Soft magnetic amorphous nanocrystalline, control preparation method thereof and electronic device

Abstract

The invention provides a soft magnetic amorphous nanocrystal, a control preparation method thereof and an electronic device, and the control preparation method comprises the step of processing a soft magnetic iron-based amorphous alloy by adopting pulse current to obtain the soft magnetic amorphous nanocrystal. According to the method, the amorphous alloy can be crystallized in a short time, so that the saturation flux density is greatly improved; and meanwhile, the excellent internal stress and pinning site removal effect is achieved, and the coercive force is further reduced. According to the method, the treatment efficiency and the soft magnetic performance of the soft magnetic amorphous nanocrystalline alloy are greatly improved, and the method can be applied to the field of soft magnetic material treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material processing, and in particular, to a soft magnetic amorphous nanocrystal, a control preparation method thereof, and an electronic device. Background Art

[0002] As an important part of magnetic materials, soft magnetic materials have been widely used in the fields of power electronics technology, communication technology, and sensors. To meet the requirements of miniaturization, integration, and low loss of electronic devices, materials are often required to have a high saturation magnetic induction intensity and a low coercive force. Amorphous alloys are special metal materials obtained by rapid solidification technology, with a long-range disordered and short-range ordered structure. Due to their unique microstructure, they have excellent soft magnetic properties. Since the advent of iron-based amorphous nanocrystalline alloys decades ago, with the continuous in-depth research on them, although the performance of the materials has become increasingly excellent, it has always been difficult to break the inverse relationship between the saturation magnetic induction intensity and the coercive force.

[0003] Therefore, it is particularly important to find a suitable and efficient process that can obtain a large number of uniform and fine nanocrystals while further reducing the coercive force through a special action mechanism. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a soft magnetic amorphous nanocrystal, a control preparation method thereof, and an electronic device. The method anneals an iron-based amorphous alloy by pulsed current, causing the amorphous alloy to precipitate a nanocrystalline phase, resulting in an amorphous nanocrystalline structure in the final product, thereby having excellent comprehensive soft magnetic properties.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides a control preparation method of a soft magnetic amorphous nanocrystal, the control preparation method comprising: treating a soft magnetic iron-based amorphous alloy with pulsed current to obtain a soft magnetic amorphous nanocrystal.

[0007] In the pulse current treatment method described in this invention patent, it can effectively reduce the nucleation barrier, making it easier for the amorphous matrix to nucleate. At the same time, since the resistivity of the crystal phase is lower, it means that its conductivity is better than that of the amorphous matrix. The pulse current can increase the nucleation rate and is more likely to precipitate fine nanocrystals. On the one hand, the pulse current treatment method has an effect similar to magnetic field annealing in adjusting the easy magnetization direction, and this effect can effectively reduce the coercivity. On the other hand, the pulse current has a better effect in eliminating the pinning sites of magnetic domains. The current will concentrate at the inhomogeneous structure. At this time, the temperature gradient generated by the current will cause gradient thermal stress at the non-uniform structure. Under the action of this thermal stress, the pulse current can promote the self-repair of defects such as vacancies inside the amorphous. Under this effect, the finally obtained microstructure is more uniform, further reducing the coercivity and having extremely excellent soft magnetic properties.

[0008] Preferably, the crystallization rate of the soft magnetic amorphous nanocrystals increases with the increase of the number of pulses.

[0009] Preferably, for every 100 additional pulses, the crystallization rate of the soft magnetic amorphous nanocrystals increases by 10 - 15%, for example, it can be 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5% or 15%, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0010] Preferably, the pulse period of the pulse current is 0.1 - 180 ms, for example, it can be 0.1 ms, 20 ms, 40 ms, 60 ms, 80 ms, 110 ms, 140 ms, 170 ms or 180 ms, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0011] Preferably, the pulse width of the pulse current is 0.05 - 80 ms, for example, it can be 0.05 ms, 10 ms, 20 ms, 30 ms, 40 ms, 55 ms, 70 ms, 75 ms or 80 ms, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0012] Preferably, the duty cycle of the pulse current is 10 - 70%, for example, it can be 10%, 17%, 24%, 30%, 37%, 44%, 50%, 57%, 64% or 70%, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable, and preferably 50%.

[0013] In the present invention, the selection of the duty cycle of the pulsed current has the effect of regulating the crystallization rate. When the duty cycle is relatively high, the crystallization rate is extremely fast and it is difficult to achieve the ideal crystallization degree. When the duty cycle is too high, there may be a situation where the material burns out. When the duty cycle is relatively low, the crystallization rate is slow and the required processing time will become very long. When the duty cycle is too low, there may be a situation where the crystallization threshold is not reached and the sample cannot be crystallized.

[0014] Preferably, the number of pulses of the pulsed current is 10 to 100,000 times, for example, it can be 10 times, 11,120 times, 22,230 times, 33,340 times, 44,450 times, 55,560 times, 66,670 times, 77,780 times, 88,890 times or 100,000 times, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable, and preferably 25 to 2,000 times.

[0015] Preferably, the pulsed peak current density of the pulsed current is 3×10 7 ~5.50×10 7 A / m 2 For example, it can be 3.0×10 7 A / m 2 、3.6×10 7 A / m 2 、4.2×10 7 A / m 2 、4.8×10 7 A / m 2 、5.4×10 7 A / m 2 or 5.5×10 7 A / m 2 etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0016] In the present invention, when the pulsed peak current density is too low, there are problems such as too slow crystallization rate, long processing time and even the sample cannot be crystallized; when the pulsed peak current density is too high, there are problems such as too fast crystallization, inability to obtain the ideal crystallization rate and even the sample burns out.

[0017] Preferably, the resolution of the pulsed current is microsecond level or above.

[0018] Preferably, the thickness of the soft magnetic iron-based amorphous alloy is ≥20 μm, for example, it can be 20 μm, 21 μm, 22 μm, 23 μm, 25 μm, 28 μm, 30 μm, 32 μm or 35 μm, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0019] Preferably, the width of the soft magnetic iron-based amorphous alloy is ≥ 0.8 mm, for example, it can be 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2.0 mm, 2.5 mm, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0020] Preferably, the length of the soft magnetic iron-based amorphous alloy is ≥ 50 mm, for example, it can be 50 mm, 55 mm, 60 mm, 65 mm, 80 mm, 100 mm, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0021] Preferably, the composition of the soft magnetic iron-based amorphous alloy is Fe a Co b Si c B x P y Cu z , where 80 ≤ a ≤ 86 at%, 0 ≤ b ≤ 4 at%, 0 ≤ c ≤ 8 at%, 4 ≤ x ≤ 10 at%, 1 ≤ y ≤ 4 at%, 0.3 ≤ z ≤ 1.3 at%.

[0022] The component of the amorphous alloy in the present invention is Fe a Co b Si c B x P y Cu zAn alloy composition, where 81 ≤ a ≤ 86 at%, for example, it can be 81 at%, 81.5 at%, 82 at%, 82.5 at%, 83 at%, 83.5 at%, 84 at%, 84.5 at%, 85 at%, 85.5 at% or 86 at% etc., but not limited to the listed values, and other unlisted values within this range are equally applicable; 0 ≤ b ≤ 4 at%, for example, it can be 0, 0.5 at%, 1 at%, 1.5 at%, 2 at%, 2.5 at%, 3 at%, 3.5 at% or 4 at% etc., but not limited to the listed values, and other unlisted values within this range are equally applicable; 0 ≤ c ≤ 8 at%, for example, it can be 0, 1 at%, 2 at%, 3 at%, 4 at%, 5 at%, 6 at%, 7 at% or 8 at% etc., but not limited to the listed values, and other unlisted values within this range are equally applicable; 4 ≤ x ≤ 10 at%, for example, it can be 4 at%, 4.5 at%, 5 at%, 5.5 at%, 6 at%, 6.5 at%, 7 at%, 7.5 at%, 8 at%, 8.5 at%, 9 at%, 9.5 at% or 10 at% etc., but not limited to the listed values, and other unlisted values within this range are equally applicable; 1 ≤ y ≤ 4 at%, for example, it can be 1 at%, 1.5 at%, 2 at%, 2.5 at%, 3 at%, 3.5 at% or 4 at% etc., but not limited to the listed values, and other unlisted values within this range are equally applicable; 0.3 ≤ z ≤ 1.3 at%, for example, it can be 0.3 at%, 0.4 at%, 0.5 at%, 0.6 at%, 0.7 at%, 0.8 at%, 0.9 at%, 1.0 at%, 1.1 at%, 1.2 at% or 1.3 at% etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0023] It should be noted that in order to pursue a higher saturation magnetic induction intensity, the iron element content in the alloy is high, hoping to precipitate more α-Fe nanocrystals. However, how to ensure the grain size of α-Fe nanocrystals and reduce the magnetocrystalline anisotropy is the current difficulty of high-iron soft magnetic amorphous alloys.

[0024] The present invention preferably uses the amorphous alloy with the above composition for pulsed current treatment to prepare soft magnetic amorphous nanocrystals. This is because this amorphous alloy has a high iron content and can be easily crystallized during the pulsed current treatment, and the obtained saturation magnetic induction intensity is relatively high. Compared with other amorphous alloys with lower iron element content such as 1K101, it has the advantages of being easily crystallized and having a high saturation magnetic induction intensity. This amorphous alloy can better combine with the pulsed current treatment process to obtain soft magnetic amorphous nanocrystals with excellent soft magnetic properties.

[0025] As a preferred technical solution of the present invention, the control preparation method includes:

[0026] Treating a soft magnetic Fe-based amorphous alloy with a thickness ≥ 20 μm, a width ≥ 0.8 mm and a length ≥ 50 mm by pulsed current, and the composition of the soft magnetic Fe-based amorphous alloy is Fe a Co b Si c B x P y Cu z , where 80 ≤ a ≤ 86 at%, 0 ≤ b ≤ 4 at%, 0 ≤ c ≤ 8 at%, 4 ≤ x ≤ 10 at%, 1 ≤ y ≤ 4 at%, 0.3 ≤ z ≤ 1.3 at%, the pulse period of the pulsed current is 0.1 - 400 ms, the pulse width is 0.05 - 200 ms, the duty cycle is 10 - 70%, and the pulsed peak current density is 3×10 7 ~10×10 7 A / m 2 , and different pulse numbers are selected within the range of 10 - 100000 times according to the crystallization rate range to obtain soft magnetic amorphous nanocrystals with different crystallization rates.

[0027] In a second aspect, the present invention provides a soft magnetic amorphous nanocrystal, which is prepared by the control preparation method of the soft magnetic amorphous nanocrystal described in the first aspect.

[0028] Preferably, the nanocrystals in the soft magnetic amorphous nanocrystal are α-Fe nanocrystals.

[0029] Preferably, the content of α-Fe nanocrystals in the soft magnetic amorphous nanocrystal is 30 - 60%, for example, it can be 30%, 32%, 33%, 35%, 40%, 42%, 45%, 50%, 55% or 60%, etc.

[0030] Preferably, the crystallization rate of the soft magnetic amorphous nanocrystal is 45 - 100%, for example, it can be 45%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 100%, etc.

[0031] Preferably, the average grain size of α-Fe nanocrystals in the soft magnetic amorphous nanocrystal is 10 - 40 nm, for example, it can be 10 nm, 12 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm or 40 nm, etc.

[0032] Preferably, the saturation magnetic induction intensity of the soft magnetic amorphous nanocrystals is ≥ 1.6 T, and can be, for example, 1.6 T, 1.7 T, 1.8 T, 1.9 T, 2.0 T, 2.2 T, etc. And the coercivity of the soft magnetic amorphous nanocrystals is ≤ 4.7 A / m, and can be, for example, 4.7 A / m, 4.6 A / m, 4.5 A / m, 4.0 A / m, 3.5 A / m, etc.

[0033] In a third aspect, the present invention provides an electronic device, which includes the soft magnetic amorphous nanocrystals prepared by the controlled preparation method of the soft magnetic amorphous nanocrystals described in the first aspect or includes the soft magnetic amorphous nanocrystals described in the second aspect.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] (1) The controlled preparation method of the soft magnetic amorphous nanocrystals provided by the present invention can promote the nucleation of nanocrystals to play a role in refining the crystal grains, and the ideal crystallization degree can be obtained by controlling the number of pulses; thus, it can enable the sample to have a very low coercivity while having a high saturation magnetic induction intensity;

[0036] (2) The controlled preparation method of the soft magnetic amorphous nanocrystals provided by the present invention can regulate the magnetic domain structure by changing the easy magnetization direction and eliminating the pinning sites, so as to reduce the coercivity, and is expected to become a new generation of process for preparing soft magnetic amorphous nanocrystalline alloys to obtain excellent soft magnetic properties;

[0037] (3) The soft magnetic amorphous nanocrystals provided by the present invention have uniform and appropriate nanocrystal sizes, controllable crystallization rate, excellent high saturation magnetic induction intensity and low coercivity. Description of the Drawings

[0038] Figure 1 It is a comparison chart of the soft magnetic properties of the amorphous nanocrystalline alloy sample obtained by the processing method in the present invention and the traditional soft magnetic alloy system.

[0039] Figure 2 It is the XRD pattern of the soft magnetic amorphous nanocrystals obtained in Example 1 of the present invention.

[0040] Figure 3 It is the DSC pattern of the soft magnetic amorphous nanocrystals obtained in Example 1 of the present invention.

[0041] Figure 4 It is a graph showing the variation law of the soft magnetic properties of the soft magnetic amorphous nanocrystals obtained in Example 1 of the present invention with the number of pulses.

[0042] Figures 5 to 7 It is the microscopic structure characterization diagram of the soft magnetic amorphous nanocrystals obtained in Example 1 of the present invention.

[0043] Figure 8This is the particle size distribution diagram of nanocrystals in the soft magnetic amorphous nanocrystals obtained in Example 1 of the present invention.

[0044] Figures 9 to 11 This is the diagram of the change in the magnetic domain structure of the soft magnetic amorphous nanocrystals obtained in Example 1 of the present invention.

[0045] Figure 12 This is the XRD pattern of the soft magnetic amorphous nanocrystals obtained in Example 2 of the present invention.

[0046] Figure 13 This is the diagram of the variation law of the soft magnetic properties of the soft magnetic amorphous nanocrystals obtained in Example 2 of the present invention with the number of pulses. Detailed implementation manners

[0047] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation manners.

[0048] The present invention will be further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0049] In the description of this specification, it should be noted that unless otherwise clearly specified and limited, the term "pulse current treatment" should be understood in a broad sense. For example, direct current can be used for treatment, alternating current can also be used for treatment, and current with any waveform, frequency, and current density can also be used for treatment. For those of ordinary skill in the art, the specific meaning of the above terms in the present invention can be understood according to specific circumstances.

[0050] Example 1

[0051] This example provides a control preparation method for soft magnetic amorphous nanocrystals, and the control preparation method includes:

[0052] A soft magnetic iron-based amorphous alloy with a thickness of 20 μm, a width of 0.8 mm, and a length of 50 mm is treated with a pulse current. The composition of the soft magnetic iron-based amorphous alloy is Fe 83.3 Si 4 B 8 P 4 Cu 0.7 , the pulse period of the pulse current is 60 ms, the pulse width is 30 ms, the duty cycle is 50%, and the pulse peak current density is 5.5×10 7 A / m 2 , and different pulse numbers are selected within the range of 100 to 600 according to the crystallization rate range to obtain soft magnetic amorphous nanocrystals with different crystallization rates.

[0053] Specifically, pulsed current treatments were carried out 100 times, 200 times, 300 times, 400 times, 500 times, and 600 times respectively.

[0054] XRD tests were performed on the treated samples, and the results are as Figure 2 shown. As the number of pulses increases, the sample gradually changes from a completely amorphous state to a crystalline state, and sharp Bragg diffraction peaks gradually appear. This shows that the treatment method described in the present invention can cause the crystallization of amorphous alloys and can obtain an ideal crystallization rate by controlling the number of pulses.

[0055] DSC tests were performed on the treated samples, and the results are as Figure 3 shown. Consistent with the XRD experimental results, as the number of pulses increases, the area of the first exothermic peak of the soft magnetic amorphous nanocrystals gradually decreases, indicating that α-Fe nanocrystals are continuously precipitating.

[0056] Soft magnetic property tests were performed on the treated samples, and the results are as Figure 4 shown. The saturation magnetic induction intensity first increases, then tends to be stable, and finally decreases slightly. This is because the saturation magnetic induction intensity of the α-Fe nanocrystals precipitated after the crystallization of the sample is higher. As the content of the precipitated nanocrystals increases continuously, the overall saturation magnetic induction intensity of the alloy is greatly improved. The coercivity first decreases and then rises slowly. As the number of pulses and the annealing degree increase, the internal stress generated during quenching in the strip sample is gradually eliminated, and the coercivity decreases; as the number of pulses increases more, the amorphous alloy gradually crystallizes, and its magnetocrystalline anisotropy rapidly rises, causing the coercivity to rise rapidly. The best soft magnetic properties are a saturation magnetic induction intensity of 1.78 T and a coercivity of 1.6 A / m.

[0057] Microstructure tests were performed on the treated samples, and the results are as Figures 5 to 7 shown. From Figures 5 to 7 it can be seen that α-Fe nanocrystals precipitate from the amorphous matrix, and the grain distribution is relatively uniform. Its particle size distribution diagram is as Figure 8 shown. From Figure 8 it can be calculated that its average grain size is about 26 nm. Figure 5 In , a is the scanning image, b is the selected electron diffraction pattern, and c is the regional fast Fourier transform pattern.

[0058] Magnetic domain structure tests were performed on the treated samples, and the results are as Figures 9 to 11 shown. Figures 9 to 11 Shows the specific magnetic field values of the magnetic domain evolution law during the demagnetization process of the sample, Figure 9 which is 0.08 mT; Figure 10 which is 0.14 mT; Figure 11 which is 0.22 mT; It can be seen from this that the magnetic domains show a trend of overall movement of large domains, and the magnetic domain walls are along the length direction of the strip, and there are basically no pinning sites.

[0059] Example 2

[0060] This example provides a method for controlled preparation of soft magnetic amorphous nanocrystals, and the controlled preparation method includes:

[0061] Using pulsed current to process a soft magnetic Fe-based amorphous alloy with a thickness of 20 μm, a width of 0.8 mm and a length of 50 mm, and the composition of the soft magnetic Fe-based amorphous alloy is Fe 80.3 Co 4 Si 4 B 8 P 3 Cu 0.7 , the pulse period of the pulsed current is 50 ms, the pulse width is 30 ms, the duty cycle is 60%, and the pulse peak current density is 4.5×10 7 A / m 2 , and different pulse numbers are selected within the range of 50 - 600 times according to the crystallization rate range to obtain soft magnetic amorphous nanocrystals with different crystallization rates.

[0062] Specifically, pulsed current treatments of 50 times, 100 times, 200 times, 300 times, 400 times, 500 times, and 600 times were carried out respectively.

[0063] The treated samples were subjected to XRD tests, and the results are as Figure 12 shown. As the number of pulses increases, the sample gradually changes from a completely amorphous state to a crystalline state.

[0064] The treated samples were subjected to soft magnetic property tests, and the results are as Figure 13 shown. The variation law of the soft magnetic properties is basically similar to that of Example 1. The best performance is a saturation magnetic induction intensity of 1.88 T and 4.7 A / m.

[0065] The soft magnetic property diagrams of the soft magnetic amorphous nanocrystals prepared in Example 1 and Example 2 and the comparison diagram of the soft magnetic properties of the materials recorded in the existing literature are as Figure 1 shown. From Figure 1 it can be seen that the soft magnetic amorphous nanocrystals prepared by the present invention have excellent comprehensive soft magnetic properties.

[0066] Example 3

[0067] This example provides a method for controlled preparation of soft magnetic amorphous nanocrystals, and the controlled preparation method includes:

[0068] Using pulsed current to process a soft magnetic Fe-based amorphous alloy with a thickness of 21 μm, a width of 1.0 mm and a length of 60 mm, and the composition of the soft magnetic Fe-based amorphous alloy is Fe 81 Co 4 Si 4 B7 P 3 Cu 1 The pulse period of the pulsed current is 120 ms, the pulse width is 60 ms, the duty cycle is 50%, and the pulsed peak current density is 5.5×10 7 A / m 2 , and the number of pulses is 400 times, obtaining soft magnetic amorphous nanocrystals.

[0069] Example 4

[0070] This example provides a control preparation method for soft magnetic amorphous nanocrystals. The control preparation method includes:

[0071] Treating a soft magnetic iron-based amorphous alloy with a thickness of 25 μm, a width of 1.2 mm, and a length of 60 mm by pulsed current. The composition of the soft magnetic iron-based amorphous alloy is Fe 80.3 Co 4 Si 4 B 8 P 3 Cu 0.7 , the pulse period of the pulsed current is 70 ms, the pulse width is 14 ms, the duty cycle is 20%, and the pulsed peak current density is 3×10 7 A / m 2 , and the number of pulses is 450 times, obtaining soft magnetic amorphous nanocrystals.

[0072] Example 5

[0073] This example provides a control preparation method for soft magnetic amorphous nanocrystals. Except that the pulsed peak current density is 7.5×10 7 A / m 2 is different, the rest are the same as in Example 1 and will not be elaborated here.

[0074] When the pulsed peak current density is on the high side, the crystallization rate will increase sharply, and a relatively high crystallization rate can be obtained with fewer pulse times. When the pulsed peak current density is too high, there may be a situation where the sample burns out. That is, when the number of pulses is 600 times, the sample burns out. Example 6

[0075] This example provides a control preparation method for soft magnetic amorphous nanocrystals. Except that the pulsed peak current density is 2×10 7 A / m 2 is different, the rest are the same as in Example 1 and will not be elaborated here.

[0076] When the pulse peak current density is low, the crystallization rate will decrease, and the crystallization rate will be lower when the number of pulses is the same. If the same crystallization rate is required, more pulse numbers and processing time are needed. When the pulse peak current density is too low, it is possible that the sample will not crystallize at all.

[0077] Example 7

[0078] This example provides a method for controlling the preparation of soft magnetic amorphous nanocrystals. Except that the duty cycle is 80% different and the pulse period is kept the same, the rest are the same as in Example 1 and will not be elaborated here. When the duty cycle is relatively high, the crystallization rate will increase sharply, and a relatively high crystallization rate can be obtained with fewer pulse numbers. When the duty cycle is too high, it is possible that the sample will be burned out. When the number of pulses is 500 - 600, the sample will be burned out.

[0079] Example 8

[0080] This example provides a method for controlling the preparation of soft magnetic amorphous nanocrystals. Except that the duty cycle is 5% different and the pulse period is kept the same, the rest are the same as in Example 1 and will not be elaborated here.

[0081] When the duty cycle is low, the crystallization rate will decrease, and the crystallization rate will be lower when the number of pulses is the same. If the same crystallization rate is required, more pulse numbers and processing time are needed. When the duty cycle is too low, it is possible that the sample will not crystallize at all.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing soft magnetic amorphous nanocrystals. Except that heat treatment is used, the heat treatment temperature is 360 °C, and the time is 10 min, the rest are the same as in Example 1 and will not be elaborated here.

[0084] Compared with Example 1, the traditional annealing used in Comparative Example 1 has a longer processing time and needs to be processed under high vacuum conditions, and the processing conditions are relatively more stringent. The coercivity of the sample processed by the method used in Comparative Example 1 deteriorates greatly, far lower than the coercivity level in Example 1.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing soft magnetic amorphous nanocrystals. Except that pulse magnetic field treatment is used, the rest are the same as in Example 1 and will not be elaborated here.

[0087] Specifically, the steps of pulse magnetic field treatment include: at 360 °C, the vacuum degree is 3×10 -4Under the condition of Pa, pulsed magnetic field annealing was carried out. The annealing time was 10 min, and the applied pulsed magnetic field intensity was 0.1 T.

[0088] Compared with Example 1, the processing time of the traditional annealing used in Comparative Example 2 was longer. It needed to be processed under the condition of high vacuum and an external large magnetic field was required. Its processing conditions were more stringent compared to Example 1 and even Comparative Example 2. The coercivity of the sample processed by the method used in Comparative Example 2 was greatly optimized compared with Comparative Example 1, but it was still higher than the coercivity level in Example 1.

[0089] The vibrating sample magnetometer (VSM) mode of a magnetic measurement system (MPMS3) produced by Quantum Design was used to test the saturation magnetic induction intensity of the sample strips before and after annealing. During the experiment, the strip was cut into 3 samples with a length of 4 mm, and its mass was about 1 - 2 mg. The samples were adhered to the center of the quartz rod in a cross shape and placed into the equipment. Before the test, a small magnetic field was applied to position the samples, and then an external magnetic field of 1.5 T was applied to saturate the magnetization of the samples, and its hysteresis loop was tested. The unit of the obtained sample saturation magnetization intensity was emg. Dividing by the sample mass, the unit of the saturation magnetic induction intensity Ms was emu / g. By testing the density of the sample and using the following formula to convert Ms, the saturation magnetic induction intensity Bs with the unit of T could be obtained.

[0090] Bs = 4πρMs where ρ is the sample density;

[0091] A DC B-H meter (Riken Denshi Co., Ltd. BHS-40 type) was used to test the coercivity of the sample. The strip sample was adhered to the sample rod and the sample rod was placed in the center of the solenoid. Then, the size information of the sample was input, and the hysteresis loop of the sample was measured under an external magnetic field of 10 Oe, and then its Hc value was obtained.

[0092] The Tecnai G2 F20 S-TWIN transmission electron microscope produced by FEI Company was used to characterize the microstructure of the sample. Since the thickness of the sample strip was 20 μm, a 3-mm long strip was directly taken for ion thinning to the ideal size for the transmission experiment. The microstructure diagram, high-resolution image, and electron diffraction pattern of the sample were observed to judge the content, size of the nanocrystals, and whether the grains were α-Fe nanocrystals.

[0093] The tests were carried out using a DSC404F3 series high-temperature differential scanning calorimeter from Netzsch, Germany. In the experiment, the amorphous ribbon samples were cut into pieces and about 10 mg was weighed and placed in an alumina crucible. An empty alumina crucible was used for reference. The heating rate was set at 20 °C / min, and argon gas was used as the protective gas throughout the process to prevent sample oxidation. To make the experimental results more accurate, each experiment was measured twice, and the actual DSC curve was obtained by subtracting the two curves. The crystallization rate was calculated as the reduction ratio of the first crystallization enthalpy of the annealed sample compared to the sample before annealing.

[0094] The test results of the above examples and comparative examples are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] In Table 1, " / " indicates no relevant data.

[0099] It can be seen from Table 1 that in terms of performance, the controlled preparation method of the soft magnetic amorphous nanocrystals provided by the present invention, under the preferred conditions, has a coercivity better than that of the magnetic field annealing treatment method in Comparative Example 2 and is overall better than the traditional ordinary annealing treatment method in Comparative Example 1. In terms of experimental conditions, the treatment method used in the present invention requires the simplest conditions, without the need for a vacuum environment, a magnetic field environment, or long-time treatment, which is a great advantage compared to Comparative Example 1 and Comparative Example 2.

[0100] The present invention uses the above examples to illustrate the detailed structural features of the present invention, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of the components selected by the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for controllably preparing soft magnetic amorphous nanocrystals, characterized in that, the controllable preparation method includes: treating a soft magnetic iron-based amorphous alloy with pulsed current to obtain soft magnetic amorphous nanocrystals.

2. The controllable preparation method according to claim 1, characterized in that, the crystallization rate of the soft magnetic amorphous nanocrystals increases with the increase of the number of pulses; preferably, for every 100 additional pulses, the crystallization rate of the soft magnetic amorphous nanocrystals increases by 10-15%.

3. The controllable preparation method according to claim 1 or 2, characterized in that, the pulse period of the pulsed current is 0.1-180 ms; preferably, the pulse width of the pulsed current is 0.05-80 ms; preferably, the duty cycle of the pulsed current is 10-70%, preferably 45-55%.

4. The controllable preparation method according to any one of claims 1-3, characterized in that, the number of pulses of the pulsed current is 10-100,000 times, preferably 25-2,000 times; Preferably, the pulse peak current density of the pulsed current is 3×10 7 ~5.5×10 7 A / m 2 ; preferably, the resolution of the pulsed current is microsecond level or above.

5. The controllable preparation method according to any one of claims 1-4, characterized in that, the thickness of the soft magnetic iron-based amorphous alloy ≥ 20 μm; preferably, the width of the soft magnetic iron-based amorphous alloy ≥ 0.8 mm; preferably, the length of the soft magnetic iron-based amorphous alloy ≥ 50 mm.

6. The controllable preparation method according to any one of claims 1-5, characterized in that, The composition of the soft magnetic Fe-based amorphous alloy is Fe a Co b Si c B x P y Cu z , wherein, 80 ≤ a ≤ 86 at%, 0 ≤ b ≤ 4 at%, 0 ≤ c ≤ 8 at%, 4 ≤ x ≤ 10 at%, 1 ≤ y ≤ 4 at%, 0.3 ≤ z ≤ 1.3 at%.

7. The controllable preparation method according to any one of claims 1-6, characterized in that, the controllable preparation method includes: The soft magnetic Fe-based amorphous alloy with a thickness ≥ 20 μm, a width ≥ 0.8 mm and a length ≥ 50 mm is processed by pulsed current, and the composition of the soft magnetic Fe-based amorphous alloy is Fe a Co b Si c B x P y Cu z , where 80 ≤ a ≤ 86 at%, 0 ≤ b ≤ 4 at%, 0 ≤ c ≤ 8 at%, 4 ≤ x ≤ 10 at%, 1 ≤ y ≤ 4 at%, 0.3 ≤ z ≤ 1.3 at%. The pulse period of the pulsed current is 0.1 - 180 ms, the pulse width is 0.05 - 8 ms, the duty cycle is 10 - 70%, and the pulsed peak current density is 3×10 7 ~5.5×10 7 A / m 2 . Different pulse numbers are selected within the range of 10 - 100,000 times according to the crystallization rate range to obtain soft magnetic amorphous nanocrystals with different crystallization rates.

8. A soft magnetic amorphous nanocrystal, characterized in that, the soft magnetic amorphous nanocrystal is prepared by the method for controllably preparing soft magnetic amorphous nanocrystals according to any one of claims 1-7.

9. The soft magnetic amorphous nanocrystal according to claim 8, characterized in that, the nanocrystals in the soft magnetic amorphous nanocrystal are α-Fe nanocrystals; preferably, the content of α-Fe nanocrystals in the soft magnetic amorphous nanocrystal is 30-60%; preferably, the average grain size of α-Fe nanocrystals in the soft magnetic amorphous nanocrystal is 10-40 nm; preferably, the saturation magnetic induction intensity of the soft magnetic amorphous nanocrystal ≥ 1.6 T; preferably, the coercivity of the soft magnetic amorphous nanocrystal ≤ 4.7 A / m.

10. An electronic device, characterized in that, the electronic device includes soft magnetic amorphous nanocrystals prepared by the method for controllably preparing soft magnetic amorphous nanocrystals according to any one of claims 1-7 or includes the soft magnetic amorphous nanocrystals according to claim 8 or 9.

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