Soft magnetic high-entropy alloy with high strength and plasticity, preparation method and application thereof

Abstract

This invention provides a soft magnetic high-entropy alloy with both high strength and ductility, its preparation method, and its applications. The general formula of the soft magnetic high-entropy alloy with both high strength and ductility is Fe. a Co b Ni c Al d Nb e B f The composition is as follows: 30% ≤ a ≤ 45%, 30% ≤ b ≤ 40%, 15% ≤ c ≤ 25%, 2% ≤ d ≤ 10%, 2% ≤ e ≤ 10%, 0.01% ≤ f ≤ 1%, and a + b + c + d + e + f = 100%, where a, b, c, d, e, and f are the molar percentages of the corresponding elements. This invention's soft magnetic high-entropy alloy possesses both excellent strong plasticity and soft magnetic properties. Its saturation magnetization (Ms) exceeds 130 emu / g, coercivity (Hc) is less than 3.00 Oe, room temperature tensile yield strength reaches 1000 MPa, tensile strength reaches 1300 MPa, and elongation after fracture reaches 40%, with comprehensive performance far exceeding most soft magnetic alloys.

Description

Soft magnetic high-entropy alloys with both high strength and ductility, their preparation methods and applications Technical Field

[0001] This invention relates to high-entropy alloy technology, and more particularly to a soft magnetic high-entropy alloy that combines high strength and ductility, its preparation method, and its applications. Background Technology

[0002] Soft magnetic materials are key materials in energy conversion devices (such as motors and transformers), and their low coercivity is crucial for improving energy conversion efficiency and reducing energy loss. However, in high-speed motors, soft magnetic materials not only need excellent soft magnetic properties to improve energy conversion efficiency, but also must withstand severe mechanical loads. That is, the material must possess both excellent soft magnetic properties and high strength and ductility to ensure the safe and stable operation of the device. Traditional soft magnetic alloys, including FeSi alloys, FeCo alloys, and FeNi alloys, have low strength and cannot meet the application requirements of soft magnetic materials under extreme load conditions. Ferrite, amorphous, and nanocrystalline soft magnetic materials have extremely low ductility and are prone to catastrophic damage under extreme load conditions. Therefore, it is urgent to design and fabricate a soft magnetic material that combines high strength and ductility to meet the application requirements of soft magnetic materials under extreme load conditions.

[0003] The strengthening of metallic materials is typically achieved through the interaction of dislocations, grain boundaries, and precipitates. This leads to a sharp increase in the internal stress level of the material. While strengthening the material, it also severely hinders the movement of magnetic domain walls, increasing the material's coercivity and causing it to lose its soft magnetic properties. In other words, alloys with excellent mechanical properties are designed by increasing the internal stress level, while high-performance soft magnetic alloys are often designed by reducing the internal stress. These two design strategies are almost contradictory. Therefore, finding a balance between these two design strategies to prepare soft magnetic materials that combine high strength and ductility is extremely challenging. Summary of the Invention

[0004] The purpose of this invention is to address the contradiction between strength and soft magnetic properties in traditional alloys by proposing a soft magnetic high-entropy alloy that combines high strength and plasticity. This alloy has excellent soft magnetic properties, while also possessing extremely high tensile strength and fracture toughness.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a soft magnetic high-entropy alloy possessing both high strength and ductility, with the general formula Fe. a Co b Ni c Al d Nb e B fWhere 30%≤a≤45%, 30%≤b≤40%, 15%≤c≤25%, 2%≤d≤10%, 2%≤e≤10%, 0.01%≤f≤1%, and a+b+c+d+e+f=100%, where a, b, c, d, e, and f are the molar percentages of the corresponding elements.

[0006] Furthermore, in the general formula, 31.2% ≤ a ≤ 41.9%, 31.2% ≤ b ≤ 39.4%, 16.3% ≤ c ≤ 22.5%, 4% ≤ d ≤ 8%, 3% ≤ e ≤ 7%, and 0.01% ≤ f ≤ 0.5%.

[0007] Furthermore, the soft magnetic high-entropy alloy, which combines high strength and ductility, has a saturation magnetization (Ms) of 130–150 emu / g, a coercivity (Hc) of 2.0–3.0 Oe, a room temperature tensile yield strength of 800 MPa–1000 MPa, a tensile strength of 1100 MPa–1300 MPa, and an elongation after fracture of 20%–40%, with comprehensive performance far exceeding that of most soft magnetic alloys.

[0008] Another object of the present invention discloses a method for preparing a soft magnetic high-entropy alloy that combines high strength and ductility, comprising the following steps:

[0009] Step 1: Weigh the raw materials Fe, Co, Ni, Al, Nb and B according to the molar ratio of each component in the general formula;

[0010] Step 2: Place the weighed raw materials into a vacuum arc melting furnace and melt them under argon protection to obtain a soft magnetic high-entropy alloy ingot.

[0011] Step 3: Hot-roll the soft magnetic high-entropy alloy ingot, and then perform high-temperature solution treatment and aging treatment on the hot-rolled alloy to prepare a soft magnetic high-entropy alloy with both high strength and plasticity.

[0012] Furthermore, the raw materials Fe, Co, Ni, Al, Nb and B mentioned in step one are all industrial-grade pure raw materials with a purity of 99.5 wt.% or higher.

[0013] Furthermore, before melting the alloy raw materials in step two, low-melting-point Al and non-metallic element B are placed at the bottom of the crucible, while high-melting-point Nb is placed at the top to prevent the low-melting-point elements from volatilizing.

[0014] Furthermore, in step two, before melting, a molecular pump is used to evacuate the electric arc furnace to a vacuum level of 3 × 10⁻⁶. -3 ~4×10 -3 Pa, then purged with argon to -0.05 to -0.04 MPa, and the Ti ingot needs to be melted 3 to 5 times before melting, each time for 60 to 80 seconds.

[0015] Furthermore, in step two, the melting current is 300-500A, and the melting is repeated 5-7 times, with the melting arc lasting 2-3 minutes each time.

[0016] Furthermore, the alloy is air-cooled after hot rolling, followed by solution treatment and aging treatment, and then water-quenched.

[0017] Further, in step three, the rolling temperature is 1000–1200°C, and the rolling deformation is 70%–90%. Preferably, the rolling temperature is 1000–1100°C, and the rolling deformation is 80%–90%.

[0018] Furthermore, the heat treatment temperature for the high-temperature solution treatment in step three is 1150℃~1250℃, and the time is 10~60min. The preferred heat treatment temperature is 1150℃~1200℃, and the time is 20~40min, which saves energy while ensuring performance.

[0019] Further, the aging treatment in step three is carried out at a temperature of 650–850°C for a time of 0.5–10 h. Preferably, the aging treatment is carried out at a temperature of 700–800°C for a time of 0.5–5 h.

[0020] Another object of the present invention is to disclose the use of a soft magnetic high-entropy alloy with both high strength and ductility in the electromagnetic field under high load conditions.

[0021] Furthermore, the high-strength, soft, magnetic, and high-entropy alloy is used in key metal components of electromagnetic equipment such as high-speed motors and solenoid valves.

[0022] The soft magnetic high-entropy alloy of this invention, which combines high strength and ductility, has a scientific and reasonable formulation, and its preparation method is simple and easy to implement. Compared with the prior art, it has the following advantages:

[0023] 1. The soft magnetic high-entropy alloy of the present invention, which combines high strength and plasticity, includes specific element selection and reasonable combination. Fe and Co are used to improve the magnetic properties of the alloy. Ni element can improve the magnetic properties of the material and enable the material to form an FCC structure. Al and Nb elements can combine with Ni element to form L12 nano-precipitates to improve the mechanical properties of the material. B element can purify the grain boundaries and inhibit abnormal precipitation on the grain boundaries, thereby improving the mechanical properties of the material.

[0024] 2. The soft magnetic high-entropy alloy of the present invention, which combines high strength and plasticity, exhibits excellent mechanical properties after high-temperature hot rolling and heat treatment. The room temperature tensile yield strength is 800MPa~1000MPa (preferably 850MPa~1000MPa), the tensile strength is 1100MPa~1300MPa (1180MPa~1300MPa), and the elongation after fracture is 20%~40% (38%~40%). Its comprehensive performance far exceeds that of most soft magnetic alloys.

[0025] 3. The soft magnetic high-entropy alloy of the present invention, which combines high strength and plasticity, has excellent soft magnetic properties, with a saturation magnetization (Ms) of 130-150 emu / g (preferably 135 emu / g-150 emu / g) and a coercivity (Hc) of 2.0-3.0 Oe (preferably 2.0-2.86 O).

[0026] 4. The raw materials of the soft magnetic high-entropy alloy of this invention, which combines high strength and plasticity, are easy to obtain and the preparation process is simple and easy. The combination of excellent soft magnetic properties and mechanical properties makes the alloy have broad application prospects in the field of soft magnetic materials under extreme load conditions. Attached Figure Description

[0027] Figure 1 shows the Fe prepared in Example 1 of the present invention. 34.9 Co 38 Ni 18 Al6Nb3B 0.1 Room temperature tensile curves of high-strength, ductile, soft, magnetic, and high-entropy alloys.

[0028] Figure 2 shows the Fe prepared in Example 1 of the present invention. 34.9 Co 38 Ni 18 Al6Nb3B 0.1 Hysteresis loop diagram (a) and magnified view of the central region (b) of a high-strength, ductile, soft, magnetic, high-entropy alloy.

[0029] Figure 3 shows the Fe prepared in Example 1 of this invention. 34.9 Co 38 Ni 18 Al6Nb3B 0.1 XRD diffraction pattern of a high-strength, ductile, soft, magnetic, high-entropy alloy.

[0030] Figure 4 shows the Fe prepared in Example 1 of this invention. 34.9 Co 38 Ni 18 Al6Nb3B 0.1 SEM microstructure of a high-strength, ductile, soft, magnetic, high-entropy alloy.

[0031] Figure 5 shows the Fe prepared in Example 1 of this invention. 34.9 Co 38 Ni 18 Al6Nb3B 0.1 TEM microstructure of high-strength, ductile, soft, magnetic, high-entropy alloy (a) and corresponding selected area electron diffraction pattern (b).

[0032] Figure 6 shows the Fe prepared in Example 2 of this invention. 37.9 Co 35 Ni 18 Al6Nb3B0.1 Room temperature tensile curves of high-strength, ductile, soft, magnetic, and high-entropy alloys.

[0033] Figure 7 shows the Fe prepared in Example 2 of this invention. 37.9 Co 35 Ni 18 Al6Nb3B 0.1 Hysteresis loop diagram (a) and magnified view of the central region (b) of a high-strength, ductile, soft, magnetic, high-entropy alloy.

[0034] Figure 8 shows the Fe prepared in Example 2 of the present invention. 37.9 Co 35 Ni 18 Al6Nb3B 0.1 XRD diffraction pattern of a high-strength, ductile, soft, magnetic, high-entropy alloy.

[0035] Figure 9 shows the Fe prepared in Example 2 of this invention. 37.9 Co 35 Ni 18 Al6Nb3B 0.1 SEM microstructure of a high-strength, ductile, soft, magnetic, high-entropy alloy. Detailed Implementation

[0036] The present invention will be further described below with reference to the embodiments:

[0037] Example 1

[0038] This embodiment discloses a Fe-Co-Ni-Al-Nb-B soft magnetic high-entropy alloy that combines high strength and ductility, with the general formula Fe. 34.9 Co 38 Ni 18 Al6Nb3B 0.1 .

[0039] In this embodiment, the preparation method of the Fe-Co-Ni-Al-Nb-B soft magnetic high-entropy alloy with both high strength and ductility is as follows:

[0040] Industrial-grade pure raw materials Fe, Co, Ni, Al, Nb, and B with a purity of 99.5 wt.% or higher were weighed according to the molar ratio of each component in the general formula. The prepared raw materials were placed in a vacuum arc melting furnace, with the low-melting-point Al and non-metallic element B placed at the bottom of the crucible, and the high-melting-point Nb element placed at the top. The vacuum degree was evacuated to 3 × 10⁻⁶. -3The process involves filling the furnace with high-purity argon gas to achieve a vacuum of -0.05 MPa. Before melting, the Ti ingot is melted 3-5 times, each time for 60-80 seconds, to remove residual oxygen from the furnace. Then, the soft magnetic high-entropy alloy is melted. During the melting process, the current is controlled at 300-500 A, and the melting is repeated 6 times, with each melting arc lasting 2-3 minutes, to obtain a soft magnetic high-entropy alloy ingot. The soft magnetic high-entropy alloy ingot obtained in step two is then hot-rolled at 1000℃ with a rolling deformation of 90%, followed by air cooling. The hot-rolled alloy undergoes high-temperature solution treatment at 1200℃ for 30 minutes, water quenching, and then aging treatment at 750℃ for 1 hour, followed by water quenching, to prepare the Fe-Co-Ni-Al-Nb-B high-strength, ductile, soft magnetic high-entropy alloy.

[0041] Figure 1 shows the Fe prepared in Example 1. 34.9 Co 38 Ni 18 Al6Nb3B 0.1 The room temperature tensile stress-strain curves of the high-strength, ductile, soft magnetic, high-entropy alloy show excellent mechanical properties, with room temperature tensile yield strength, tensile strength, and elongation at break of 850 MPa, 1180 MPa, and 38%, respectively. Figure 2 shows the hysteresis loop and a magnified view of the central region of the high-strength, ductile, soft magnetic, high-entropy alloy prepared in Example 1. Its saturation magnetization (Ms) and coercivity (Hc) are 135 emu / g and 2.86 Oe, respectively, exhibiting excellent soft magnetic properties that meet the requirements for soft magnetic materials under extreme load conditions. Figures 3 and 4 show the XRD diffraction pattern and SEM microstructure of the high-strength, ductile, soft magnetic, high-entropy alloy prepared in Example 1, respectively, indicating that the alloy is mainly composed of the FCC structural phase. Figure 5 shows the TEM microstructure and corresponding selected area electron diffraction pattern of the high-strength, ductile, soft magnetic, high-entropy alloy prepared in Example 1. Figure 5(a) shows that a large number of nano-precipitates are distributed in the FCC matrix, which improves the strength of the alloy. The superlattice diffraction spots in Figure 5(b) show that the nano-precipitates are of L12 ordered structure and are completely coherent with the FCC matrix. They can maintain excellent soft magnetic properties during the strengthening process of the alloy.

[0042] Example 2

[0043] This embodiment discloses a Fe-Co-Ni-Al-Nb-B soft magnetic high-entropy alloy that combines high strength and ductility, with the general formula Fe. 37.9 Co 35 Ni 18 Al6Nb3B 0.1 .

[0044] In this embodiment, the preparation method of the Fe-Co-Ni-Al-Nb-B soft magnetic high-entropy alloy, which combines high strength and ductility, is the same as in Example 1.

[0045] Figure 6 shows the Fe prepared in Example 2. 37.9 Co 35 Ni 18 Al6Nb3B 0.1 The room temperature tensile curves of the high-strength, ductile, soft magnetic, high-entropy alloy show excellent mechanical properties, with room temperature tensile yield strength, tensile strength, and elongation at break of 845 MPa, 1170 MPa, and 20%, respectively. Figure 7 shows the hysteresis loop and a magnified view of the central region of the high-strength, ductile, soft magnetic, high-entropy alloy prepared in Example 2. Its saturation magnetization (Ms) and coercivity (Hc) are 137.6 emu / g and 2.3 Oe, respectively, exhibiting excellent soft magnetic properties that meet the requirements for use of soft magnetic materials under extreme load conditions. Figures 8 and 9 show the Fe prepared in Example 2. 37.9 Co 35 Ni 18 Al6Nb3B 0.1 The XRD diffraction pattern and SEM microstructure of the high-strength, ductile, soft magnetic, and high-entropy alloy show that its microstructure is similar to that of Example 1, mainly composed of the FCC phase.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A soft magnetic high-entropy alloy possessing both high strength and ductility, characterized in that, Its general formula is Fe a Co b Ni c Al d Nb e B f The values ​​are: 30%≤a≤45%, 30%≤b≤40%, 15%≤c≤25%, 2%≤d≤10%, 2%≤e≤10%, 0.01%≤f≤1%, and a+b+c+d+e+f=100%, where a, b, c, d, e, and f are the molar percentages of the corresponding elements. The saturation magnetization of the soft magnetic high-entropy combination with high strength and plasticity is 130~150 emu / g, the coercivity is 2.0~3.0 Oe, the room temperature tensile yield strength is 800MPa~1000MPa, the tensile strength is 1100MPa~1300MPa, and the elongation after fracture is 20%~40%.

2. A method for preparing a soft magnetic high-entropy alloy with both high strength and ductility as described in claim 1, characterized in that, Includes the following steps: Step 1: Weigh the raw materials Fe, Co, Ni, Al, Nb, and B according to the molar ratio of each component in the general formula; Step 2: Place the weighed raw materials into a vacuum arc melting furnace and melt them under argon protection to obtain a soft magnetic high-entropy alloy ingot; Step 3: Hot-roll the soft magnetic high-entropy alloy ingot, and then perform high-temperature solution treatment and aging treatment on the hot-rolled alloy to prepare a soft magnetic high-entropy alloy with both high strength and plasticity.

3. The method for preparing a soft magnetic high-entropy alloy with both high strength and ductility according to claim 2, characterized in that, Before melting the alloy raw materials in step two, place the low-melting-point Al and non-metallic element B at the bottom of the crucible, and place the high-melting-point Nb element at the top.

4. The method for preparing a soft magnetic high-entropy alloy with both high strength and ductility according to claim 2, characterized in that, Step 2: Before melting, use a molecular pump to evacuate the electric arc furnace to a vacuum level of 3×10⁻⁶. -3 ~4×10 -3 Pa, then purged with argon to -0.05 to -0.04 MPa, and the Ti ingot was melted 3 to 5 times before melting, each time for 60 to 80 seconds.

5. The method for preparing a soft magnetic high-entropy alloy with both high strength and ductility according to claim 2, characterized in that, Step 2: The melting current is 300~500A, and the melting is repeated 5~7 times. Each melting arc should last for 2~3 minutes.

6. The method for preparing a soft magnetic high-entropy alloy with both high strength and ductility according to claim 2, characterized in that, After hot rolling, the alloy is air-cooled, followed by solution treatment and aging treatment, and then water-quenched.

7. The method for preparing a soft magnetic high-entropy alloy with both high strength and ductility according to claim 2, characterized in that, Step 3: The rolling temperature is 1000~1200℃, and the rolling deformation is 70%~90%.

8. The method for preparing a soft magnetic high-entropy alloy with both high strength and ductility according to claim 2, characterized in that, The heat treatment temperature for step three, high-temperature solution treatment, is 1150℃~1250℃, and the time is 10~60min.

9. The method for preparing a soft magnetic high-entropy alloy with both high strength and ductility according to claim 2, characterized in that, The aging treatment in step three is carried out at a temperature of 650~850℃ for 0.5h~10h.

10. Use of the soft magnetic high-entropy alloy of claim 1, which combines high strength and ductility, in the electromagnetic field under high load conditions.

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