5: when the temperature of the tubular furnace reaches 250 °C, push the quartz tube into the tubular furnace again, and at the same time apply a magnetic field with an external magnetic field strength of 500 Oe, and keep it warm for 20 min. The remaining steps are the same as those in Example 3.

[0098] Example 19

[0099] The composition of the iron-based amorphous soft magnetic alloy prepared in this example is the same as that in Example 3. During the preparation process, the process parameters for preparing the amorphous alloy ribbon in Step 3 are changed as follows: the injection pressure is 0.03 MPa, the injection temperature is 1200 °C, and the surface linear velocity of the copper roller is 35 m / s; the heat treatment conditions in the second stage of the step-by-step magnetic field in Step 5 are changed: when the temperature of the tube furnace reaches 350 °C, the quartz tube is pushed into the tube furnace again, and at the same time, a magnetic field with an external magnetic field intensity of 1500 Oe is applied and kept warm for 1 min. The remaining steps are the same as those in Example 3.

[0100] Comparative Example 1

[0101] Prepare an iron-based amorphous soft magnetic alloy with the molecular formula Fe 78 Si 9 B 13 :

[0102] Step 1: Weigh and mix the raw materials of Fe, Si, and B with a purity greater than 99% according to the alloy composition molecular formula Fe 78 Si 9 B 13 to obtain 25 g of the mixed material.

[0103] Step 2: Put the mixed material prepared in Step 1 into the crucible of the induction melting furnace and melt it in an argon atmosphere. After cooling, a homogeneous master alloy ingot is obtained;

[0104] Step 3: Use a melt spinning and quenching equipment. After crushing the master alloy ingot obtained in Step 2, appropriately load it into a quartz tube with a nozzle at the bottom. Fix the quartz tube in the induction coil, adjust the vertical position of the quartz tube to control the distance between the tube orifice and the roller surface to be 0.2 mm. After evacuating the chamber to a high vacuum, fill it with an appropriate amount of protective gas (high-purity argon), set the pressure difference to 0.02 MPa, set the surface linear velocity of the copper roller to 30 m / s, turn on the heating current, wait for the solenoid to heat and melt the master alloy to quickly reach the molten state, then turn off the heating power supply. When the alloy melt cools to 1150 °C, press the injection button, and use the air pressure difference inside the quartz tube and the chamber to quickly spray the molten alloy liquid onto the surface of the high-speed rotating copper roller for rapid cooling, and prepare a continuous amorphous alloy ribbon with a width of 1.5 mm and a thickness of 29 - 32 μm;

[0105] Step 4: After intercepting 60 mm from the amorphous ribbon prepared in Step 3, load it into a quartz tube matching the tube annealing furnace, evacuate to a high vacuum of 5×10 -3 Pa; when the temperature of the tube furnace reaches the preset value (in the temperature range of 360 - 420 °C, every 20 °C is used as a holding temperature, and the optimal holding temperature is determined according to the minimum coercivity of the alloy), push the quartz tube into the tube furnace and keep it warm for 10 min, and finally water quench and cool to room temperature to obtain a structurally relaxed iron-based amorphous alloy.

[0106] Step 5: After cutting 60 mm from the amorphous strip prepared in Step 3, load it into a quartz tube matching the tube-type annealing furnace, and pump it to a high vacuum of 5×10 -3 Pa; when the temperature of the tube furnace reaches the preset value (in the temperature range of 360 - 420 °C, with each interval of 20 °C as a holding temperature), push the quartz tube into the tube furnace and hold for 10 min, then quench and cool to room temperature; then reset the temperature of the tube furnace. When the temperature of the tube furnace reaches 300 °C, push the quartz tube into the tube furnace again, and apply an external magnetic field at the same time. The direction of the magnetic field is parallel to the strip direction, and the magnetic field intensity is 1000 Oe. Hold for 10 min, and finally water quench and cool to room temperature to obtain the iron-based amorphous alloy after step-by-step magnetic field heat treatment.

[0107] Step 6: The same as Step 3, except that by adjusting the surface linear velocity of the copper roller, amorphous strips with different thicknesses are prepared by changing the cooling rate, and the microstructure of the strip is analyzed by XRD. The maximum thickness of the fully amorphous alloy strip obtained is the critical thickness of amorphous formation for the corresponding composition.

[0108] Comparative Example 2

[0109] Select Example 5 described in Patent CN109830352A as Comparative Example 2. The iron-based amorphous soft magnetic alloy prepared in this comparative example has the molecular formula Fe 80 Ni 4 Si 4 B 12 :

[0110] Step 1: Weigh and mix the raw materials of Fe, Ni, Si, and B with a purity greater than 99% according to the alloy composition molecular formula Fe 80 Ni 4 Si 4 B 12 to obtain 25 g of the mixed material.

[0111] Step 2: Load the mixed material prepared in Step 1 into the crucible of the induction melting furnace and melt it in an argon atmosphere. After cooling, a master alloy ingot with uniform composition is obtained;

[0112] Step 3: Use a melt spinning and quenching equipment. Crush the master alloy ingot obtained in Step 2 and appropriately load it into a quartz tube with a nozzle at the bottom. Fix the quartz tube in the induction coil, adjust the vertical position of the quartz tube to control the distance between the tube orifice and the roll surface to be 0.2 mm. After evacuating the chamber to a high vacuum, fill it with an appropriate amount of protective gas (high-purity argon), set the differential pressure to 0.02 MPa, set the surface linear velocity of the copper roll to 50 m / s, turn on the heating current, wait for the solenoid to heat and melt the master alloy to quickly reach the molten state, then turn off the heating power supply. When the alloy melt cools to 1200 °C, press the ejection button, and use the pressure difference between the inside of the quartz tube and the chamber to quickly spray the molten alloy liquid onto the surface of the rapidly rotating copper roll for rapid cooling, to prepare a continuous amorphous alloy strip with a width of 1.2 mm and a thickness of 18 - 20 μm;

[0113] Step 4: Cut 60 mm from the amorphous strip prepared in Step 3 and load it into a quartz tube matching the tube annealing furnace. Evacuate to a high vacuum to 5×10 -3 Pa; when the temperature of the tube furnace reaches the preset value (in the temperature range of 360 - 420 °C, every 20 °C is used as a holding temperature, and the optimal holding temperature is determined according to the minimum coercivity of the alloy), push the quartz tube into the tube furnace for holding for 10 min, and finally water quench to room temperature to obtain a structurally relaxed iron-based amorphous alloy.

[0114] In Comparative Example 2, the atomic percentage of Fe + Ni ≥ 84, and a completely amorphous sample cannot be obtained with a ribbon-making rate of 30 m / s, and the amorphous formation ability of this alloy is poor.

[0115] Systematically evaluate the amorphous formation ability of the alloys in Examples 1 - 17, and compare them with the alloys in the comparative examples. The comparison results are as Figure 1 shown. Fe a Ni b Si c B d The alloys within the composition range of the claims of the present invention (76 ≤ a ≤ 80, 1 ≤ b ≤ 8, 3 ≤ c ≤ 11, 7 ≤ d ≤ 15, a + b ≤ 83) have strong amorphous formation ability, especially in the preferred range (76 ≤ a ≤ 80, 1 ≤ b ≤ 5, 4 ≤ c ≤ 10, 8 ≤ d ≤ 14, a + b ≤ 82). The critical thicknesses of the representative compositions in Examples 1 and 3 reach 49 μm and 51 μm respectively, which are significantly better than the alloy in Comparative Example 1. The large amorphous formation ability enables the alloys of the present invention to achieve large-scale production based on the existing amorphous ribbon production equipment and processes, and can ensure the excellent magnetic properties and performance consistency of the products.

[0116] Use a differential scanning calorimeter (DSC) to measure the thermal performance parameters of the as-quenched alloy strips prepared in Step 3 of Examples 1 - 17. The thermal performance parameters of the amorphous alloys in Examples 1 - 17 of the present invention, including the Curie temperature T c 、crystallization temperature Tx 、Melting start temperature T m 、Melting end temperature T lm and liquidus temperature T ls See Table 1 below. The alloys of Examples 1-17 have a low liquidus temperature T ls . A low liquidus temperature can not only reduce the energy consumption in production, but also be of great significance for prolonging the service life of refractory materials. At the same time, the research on the melting and solidification processes of the alloys of Examples 1-17 shows that Fe a Ni b Si c B d alloys have a large supercooling degree ΔT L (ΔT L = T lm - T ls ) within the composition range of the claims of the present invention (76 ≤ a ≤ 80, 1 ≤ b ≤ 8, 3 ≤ c ≤ 11, 7 ≤ d ≤ 15, a + b ≤ 83), reaching 90-170 °C, while the supercooling degrees of the alloys of Comparative Examples 1 and 2 are extremely small, being 39 and 19 °C respectively. Figure 2 is the DSC curve of the melting and solidification of the representative composition of the example of the present invention and the amorphous alloy of Comparative Example 1. The large supercooling degree ΔT L of the example alloy is beneficial to enhancing the thermal stability during the cooling process and obtaining a high amorphous formation ability.

[0117] The Curie temperature T C of the alloys of Examples 1-17 are all lower than 410 °C and the crystallization temperature T x are all lower than 510 °C. Since the as-quenched strips need to be stress-relieved heat-treated at the crystallization temperature T x , and the magnetic field heat treatment needs to be carried out below the Curie temperature T C of the alloy, the iron-based amorphous soft magnetic alloy described in the present invention can be heat-treated at a lower temperature. The low heat treatment temperature is beneficial to reducing the energy consumption during the heat treatment process and also improving the heat treatment brittleness of the amorphous alloy.

[0118] Table 1 Thermal property parameters of the amorphous soft magnetic alloys prepared in Examples 1-17 and Comparative Examples 1-2

[0119]

[0120] The effective permeability of the alloy sample was measured using an impedance analyzer under the conditions of 1 kHz and 1 A / m. The coercivity of the alloy sample was measured using a DC hysteresis loop measuring instrument under a magnetic field of 1 kA / m. The loss of the alloy sample at different magnetic flux densities was measured using an AC hysteresis loop measuring instrument. The saturation magnetic flux density of the alloy sample was measured using a vibrating sample magnetometer under a magnetic field of 800 kA / m.

[0121] Figure 3 It is the curve of the change of loss with magnetic flux density at 50 Hz for the alloy sample after ordinary heat treatment at the optimal heat treatment temperature in step 4 of the representative component of the embodiment of the present invention and the alloy sample after ordinary heat treatment at the optimal heat treatment temperature in step 4 of Comparative Example 1. Fe a Ni b Si c B d The alloy has low loss within the composition range of the claims of the present invention (76 ≤ a ≤ 80, 1 ≤ b ≤ 8, 3 ≤ c ≤ 11, 7 ≤ d ≤ 15, a + b ≤ 83), especially in the preferred range (76 ≤ a ≤ 80, 1 ≤ b ≤ 5, 4 ≤ c ≤ 10, 8 ≤ d ≤ 14, a + b ≤ 82). The losses of representative component Examples 3 and 7 under the working conditions of 1.3 T / 50 Hz are 0.104 W / kg and 0.118 W / kg respectively. This provides a large space for further optimizing the soft magnetic properties by performing step-by-step magnetic field heat treatment in step 5 of the subsequent examples.

[0122] Table 2 details the effective magnetic permeability, coercive force, saturation magnetic flux density and loss under the working conditions of 1.0 T / 50 Hz of the alloy samples after ordinary heat treatment at the optimal heat treatment temperature in step 4 of Examples 1 - 17 and the alloy samples after ordinary heat treatment at the optimal heat treatment temperature in step 4 of Comparative Examples 1 - 2. The meanings of the symbols in Table 2 are as follows: μ e is the effective magnetic permeability, H c is the coercive force, P is the loss, B s is the saturation magnetic flux density. The series of iron-based amorphous alloys of the present invention have excellent comprehensive soft magnetic properties after ordinary heat treatment, with a saturation magnetic flux density of 1.61 - 1.68 T, a coercive force of 1.7 - 6.9 A / m, an effective magnetic permeability of 4900 - 10300 at 1 kHz and 1 A / m, and a loss of 0.028 - 0.178 W / kg at 1.0 T / 50 Hz. In contrast, the saturation magnetic flux density of the alloy in Comparative Example 1 is only 1.59 T, resulting in a relatively high loss of 0.041 W / kg under a working magnetic induction of 1.0 T. While the coercive force of the alloy in Comparative Example 2 is as high as 15.6 A / m, and the loss at 1.0 T / 50 Hz is as high as 0.224 W / kg.

[0123] Table 2 Magnetic properties of the amorphous soft magnetic alloys prepared in Examples 1 - 17 and Comparative Examples 1 - 2

[0124]

[0125]

[0126] Figure 4It is the curve of the loss varying with the magnetic flux density under the condition of 50 Hz frequency for the alloy samples that are subjected to ordinary heat treatment at the optimal heat treatment temperature and then step magnetic field heat treatment in step 5 of the representative component of the embodiment of the present invention, and the alloy samples that are subjected to ordinary heat treatment at the optimal heat treatment temperature and then step magnetic field heat treatment in step 5 of Comparative Example 1. Fe a Ni b Si c B d The alloy has low loss within the composition range of the claims of the present invention (76 ≤ a ≤ 80, 1 ≤ b ≤ 8, 3 ≤ c ≤ 11, 7 ≤ d ≤ 15, a + b ≤ 83), especially in the preferred range (76 ≤ a ≤ 80, 1 ≤ b ≤ 5, 4 ≤ c ≤ 10, 8 ≤ d ≤ 14, a + b ≤ 82). The losses of the representative components of Examples 3 and 7 under the working conditions of 1.3 T / 50 Hz are 0.081 W / kg and 0.105 W / kg respectively.

[0127] Table 3 lists the effective magnetic permeability, coercive force, saturation magnetic flux density and the loss under the working condition of 1.0 T / 50 Hz of the alloy samples that are subjected to ordinary heat treatment at the optimal heat treatment temperature and then step magnetic field heat treatment in step 5 of the representative component of the embodiment, and the alloy samples that are subjected to ordinary heat treatment at the optimal heat treatment temperature and then step magnetic field heat treatment in step 5 of Comparative Example 1. After the step magnetic field heat treatment, this series of iron-based amorphous alloys have more excellent comprehensive soft magnetic properties compared with ordinary heat treatment. The saturation magnetic flux density is as high as 1.66 - 1.68 T, the coercive force is as low as 1.4 - 2.1 A / m, the effective magnetic permeability at 1 kHz and 1 A / m is 7900 - 12600, and the loss at 1.3 T / 50 Hz is 0.081 - 0.122 W / kg, realizing the optimization of magnetic properties. While the saturation magnetic flux density of Comparative Example 1 is relatively low, only 1.60 T, which increases its loss under the working condition of 1.3 T / 50 Hz, up to 0.142 W / kg.

[0128] Table 3 Magnetic property table of the alloy samples of the representative components of the embodiment and Comparative Example 1 after step magnetic field heat treatment

[0129]

[0130] The magnetization process of the alloy samples was observed by a magneto-optical Kerr microscope. The dynamic magnetic domain evolution of the alloy samples of Comparative Example 1 after ordinary heat treatment at the optimal heat treatment temperature is as Figure 5 shown. The magnetic domains have more edges and bifurcations, and are oriented transversely along the near-stripes, showing a strong pinning effect. The sample undergoes inhomogeneous magnetization rotation, and the single domain transforms into multiple parallel narrow domains. The dynamic magnetic domain evolution of the alloy samples of Example 3 after ordinary heat treatment at the optimal heat treatment temperature is as Figure 6As shown, it can be seen that for the alloy after ordinary heat treatment, the sample presents relatively wide plate-like magnetic domains, the domain walls bifurcate, there are a small number of pinning points, and it is slightly deviated from the direction of the strip axis and arranged orientationally.

[0131] In Example 3, the dynamic magnetic domain evolution of the alloy sample after step-by-step magnetic field heat treatment is as Figure 7 shown. It can be seen that for the alloy after step-by-step magnetic field heat treatment, its magnetic domains are regularly arranged, the orientation is basically consistent with the direction of the applied magnetic field, the width exceeds 480 μm, the domain walls are straight and smooth, there are no obvious pinning points, and the magnetization mechanism is dominated by uniform domain wall displacement.

[0132] It can be seen from Comparative Example 1 and Step 4 of Example 3 that the addition of Ni element promotes its comprehensive soft magnetic properties; it can be known from Step 4 and Step 5 of Example 3 that step-by-step magnetic field heat treatment is beneficial for the composition system of the present invention to obtain excellent soft magnetic properties.

[0133] Figure 8 Figure 12 is a physical picture of the strip after being bent 180° after annealing at 360 °C for 10 min in Comparative Example 1 and Examples 1 and 3. Obviously, the alloy strip of the present invention has excellent toughness after high-temperature heat treatment, and can be bent 180° repeatedly without breaking, while Comparative Example 1 breaks after being bent once. The brittleness problem of the amorphous alloy after heat treatment increases the difficulty of magnetic core processing, and the excellent toughness of the alloy of the present invention is beneficial to broaden the application prospects of the amorphous alloy.

[0134] Figure 9 Figure 16 is a physical picture of the alloy of the composition of Example 3 melted with industrial raw materials, and then the 142 mm wide iron-based amorphous alloy strip is prepared by the planar flow casting method. The surface of the alloy strip is flat and smooth, and the alloy strip has good toughness. The strip is a completely amorphous structure detected by XRD.

[0135] In summary, the present invention provides an iron-based amorphous soft magnetic alloy with both high saturation magnetic flux density and low loss. On the premise of meeting the large amorphous formation ability required for preparation, by adding Ni element, the content of ferromagnetic elements in the alloy system is increased, effectively improving the saturation magnetic flux density and the anti-bending performance of the alloy after heat treatment. The present invention also provides a preparation method for the amorphous soft magnetic alloy, that is, step-by-step magnetic field heat treatment of the amorphous alloy strip, realizing effective regulation of soft magnetic properties. Through a large number of experiments, the optimal matching of magnetic field heat treatment temperature and magnetic field strength is established, making the alloy have excellent comprehensive soft magnetic properties. The examples show that the saturation magnetic flux density of the iron-based amorphous soft magnetic alloy of the present invention reaches 1.66 - 1.68 T, the coercivity is as low as 1.4 - 2.1 A / m, the effective magnetic permeability is 7900 - 12600, the loss at 1.0 T / 50 Hz is 0.022 - 0.034 W / kg, and the loss at 1.3 T / 50 Hz is 0.081 - 0.122 W / kg. The heat treatment method of the present invention has a simple process and a relatively low heat treatment temperature, has the advantages of reducing production energy consumption and cost, and improving production efficiency, and has broad application prospects.

[0136] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims, that is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A high saturation flux density and low loss iron-based amorphous soft magnetic alloy, characterized in that: The iron-based amorphous soft magnetic alloy composition satisfies the molecular formula: Fe a Ni b Si c B d , where a, b, c, and d represent the atomic percentages of the corresponding alloy elements, respectively, and satisfy the following conditions: 76≤a≤80, 1≤b≤8, 3≤c≤11, 7≤d≤15, a+b≤83, and a+b+c+d=100.

2. The high saturation flux density and low loss iron-based amorphous soft magnetic alloy according to claim 1, characterized in that: The Fe a Ni b Si c B d In the molecular formula, the atomic percentage of Ni is 1≤b≤5, the atomic percentage of Si is 4≤c≤10, and the atomic percentage of B is 8≤d≤14.

3. The high saturation flux density and low loss Fe-based amorphous soft magnetic alloy according to claim 1, characterized in that: The Fe a Ni b Si c B d In the molecular formula, the atomic percentage of Fe and Ni is a+b≤82.

4. The high saturation flux density and low loss Fe-based amorphous soft magnetic alloy according to claim 1, characterized in that: The iron-based amorphous soft magnetic alloy has a saturation magnetic flux density of 1.66-1.68 T, a coercive force as low as 1.4-2.1 A / m, an effective magnetic permeability of 7900-12600, a loss of 0.022-0.034 W / kg at 1.0 T / 50 Hz, and a loss of 0.081-0.122 W / kg at 1.3 T / 50 Hz.

5. A method for preparing a high saturation flux density and low loss iron-based amorphous soft magnetic alloy according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Fe, Ni, Si and B in the alloy components are mixed according to the alloy composition formula Fe a Ni b Si c B d Weighing ingredients; Step 2, loading the raw materials prepared in step 1 into an induction melting furnace, performing induction melting in an inert gas atmosphere, and obtaining a master alloy ingot with uniform composition after cooling; Step 3, preparing a continuous amorphous alloy strip from the master alloy ingot by melt rapid quenching strip spinning equipment; Step 4: subjecting the amorphous alloy strip to a step-by-step magnetic field heat treatment under vacuum conditions or in an inert atmosphere to obtain an iron-based amorphous soft magnetic alloy.

6. The method for preparing the high saturation flux density and low loss Fe-based amorphous soft magnetic alloy according to claim 5, characterized in that: In the step 3, the process parameters for preparing the amorphous alloy strip are: injection pressure 0.01-0.03 MPa, injection temperature 1150-1200° C., and copper roller surface linear speed 15-35 m / s.

7. The method for preparing the high saturation flux density and low loss Fe-based amorphous soft magnetic alloy according to claim 5, characterized in that: In step 4, the step-by-step magnetic field heat treatment method is: In the first stage, the amorphous alloy strip is heated from room temperature to a first temperature and then kept warm. After the warming is completed, the strip is cooled to room temperature by water quenching. In the second stage, the amorphous alloy strip is heated from room temperature to a second temperature and then kept warm, a longitudinal magnetic field is applied while heating, and after the warming is completed, the strip is water quenched and cooled to room temperature; wherein the first temperature is greater than the second temperature.

8. The method for preparing the high saturation flux density and low loss Fe-based amorphous soft magnetic alloy according to claim 5, characterized in that: The first temperature is 360-420°C, the second temperature is 250-350°C; and the magnetic field strength is 500-1500Oe.

9. The method for preparing the high saturation flux density and low loss Fe-based amorphous soft magnetic alloy according to claim 5, characterized in that: The step-by-step magnetic field heat treatment method causes the iron-based amorphous soft magnetic alloy to have regular magnetic domains, and regulates the orientation of the magnetic domains along the direction of the magnetic field. The magnetic domain width exceeds 480 μm, the domain wall is straight and smooth, and the magnetization mechanism is dominated by uniform domain wall displacement.

10. The method for preparing the high saturation flux density and low loss Fe-based amorphous soft magnetic alloy according to claim 5, characterized in that: The alloy prepared by this preparation method has a large amorphous forming ability and excellent bending resistance. The alloy supercooling reaches 90-170°C, and after undergoing heat treatment at a temperature as high as 360°C for 10 minutes, it has good toughness and can be repeatedly folded at 180° without breaking.

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