A two-step current annealing method for inhibiting annealing brittleness of amorphous alloy

Abstract

The application relates to a method for inhibiting amorphous alloy annealing brittleness and improving mechanical properties of amorphous materials by two-step current annealing, belonging to the field of amorphous alloy materials. In the first step, amorphous strips are treated by current annealing, and annealing is carried out under a small current; with the increase of the annealing time, the sample is obviously annealed and is prone to breakage; in the second step, the amorphous strips with obvious annealing brittleness are further treated by a current slightly larger than that in the first step; the annealing brittleness of the strips disappears in a short treatment time, and the sample restores the toughness again; finally, phase, thermodynamics and mechanical tests are carried out on the samples in different current treatment states. The amorphous strips treated by the method still maintain the amorphous state and have the same toughness as the initial state, and the annealing brittleness in the annealing process of the amorphous alloy is obviously inhibited. The amorphous strips treated by the application are uniformly treated by current annealing, the material is prevented from being embrittled in the heat treatment source process, the toughness is ensured, the use efficiency is improved, and the cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of amorphous alloy materials, and specifically relates to a two-step current annealing method for suppressing annealing brittleness in amorphous alloys. Background Technology

[0002] Amorphous alloys are formed by the rapid cooling of alloy melts, exhibiting short-range order but long-range disorder. Compared to traditional metals and alloys, amorphous alloys do not contain defects such as dislocations and grain boundaries, thus displaying superior mechanical properties such as high strength, high hardness, and high elastic limit. Furthermore, due to the absence of anisotropy characteristic of crystals, amorphous materials also exhibit excellent magnetic properties, making them promising for applications in machinery, electronics, aerospace, and other fields.

[0003] Rapid cooling during the preparation of amorphous alloys introduces significant internal stress, which greatly affects the material's mechanical and magnetic properties. Currently, vacuum isothermal annealing is commonly used to eliminate this internal stress. However, this process can cause significant annealing brittleness in amorphous alloys, reducing their mechanical properties and consequently impacting their industrial applications and service life.

[0004] Annealing brittleness in amorphous alloys is a major obstacle to their application and limits the realization of their other superior properties. Suppressing brittleness during annealing is a key issue that needs to be addressed, and currently, rejuvenation is commonly used in laboratories. Rejuvenation is the reverse process of relaxation; it increases the energy state of the amorphous alloy, thereby improving its plasticity. Common rejuvenation methods can be categorized into two main types: mechanically activated rejuvenation and thermally activated rejuvenation. Mechanically activated rejuvenation has a low degree of rejuvenation and is prone to causing irreversible damage to amorphous components; while thermally activated rejuvenation relaxes the material and makes it more susceptible to embrittlement. Therefore, there is an urgent need for a method to prevent annealing brittleness in amorphous materials from the source of heat treatment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to suppress the brittleness during the annealing process of amorphous alloys. This method employs a two-step current annealing process to suppress the brittleness problems caused by traditional heat treatment.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A two-step current annealing method for suppressing annealing brittleness in amorphous alloys, the method comprising the following steps:

[0008] (1) Material preparation: The amorphous alloy includes, but is not limited to, iron-based, zirconium-based, copper-based and other amorphous systems.

[0009] (2) First step current annealing: The amorphous ribbon is subjected to long-term annealing at a low current density. The energy input can be expressed as Q = I12 Rt1, where I1 is the current density, R is the resistivity, and t1 is the processing time.

[0010] (3) Second step current annealing: The amorphous ribbon after the annealing in step (2) is further annealed for a short time under a large current density. The energy input at this time can be expressed as Q = I2. 2 Rt2, where I2 is the current density, R is the resistivity, and t2 is the processing time. The energy input ratio Q1:Q2 for controlling the two-step current annealing ranges from 10 to 100.

[0011] (4) End the two-step current annealing process and conduct tests on phase, thermodynamic and mechanical properties.

[0012] The amorphous alloy in step (1) includes all amorphous alloy samples prepared by rapid solidification.

[0013] In step (2), the sample will exhibit obvious annealing brittleness and is prone to breakage when subjected to long-term treatment with low current in the first step.

[0014] In step (3), the second step is a high current short-time treatment, which controls the energy input ratio Q1:Q2 of the two-step current annealing to be in the range of 10 to 100. The annealing brittleness of the sample disappears and the sample regains its toughness. This invention suppresses annealing brittleness in amorphous alloys through a two-step current annealing process; the key technical issues are the current density and processing time of the two-step current treatment.

[0015] The design principle of this invention is as follows:

[0016] Rapid cooling during the preparation of amorphous alloys introduces significant internal stress, which greatly affects their mechanical and magnetic properties. Traditional heat treatment for amorphous alloys is often performed with prolonged holding times, making control difficult. This not only leads to annealing brittleness and reduced mechanical properties but also results in significant regional temperature inhomogeneities, causing poor performance consistency. Compared to vacuum annealing, which takes several hours, current annealing of amorphous alloys achieves the same effect in just minutes or even seconds. However, single-step current treatment still cannot overcome the annealing brittleness of amorphous alloys. By re-treating amorphous alloys with a higher current density, the system energy is increased, and the brittle material becomes tough again, thus suppressing brittleness during the heat treatment process.

[0017] Based on the above theory, the general idea of ​​this invention is to use a two-step current annealing method: the first step is a low-current long-time annealing treatment to eliminate defects such as internal stress in the amorphous ribbon preparation process, but it will also lead to annealing brittleness. The second step is a high-current short-time treatment to eliminate annealing brittleness again, while retaining the beneficial effects of the first step annealing on the material structure and physical properties such as magnetism.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. Current annealing allows for precise control of the sample's annealing state by adjusting the current intensity and annealing time. Traditional heat treatment suffers from uneven local temperatures, leading to localized embrittlement of amorphous ribbons and the resulting debris affecting subsequent industrial use. Amorphous ribbons treated with this invention undergo uniform current annealing, preventing material embrittlement from the source of the heat treatment process, ensuring sufficient toughness, improving efficiency, and reducing costs.

[0020] 2. Current annealing only requires a few minutes of annealing time, significantly reducing the time required for conventional industrial annealing, shortening the heat treatment cycle, saving energy, and improving efficiency.

[0021] 3. The strip treated by the present invention is not easy to break, ensuring sufficient toughness and solving the brittleness problem caused by heat treatment.

[0022] 4. The process of this invention is simple, can be applied to various amorphous alloys, is non-destructive, provides uniform treatment, and has strong prospects for industrial application. Attached Figure Description

[0023] Figure 1 The XRD curves are for the initial state sample, the first-step current annealing state sample, and the second-step current annealing state sample.

[0024] Figure 2 The DSC curves are for the initial state sample, the first-step current annealing state sample, and the second-step current annealing state sample.

[0025] Figure 3 These are graphs showing the bending properties of samples after two-step current annealing. Figure 3 a is the sample in the first step of current annealing. Figure 3 b is the sample in the second-step current-annealed state. Detailed Implementation

[0026] This invention employs a two-step current annealing process for amorphous ribbons. By adjusting the current parameters and optimizing the current treatment time, the process can be controlled for widely used iron-based, zirconium-based, and copper-based amorphous ribbons. This avoids material brittleness from the initial heat treatment stage, ensuring sufficient toughness. Common systems and their corresponding composition ranges are shown in the table below, but the invention is not limited to these systems.

[0027] Table 1 Amorphous Material Systems

[0028] Fe-based Fe-Si-B 70≤Fe≤80, 7≤Si≤10, 10≤B≤14 Zr-based Zr-Cu-Al-Ni Zr=55, Cu=30, Al=10, Ni=5 Cu-based Cu-Zr-Al Cu = 46, Zr = 46, Al = 8 Specific Implementation Example 1

[0030] (1) Sample preparation: The sample is an industrial 1K101 amorphous ribbon with a length of 20cm, a width of 6mm, and a thickness of 30-35μm.

[0031] (2) Current annealing parameters: First step current intensity 3A-3.5A, processing time 5min-10min; Second step current intensity 4A-4.2A, processing time 3s-15s.

[0032] (3) Two-step current annealing treatment: The amorphous strip was treated with the first step current intensity in (2). As the current annealing time increased, the sample showed obvious annealing brittleness. The current parameters were adjusted, and the amorphous strip that showed annealing brittleness was treated with the second step current intensity in (2). After a short treatment, the energy input ratio Q1:Q2 of the two-step current annealing was controlled to be in the range of 10 to 100. The brittleness of the sample in the first step of annealing disappeared and the toughness was restored.

[0033] (4) The amorphous strip samples after step (3) were subjected to phase and thermodynamic tests by XRD, DSC and other testing methods. Figure 1 It can be seen that the samples treated with different currents all have steamed bun peaks and no crystal diffraction peaks were found, indicating that the samples still maintain an amorphous structure after current annealing. Figure 2 The sample exhibited an increased enthalpy change, indicating a rejuvenation phenomenon. Figure 3 The sample annealed in the first step of current annealing exhibits obvious annealing brittleness. Figure 3 b shows the recovery of toughness in the sample after the second-step current annealing. Specific Implementation Example 2

[0035] (1) Preparation of Zr 55 Cu 30 A l 10 Ni5 amorphous ribbon: Four metals, Zr, Cu, Al and Ni with a purity ≥99.9%, are mixed in an atomic ratio of 55:30:10:5. Then, under the protection of a high-purity argon atmosphere, they are melted in an electric arc melting furnace and the melting is repeated at least 5 times to form an alloy ingot. Then, about 5g of sample is cut from the alloy ingot and then melted using an induced current under the protection of a high-purity argon atmosphere. The melted alloy ingot is then sprayed onto rollers to form an amorphous ribbon with a width of 1.5cm and a thickness of about 40μm.

[0036] (2) Sample preparation: The material in (1) was processed into an amorphous strip with a length of 15cm, a width of 1.5cm, and a thickness of about 40μm.

[0037] (3) Two-step current annealing: the first step current intensity is 2-2.5A and the processing time is 5-10min; the second step current intensity is 3.2-3.5A and the processing time is 3-10s. Specific Implementation Example 3

[0039] (1) Preparation of Cu 46 Zr 46 Al8 amorphous ribbon: Cu, Zr and Al with a purity ≥ 99.9% are mixed in an atomic percentage ratio of 46:46:8, and similarly

[0034] an amorphous ribbon with a width of 2cm and a thickness of about 30μm is formed.

[0040] (2) Sample preparation: The material (1) was processed into an amorphous strip with a length of 10cm, a width of 2cm and a thickness of about 30μm.

[0041] (3) Two-step DC annealing: the first step has a current intensity of 2.5-3A and a processing time of 5-10min; the second step has a current intensity of 2.8-3.2A and a processing time of 3-10s.

[0042] Both Specific Embodiment 2 and Specific Embodiment 3 yielded current-annealed samples with sufficient toughness.

Claims

1. A two-step current annealing method for suppressing annealing brittleness in amorphous alloys, the method comprising the following steps: (1) Material preparation: The amorphous alloy includes, but is not limited to, iron-based, zirconium-based, and copper-based amorphous systems; (2) First step current annealing: The amorphous ribbon is subjected to long-term annealing at a low current density. The energy input is expressed as Q1 = I1 2 Rt1, where I1 is the current density, R is the resistivity, and t1 is the processing time; (3) Second step current annealing: The amorphous ribbon after the annealing in step (2) is further annealed for a short time under a large current density. The energy input at this time is expressed as Q2=I2. 2 Rt2, where I2 is the current density, R is the resistivity, and t2 is the processing time; the energy input ratio Q1:Q2 for controlling the two-step current annealing ranges from 10 to 100; (4) End the two-step current annealing process and perform phase, thermodynamic and mechanical property tests; In step (2), the small current density is 3-3.5A, 2-2.5A or 2.5-3A, and the corresponding larger current density in step (3) is 4-4.2A, 3.2-3.5A or 2.8-3.2A.

2. The two-step current annealing method for suppressing annealing brittleness of amorphous alloys according to claim 1, characterized in that... The amorphous alloy in step (1) includes all amorphous alloy samples prepared by rapid solidification.

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