Cobalt-based amorphous wire and preparation method thereof

Abstract

The invention provides a cobalt-based amorphous wire and a preparation method thereof. The cobalt-based amorphous wire comprises a cobalt-based amorphous alloy core material and a self-healing interface layer coating the cobalt-based amorphous alloy core material, the cobalt-based amorphous alloy core material comprises, by atomic percent, 4%-6% of Fe, 16%-19% of B, 5%-7% of Si, 1%-2% of Mo, 0.1%-0.5% of Tb0. 2Dy0. 8Fe2 and the balance Co. And the self-healing interface layer is a CoO-MoO3 compound. According to the cobalt-based amorphous wire and the preparation method thereof, a CoO-MoO3 compound self-healing interface layer is generated through pre-oxidation, a reversible oxidation-reduction reaction can be generated, micro-defect self-repairing is achieved, defect expansion is prevented, and interface brittleness is inhibited; and collaborative optimization of the microstructure, the interface quality and the magnetic performance of the amorphous wire is realized by adopting magnetic field-ultrasonic field collaborative wiredrawing, multi-field coupling cooling, green coating layer removal and multi-stage magnetic field annealing.

Description

Technical Field

[0001] This invention belongs to the field of amorphous alloy materials technology, specifically relating to a cobalt-based amorphous wire and its preparation method. Background Technology

[0002] Cobalt-based amorphous alloys (also known as metallic glasses) have become key materials in high-end fields such as magnetic sensors, microactuators, electronic information, biomedicine, and aerospace due to their unique soft magnetic properties (such as low coercivity and high permeability), excellent mechanical properties (high strength and high elasticity), and good corrosion resistance. In particular, cobalt-based amorphous alloy wires are increasingly important in high-precision magnetic sensors and magnetic navigation medical guidewires due to their high sensitivity, low noise, and stability.

[0003] Currently, glass coating is the mainstream process for the continuous preparation of micron-sized cobalt-based amorphous alloy wires. This technology involves encapsulating molten metal within a glass tube, drawing it at high temperature, and rapidly cooling it to form an amorphous structure. This method enables continuous production and yields fine-diameter, uniform amorphous wires, which are widely used in high-precision sensors and electronic devices. For example, Chinese patent document CN109023163A discloses a cobalt-based amorphous alloy wire and its preparation method, employing an improved glass coating method for the continuous preparation of cobalt-based amorphous alloy wires. However, this process still faces a series of technical challenges in engineering applications, particularly bottlenecks in interface stability, amorphous formation capability, magnetic property control, and environmental safety.

[0004] The existing glass coating method has the following main problems in practical applications: Interface metallurgical defects: During high-temperature wire drawing, oxidation and interdiffusion of elements easily occur between the alloy and the glass, forming a brittle transition layer (such as CoO or SiO2) with a thickness typically ≥500 nm. The thermal expansion coefficients of this layer differ significantly from those of the alloy matrix, generating high residual stress during cooling, resulting in a wire breakage rate typically exceeding 20%, which seriously affects production continuity and product reliability.

[0005] Insufficient amorphous forming capability: Due to the limited thermal conductivity of the glass sleeve, the actual cooling rate is typically only 1×10⁻⁶. 4 - 5×10 4 At a speed of K / s, it is difficult to completely suppress crystal nucleation, resulting in ≥5 vol% of crystalline phase remaining in the wire. The crystalline phase not only degrades the mechanical properties but also becomes a magnetic domain pinning center, increasing coercivity and affecting soft magnetic properties, resulting in a giant magnetoresistance (GMI) change rate at 20 MHz that is usually less than 180%.

[0006] Poor dimensional and geometric accuracy control: Rheological instability of the alloy and glass during the wire drawing process can easily cause wire diameter fluctuations and concentricity deviations, with wire diameter tolerances often exceeding ±3 µm. The subsequent acid etching process to remove the glass layer further damages the wire surface, increasing its roughness (Ra≥0.2 μm) and easily introducing defects such as scratches and pits.

[0007] Environmental safety risks: Traditional glass removal processes often use highly corrosive chemicals such as hydrofluoric acid (HF), posing operational safety hazards and generating harmful waste liquids. Acid etching may also induce hydrogen embrittlement or excessive corrosion of the wire, increasing post-processing costs and process complexity.

[0008] Poor performance consistency and limited functionality: Existing processes have difficulty effectively controlling the orientation of magnetic domains and cannot stably write the required circumferential magnetic anisotropy, resulting in large performance fluctuations between product batches (such as permeability fluctuations of up to ±20%). Furthermore, the limited functionality makes it difficult to meet the stringent requirements of high-precision magnetic sensors for sensitivity, linearity, and consistency.

[0009] Therefore, there is a need to provide a cobalt-based amorphous wire and its preparation method to solve problems such as interfacial metallurgical defects, insufficient amorphous formation ability, poor control of size and geometric accuracy, and environmental safety risks. Summary of the Invention

[0010] The technical problem solved by this invention is to provide a cobalt-based amorphous wire and its preparation method. A CoO-MoO3 composite self-healing interface layer is generated through pre-oxidation, which can undergo reversible oxidation-reduction reaction to achieve self-repair of micro-defects, prevent defect expansion, and suppress interface brittleness. Furthermore, magnetic field-ultrasonic field synergistic wire drawing, multi-field coupled cooling, green removal of coating layer, and multi-stage magnetic field annealing technology are adopted to successfully achieve synergistic optimization of the microstructure, interface quality, and magnetic properties of the amorphous wire.

[0011] To address the aforementioned problems, a first aspect of the present invention provides a cobalt-based amorphous wire, comprising a cobalt-based amorphous alloy core and a self-healing interface layer covering the cobalt-based amorphous alloy core; the cobalt-based amorphous alloy core comprises, by atomic percentage: Fe 4%-6%, B 16%-19%, Si 5%-7%, Mo 1%-2%, Tb 0.2 Dy 0.8 Fe2+ ​​0.1%-0.5%, balance Co, of which Tb 0.2 Dy 0.8 The atomic ratio of Fe2 is calculated as the percentage of the sum of the number of Tb, Dy, and Fe atoms to the total number of atoms; the self-healing interface layer is a CoO-MoO3 composite.

[0012] Preferably, the thickness of the self-healing interface layer is no greater than 100 nm.

[0013] A second aspect of the present invention provides a structure for preparing cobalt-based amorphous wires, comprising, from the inner layer to the outer layer, a matrix alloy, a self-healing interface layer, a soluble glass layer, and a supporting glass layer; wherein the matrix alloy comprises, by atomic percentage: Fe 4%-6%, B 16%-19%, Si 5%-7%, Mo 1%-2%, and pre-alloyed Tb 0.2 Dy 0.8 Fe2+ ​​0.1%-0.5%, balance Co, including pre-alloyed Tb 0.2 Dy 0.8 The atomic ratio of Fe2 is calculated as the percentage of the sum of the number of Tb, Dy, and Fe atoms to the total number of atoms; the self-healing interface layer is a CoO-MoO3 composite; the soluble glass layer comprises the following components by mass percentage: P2O5 45%-55%, Na2O 20%-30%, CaO 10%-15%; the supporting glass layer comprises the following components by mass percentage: SiO2 72%-75%, Al2O3 10%-12%, CaO 15%-18%.

[0014] A third aspect of the present invention provides a method for preparing cobalt-based amorphous wires, comprising the following steps: S1. Preparation of a matrix alloy, wherein the raw materials for preparing the matrix alloy, calculated by atomic percentage, include: Fe 4%-6%, B 16%-19%, Si 5%-7%, Mo 1%-2%, and pre-alloyed Tb. 0.2 Dy 0.8 Fe2+ ​​0.1%-0.5%, balance Co, including pre-alloyed Tb 0.2 Dy 0.8 The atomic ratio of Fe2 is calculated as the percentage of the sum of the number of Tb, Dy, and Fe atoms to the total number of atoms; S2. Pre-oxidize the base alloy to form a self-healing interface layer on the surface of the base alloy; S3. The pre-oxidized matrix alloy is encapsulated in a glass tube to obtain a composite billet; S4. The composite blank is drawn into wire and then cooled to obtain composite filament; S5. Remove the glass cladding layer of the composite filament to obtain the filament; S6. Anneal the filament to obtain the cobalt-based amorphous filament.

[0015] Preferably, in step S2, the pre-oxidation conditions are: in an oxygen-containing atmosphere, at 280-320°C for 25-35 minutes.

[0016] Preferably, in step S3, the glass tube comprises a soluble glass layer and a supporting glass layer arranged from the inside out; the soluble glass layer comprises the following components by mass percentage: P2O5 45%-55%, Na2O 20%-30%, CaO 10%-15%; the supporting glass layer comprises the following components by mass percentage: SiO2 72%-75%, Al2O3 10%-12%, CaO 15%-18%; Step S3 specifically includes the following steps: encapsulating the pre-oxidized matrix alloy in a glass tube, and evacuating the glass tube to a pressure not exceeding 5 × 10⁻⁶. -3 Pa, then fill with high-purity argon gas and seal to obtain composite billet; Step S5 specifically includes the following steps: placing the composite filament in water at 60-80℃ and subjecting it to ultrasonic field oscillation at 300-500W for 25-35 minutes to dissolve the soluble glass layer and peel off the supporting glass layer to obtain the filament.

[0017] Preferably, in step S4, the drawing of the composite billet specifically includes the following steps: evacuating the vacuum, then introducing an inert gas, and drawing the billet at a temperature 50-100°C above the alloy liquidus temperature, wherein the alloy liquidus temperature is 1100-1150°C; simultaneously applying an axial static magnetic field, a rotating magnetic field, and a high-frequency ultrasonic field during the drawing process; the magnetic field strength of the axial static magnetic field is 0.2-0.4 T; the magnetic field strength of the rotating magnetic field is 0.1-0.15 T; and the frequency of the high-frequency ultrasonic field is 40 kHz, with a sound intensity of 5-10 W / cm². 2 .

[0018] Preferably, in step S4, the cooling specifically includes the following steps: using a mixture of argon and liquid nitrogen for atomized cooling, and controlling the instantaneous cooling rate at 1×10⁻⁶ by periodic modulation of 0.5-1s. 6 - 5×10 6 K / s.

[0019] Preferably, step S6 specifically includes the following steps: first, annealing at 300℃ and under an axial magnetic field of 0.1 T for 30-60 min; then, annealing at 260-280℃ and under a circumferential magnetic field of 0.08-0.15 T for 20-40 min; and finally, annealing at 150-200℃ and under an inert atmosphere for 10-20 min.

[0020] Preferably, the process further includes electrochemical polishing and oxygen plasma cleaning and passivation of the wire material sequentially after step S5 and before step S6; the electrochemical polishing uses a phosphoric acid-sulfuric acid system with a current density of 1-3 A / dm² and an electrochemical polishing time of 5-10 min; the oxygen plasma cleaning and passivation temperature is 80-120℃ and the time is 10-20 min.

[0021] Compared with the prior art, the present invention has the following advantages: The cobalt-based amorphous wire and its preparation method of this invention feature a self-healing interface layer formed on the surface of a matrix alloy through pre-oxidation treatment. The CoO-MoO3 composite is a reversible oxide buffer layer. In-situ XPS analysis confirmed that this layer can undergo a reversible oxidation-reduction reaction during thermal cycling, enabling self-repair of microscopic defects, preventing defect expansion, and fundamentally suppressing interface brittleness. Compared with single, brittle oxide layers formed by traditional processes, such as pure CoO, the CoO-MoO3 composite layer is more stable, can buffer thermal stress, and, more importantly, possesses reversible self-healing capabilities. This cobalt-based amorphous alloy core material, through Tb... 0.2 Dy 0.8 The introduction of Fe2 magnetostrictive particles significantly enhances the magnetostrictive effect and magnetic domain control capability of cobalt-based amorphous wires.

[0022] The cobalt-based amorphous wire and its preparation method of this invention, through the synergy of "pre-oxidation layer interface protection" and "multi-field coupling rapid cooling", achieve a stable amorphous phase content of ≥99%. Combined with magnetostrictive particles and multi-stage magnetic field annealing, the product's coercivity is ≤1.5 A / m, and the GMI change rate is ≥300%. Field-coordinated wire drawing and precision post-processing result in a wire diameter tolerance of ±0.5 μm and a surface roughness Ra ≤0.03 μm.

[0023] The cobalt-based amorphous wire and its preparation method of the present invention completely eliminate hydrofluoric acid by using a warm water ultrasonic exfoliation process, thereby eliminating safety risks and environmental pollution from the source, and the concentration of fluoride ions in the waste liquid is less than 5 ppm (ICP-MS detection).

[0024] The cobalt-based amorphous wire and its preparation method of the present invention are particularly suitable for high-sensitivity magnetocardiogram sensors (signal-to-noise ratio improved by ≥40 dB), magnetic navigation medical guidewires (positioning error under MRI <0.1 mm), and high-frequency micro magnetoelectric devices, showing great industrialization potential. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] A first aspect of this invention provides a cobalt-based amorphous wire, comprising a cobalt-based amorphous alloy core and a self-healing interface layer covering the cobalt-based amorphous alloy core; the cobalt-based amorphous alloy core comprises, by atomic percentage: Fe 4%-6%, B 16%-19%, Si 5%-7%, Mo 1%-2%, Tb 0.2 Dy 0.8 Fe2+ ​​0.1%-0.5%, balance Co, of which Tb 0.2 Dy 0.8 The atomic ratio of Fe2 is calculated as the percentage of the sum of the number of Tb, Dy, and Fe atoms to the total number of atoms; the self-healing interface layer is a CoO-MoO3 composite.

[0027] The cobalt-based amorphous wire of this invention features a self-healing interface layer formed on the surface of the matrix alloy through pre-oxidation treatment of a CoO-MoO3 composite. This layer stabilizes structurally during subsequent wire drawing and heat treatment and is retained as an important component of the final product. The CoO-MoO3 composite is a reversible oxide buffer layer. In-situ XPS analysis confirmed that this layer can undergo a reversible oxidation-reduction reaction during thermal cycling, enabling self-repair of microscopic defects, preventing defect expansion, and fundamentally suppressing interface brittleness. Compared to single, brittle oxide layers formed by traditional processes, such as pure CoO, the CoO-MoO3 composite layer is more stable, can buffer thermal stress, and, more importantly, possesses reversible self-healing capabilities. This cobalt-based amorphous alloy core material, through Tb... 0.2 Dy 0.8 The introduction of Fe2 magnetostrictive particles significantly enhances the magnetostrictive effect and magnetic domain control capability of cobalt-based amorphous wires.

[0028] Preferably, the thickness of the self-healing interface layer is no greater than 100 nm. By forming a self-healing interface layer of CoO-MoO3 composite, the thickness of the brittle layer is controlled within 100 nm. Combined with the reversible characteristics of the self-healing interface layer, the wire breakage rate of cobalt-based amorphous wires can be reduced from ≥20% in the traditional process to ≤3%.

[0029] Preferably, the matrix alloy has a gradient microstructure consisting of an amorphous core and a nanocrystalline shell, wherein the thickness of the nanocrystalline shell is 50-100 nm.

[0030] A second aspect of this invention provides a structure for preparing cobalt-based amorphous wires, comprising a matrix alloy, a self-healing interface layer, a soluble glass layer, and a supporting glass layer, arranged sequentially from the inner to the outer layers; the matrix alloy comprises, by atomic percentage: Fe 4%-6%, B 16%-19%, Si 5%-7%, Mo 1%-2%, Tb 0.2 Dy 0.8Fe2+ ​​0.1%-0.5%, balance Co, of which Tb 0.2 Dy 0.8 The atomic ratio of Fe2 is calculated as the percentage of the sum of the number of Tb, Dy, and Fe atoms to the total number of atoms; the self-healing interface layer is a CoO-MoO3 composite; the soluble glass layer comprises the following components by mass percentage: P2O5 45%-55%, Na2O 20%-30%, CaO 10%-15%; the supporting glass layer comprises the following components by mass percentage: SiO2 72%-75%, Al2O3 10%-12%, CaO 15%-18%.

[0031] This structure is used to prepare cobalt-based amorphous wires. The self-healing interface layer is a CoO-MoO3 composite formed on the surface of the matrix alloy through pre-oxidation treatment. This composite is a reversible oxide buffer layer that undergoes a reversible oxidation-reduction reaction during thermal cycling, enabling self-repair of microscopic defects, preventing defect propagation, and fundamentally suppressing interface brittleness. The soluble glass layer can be dissolved in warm water, while the supporting glass layer provides the main mechanical support. Both the soluble and supporting glass layers can be removed ultrasonically with warm water, eliminating the need for hydrofluoric acid and thus eliminating safety risks and environmental pollution at the source. The fluoride ion concentration in the waste liquid is less than 5 ppm (ICP-MS detection). This achieves efficient and green exfoliation of the coating layer.

[0032] A third aspect of this invention provides a method for preparing cobalt-based amorphous wires, comprising the following steps: S1. Preparation of a matrix alloy, wherein the raw materials for preparing the matrix alloy, calculated by atomic percentage, include: Fe 4%-6%, B 16%-19%, Si 5%-7%, Mo 1%-2%, and pre-alloyed Tb. 0.2 Dy 0.8 Fe2+ ​​0.1%-0.5%, balance Co, including pre-alloyed Tb 0.2 Dy 0.8 The atomic ratio of Fe2 is calculated as the percentage of the sum of the number of Tb, Dy, and Fe atoms to the total number of atoms; S2. Pre-oxidize the base alloy to form a self-healing interface layer on the surface of the base alloy; S3. The pre-oxidized matrix alloy is encapsulated in a glass tube to obtain a composite billet; S4. The composite blank is drawn into wire and then cooled to obtain composite filament; S5. Remove the glass cladding layer of the composite filament to obtain the filament; S6. Anneal the filament to obtain the cobalt-based amorphous filament.

[0033] The preparation method of cobalt-based amorphous wire in this embodiment of the invention: 1. Pre-alloyed Tb is added to the raw materials for preparing the matrix alloy. 0.2 Dy 0.8 Fe2 magnetostrictive particles significantly enhance the magnetostrictive effect and magnetic domain control capability of cobalt-based amorphous wires. 2. The matrix alloy underwent pre-oxidation treatment, forming a CoO-MoO3 composite on its surface. This CoO-MoO3 composite acts as a reversible oxide buffer layer. In-situ XPS analysis confirmed that this layer can undergo a reversible oxidation-reduction reaction during thermal cycling, enabling self-repair of micro-defects, preventing defect propagation, and fundamentally suppressing interfacial brittleness. Furthermore, compared to single, brittle oxide layers formed by traditional processes, such as pure CoO, the CoO-MoO3 composite layer is more stable and can buffer thermal stress.

[0034] Preferably, in step S2, the pre-oxidation conditions are: in an oxygen-containing atmosphere, at 280-320°C for 25-35 minutes.

[0035] Preferably, in step S3, the glass tube comprises a soluble glass layer and a supporting glass layer arranged from the inside out; the soluble glass layer comprises the following components by mass percentage: P2O5 45%-55%, Na2O 20%-30%, CaO 10%-15%; the supporting glass layer comprises the following components by mass percentage: SiO2 72%-75%, Al2O3 10%-12%, CaO 15%-18%; Step S3 specifically includes the following steps: encapsulating the pre-oxidized matrix alloy in a glass tube, and evacuating the glass tube to a pressure not exceeding 5 × 10⁻⁶. -3 Pa, then fill with high-purity argon gas and seal to obtain composite billet; Step S5 specifically includes the following steps: placing the composite filament in water at 60-80℃ and subjecting it to ultrasonic field oscillation at 300-500W for 25-35 minutes to dissolve the soluble glass layer and peel off the supporting glass layer to obtain the filament.

[0036] The cobalt-based amorphous wire preparation method in this embodiment adopts a warm water ultrasonic glass removal process, which completely eliminates hydrofluoric acid, thereby eliminating safety risks and environmental pollution from the source. The fluoride ion concentration in the waste liquid is less than 5 ppm (ICP-MS detection).

[0037] Preferably, in step S4, the drawing of the composite billet specifically includes the following steps: evacuating the vacuum, then introducing an inert gas, and drawing the billet at a temperature 50-100°C above the alloy liquidus temperature, wherein the alloy liquidus temperature is 1100-1150°C; simultaneously applying an axial static magnetic field, a rotating magnetic field, and a high-frequency ultrasonic field during the drawing process; the magnetic field strength of the axial static magnetic field is 0.2-0.4 T; the magnetic field strength of the rotating magnetic field is 0.1-0.15 T; and the frequency of the high-frequency ultrasonic field is 40 kHz, with a sound intensity of 5-10 W / cm². 2 .

[0038] The method for preparing cobalt-based amorphous wires in this embodiment employs a multi-field synergistic drawing process involving magnetic and ultrasonic fields, which can stabilize melt flow, refine the microstructure, and improve dimensional and geometric accuracy.

[0039] Preferably, in step S4, the cooling specifically includes the following steps: using a mixture of argon and liquid nitrogen for atomized cooling, and controlling the instantaneous cooling rate at 1×10⁻⁶ by periodic modulation of 0.5-1s. 6 - 5×10 6 K / s. Periodic modulation refers to the cyclical opening and closing of the argon and liquid nitrogen cooling medium injection via a solenoid valve with a period of 0.5-1s. This intermittent cooling, through alternating cycles of "intense cooling-relaxation," achieves instantaneous ultra-high-speed cooling (1×10 K / s) of the metal core during the intense cooling pulse phase. 6 - 5×10 6 K / s) ensures amorphous formation; it also allows the thermal stress inside the glass cladding to be released during the relaxation stage, preventing the glass from cracking due to sudden cooling, thus simultaneously solving the technical contradiction between ultra-high cooling rate and glass layer integrity.

[0040] The cobalt-based amorphous wire preparation method of this embodiment achieves a stable amorphous phase content of ≥99% through the synergy of "pre-oxidation layer interface protection" and "multi-field coupling rapid cooling".

[0041] Preferably, step S6 specifically includes the following steps: first, annealing at 300℃ and under an axial magnetic field of 0.1 T for 30-60 min; then, annealing at 260-280℃ and under a circumferential magnetic field of 0.08-0.15 T for 20-40 min; and finally, annealing at 150-200℃ and under an inert atmosphere for 10-20 min.

[0042] The method for preparing cobalt-based amorphous wires in this embodiment employs multi-stage magnetic field annealing, sequentially performing stress-relieving annealing, magnetic domain structure regulation annealing, and performance stabilization annealing. This optimizes magnetic properties and improves long-term stability. Combined with magnetostrictive particles and multi-stage magnetic field annealing, the product's coercivity can be ≤1.5 A / m, and the GMI change rate ≥300%.

[0043] Preferably, the process further includes electrochemical polishing and oxygen plasma cleaning passivation of the wire material sequentially after step S5 and before step S6; the electrochemical polishing uses a phosphoric acid-sulfuric acid system with a current density of 1-3 A / dm³. 2 The electrochemical polishing time is 5-10 min; the oxygen plasma cleaning and passivation temperature is 80-120℃, and the time is 10-20 min. By using multi-field synergistic wire drawing and precision post-processing, the wire diameter tolerance can be ±0.5 μm and the surface roughness Ra≤0.03 μm.

[0044] In the following embodiments, Tb 0.2 Dy 0.8 Fe2 represents pre-alloyed magnetostrictive particles with a stoichiometry of Tb:Dy:Fe = 0.2:0.8:2. When added in atomic percentages, Tb... 0.2 Dy 0.8 The amount of Fe2 added corresponds to the percentage of the sum of (Tb+Dy+Fe) atoms introduced by this compound relative to the total number of atoms. Pre-alloyed Tb 0.2 Dy 0.8 Fe2 can be prepared by smelting.

[0045] Example 1

[0046] This embodiment describes a method for preparing a cobalt-based amorphous wire, comprising the following steps: 1. Preparation of the matrix alloy. The raw materials for preparing the matrix alloy, calculated by atomic percentage, include: Fe 5%, B 17.5%, Si 6%, Mo 1.5%, Tb 0.2 Dy 0.8 Fe2+ ​​0.3%, balance Co. Weigh high-purity (≥99.9 wt.%) raw material according to the above composition, wherein Tb 0.2 Dy 0.8 Fe2 magnetostrictive particles were added in pre-alloyed powder form and melted at 1600°C using vacuum induction melting, and remelted repeatedly at least four times to obtain a homogeneous master alloy ingot. The master alloy ingot was then remelted and rapidly cooled using a copper mold suction casting method to prepare an alloy billet with a diameter of 5 mm, which is the base alloy.

[0047] 2. The base alloy is pre-oxidized and kept at 300°C for 30 minutes in air to form a uniform and dense CoO-MoO3 composite layer on the surface of the base alloy, which is the self-healing interface layer. 3. The pre-oxidized matrix alloy is used as the core material and placed into a glass tube. The glass tube consists of an inner soluble glass layer and an outer supporting glass layer. The glass tube containing the matrix alloy is evacuated to a pressure not exceeding 5 × 10⁻⁶. -3Pa, then high-purity argon gas (purity ≥99.99%) is introduced as a protective atmosphere, and finally sealed to obtain a composite blank; wherein, the soluble glass layer comprises the following components by mass percentage: P2O5 55%, Na2O 30%, CaO 15%; the supporting glass layer comprises the following components by mass percentage: SiO2 73%, Al2O3 12%, CaO 15%; 4. Place the sealed composite billet in a wire drawing furnace, evacuate the furnace, and then introduce argon gas. Under argon protection, induction heating is used to raise the temperature to 1200℃ (above the alloy liquidus temperature) to completely melt the core alloy. Simultaneously with hot wire drawing, an axial static magnetic field of 0.3T, a rotating magnetic field of 0.15T, and a high-frequency ultrasonic field (40 kHz, 5 W / cm²) are applied. 2 ).

[0048] 5. The drawn high-temperature glass / metal composite wire is immediately atomized and cooled using a mixture of argon and liquid nitrogen. The instantaneous cooling rate is controlled at 3 × 10⁻⁶ by periodic modulation every 0.8 seconds. 6 K / s is used to ensure that the molten alloy is supercooled below its glass transition temperature to form an amorphous solid, and a nanocrystalline shell is induced to form on the surface of the wire to obtain a composite wire.

[0049] 6. Immerse the cooled composite filament in deionized water at 70°C and treat it with ultrasonic oscillation (power 400 W, frequency 40 kHz) for 30 min. Utilize the dissolution of the inner soluble glass and the cavitation effect and mechanical action of ultrasound to peel off the glass layer and obtain the filament.

[0050] 7. The obtained filament is subjected to electrochemical polishing (in a phosphoric acid-sulfuric acid mixture, current density 2 A / dm³). 2 The surface roughness was reduced by plasma cleaning (8 min). Subsequently, oxygen plasma cleaning and passivation treatment (100℃, 15 min) was performed to clean the surface and form a passivation film.

[0051] 8. The wire material after the above treatment is subjected to multi-stage magnetic field heat treatment in sequence: stress relief annealing: held at 300℃ and 0.1T axial static magnetic field for 45min; magnetic domain structure control annealing: at 270℃, a circumferential magnetic field with an intensity of 0.1T and a space reversal period of 1 mm is applied and held for 30min; performance stabilization annealing: held at 180℃ in an inert atmosphere for 15min and then cooled to room temperature in the furnace to obtain the cobalt-based amorphous wire.

[0052] Example 2 This embodiment describes a method for preparing a cobalt-based amorphous wire, comprising the following steps: 1. Preparation of the matrix alloy. The raw materials for preparing the matrix alloy, calculated by atomic percentage, include: Fe 5.5%, B 18%, Si 6.5%, Mo 1%, Tb 0.2 Dy 0.8 Fe2+ ​​0.2%, balance Co. Weigh high-purity (≥99.9 wt.%) raw material according to the above composition, wherein Tb 0.2 Dy 0.8 Fe2 magnetostrictive particles were added in pre-alloyed powder form and melted at 1600 °C using vacuum induction melting, and remelted repeatedly at least 4 times to obtain a homogeneous master alloy ingot. The master alloy ingot was then remelted and rapidly cooled using a copper mold suction casting method to prepare an alloy billet with a diameter of 5 mm, which is the base alloy.

[0053] 2. The base alloy is pre-oxidized and kept at 290°C for 28 minutes in air atmosphere to form a uniform and dense CoO-MoO3 composite layer on the surface of the base alloy, which is the self-healing interface layer. 3. The pre-oxidized matrix alloy is used as the core material and placed into a glass tube. The glass tube consists of an inner layer of soda-lime silicate glass and an outer layer of borosilicate glass. The glass tube containing the matrix alloy is evacuated to a pressure not exceeding 5 × 10⁻⁶. -3 Pa, then high-purity argon gas (purity ≥99.99%) is introduced as a protective atmosphere, and finally sealed to obtain a composite blank; wherein, the soluble glass layer comprises the following components by mass percentage: P2O5 50%, Na2O 25%, CaO 15%; the supporting glass layer comprises the following components by mass percentage: SiO2 73%, Al2O3 12%, CaO 15%; 4. Place the sealed composite billet in a wire drawing furnace, evacuate the furnace, and then introduce argon gas. Under argon protection, induction heating is used to raise the temperature to 1150℃ (above the alloy liquidus temperature) to completely melt the core alloy. Simultaneously with hot wire drawing, an axial static magnetic field (0.25 T), a rotating magnetic field (0.1 T), and a high-frequency ultrasonic field (40 kHz, 7 W / cm²) are applied. 2 ).

[0054] 5. The drawn high-temperature glass / metal composite wire is immediately atomized and cooled using a mixture of argon and liquid nitrogen. The instantaneous cooling rate is controlled at 3 × 10⁻⁶ by periodic modulation every 0.8 seconds. 6 K / s is used to ensure that the molten alloy is supercooled below its glass transition temperature to form an amorphous solid, and a nanocrystalline shell is induced to form on the surface of the wire to obtain a composite wire.

[0055] 6. Immerse the cooled composite filament in deionized water at 70°C and treat it with ultrasonic oscillation (power 400 W, frequency 40 kHz) for 30 min. Utilize the dissolution of the inner soluble glass and the cavitation effect and mechanical action of ultrasound to peel off the glass layer and obtain the filament.

[0056] 7. The obtained filament was electrochemically polished (in a phosphoric acid-sulfuric acid mixture, at a current density of 2 A / dm³). 2 The surface roughness was reduced by plasma cleaning (8 min). Subsequently, oxygen plasma cleaning and passivation treatment (100 °C, 15 min) was performed to clean the surface and form a passivation film.

[0057] 8. The wire material after the above treatment is subjected to multi-stage magnetic field heat treatment in sequence: stress relief annealing: held at 300℃ and 0.1T axial static magnetic field for 45min; magnetic domain structure control annealing: at 270℃, a circumferential magnetic field with an intensity of 0.1T and a space reversal period of 1 mm is applied and held for 30min; performance stabilization annealing: held at 180℃ in an inert atmosphere for 15min and then cooled to room temperature in the furnace to obtain the cobalt-based amorphous wire.

[0058] Example 3 The preparation method of cobalt-based amorphous wire in this embodiment is the same as that in Example 1, except that: In step 1, when preparing the matrix alloy, the raw materials for preparing the matrix alloy, excluding pre-alloyed Tb, are expressed as atomic percentages. 0.2 Dy 0.8 Except for adjusting Fe2 to 0.5% and correspondingly adjusting the amount of Co, the types and amounts of other raw materials are the same as in Example 1; In step 2, the base alloy is pre-oxidized under the following conditions: in an air atmosphere, it is held at 310°C for 32 minutes. In step 4, while hot drawing is being performed, an axial static magnetic field (strength 0.3 T), a rotating magnetic field (strength 0.12 T), and a high-frequency ultrasonic field (frequency 40 kHz, sound intensity 7 W / cm²) are simultaneously applied. In step 5, the instantaneous cooling rate is controlled at 4.5 × 10⁻⁶. 6 K / s; In step 6, the cooled composite filament is immersed in deionized water at 75°C and treated with ultrasonic oscillation (power 450W, frequency 40 kHz) for 32 minutes to dissolve the soluble glass layer and peel off the supporting glass layer.

[0059] Example 4 The method for preparing a cobalt-based amorphous wire in this embodiment is the same as that in Example 1, except that: In step 1, when preparing the matrix alloy, the raw materials for preparing the matrix alloy are calculated by atomic percentage, and the amounts of the remaining raw materials are the same as in Example 1. The pre-alloyed Tb... 0.2 Dy 0.8 The Fe2 content was adjusted to 0.2%, and the Co content was adjusted accordingly.

[0060] In step 2, the base alloy is pre-oxidized under the following conditions: in an air atmosphere, it is held at 280°C for 35 minutes.

[0061] In step 4, while hot drawing is being performed, an axial static magnetic field (strength 0.35 T), a rotating magnetic field (strength 0.1 T), and a high-frequency ultrasonic field (frequency 40 kHz, sound intensity 8 W / cm²) are simultaneously applied.

[0062] In step 5, the instantaneous cooling rate is controlled at 5 × 10⁻⁶. 6 K / s.

[0063] In step 6, the cooled composite filament is immersed in deionized water at 80°C and treated with ultrasonic oscillation (power 500W, frequency 40 kHz) for 35 minutes.

[0064] Example 5 The method for preparing a cobalt-based amorphous wire in this embodiment is the same as that in Example 1, except that: In step 1, when preparing the matrix alloy, the raw materials for preparing the matrix alloy are calculated by atomic percentage, and the amounts of the remaining raw materials are the same as in Example 1. The pre-alloyed Tb... 0.2 Dy 0.8 The Fe2 content was adjusted to 0.4%, and the amount of Co was adjusted accordingly.

[0065] In step 2, the base alloy is pre-oxidized under the following conditions: in an air atmosphere, it is held at 295°C for 28 minutes.

[0066] In step 4, while the hot drawing process is underway, an axial static magnetic field (strength 0.3 T), a rotating magnetic field (strength 0.1 T), and a high-frequency ultrasonic field (frequency 40 kHz, sound intensity 7 W / cm²) are simultaneously applied. 2 ).

[0067] In step 5, the instantaneous cooling rate is controlled at 3.5 × 10⁻⁶. 6 K / s.

[0068] In step 6, the cooled composite filament is immersed in deionized water at 68°C and treated with ultrasonic oscillation (power 380W, frequency 40 kHz) for 28 minutes.

[0069] Example 6 The method for preparing a cobalt-based amorphous wire in this embodiment is the same as that in Example 1, except that: In step 1, when preparing the matrix alloy, the raw materials for preparing the matrix alloy are calculated by atomic percentage, and the amounts of the remaining raw materials are the same as in Example 1. The pre-alloyed Tb... 0.2 Dy 0.8 Fe2 was adjusted to 0.25%, and the amount of Co was adjusted accordingly.

[0070] In step 2, the base alloy is pre-oxidized under the following conditions: in an air atmosphere, it is held at 305°C for 33 minutes.

[0071] In step 4, while the hot drawing process is underway, an axial static magnetic field (strength 0.33 T), a rotating magnetic field (strength 0.1 T), and a high-frequency ultrasonic field (frequency 40 kHz, sound intensity 7 W / cm²) are simultaneously applied. 2 ).

[0072] In step 5, the instantaneous cooling rate is controlled at 4 × 10⁻⁶. 6 K / s.

[0073] In step 6, the cooled composite filament is immersed in deionized water at 72°C and treated with ultrasonic oscillation (power 420W, frequency 40 kHz) for 33 minutes.

[0074] Example 7 The method for preparing a cobalt-based amorphous wire in this embodiment is the same as that in Example 1, except that: In step 1, the raw materials for preparing the matrix alloy, calculated by atomic percentage, include: Fe 4%, B 19%, Si 5%, Mo 2%, and pre-alloyed Tb. 0.2 Dy 0.8 Fe2+ ​​0.1%, balance Co.

[0075] In step 2, the base alloy is pre-oxidized under the following conditions: in an air atmosphere, it is held at 280°C for 35 minutes.

[0076] In step 4, an axial static magnetic field (0.4T), a rotating magnetic field (0.1T), and a high-frequency ultrasonic field (40 kHz, 10 W / cm²) are applied. In step 5, the instantaneous cooling rate is controlled at 1×10⁻⁶. 6 K / s.

[0077] In step 6, the cooled composite filament is immersed in deionized water at 60°C and treated with ultrasonic oscillation (power 300W, frequency 40 kHz) for 35 minutes.

[0078] In step 7, electrochemical polishing (in a phosphoric acid-sulfuric acid mixture, current density 1 A / dm³) is performed. 2 Oxygen plasma cleaning and passivation treatment (120℃, 10 min).

[0079] Example 8 The method for preparing a cobalt-based amorphous wire in this embodiment is the same as that in Example 1, except that: In step 1, the raw materials for preparing the matrix alloy, calculated by atomic percentage, include: Fe 6%, B 16%, Si 7%, Mo 1%, and pre-alloyed Tb. 0.2 Dy 0.8 Fe2+ ​​0.5%, balance Co.

[0080] In step 2, the base alloy is pre-oxidized under the following conditions: in an air atmosphere, it is held at 300°C for 25 minutes.

[0081] In step 4, an axial static magnetic field (0.2T), a rotating magnetic field (0.15T), and a high-frequency ultrasonic field (40 kHz, 5 W / cm²) are applied. In step 5, the instantaneous cooling rate is controlled at 5 × 10⁻⁶. 6 K / s.

[0082] In step 6, the cooled composite filament is immersed in deionized water at 80°C and treated with ultrasonic oscillation (power 500W, frequency 40 kHz) for 25 minutes.

[0083] In step 7, electrochemical polishing (in a phosphoric acid-sulfuric acid mixture, current density 3 A / dm³) is performed. 2 Oxygen plasma cleaning and passivation treatment (80℃, 20min, 5 min).

[0084] Comparative Example 1 The preparation method of the cobalt-based amorphous wire in this comparative example is the same as that in Example 1, except that: 1. No pre-alloyed Tb is added to the raw materials. 0.2 Dy 0.8 Fe 22 The magnetostrictive particles have the following matrix alloy composition by atomic percentage: Fe 5%, B 17.5%, Si 6%, Mo 1.5%, with the balance being Co. 2. In step 3, a conventional single-layer SiO2-Al2O3-CaO glass coating (SiO2 70%, Al2O3 10%, CaO 20%) is used. 3. In step 4, no magnetic or ultrasonic fields are applied during the wire drawing process. 4. In step 5, conventional argon cooling is used (cooling rate approximately 5 × 10⁻⁶). 4K / s). 5. In step 6, the glass is etched using a 20wt% hydrofluoric acid solution.

[0085] Comparative Example 2 The preparation method of the cobalt-based amorphous wire in this comparative example is the same as that in Example 1, except that step 2, which involves pre-oxidation of the matrix alloy, is omitted, and therefore no self-healing interface layer is formed.

[0086] Comparative Example 3 The preparation method of the cobalt-based amorphous wire in this comparative example is the same as that in Example 1, except that the wire drawing temperature in step 4 is 1150℃ (lower than the alloy liquidus temperature).

[0087] Comparative Example 4 The preparation method of the cobalt-based amorphous wire in this comparative example is the same as that in Example 1, except that in step 5, the instantaneous cooling rate is controlled at 0.5 × 10⁻⁶. 6 K / s.

[0088] Comparative Example 5 The preparation method of the cobalt-based amorphous wire in this comparative example is the same as that in Example 1, except that in step 6, a 20wt% hydrofluoric acid solution is used to etch for 30 minutes at room temperature to remove the glass coating layer, and ultrasonic assistance is not used.

[0089] Comparative Example 6 The preparation method of the cobalt-based amorphous wire in this comparative example is the same as that in Example 1, except that the multi-stage magnetic field heat treatment step in step 8 is removed.

[0090] The performance of the cobalt-based amorphous wires obtained in the above embodiments and comparative examples was measured, and the results are shown in Table 1 below. The interface layer thickness was observed by scanning electron microscopy (SEM) of the wire cross-section and measured using image analysis software (such as ImageJ).

[0091] Table 1

[0092] As can be seen from the experimental data in Table 1, Examples 1-8 exhibit significant comprehensive performance advantages compared to traditional processes and comparative examples.

[0093] First, in terms of structural characteristics, the amorphous phase content of each embodiment is higher than 99%, with Example 3 reaching 99.7%, which is significantly better than the traditional process (about 94%). This indicates that it has excellent amorphous formation ability, providing a structural basis for the soft magnetic properties of the material.

[0094] Regarding the interface structure, the thickness of the self-healing interface layer in the embodiments was effectively controlled. For example, the interface layer thicknesses in Embodiments 3 and 5 did not exceed 40 nm and 60 nm, respectively, which is far lower than the approximately 600 nm brittle layer formed by conventional processes. This thin-layer structure significantly reduces interface defects and thermal stress, thereby improving the interface stability and overall reliability of the material.

[0095] Regarding soft magnetic properties, the coercivity of each embodiment is generally low. In particular, the coercivity of Example 3 is only ≤0.9 A / m, while its giant magnetoresistance (GMI) change rate is as high as 350%, which is far superior to the conventional process (about 150%) and Comparative Example 2 (≥260%). This indicates that it performs outstandingly in terms of magnetic response sensitivity and stability, and is suitable for high-end applications such as high-precision magnetic sensors.

[0096] In terms of dimensional accuracy and surface quality, the wire diameter tolerance of Example 3 is controlled within ±0.3 μm, and the surface roughness Ra does not exceed 0.02 μm, demonstrating good geometric consistency and surface finish. In contrast, the wire diameter tolerance of the traditional process is approximately ±3.5 μm, and the surface roughness is as high as 0.25 μm, which is difficult to meet the requirements of high-precision devices.

[0097] Furthermore, the fiber breakage rate of the embodiments was significantly reduced. For example, the fiber breakage rates of Embodiments 3 and 5 were no more than 1% and 1.2%, respectively, which are far lower than the approximately 25% of the conventional process. This indicates that the optimized process has higher production stability and yield.

[0098] In summary, Examples 1-8, through a comprehensive process including composition design, interface engineering, multi-field coupling wire drawing, rapid cooling, and green post-processing, significantly outperform traditional processes and comparative examples in terms of amorphous formation capability, soft magnetic properties, dimensional control, surface quality, and production stability, demonstrating promising prospects for industrial application.

[0099] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A cobalt-based amorphous wire, characterized in that: It includes a cobalt-based amorphous alloy core and a self-healing interface layer covering the cobalt-based amorphous alloy core; Based on atomic percentage, the cobalt-based amorphous alloy core material comprises: Fe 4%-6%, B 16%-19%, Si 5%-7%, Mo 1%-2%, Tb 0.2 Dy 0.8 Fe2+ ​​0.1%-0.5%, balance Co, of which Tb 0.2 Dy 0.8 The atomic ratio of Fe2 is calculated as the percentage of the sum of the number of Tb, Dy, and Fe atoms to the total number of atoms; the self-healing interface layer is a CoO-MoO3 composite.

2. The cobalt-based amorphous wire according to claim 1, characterized in that: The thickness of the self-healing interface layer is no greater than 100 nm.

3. A structure for preparing cobalt-based amorphous wires, characterized in that: It comprises, from the innermost layer to the outermost layer, a matrix alloy, a self-healing interface layer, a soluble glass layer, and a supporting glass layer; the matrix alloy comprises, by atomic percentage: Fe 4%-6%, B 16%-19%, Si 5%-7%, Mo 1%-2%, and pre-alloyed Tb 0.2 Dy 0.8 Fe2+ ​​0.1%-0.5%, balance Co, including pre-alloyed Tb 0.2 Dy 0.8 The atomic ratio of Fe2 is calculated as the percentage of the sum of the number of Tb, Dy, and Fe atoms to the total number of atoms; the self-healing interface layer is a CoO-MoO3 composite; the soluble glass layer comprises the following components by mass percentage: P2O5 45%-55%, Na2O 20%-30%, CaO 10%-15%; the supporting glass layer comprises the following components by mass percentage: SiO2 72%-75%, Al2O3 10%-12%, CaO 15%-18%.

4. A method for preparing a cobalt-based amorphous wire, characterized in that, Includes the following steps: S1. Preparation of a matrix alloy, wherein the raw materials for preparing the matrix alloy, calculated by atomic percentage, include: Fe 4%-6%, B 16%-19%, Si 5%-7%, Mo 1%-2%, and pre-alloyed Tb. 0.2 Dy 0.8 Fe2+ ​​0.1%-0.5%, balance Co, including pre-alloyed Tb 0.2 Dy 0.8 The atomic ratio of Fe2 is calculated as the percentage of the sum of the number of Tb, Dy, and Fe atoms to the total number of atoms; S2. Pre-oxidize the base alloy to form a self-healing interface layer on the surface of the base alloy; S3. The pre-oxidized matrix alloy is encapsulated in a glass tube to obtain a composite billet; S4. The composite blank is drawn into wire and then cooled to obtain composite filament; S5. Remove the glass cladding layer of the composite filament to obtain the filament; S6. Anneal the filament to obtain the cobalt-based amorphous filament.

5. The preparation method according to claim 4, characterized in that: In step S2, the pre-oxidation conditions are: in an oxygen-containing atmosphere, at 280-320℃ for 25-35 minutes.

6. The preparation method according to claim 4, characterized in that: In step S3, the glass tube includes a soluble glass layer and a supporting glass layer arranged from the inside out; the soluble glass layer comprises the following components by mass percentage: P2O5 45%-55%, Na2O 20%-30%, CaO 10%-15%; the supporting glass layer comprises the following components by mass percentage: SiO2 72%-75%, Al2O3 10%-12%, CaO 15%-18%. Step S3 specifically includes the following steps: encapsulating the pre-oxidized matrix alloy in a glass tube, and evacuating the glass tube to a pressure not exceeding 5 × 10⁻⁶. -3 Pa, then fill with high-purity argon gas and seal to obtain composite billet; Step S5 specifically includes the following steps: placing the composite filament in water at 60-80℃ and subjecting it to ultrasonic field oscillation at 300-500W for 25-35 minutes to dissolve the soluble glass layer and peel off the supporting glass layer to obtain the filament.

7. The preparation method according to claim 4, characterized in that: In step S4, the drawing of the composite billet specifically includes the following steps: vacuuming, then introducing an inert gas, heating the composite billet to a temperature 50-100°C above the alloy liquidus temperature and drawing it into wires, wherein the alloy liquidus temperature is 1100-1150°C; during this process, an axial static magnetic field, a rotating magnetic field, and a high-frequency ultrasonic field are simultaneously and collaboratively applied; wherein the magnetic field strength of the axial static magnetic field is 0.2-0.4 T, the magnetic field strength of the rotating magnetic field is 0.1-0.15 T, and the frequency of the high-frequency ultrasonic field is 40 kHz with a sound intensity of 5-10 W / cm². 2 .

8. The preparation method according to claim 4, characterized in that: In step S4, the cooling specifically includes the following steps: using a mixture of argon and liquid nitrogen for atomized cooling, and controlling the instantaneous cooling rate at 1×10⁻⁶ by periodic modulation of 0.5-1s. 6 - 5×10 6 K / s.

9. The preparation method according to claim 4, characterized in that: Step S6 specifically includes the following steps: first, annealing at 300℃ and under an axial magnetic field of 0.1 T for 30-60 min; then annealing at 260-280℃ and under a circumferential magnetic field of 0.08-0.15 T for 20-40 min; and finally annealing at 150-200℃ in an inert atmosphere for 10-20 min.

10. The preparation method according to claim 4, characterized in that: The process also includes electrochemical polishing and oxygen plasma cleaning passivation of the wire material sequentially after step S5 and before step S6; the electrochemical polishing uses a phosphoric acid-sulfuric acid system with a current density of 1-3 A / dm³. 2 The electrochemical polishing time is 5-10 min; the oxygen plasma cleaning and passivation temperature is 80-120℃ and the time is 10-20 min.

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