Amorphous soft magnetic alloy and manufacturing method therefor

Abstract

The present invention relates to an amorphous soft magnetic alloy and, more particularly, to a Fe-based amorphous soft magnetic alloy that can be used in the high-frequency ribbon core-related industry, and a manufacturing method therefor. According to one embodiment of the present invention, the amorphous soft magnetic alloy can be represented by chemical formula (1): FeaBbCecLad의<sb / >, where a, b, c, and d represent atomic percentages (at %) of respectively corresponding components, and can satisfy 73.5≤a≤83.2, 16.0≤b≤24.0, 0.52≤c≤2.27, 0.28≤d≤1.23 and a+b+c+d=100.

Description

Amorphous soft magnetic alloy and method for manufacturing the same

[0001] The present invention relates to an amorphous soft magnetic alloy, and more specifically, to an Fe-based amorphous soft magnetic alloy applicable to the high-frequency ribbon core related industry and a method for manufacturing the same.

[0002] The present invention is the result of research conducted with support from the Ministry of Trade, Industry and Energy's 'Materials, Parts, and Equipment Technology Development' [Project Name: Development of Manufacturing and Application Technology for Iron-based Soft Magnetic Powder with Saturation Magnetization of 1.65T or Higher for Chip Inductors (1 / 2), Project No.: KM240211, Project Management (Specialized) Agency: Korea Institute of Industrial Technology Planning and Evaluation, Project Executing Agency: Korea Institute of Industrial Technology].

[0003] Amorphous soft magnetic alloys possess low coercivity due to the absence of internal crystal grains and can be utilized in energy-efficient soft magnetic cores. Among these, Fe-based amorphous soft magnetic alloys play a significant role in electronic devices and high-frequency applications, and are particularly widely used in the high-frequency ribbon core industry. Fe-based amorphous soft magnetic alloys can secure amorphous forming ability by adding metalloids such as B, Si, C, and P. Additionally, soft magnetism can be enhanced while maintaining an amorphous structure by inducing nanocrystallization or stabilizing the α-Fe phase through the addition of transition metal elements such as Cu, Nb, Zr, and Mo.

[0004] However, during the process of optimizing the properties of amorphous soft magnetic alloys, an increase in metalloid content can lead to an increase in coercivity. This can result in a degradation of soft magnetic properties and act as a disadvantage in applications requiring high permeability. While stress relief heat treatment is generally performed at temperatures lower than the crystallization temperature to reduce coercivity, this method has limitations in achieving a reduction beyond a certain level. Therefore, a new alloy technology is required that can effectively control coercivity while simultaneously adjusting the metalloid content.

[0005] Current technology has evolved in the direction of maintaining an amorphous structure and improving soft magnetism by adding transition metal elements. However, to achieve high permeability while maintaining low coercivity, an innovative approach is required that involves reducing the metalloid content and introducing new elements instead of existing transition metals to preserve amorphous formation performance. Against this backdrop, there is an urgent need for the development of new Fe-based amorphous soft magnetic alloys capable of overcoming the limitations of existing technologies.

[0006] The present invention aims to solve various problems, including those mentioned above, by providing an amorphous soft magnetic alloy having a new composition capable of reducing coercivity while maintaining amorphous forming performance (AFA) while reducing the content of metalloid elements, and a method for manufacturing the same. However, these objectives are exemplary and do not limit the scope of the present invention.

[0007] According to one embodiment of the present invention, the amorphous soft magnetic alloy is Fe a B b Ce c La d of It is represented by the chemical formula (1), where a, b, c, and d each represent the atomic percentage (at%) of the corresponding components, and can satisfy 73.5≤a≤83.2, 16.0≤b≤24.0, 0.52≤c≤2.27, 0.28≤d≤1.23 and a+b+c+d=100.

[0008] According to one embodiment of the present invention, the total of Ce and La may be 0.8 at% to 3.5 at%.

[0009] According to one embodiment of the present invention, in atomic percentage, the ratio of Ce to the total sum of Ce and La (A Ce / (A Ce + / A La ), A m (meaning the atomic percentage of element m) can be 0.6 to 0.7.

[0010] According to one embodiment of the present invention, the crystallization temperature of the amorphous soft magnetic alloy may be 470°C to 570°C.

[0011] According to one embodiment of the present invention, the coercivity of the amorphous soft magnetic alloy may be 12 A / m to 26 A / m.

[0012] According to one embodiment of the present invention, a method for manufacturing an amorphous soft magnetic alloy may include: a step of preparing a molten alloy having an atomic percentage (at%) of B: 16.0~24.0, Ce: 0.52~2.27, La: 0.28~1.23, with the remainder being Fe and unavoidable impurities; and a step of manufacturing an amorphous soft magnetic alloy represented by the aforementioned chemical formula (1) by rapidly cooling the molten alloy.

[0013] According to one embodiment of the present invention, the method for rapidly cooling the alloy melt may include a Planar Flow Casting (PFC) process or a Rapid Solidification (RSP) process.

[0014] According to one embodiment of the present invention, after the step of manufacturing the amorphous soft magnetic alloy, the method may further include the step of performing a stress relief heat treatment at a temperature below the crystallization temperature of the amorphous soft magnetic alloy.

[0015] According to one embodiment of the present invention, the temperature range of the stress relief heat treatment may be a temperature range of 75% to 85% of the crystallization temperature.

[0016] According to one embodiment of the present invention, the temperature of the stress relief heat treatment may be in the range of 352°C to 485°C.

[0017] According to one embodiment of the present invention, a noise filter for an onboard charger (OBC) for an electric vehicle may be manufactured from the aforementioned amorphous soft magnetic alloy.

[0018] According to the Fe-based amorphous soft magnetic alloy of one embodiment of the present invention constructed as described above, coercivity can be reduced by adding Ce and La, which have large atomic radii, in appropriate compositional ranges instead of adding Si, a metalloid element, during alloy design. Furthermore, the Fe-based amorphous soft magnetic alloy of one embodiment of the present invention has a high crystallization temperature, which allows for effective stress relief heat treatment performed to remove stress within the alloy, thereby inducing an additional reduction in coercivity. The amorphous soft magnetic alloy according to this embodiment can exhibit superior performance in the manufacture of high-permeability soft magnetic cores. Of course, the scope of the present invention is not limited by these effects.

[0019] Hereinafter, several preferred embodiments of the present invention will be described in detail.

[0020] The embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, and the following embodiments may be modified in various different forms, and the scope of the invention is not limited to the following embodiments. Rather, these embodiments are provided to make the disclosure more faithful and complete and to fully convey the spirit of the invention to those skilled in the art.

[0021] An Fe-based amorphous soft magnetic alloy according to one embodiment of the present invention possesses excellent magnetic properties and thermal stability, and the alloy composition for achieving these properties is described in detail below.

[0022] Amorphous soft magnetic alloy

[0023] An amorphous soft magnetic alloy according to one embodiment of the present invention is a quaternary alloy comprising Fe, B, Ce, and La, and is represented by the following chemical formula (1).

[0024] Chemical formula (1): Fe a B b Ce c La d

[0025] Here, a, b, c, and d each represent the atomic percentage (at%) of the corresponding components. Specifically, a, b, c, and d satisfy the following ranges.

[0026] 73.5 ≤ a ≤ 83.2

[0027] 16.0 ≤ b ≤ 24.0

[0028] 0.52 ≤ c ≤ 2.27

[0029] 0.28 ≤ d ≤ 1.23

[0030] The sum of the atomic percentages of the amorphous soft magnetic alloy composed in this way must satisfy 100 (a + b + c + d = 100).

[0031] Generally, it is advantageous for amorphous soft magnetic alloys used in the high-frequency ribbon core industry to have a low coercivity value. To this end, in the present invention, Ce and La, which have large atomic radii, were added instead of the transition metals (Cu, Nb, Zr, Mo, etc.) commonly used when designing Fe-based amorphous soft magnetic alloys to increase the difference in atomic radius between elements, thereby enabling a reduction in coercivity along with amorphous formation ability. The coercivity of the Fe-based amorphous soft magnetic alloy according to one embodiment of the present invention can, for example, range from 12 A / m to 26 A / m.

[0032] Ce and La are elements that play important roles, and controlling their content directly affects the magnetic properties of amorphous soft magnetic alloys. In accordance with the technical concept of the present invention, the total amount of Ce and La is limited to 0.8 at% to 3.5 at%. This is to optimize coercivity while maintaining the amorphous forming performance of the amorphous soft magnetic alloy.

[0033] At this time, the ratio of Ce and La content added can be appropriately controlled, for example, the ratio of Ce to the total sum of Ce and La can be controlled to have a value between 0.6 and 0.7.

[0034] The crystallization temperature of an amorphous soft magnetic alloy is a temperature that provides stable magnetic properties by maintaining an amorphous state even at high temperatures, and it must be maintained above a certain level. In the case of an amorphous soft magnetic alloy, coercivity can be reduced through stress relief heat treatment after alloy manufacturing, and the higher the heat treatment temperature, the more the effect of stress relief can be enhanced. However, in this case, it is necessary for the amorphous alloy to maintain an amorphous state without crystallizing during the stress relief heat treatment process; therefore, to secure excellent magnetic properties, it is advantageous for the amorphous soft magnetic alloy to have a high crystallization temperature. In one embodiment of the present invention, the crystallization temperature of the Fe-based amorphous soft magnetic alloy could be increased through the addition of Ce and La. The crystallization temperature of the Fe-based amorphous soft magnetic alloy according to one embodiment of the present invention may be, for example, 470°C to 570°C.

[0035] Hereinafter, a method for manufacturing an amorphous soft magnetic alloy according to one embodiment of the present invention is described.

[0036] Method for manufacturing amorphous soft magnetic alloy

[0037] Generally, amorphous soft magnetic alloys form an amorphous structure by rapidly cooling an alloy molten at high temperatures. The aforementioned rapid cooling method may include a Planar Flow Casting (PFC) process or a Rapid Solidification (RSP) process. Both the Planar Flow Casting (PFC) and Rapid Solidification (RSP) processes are methods for manufacturing amorphous materials by supplying a high-temperature molten metal through a nozzle to a rotating cooling roll to rapidly cool and solidify it. As these are well-known technologies in the field of amorphous material manufacturing, a detailed explanation is omitted.

[0038] A method for manufacturing an amorphous soft magnetic alloy according to one embodiment of the present invention includes the steps of preparing a molten alloy and rapidly cooling it.

[0039] Specifically, a molten alloy can be prepared in which the atomic percentages (at%) are B: 16.0–24.0, Ce: 0.52–2.27, La: 0.28–1.23, and the remainder is Fe and unavoidable impurities. The molten alloy can be manufactured by introducing the corresponding elements into a container and melting them according to the designed compositional range. Subsequently, the prepared molten alloy can be rapidly cooled and solidified through a Planar Flow Casting (PFC) or Rapid Solidification Process (RSP) process to produce an amorphous soft magnetic alloy having an amorphous structure.

[0040] The amorphous soft magnetic alloy produced in this way can be manufactured as an amorphous soft magnetic alloy represented by the chemical formula (1), as described above.

[0041] Chemical formula (1): Fe a B b Ce c La d

[0042] (A, b, c, and d above represent the atomic percentage (at%) of the corresponding components, satisfying 73.5≤a≤83.2, 16.0≤b≤24.0, 0.52≤c≤2.27, 0.28≤d≤1.23, and a+b+c+d=100)

[0043] After optionally manufacturing an amorphous soft magnetic alloy, stress relief heat treatment can be performed to remove internal stress and optimize coercivity. In the case of amorphous soft magnetic alloys, internal stress may remain during the rapid solidification process, and such internal stress can be removed by appropriately heat treating at a temperature that maintains the amorphous state.

[0044] This stress relief heat treatment can be performed in a temperature range of 75% to 85% of the crystallization temperature. Since the crystallization temperature of the Fe-based amorphous soft magnetic alloy according to one embodiment of the present invention is in the range of 470°C to 570°C, the stress relief heat treatment can be performed in a temperature range of approximately 352°C to 485°C. This is a step that can be selected to maximize the magnetic properties of the alloy by relieving internal stress without crystallization occurring. To successfully perform this stress relief heat treatment, it is necessary for the crystallization temperature to have a high value. A high level of crystallization temperature could be secured through compositional control of the amorphous soft magnetic alloy according to one embodiment of the present invention.

[0045] A noise filter used in an on-board charger (OBC) for electric vehicles can be manufactured using the amorphous soft magnetic alloy material produced in this way. The noise filter for the on-board charger (OBC) is used to effectively suppress high-frequency electromagnetic interference (EMI) generated in power conversion systems such as electric vehicles. As described above, the amorphous soft magnetic alloy according to one embodiment of the present invention is characterized by low coercivity, which helps to efficiently absorb and filter high-frequency noise.

[0046] Preferred experimental examples are presented below to aid in understanding the present invention. However, the following experimental examples are intended only to aid in understanding the present invention and do not limit the present invention. Details not described herein can be sufficiently technically inferred by those skilled in the art, so their description is omitted.

[0047] <Experimental Example>

[0048] The compositions of alloy samples prepared to verify the magnetic properties of an amorphous soft magnetic alloy according to one embodiment of the present invention are summarized in Table 1 below. The alloy samples having the compositions in Table 1 were prepared by Planar Flow Casting (PFC). The coercivity (Hci), crystallization temperature (Tx), and coercivity after stress relief heat treatment of each prepared sample were measured and summarized in Table 2. The coercivity after stress relief heat treatment was measured according to the stress relief heat treatment conditions, and the stress relief heat treatment conditions were performed at temperatures corresponding to 85%, 80%, and 75% of the crystallization temperature (Tx) in the heat treatment furnace. In Table 2, the stress relief heat treatment conditions are indicated as 0.85 Tx, 0.80 Tx, and 0.75 Tx, respectively. In Table 1, the unit of coercivity is [A / m], and the unit of crystallization temperature is [°C].

[0049] Sample Composition (at%) FeBSiCeLaCe+La Comparative Example 180 6.5 13.5000 Comparative Example 284 160000 Comparative Example 382 180000 Comparative Example 480 200000 Comparative Example 578 220000 Comparative Example 676 240000 Comparative Example 783.8 1600 0.1 30.0 70.2 Comparative Example 883.4 1600 0.3 90.2 10.6 Example 183.2 1600 0.5 20.2 80.8 Example 283 1600 0.6 50.3 51 Example 382.5 1600 0.9 80.5 21.5 Example 482 1601 30.7 2 Example 581.51601.630.872.5 Example 6811601.951.053 Example 780.51602.271.233.5 Example 879.51801.630.872.5 Example 977.52001.630.872.5 Example 1075.52201.630.872.5 Example 1173.52401.630.872.5

[0050] Sample Coercivity Hci [A / m] Crystallization Temperature (Tx) (°C) Coercivity after Stress Relief Heat Treatment (A / m) 0.85 Tx 0.80 Tx 0.75 Tx Comparative Example 1 1.35 48 0.2 ХХХ Comparative Example 2 25.8 34 27.6 35 24.32 ХХ Comparative Example 3 30.4 44 6 1.4 29 18.64 ХХ Comparative Example 4 31.6 54 46.6 21 11 2.17 ХХ Comparative Example 5 25.8 34 46.6 36 6.51 ХХ Comparative Example 6 23.1 34 41.9 8 39.86 ХХ Comparative Example 7 45.6 94 6 9.5 53 8.5 62 9.4 93 5.48 Comparative Example 832.3470.0716.4914.1923.04 Example 1 21.6474.4915.1515.2616.97 Example 2 23.34473.0618.1212.4418.64 Example 3 25.58486.1213.9514.4617.77 Example 4 20.75503.1816.5812.5118.05 Example 5 18.29500.3714.3716.3415.54 Example 6 20.78519.112.0614.2615.28 Example 7 19.4524.3615.3515.4515.43 Example 812.83533.2712.0812.5112.08 Example 922.86541.515.7412.6815.41 Example 1021.94564.8720.0114.8612.94 Example 1125.28543.4615.4321.3216.83

[0051] Referring to Tables 1 and 2, the coercivity of Examples 1 to 11 all showed low values ​​of 26 A / m or less, and the crystallization temperature showed high values ​​exceeding 470°C. In particular, the crystallization temperature of Examples 4 to 11 all exceeded 500°C.

[0052] Examples 1 to 11 all had a sum of Ce and La in the range of 0.8 at% to 3.5 at%, and the ratio of Ce to the total sum of Ce and La in atomic percentage (at%) (A Ce / (A Ce + / A La )) showed approximately 0.65 (A m (represents the atomic percentage of element m).

[0053] In contrast, Comparative Example 1, which is an Fe-B-Si ternary amorphous alloy, showed a coercivity of about 41 A / m, which was about 1.5 to 2.3 times higher than that of the examples.

[0054] In Comparative Examples 2 to 6, which are Fe-B binary alloys without added Ce and La, Comparative Examples 3 and 4 both exhibited higher coercivity compared to the Examples, and the crystallization temperature also showed lower values ​​compared to the Examples. Meanwhile, although Comparative Examples 2, 5, and 6 showed coercivity of 26 A / m or less, the crystallization temperature was all less than 470°C, which is lower than that of the Examples.

[0055] In the case of Comparative Examples 7 and 8, in which the Ce content of the Fe-B-Ce-La quaternary alloy was less than 0.52 at% and the La content was less than 0.28 at%, higher coercivity was exhibited compared to the Examples, and in the case of Comparative Example 7, the crystallization temperature was lower than that of the Examples.

[0056] Through this, it was confirmed that in the case of an Fe-B-Ce-La amorphous soft magnetic alloy in which Si is not added and Ce and La, which have large atomic radii, are added in predetermined amounts instead of conventional transition metal elements, lower coercivity and superior thermal stability can be achieved compared to conventional Fe-B-Si amorphous soft magnetic alloys.

[0057] Regarding coercivity after stress relief heat treatment, as a result of heat treatment at 0.85 Tx, in the case of Comparative Examples 2 to 6, the coercivity actually increased after heat treatment, and in particular, in the case of Comparative Examples 2 to 4, which did not contain Ce and La, a characteristic of significantly increased coercivity was observed. This means that the thermal stability of the amorphous alloys corresponding to Comparative Examples 2 to 4 is very poor.

[0058] In contrast, it was confirmed that the coercivity decreased after heat treatment in all the examples. In the case of the examples, it was confirmed that the reduction in coercivity occurred as stress was removed through heat treatment. From this, it implies that the thermal stability of the Fe-based amorphous soft magnetic alloy was significantly improved due to the addition of Ce and La, and that stress relief heat treatment can be performed stably.

[0059] In the case of the examples, a decrease in coercivity due to stress relief was observed even when the stress relief heat treatment conditions were 0.80 Tx and 0.75 Tx.

[0060] As described above, the amorphous soft magnetic alloy of the present invention provides superior magnetic properties compared to conventional Fe-based amorphous soft magnetic alloys and can exhibit enhanced performance in high-frequency applications. In particular, by simultaneously satisfying high permeability and low coercivity through the combination of Ce and La and optimized heat treatment conditions, it can be usefully employed in electronic devices where energy efficiency is critical.

[0061] Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims.

Claims

1. An amorphous soft magnetic alloy represented by the following chemical formula (1), Chemical formula (1): Fe a B b Ce c La d The above a, b, c, and d each represent the atomic percentage (at%) of the corresponding components, satisfying 73.5≤a≤83.2, 16.0≤b≤24.0, 0.52≤c≤2.27, 0.28≤d≤1.23 and a+b+c+d=100, Amorphous soft magnetic alloy.

2. In Paragraph 1, The total sum of the above Ce and La is 0.8 at% to 3.5 at%, Amorphous soft magnetic alloy.

3. In Paragraph 1, In atomic percentage, the ratio of Ce to the total sum of Ce and La (A Ce / (A Ce + / A La ), A m (meaning the atomic percentage of element m) is 0.6 to 0.7, Amorphous soft magnetic alloy.

4. In Paragraph 1, The crystallization temperature of the above amorphous soft magnetic alloy is 470℃ to 570℃, Amorphous soft magnetic alloy.

5. In Paragraph 1, The coercivity of the above amorphous soft magnetic alloy is 12 A / m to 26 A / m, Amorphous soft magnetic alloy.

6. A step of preparing an alloy melt having atomic percentages (at%) of B: 16.0–24.0, Ce: 0.52–2.27, La: 0.28–1.23, with the remainder being Fe and unavoidable impurities; and A step of manufacturing an amorphous soft magnetic alloy represented by chemical formula (1) by rapidly cooling the above-mentioned alloy melt; comprising Method for manufacturing an amorphous soft magnetic alloy. Chemical formula (1): Fe a B b Ce c La d (A, b, c, and d above represent the atomic percentage (at%) of the corresponding components, satisfying 73.5≤a≤83.2, 16.0≤b≤24.0, 0.52≤c≤2.27, 0.28≤d≤1.23, and a+b+c+d=100) 7. In Paragraph 6, A method for rapidly cooling the above-mentioned alloy melt includes a Planar Flow Casting (PFC) process or a Rapid Solidification (RSP) process, Method for manufacturing an amorphous soft magnetic alloy.

8. In Paragraph 6, A method further comprising the step of performing a stress relief heat treatment at a temperature below the crystallization temperature of the amorphous soft magnetic alloy after the step of manufacturing the amorphous soft magnetic alloy. Method for manufacturing an amorphous soft magnetic alloy.

9. In Paragraph 8, The temperature range of the above stress relief heat treatment is 75% to 85% of the crystallization temperature, Method for manufacturing an amorphous soft magnetic alloy.

10. In Paragraph 8, The temperature range of the stress relief heat treatment above is 352℃ to 485℃, Method for manufacturing an amorphous soft magnetic alloy.

11. Manufactured from the amorphous soft magnetic alloy of claim 1, Noise filter for on-board chargers (OBCs) for electric vehicles.