Corrosion-resistant soft magnet-based amorphous alloy suitable for magnetic field environment as well as preparation method and application of corrosion-resistant soft magnet-based amorphous alloy

Abstract

The invention discloses a corrosion-resistant soft magnet-based amorphous alloy suitable for a magnetic field environment and a preparation method and application thereof.The iron-based amorphous alloy is composed of Fe, Co, B, Nb and Ta, the chemical formula of the iron-based amorphous alloy is (Fe0. 7Co0. 3) 75B21Nb2Ta2, and before annealing treatment, in a simulated seawater solution under a 5mT alternating magnetic field, the corrosion-resistant soft magnet-based amorphous alloy is obtained. The corrosion current density is obviously reduced to 3.5 * 10 <-9 > A / cm from 2.4 * 10 <-6 > A / cm in the absence of a magnetic field and is reduced by 3 orders of magnitude, and the unique magnetic induced enhanced corrosion resistance characteristic is shown; after annealing treatment is conducted for 20 min at 803 K, the coercive force is reduced to 4.8 A / m; and the saturation magnetization is up to 148 emu / g.

Description

TECHNICAL FIELD

[0001] The application relates to a corrosion-resistant soft magnetic iron-based amorphous alloy suitable for a magnetic field environment and a preparation method and application thereof, and belongs to the technical field of metal materials. BACKGROUND

[0002] Soft magnetic materials play a crucial role in modern electrical and electronic systems, especially in the field of energy conversion and transmission. With the development of electronic devices towards miniaturization, high frequency and high energy efficiency, higher requirements are put forward for soft magnetic materials, which need to have high saturation magnetic induction, low coercivity, high permeability and good frequency characteristics. Although traditional silicon steel has a relatively high saturation magnetic induction (1.8-2.0 T), it has a relatively high coercivity (about 30 A / m) and a relatively low permeability, and has a large eddy current loss in high-frequency applications. Although ferrite material has a relatively low loss at high frequency, its saturation magnetic induction is relatively low (usually less than 0.5 T), which limits its application in high-efficiency energy conversion systems. Amorphous alloy exhibits excellent properties such as high strength, high hardness, excellent soft magnetic properties and corrosion resistance due to its unique amorphous structure, which are not possessed by crystalline alloys. Among them, iron-based amorphous alloy exhibits excellent soft magnetic properties superior to traditional silicon steel and ferrite material.

[0003] On the other hand, in many engineering practical application environments such as marine engineering, the material also needs to have excellent corrosion resistance. Chloride ions in the marine environment can easily cause pitting corrosion and stress corrosion cracking of metal materials, and the magnetic field marine environment can also cause serious corrosion damage to the material. Traditional corrosion-resistant alloys often contain a large amount of chromium, nickel, molybdenum and other noble metal elements, which are relatively high in cost. Iron-based amorphous alloy has attracted widespread attention due to its rich raw material resources, relatively low cost and excellent soft magnetic properties. At the same time, iron-based amorphous alloy has excellent corrosion resistance due to its uniform amorphous structure, and there are no crystal defects such as grain boundaries and dislocations, so the corrosion medium is difficult to invade. Through reasonable composition design and process optimization, iron-based amorphous alloy can simultaneously realize excellent soft magnetic properties and corrosion resistance.

[0004] Chinese patent CN117721397A discloses an iron-based bulk amorphous alloy with a composition of Fe 91 Sc7Ti2 / B2 and a preparation method thereof. The patent prepares an amorphous alloy strip by introducing Ti or B elements, and the Fe 91 Sc7Ti2 composition exhibits excellent soft magnetic properties and high saturation magnetization. However, the presence of expensive scandium in the amorphous alloy makes the preparation cost relatively high, and its corrosion resistance in simulated seawater is not clear, which restricts its large-scale commercial application.

[0005] Chinese patent CN113564497A discloses an iron-based amorphous alloy with a composition of FeCrMoWCBY. The patent solves the problem of grain boundary corrosion and embrittlement caused by liquid lead-bismuth alloy in lead-cooled fast reactors by utilizing the unique grain boundary-free structure of amorphous state. In the 500℃ corrosion experiment, it shows a much lower corrosion rate than traditional steel and coating. However, the iron-based amorphous alloy contains a large amount of magnetic dilution elements W and Mo, which makes it not have excellent soft magnetic properties, and to some extent limits its application.

[0006] In the existing Fe-Co-B-Ta amorphous alloy system, the initial crystallization temperature (Tx) is usually about 808 K (Chinese patent CN110643910A), which limits its application window in higher temperature environments. The patent also does not explain the corrosion resistance of Fe-Co-B-Ta amorphous alloy in a magnetic field environment, limiting its application possibilities in a magnetic field marine environment. SUMMARY

[0007] The purpose of the present application is to provide a corrosion-resistant soft magnetic iron-based amorphous alloy suitable for a magnetic field environment, as well as its preparation method and application. The iron-based amorphous alloy has high thermal stability, excellent corrosion resistance in a magnetic field, and excellent soft magnetic properties, making it widely applicable in marine magnetic field environments that require strong soft magnetic properties and high durability.

[0008] To achieve the above purpose, the technical solution adopted by the present application is: A corrosion-resistant soft magnetic iron-based amorphous alloy suitable for a magnetic field environment, the composition of the iron-based amorphous alloy is Fe, Co, B, Nb and Ta, with atomic percentage content as follows: (Fe a Co b ) X1 B X2 Nb X3 Ta X4 , wherein a+b=1, 0.7≤a≤0.8, 0.2≤b≤0.3; x1+x2+x3+x4=100, 70≤x1≤75, 21≤x2≤25, x3=2, 2≤x4≤3; The corrosion resistance of the iron-based amorphous alloy is significantly improved after applying a magnetic field.

[0009] Preferably, the chemical formula of the iron-based amorphous alloy is any of the following: (Fe 0.7 Co 0.3) 71 B 25 Nb2Ta2, (Fe 0.7 Co 0.3 ) 72 B 24Nb2Ta2, (Fe 0.7 Co 0.3 ) 73 B 23 Nb2Ta2, (Fe 0.7 Co 0.3 ) 74 B 22 Nb2Ta2, (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2, (Fe 0.8 Co 0.2 ) 70 B 25 Nb2Ta3, (Fe 0.8 Co 0.2 ) 71 B 24 Nb2Ta3, (Fe 0.8 Co 0.2 ) 72 B 23 Nb2Ta3, (Fe 0.8 Co 0.2 ) 73 B 22 Nb2Ta3, (Fe 0.8 Co 0.2 ) 74 B 21 Nb2Ta3.

[0010] Preferably, the chemical formula of the iron-based amorphous alloy is (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2.

[0011] The preparation method of any of the above-mentioned corrosion-resistant soft magnetic iron-based amorphous alloys suitable for a magnetic field environment comprises weighing each raw material according to the atomic percentage content, melting to obtain an alloy ingot, and then preparing an amorphous ribbon through a single-roller rapid cooling method.

[0012] Preferably, the melting conditions are: vacuum degree ≤ 5 × 10 -3 Pa, argon atmosphere.

[0013] Preferably, the cooling speed of the single-roller rapid cooling method is 30-40 m / s.

[0014] Preferably, the method further comprises a step of annealing treatment after the amorphous ribbon is prepared.

[0015] Preferably, the annealing treatment conditions are: vacuum degree ≤ 5 × 10 -3 Pa, 750-850 K, 15-30 min.

[0016] Preferably, the chemical formula is (Fe 0.7 Co 0.3 ) 75 B 21 The corrosion current density of the Fe-based amorphous alloy of Nb2Ta2 in the simulated seawater solution under a 5 mT alternating magnetic field before annealing is 3.5 x 10 -9 A / cm 2 , the corrosion potential is -583 mV, and the pitting potential is -355 mV; after annealing at 803 K for 20 min, the coercivity is 4.8 A / m; the saturation magnetization is 148 emu / g, and the initial permeability is 2400 H / m.

[0017] The application of any of the above-mentioned corrosion-resistant soft magnetic Fe-based amorphous alloys suitable for a magnetic field environment in marine engineering corrosion prevention or high-frequency magnetic components in electronic power systems.

[0018] The beneficial effects of the present application are: The prepared Fe-based amorphous alloy has the following advantages: (1) excellent thermal stability and structural basis: by introducing Nb element and forming a synergistic effect with Ta, the obtained amorphous alloy exhibits high crystallization temperature (Tx> 820 K) and wide supercooled liquid region (ΔT> 35 K), which provides a key guarantee for subsequent annealing treatment and structural stability in actual high temperature environment; (2) unique corrosion-resistant magnetic enhancement characteristics: the obtained Fe-based amorphous alloy has more excellent corrosion resistance in an alternating magnetic field environment. In the simulated seawater test under the action of a 5 mT alternating magnetic field, its corrosion current density can be reduced by nearly 3 orders of magnitude compared with no magnetic field condition, and it exhibits more positive corrosion potential and pitting potential, i.e. "magnetic enhancement of corrosion resistance" effect; (3) synergistic optimization of soft magnetic properties and corrosion resistance after annealing: after annealing, while maintaining its magnetic field-enhanced corrosion resistance, the coercivity of the Fe-based amorphous alloy can be as low as 4.8 A / m, the saturation magnetization reaches 148 emu / g, and the initial permeability is 2400 H / m. This shows that through composition design and annealing process path, the unification of soft magnetic properties, structural stability and corrosion resistance of Fe-based amorphous alloy in harsh magnetic field environment has been successfully realized; (4) mature preparation process: using traditional vacuum arc melting and single-roller rapid cooling process, the process parameters are easy to control, and have good process repeatability and stability.

[0019] The corrosion-resistant soft magnetic Fe-based amorphous alloy suitable for a magnetic field environment provided by the present application can be widely applied in the fields of marine engineering corrosion prevention, high-frequency magnetic components in electronic power systems, etc., and has important application value and market prospect. Attached Figure Description

[0020] Figure 1 The XRD patterns (a) and DSC curves (b) of the iron-based amorphous alloy prepared in Example 1 in the as-cast state (without annealing) and in the relaxed state after annealing at 803 K for 20 min (hereinafter referred to as the relaxed state) are shown. Figure 2 The as-cast and relaxed states of the iron-based amorphous alloy prepared in Example 1 are shown in the potentiodynamic polarization curves in simulated seawater under 0 mT (no magnetic field) and 5 mT alternating magnetic fields. Figure 3 Impedance spectra of the as-cast and relaxed states of the iron-based amorphous alloy prepared in Example 1 under 0 mT (no magnetic field) and 5 mT alternating magnetic field; Figure 4 The image shows the corrosion morphology (SEM) of the iron-based amorphous alloy prepared in Example 1 in the as-cast and relaxed states under 0 mT (no magnetic field) and 5 mT alternating magnetic fields after simulated seawater corrosion. Figure 5 The soft magnetic properties of the iron-based amorphous alloy prepared in Example 1 are shown in (a), (b), and (c), respectively, representing coercivity, permeability, and saturation magnetization. Detailed Implementation

[0021] Example 1: This example provides a corrosion-resistant soft magnetic amorphous alloy suitable for magnetic field environments, with a nominal composition of (Fe) 0.7 Co 0.3 ) 75 B 21 The atomic percentage content of each element in Nb2Ta2 is as follows: Fe 52.5%, Co 22.5%, B 21%, Nb 2%, Ta 2%.

[0022] The preparation method includes the following steps: (1) Raw material preparation: Select metal Fe, metal Co, non-metal B, metal Nb and metal Ta with a purity of not less than 99.9% as raw materials.

[0023] (2) Smelting treatment: Accurately weigh each raw material according to the above atomic percentages, with a total weight of 30 g (Fe 17.832 g, Co 8.064 g, B 1.380 g, Nb 1.131 g, Ta 2.202 g). Place the prepared raw materials into a vacuum arc furnace and evacuate to 5×10⁻⁶. -3 Below Pa, high-purity argon gas is introduced as a protective gas, and the mixture is repeatedly smelted 6 times to obtain an alloy ingot with uniform element distribution.

[0024] (3) Rapid cooling treatment: The smelted alloy ingot is surface-polished to remove the oxide layer and impurity layer. Then, the polished alloy ingot is cut into appropriate sizes and amorphous ribbon is prepared by single-roll rapid cooling. The rapid cooling process parameters are: cooling rate 35 m / s, and the width of the resulting amorphous ribbon is 1.5 mm and the thickness is 40 μm.

[0025] The iron-based amorphous ribbon prepared in Example 1 was subjected to structural characterization and performance testing.

[0026] Figure 1 It showed (Fe) 0.7 Co 0.3 ) 75 B 21 As-cast and relaxed states of Nb2Ta2 amorphous alloys (with Fe) 0.7 Co 0.3 ) 75 B 21 Nb2Ta2 amorphous alloy is placed in a vacuum degree below 5×10 -3 The XRD pattern and DSC curve of the sample were obtained after the sample was placed in a tube furnace for isothermal annealing at 803 K for 20 min. Figure 1 As shown in region a, the XRD patterns before and after annealing exhibit a broadened diffuse diffraction peak in the 40–50° range, with no obvious crystallization peaks, indicating that the alloy has a completely amorphous structure. Figure 1 As shown in region b, the as-cast DSC curves reveal the glass transition temperature of this iron-based amorphous alloy. T g The crystallization temperature is 785 K. T x The K value is 824 K, and the supercooled liquid phase region Δ T The glass transition temperature of this iron-based amorphous alloy after annealing is 38 K. T g The crystallization temperature is 784 K. T x 820K, supercooled liquid phase region Delta T At 36 K, both before and after annealing, the amorphous alloy exhibits a high crystallization temperature and a wide supercooled liquid phase region. Existing Fe-Co-B-Ta systems... T x It is 808K (CN110643910A), while the alloy in Example 1 makes T x The K value increased by 16K. This indicates that the addition of Nb to this composition system endows the amorphous phase with excellent thermal stability, laying the foundation for the reliability of the material in higher temperature environments.

[0027] Figure 2The (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2amorphous alloy prepared in Example 1 in the simulated seawater environment. Without applying an alternating magnetic field (0 mT), the corrosion current density of the as-cast amorphous alloy is 2.4 x 10 -6 A / cm², and the corrosion potential is -610 mV. After applying a 5 mT alternating magnetic field, the corrosion current density is reduced to 3.5 x 10 -9 A / cm², the corrosion potential is positively shifted to -583 mV, the pitting potential is -355 mV, and the corrosion potential is increased by 27 mV. After annealing at 803 K for 20 min, the corrosion potential of the relaxed amorphous alloy is -638 mV, and the corrosion current density is 3.5 x 10 -6 A / cm². After applying a 5 mT alternating magnetic field, the corrosion current density is reduced to 1.2 x 10 -9 A / cm², the corrosion potential is positively shifted to -518 mV, the pitting potential is -393 mV, and the corrosion potential is increased by 120 mV. The corrosion potential of the relaxed sample after annealing is more positive, and the corrosion current density is lower, indicating that the 803 K heat treatment for 20 min effectively improves the corrosion performance of the alloy. The corrosion current density is reduced by 3 orders of magnitude after applying a magnetic field, which clearly shows that the (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2alloy prepared in Example 1 produces a significant "magnetically enhanced corrosion resistance" effect in an alternating magnetic field environment.

[0028] Table 1: Corrosion current density, corrosion potential, and pitting potential parameters of the (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2amorphous alloy prepared in Example 1 in simulated seawater without applying a magnetic field and after applying a magnetic field, as well as other alloys without applying a magnetic field

[0029] As can be seen from Table 1, the corrosion resistance of the iron-based amorphous alloy obtained in Example 1 is extremely prominent. Compared with the (Fe 0.7 Co 0.3 ) 75 B 21 Ta4alloy disclosed in patent CN110643910A, the corrosion current density of the (Fe -4 Co -2, the corrosion potential is -1032 mV, and the corrosion current density of the iron-based amorphous alloy obtained in Example 1 is 2.4 x 10 -6 A / cm -2 , the corrosion potential is -634 mV, the corrosion current density is reduced by 2 orders of magnitude, and the corrosion potential is increased by 398 mV. After applying a 5 mT magnetic field, its corrosion resistance has a qualitative leap: the corrosion current density is reduced by 3 orders of magnitude, becoming the best in corrosion resistance among all the materials in the table. At the same time, after applying a magnetic field, a significant passivation benefit is induced, and a pitting potential ( E pit ) appears, with a difference of 228 mV from the corrosion potential, indicating that the iron-based amorphous alloy obtained in Example 1 exhibits excellent pitting resistance.

[0030] Figure 3 shows the surface morphology of the as-cast and relaxed state of the (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2 amorphous alloy under 0 mT and 5 mT alternating magnetic field. With the increase of magnetic field strength, the capacitive arc of the iron-based amorphous alloy increases significantly, indicating that the passivation film formed on the surface of the iron-based amorphous alloy is more stable, and the corrosion resistance is enhanced. It also shows that applying a magnetic field can improve and control the corrosion resistance of the iron-based amorphous alloy. The capacitive arc of the relaxed state after heat treatment is slightly larger than that of the as-cast state, indicating that heat treatment can also improve the corrosion resistance of the alloy.

[0031] Figure 4 shows the surface morphology (SEM) of the as-cast and relaxed state of the (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2 amorphous alloy after corrosion in simulated seawater. Figure 4 Region a in the middle is the corrosion morphology without applying a magnetic field. The as-cast iron-based amorphous alloy surface has obvious pitting and cracks in many places, and some areas have peeling phenomenon, with corrosion products accumulated on the surface; Figure 4 Region b in the middle is the corrosion morphology after applying a 5 mT magnetic field. The as-cast iron-based amorphous alloy surface is smoother, with very small pitting; Figure 4 Region c in the middle is the corrosion morphology of the relaxed state of the iron-based amorphous alloy without applying a magnetic field. The alloy surface has obvious cracks in many places, and the corrosion area has peeling, with corrosion products accumulated on the surface; Figure 4 Region d in the middle is the corrosion morphology of the relaxed state of the iron-based amorphous alloy after applying a 5 mT magnetic field. The iron-based amorphous alloy surface becomes smooth, with only a few corrosion cracks. Figure 4Transverse comparison, the surface of the iron-based amorphous alloy after applying magnetic field shows almost no pitting, which proves that applying magnetic field can effectively inhibit the occurrence of pitting. Figure 4 Longitudinal comparison, the surface morphology of the relaxed state iron-based amorphous alloy is more flat than that of the as-cast alloy, Figure 5 Although the surface of the iron-based amorphous alloy in the medium c region has peeling, the surface after peeling has almost no pitting, which proves that annealing treatment can effectively improve the corrosion performance.

[0032] Figure 5 shows the (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2 amorphous alloy in the relaxed state has soft magnetic properties. Figure 5 The medium a region shows that with the increase of annealing time, the coercivity of the alloy first decreases and then rises, and reaches the minimum value of 4.8 A / m at 803 K annealing for 20 min; Figure 5 The medium b region shows that the initial permeability of the alloy reaches the maximum value of 2400 H / m after annealing at 803 K for 20 min; ​ The medium c region shows that the saturation magnetization of the alloy reaches the maximum value of 148 emu / g after annealing at 803 K for 20 min.

[0033] The above results show that the iron-based amorphous alloy prepared in this embodiment exhibits excellent comprehensive performance: first, by introducing the Nb element, the alloy obtains a high initial crystallization temperature (824 K) and a wide undercooled liquid phase region, showing high thermal stability. Second, the iron-based alloy can exhibit a significant "magnetic corrosion resistance enhancement" effect in the environment of applying alternating magnetic field, which is a unique phenomenon discovered and verified by the present application. Finally, through the optimized annealing process, the alloy simultaneously realizes the excellent soft magnetic properties of low coercivity (4.8 A / m) and high saturation magnetization (148 emu / g). This characteristic of high thermal stability, excellent corrosion resistance under magnetic field and excellent soft magnetic properties makes it have a wide application prospect in the marine magnetic field environment (such as ship propulsion motor, submarine sensor transformer) which requires strong soft magnetic properties and high durability at the same time.

Claims

1. A corrosion resistant soft magnetic iron-based amorphous alloy suitable for use in a magnetic field environment, characterized in that, The composition elements of the iron-based amorphous alloy are Fe, Co, B, Nb and Ta, and the atomic percentage content is: (Fe a Co b ) X1 B X2 Nb X3 Ta X4 Wherein, a+b=1, 0.7≤a≤0.8, 0.2≤b≤0.3; x1+x2+x3+x4=100, 70≤x1≤75, 21≤x2≤25, x3=2, 2≤x4≤3. The iron-based amorphous alloy has improved corrosion resistance after a magnetic field is applied.

2. The corrosion resistant soft magnetic iron-based amorphous alloy suitable for use in a magnetic field environment according to claim 1, characterized in that, Fe 0.7 Co 0.3)71 B 25 Nb2Ta2, (Fe 0.7 Co 0.3 ) 72 B 24 Nb2Ta2, (Fe 0.7 Co 0.3 ) 73 B 23 Nb2Ta2, (Fe 0.7 Co 0.3 ) 74 B 22 Nb2Ta2, (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2, (Fe 0.8 Co 0.2 ) 70 B 25 Nb2Ta3, (Fe 0.8 Co 0.2 ) 71 B 24 Nb2Ta3, (Fe 0.8 Co 0.2 ) 72 B 23 Nb2Ta3, (Fe 0.8 Co 0.2 ) 73 B 22 Nb2Ta3, (Fe 0.8 Co 0.2 ) 74 B 21 Nb2Ta3.

3. The corrosion resistant soft magnetic iron-based amorphous alloy suitable for use in a magnetic field environment according to claim 2, characterized in that, The chemical formula of the iron-based amorphous alloy is (Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2.

4. The method of producing a corrosion resistant soft magnetic iron-based amorphous alloy suitable for a magnetic field environment according to any one of claims 1 to 3, characterized in that, The alloy ingot is obtained by weighing each raw material according to the atomic percentage content and then smelting, and the amorphous strip is prepared by a single-roll rapid cooling method.

5. The method of claim 3, wherein the method is characterized by: The smelting conditions were: vacuum degree < 5 x 10 -3 Pa, argon atmosphere.

6. The method of claim 3, wherein the method is characterized by: The cooling speed of the single-roll rapid cooling method is 30-40 m / s.

7. The method of claim 3, wherein the method is characterized by: The step of annealing after the amorphous strip is prepared is further included.

8. The method of claim 7, wherein the method is characterized by: The conditions of the annealing treatment are: vacuum degree ≤ 5 x 10 -3 Pa, 750-850 K, 15-30 min.

9. The method of claim 8, wherein the method is characterized by: Fe 0.7 Co 0.3 ) 75 B 21 Nb2Ta2of the iron-based amorphous alloy, before annealing, in a simulated seawater solution under a 5mT alternating magnetic field, the corrosion current density is 3.5×10 -9 A / cm 2 , the corrosion potential is-583 mV, and the pitting potential is-355 mV; after annealing at 803K for 20min, the coercivity is 4.8 A / m; the saturation magnetization is 148 emu / g, and the initial permeability is 2400 H / m.

10. Application of the corrosion-resistant soft magnetic iron-based amorphous alloy suitable for a magnetic field environment according to any one of claims 1-3 to marine engineering corrosion prevention or high-frequency magnetic components of electronic power systems.

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