A method for preparing CuNb-enhanced niobium-tin composite wire

Abstract

The present application discloses a method for preparing a CuNb enhanced niobium-tin composite wire, comprising: placing a Sn alloy rod into a copper tube, and processing to obtain a Cu / Sn single core rod; placing the obtained Cu / Sn single core rod into a Nb alloy tube and then into a copper tube, and processing to obtain a tubular niobium-tin subcomponent; bundling the obtained tubular niobium-tin subcomponent and the CuNb single core rod into a copper tube in a fixed manner, and processing to obtain an unheat-treated CuNb enhanced niobium-tin wire, wherein the CuNb single core rod is obtained by placing an oxygen source into a Nb alloy tube and then into a copper tube to obtain an oxygen-containing CuNb single core rod blank, and processing; annealing the obtained unheat-treated CuNb enhanced niobium-tin wire to obtain a CuNb enhanced niobium-tin composite wire. The problem of low strength of niobium-tin wire after heat treatment is solved.

Description

Technical Field

[0001] The invention relates to the technical field of superconducting composite wire processing, and in particular to a method for preparing a CuNb-enhanced superconducting composite wire. Background Art

[0002] Nb3Sn (niobium tin) low-temperature superconducting wire is widely used in the production of magnets in large scientific facilities such as nuclear fusion, particle accelerators, and medical imaging due to its reliable processability and relatively low cost compared to high-temperature superconducting wire. Nb3Sn is a brittle phase with poor plasticity and is difficult to process. Industrially produced Nb3Sn is processed by separating niobium and tin. Finally, the wire is heat-treated, and the tin diffuses into the niobium to form the Nb3Sn phase. Because the heat-treated wire contains a large amount of brittle phase Nb3Sn, it has low strength and is easily damaged by the Lorentz force during service, causing the magnet to quench.

[0003] One way to solve the low strength of niobium-tin wire is to introduce other high-strength materials (such as tantalum) into the assembly of the composite wire blank. However, the high-strength materials themselves are difficult to process and have poor processing synergy with other materials in the composite wire, making the preparation of this type of wire very difficult. Therefore, ensuring the processability and strength of the wire are two mutually restrictive contradictions in the preparation process of niobium-tin wire. Summary of the invention

[0004] The embodiment of the present application provides a method for preparing a CuNb-enhanced niobium-tin composite wire, which is used to solve the problem of low strength of the niobium-tin wire after heat treatment in the prior art.

[0005] The present application embodiment provides a method for preparing a CuNb-enhanced niobium-tin composite wire, comprising the following steps:

[0006] 1. Put the Sn alloy rod into the copper tube, and obtain the Cu / Sn single core rod after multiple stretching and cutting to a fixed length;

[0007] 2. The Cu / Sn single core rod is loaded into the Nb alloy tube and then into the copper tube to obtain a tubular niobium-tin subcomponent blank, and the tubular niobium-tin subcomponent is obtained after multiple drawing, forming and cutting to size;

[0008] 3. Bundling tubular niobium-tin subcomponents and CuNb single core rods into a copper tube in a fixed manner to obtain a niobium-tin composite wire blank, and obtaining an unheat-treated CuNb enhanced niobium-tin wire after multiple drawing passes, wherein the CuNb single core rod is obtained by loading an oxygen source into a Nb alloy tube and then into a copper tube to obtain an oxygen-containing CuNb single core rod blank, and then obtaining the blank after multiple drawing passes, forming and cutting to a fixed length;

[0009] 4. The unheat-treated CuNb-enhanced niobium-tin wire is subjected to annealing heat treatment to obtain a CuNb-enhanced niobium-tin composite wire.

[0010] Optionally, the Nb alloy tube in step three is any one of Nb-Ti, Nb-Ta, Nb-Zr or Nb-Hf, wherein the addition amounts of Ti, Ta, Zr and Hf are all in the range of [0.5at.%, 5at.%].

[0011] Optionally, the oxygen source in step three includes but is not limited to any one of SnO2, CuO, Cu2O, Nb2O5, ZrO2, and MoO2.

[0012] Optionally, the CuNb single core rod and the unheat-treated CuNb enhanced niobium-tin wire in step three are both of hexagonal structure.

[0013] Optionally, the temperature range of the heat treatment in step four is [500°C, 590°C], and the heat treatment time is [3h, 50h].

[0014] The preparation method of the CuNb enhanced niobium-tin composite wire in this application has the following advantages:

[0015] The preparation method of the CuNb enhanced niobium-tin composite wire of the present invention uses a CuNb single core rod containing an oxygen source as a component in the niobium-tin composite wire blank. During the heat treatment of the finished composite wire, the oxygen in the oxygen source diffuses into the Nb alloy tube matrix to form dispersed second phase particles, which effectively plays a role in strengthening the second phase and significantly improves the strength of the composite wire. The trace additive elements in the Nb alloy tube used in the present invention form a solid solution with Nb, and at the same time, it is processed by separate cold working with the oxygen source. The oxygen in the oxygen source will not diffuse into the Nb matrix in advance during the processing of the composite wire, which effectively ensures the processability of the wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a step diagram of a method for preparing a CuNb-enhanced niobium-tin composite wire provided in an embodiment of the present application.

[0018] Figure 2 It is a schematic diagram of the structure of the subcomponents in the CuNb-enhanced niobium-tin composite wire provided in the embodiment of the present application.

[0019] Figure 3 It is a schematic structural diagram of the CuNb enhanced niobium-tin composite wire of the present invention.

[0020] Figure 4 It is a schematic structural diagram of a CuNb single core rod in the CuNb enhanced niobium-tin composite wire of the present invention.

[0021] Explanation of the accompanying drawings: 1 is the first outer square inner round oxygen-free copper tube, 2 is the first round Nb alloy tube, 3 is the first round oxygen-free copper tube, 4 is the tin rod, 5 is the second round oxygen-free copper tube, 6 is the niobium-tin subcomponent, 7 is the CuNb single core rod, 8 is the second outer square inner round oxygen-free copper tube, 9 is the second round Nb alloy tube, and 10 is the oxide powder. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] like Figure 1 As shown, the present invention introduces a CuNb single core rod containing an oxygen source into a blank of a niobium-tin composite wire, specifically comprising the following steps. It should be noted that the method steps provided in this embodiment are not the only execution steps, and the order of some steps can be adjusted according to actual conditions.

[0024] 1. Put the Sn alloy rod into the copper tube, and obtain the Cu / Sn single core rod after multiple stretching and cutting to a fixed length.

[0025] In one embodiment, material selection: Sn alloy rod: select Sn-1%Ag (mass fraction) alloy rod with a diameter of 20 mm and a length of 500 mm, and ensure that the surface of the alloy rod is smooth and free of defects.

[0026] Copper tube: Oxygen-free copper tube is used, with an inner diameter of 22mm, an outer diameter of 25mm, a length of 550mm, and a purity of 99.99%. Carefully load the Sn alloy rod into the copper tube to ensure that the alloy rod is coaxial with the copper tube. It should be noted that the copper tube here is a round copper tube. A drawing machine is used for drawing, and the initial drawing speed is set to 0.5m / s, and the drawing deformation of each pass is controlled at 10%. A total of 6 drawing passes are performed, and the material is inspected after each drawing pass to ensure that there are no cracks and uniform deformation. After the drawing is completed, it is cut to a fixed length of 200mm to obtain a Cu / Sn single-core rod, which is also a circular structure.

[0027] 2. The Cu / Sn single core rod obtained in step 1 is loaded into a Nb alloy tube and then into a copper tube to obtain a tubular niobium-tin subcomponent blank. After multiple drawing, forming and cutting to a fixed length, a tubular niobium-tin subcomponent is obtained.

[0028] In one embodiment, material selection: Nb alloy tube: select Nb-5%Ta (mass fraction) alloy tube with an inner diameter of 28mm, an outer diameter of 32mm and a length of 600mm. Copper tube (outer layer): oxygen-free copper tube of the same specification as step one. The Cu / Sn single core rod obtained in step one is loaded into the Nb alloy tube, and then the combination is loaded into the outer copper tube. The drawing speed of the drawing machine is adjusted to 0.3m / s, and the deformation amount of each drawing pass is 8%. After 8 drawing passes, forming treatment is performed to make its shape more regular. Finally, it is cut to a fixed length of 300mm to obtain a tubular niobium-tin subcomponent.

[0029] It should be noted that the subcomponent structures of the tubular niobium-tin subcomponents in step 1 and step 2 are as follows: Figure 2 As shown, Figure 2 It is a schematic diagram of the structure of the subcomponents in the CuNb enhanced niobium-tin composite wire of the present invention. Among them, 1 is the first outer square inner circle oxygen-free copper tube, 2 is the first round Nb alloy tube, 3 is the first round oxygen-free copper tube, and 4 is the tin rod. The trace additive elements in the Nb alloy tube used in the present invention form a solid solution with Nb, and at the same time, it is processed by a separate cold working method with the oxygen source. The oxygen in the oxygen source will not diffuse into the Nb matrix in advance during the processing of the composite wire, which effectively ensures the processability of the wire. Among them, the Nb alloy tube is any one of Nb-Ti, Nb-Ta, Nb-Zr or Nb-Hf, wherein the addition amount of Ti, Ta, Zr, and Hf is in the range of [0.5at.%, 5at.%]. For example, the Ti content in Nb-Ti can be 0.5at.%, 2.2.5at.% or 5at.%, and the specific content can be set according to actual conditions. It should be noted that the trace additive elements in the Nb alloy tube used in the present invention form a solid solution with Nb, and it and the oxygen source are processed by separate cold working. The oxygen in the oxygen source will not diffuse into the Nb matrix in advance during the processing of the composite wire, which effectively ensures the processability of the wire.

[0030] 3. The tubular niobium-tin subcomponent and the CuNb single core rod obtained in step 2 are bundled and loaded into a copper tube in a fixed manner to obtain a niobium-tin composite wire blank, and the unheat-treated CuNb enhanced niobium-tin wire is obtained through multiple drawing passes, wherein the CuNb single core rod is obtained by loading an oxygen source into a Nb alloy tube and then into a copper tube to obtain an oxygen-containing CuNb single core rod blank, which is obtained through multiple drawing passes, forming and cutting to a fixed length.

[0031] like Figure 3 As shown, Figure 3It is a schematic structural diagram of the CuNb enhanced niobium-tin composite wire of the present invention; wherein 5 is a second round oxygen-free copper tube, 6 is a niobium-tin subcomponent, and 7 is a CuNb single core rod.

[0032] In one embodiment, the tubular niobium-tin subcomponent 6 obtained in step 2 and the prepared CuNb single core rod 7 are bundled into a new oxygen-free copper tube in a ratio of 1:1 (the inner diameter is selected according to the size after bundling, and the outer diameter is 3 mm larger than the inner diameter). The drawing speed of the drawing machine is set to 0.2 m / s, and the deformation amount of each drawing pass is 6%. After 10 drawing passes, the unheat-treated CuNb enhanced niobium-tin wire is obtained. The drawing speed of the drawing machine is set to 0.2 m / s, and the deformation amount of each drawing pass is 6%. After 10 drawing passes, the unheat-treated CuNb enhanced niobium-tin wire is obtained.

[0033] After the niobium-tin subcomponent 6 and the CuNb single core rod 7 are inserted into the second round oxygen-free copper tube 5, a certain method can be used to further fix the positions of the niobium-tin subcomponent 6 and the CuNb single core rod 7 in the second round oxygen-free copper tube 5. For example, a cold pressing or heat shrinking process can be used to shrink the second round oxygen-free copper tube 5 to a certain extent, so as to tightly wrap the niobium-tin subcomponent 6 and the CuNb single core rod 7 inside.

[0034] Alternatively, some material with appropriate viscosity and insulation properties is filled in the second round oxygen-free copper tube 5 and in the gap between the niobium-tin subcomponent 6 and the CuNb single core rod 7 to play a role of fixing and insulation.

[0035] The specific drawing process of CuNb single core rod is as follows: SnO2 is uniformly loaded into the Nb alloy tube, and then loaded into the outer copper tube to obtain the CuNb single core rod blank containing oxygen source. The drawing speed of the drawing machine is set to 0.4m / s, and the deformation of each drawing pass is 9%. After 7 drawing and forming processes, it is cut into 250mm lengths to obtain a CuNb single core rod, such as Figure 4 As shown, Figure 4 It is a schematic structural diagram of a CuNb single core rod in a CuNb enhanced niobium-tin composite wire of the present invention; wherein 8 is a second outer square inner round oxygen-free copper tube, 9 is a second round Nb alloy tube, and 10 is oxide powder.

[0036] It should be noted that the preparation method of the CuNb enhanced niobium-tin composite wire of the present invention uses a CuNb single core rod containing an oxygen source as a component in the niobium-tin composite wire blank. During the heat treatment of the finished composite wire, the oxygen in the oxygen source diffuses into the Nb alloy tube matrix to form dispersed second phase particles, which effectively plays a role in second phase strengthening and significantly improves the strength of the composite wire.

[0037] Optionally, the oxygen source in step three includes but is not limited to any one of SnO2, CuO, Cu2O, Nb2O5, ZrO2, and MoO2.

[0038] Optionally, the CuNb single core rod and the unheat-treated CuNb enhanced niobium-tin wire in step three are both of hexagonal structure.

[0039] 4. The CuNb-enhanced niobium-tin composite wire obtained in step 3 is subjected to annealing heat treatment to obtain a CuNb-enhanced niobium-tin composite wire.

[0040] Optionally, the temperature range of the heat treatment in step four is [500°C, 590°C], and the heat treatment time is [3h, 50h].

[0041] In one embodiment, during the entire preparation process, a suitable intermediate annealing process can be selected between each drawing according to the work hardening of the material, with an annealing temperature between 500-590°C and an annealing time of 3h-50h to eliminate the work hardening and ensure that the material will not have defects such as cracks during the subsequent drawing process. At the same time, during the operation of each step, the working environment must be kept clean to prevent impurities from mixing into the material and affecting the performance of the final wire.

[0042] Example 1

[0043] Step 1: Load SnO2 powder into a Nb0.5at.%Zr alloy tube of Φ20.0 / Φ5.0mm and then into a copper tube of Φ22.4 / Φ20.5mm. The drawing speed of the drawing machine is set to 0.4m / s, and the deformation of each drawing pass is 9%. After 7 drawing and forming processes, the hexagonal CuNb single core rod of size H3.0mm is obtained after being cut into 250mm lengths.

[0044] Step 2: Load the Sn rod of Φ18.0mm into the copper tube of Φ20.0 / Φ18.5mm, and use the drawing machine to draw. The initial drawing speed is set to 0.5m / s, and the drawing deformation of each pass is controlled at 10%. A total of 6 drawing passes are performed, and the material is inspected after each drawing to ensure that there are no cracks and the deformation is uniform. After the drawing is completed, it is cut to a fixed length of 200mm to obtain a Cu / Sn single core rod. A Cu / Sn single core rod of Φ12.0mm is obtained.

[0045] Step 3: The Cu / Sn single core rod obtained in step 2 is loaded into a Nb4.0at.%Ta alloy tube with a size of Φ18.0 / Φ12.4mm and then into a copper tube with a size of Φ20.2 / Φ18.5mm to obtain a tubular niobium-tin subcomponent blank, and multiple drawing operations are performed on the drawing equipment. The drawing speed is adjusted to 0.3-0.8m / s, and the deformation amount of each pass is 8%-12%. After 10 drawing passes and cutting to a fixed length, a tubular niobium-tin subcomponent with a size of H3.0mm is obtained.

[0046] Step 4: Load the 7 CuNb single core rods and 48 tubular subcomponents obtained in Step 1 and Step 3 into a Φ30.0 / Φ25.3mm oxygen-free copper tube to obtain a niobium-tin composite wire blank. The drawing speed of the drawing machine is set to 0.2m / s, and the deformation of each drawing pass is 6%. After 10 drawing passes, an unheat-treated CuNb enhanced niobium-tin wire with a size of φ0.8mm is obtained.

[0047] Step 5: subjecting the wire obtained in step 4 to an annealing heat treatment at 500° C. / 3 h to obtain a CuNb enhanced niobium-tin composite wire.

[0048] Example 2

[0049] Step 1: CuO powder is loaded into Nb2.25at.%Zr alloy with a size of Φ20.0 / Φ5.0mm, and the deformation of each drawing pass is 9%. After 7 drawing and forming processes, it is put into a copper tube with a length of 250mm and then loaded into a copper tube with a size of Φ22.4 / Φ20.5mm. The drawing speed of the drawing machine is set to 0.4m / s, and after being cut to a fixed length, a hexagonal CuNb single core rod with a size of H3.0mm is obtained.

[0050] Step 2: Put the Sn rod with a size of Φ18.0mm into the copper tube with a size of Φ20.0 / Φ18.5mm, and use a drawing machine to draw it. The initial drawing speed is set to 0.5m / s, and the drawing deformation of each pass is controlled at 10%. A total of 6 drawing passes are performed, and the material is inspected after each drawing pass to ensure that there are no cracks and the deformation is uniform. After the drawing is completed, it is cut to a fixed length of 200mm to obtain a Cu / Sn single core rod.

[0051] Step 3: The Cu / Sn single core rod obtained in step 2 is loaded into a Nb4.0at.%Ta alloy tube with a size of Φ18.0 / Φ12.4mm and then into a copper tube with a size of Φ20.2 / Φ18.5mm to obtain a tubular niobium-tin subcomponent blank, and multiple drawing operations are performed on the drawing equipment. The drawing speed is adjusted to 0.3-0.8m / s, and the deformation amount of each pass is 8%-12%. After 10 drawing passes and cutting to a fixed length, a tubular niobium-tin subcomponent with a size of H3.0mm is obtained.

[0052] Step 4: Load the 7 CuNb single core rods and 48 tubular subcomponents obtained in Step 1 and Step 3 into a Φ30.0 / Φ25.3mm oxygen-free copper tube to obtain a niobium-tin composite wire blank. The drawing speed of the drawing machine is set to 0.2m / s, and the deformation of each drawing pass is 6%. After 10 drawing passes, an unheat-treated CuNb enhanced niobium-tin wire with a size of φ0.8mm is obtained.

[0053] Step 5: subjecting the wire obtained in step 4 to an annealing heat treatment at 545° C. / 26.5 h to obtain a CuNb enhanced niobium-tin composite wire.

[0054] Example 3

[0055] Step 1: Load SnO2 powder into a Nb5at.%Hf alloy tube of Φ20.0 / Φ4.0mm and then into a copper tube of Φ22.4 / Φ20.5mm. The drawing speed of the drawing machine is set to 0.4m / s, and the deformation of each drawing pass is 9%. After 7 drawing and forming processes, the hexagonal CuNb single core rod with a size of H2.2mm is obtained after being cut into 250mm lengths.

[0056] Step 2: Put the Sn rod with a size of Φ18.0mm into the copper tube with a size of Φ20.0 / Φ18.5mm, and use a drawing machine to draw it. The initial drawing speed is set to 0.5m / s, and the drawing deformation of each pass is controlled at 10%. A total of 6 drawing passes are performed, and the material is inspected after each drawing pass to ensure that there are no cracks and the deformation is uniform. After the drawing is completed, it is cut to a fixed length of 200mm to obtain a Cu / Sn single core rod.

[0057] Step 3: The Cu / Sn single core rod obtained in step 2 is loaded into a Nb4.0at.%Ta alloy tube with a size of Φ18.0 / Φ12.4mm and then into a copper tube with a size of Φ20.2 / Φ18.5mm to obtain a tubular niobium-tin subcomponent blank, and multiple drawing operations are performed on the drawing equipment. The drawing speed is adjusted to 0.3-0.8m / s, and the deformation amount of each pass is 8%-12%. After 10 drawing passes and cutting to a fixed length, a tubular niobium-tin subcomponent with a size of H2.2mm is obtained.

[0058] Step 4: Load the 19 CuNb single core rods and 180 tubular subcomponents obtained in Steps 1 and 3 into a Φ40.3 / Φ34.5mm oxygen-free copper tube to obtain a niobium-tin composite wire blank. The drawing speed of the drawing machine is set to 0.2m / s, and the deformation of each drawing pass is 6%. After 10 drawing passes, an unheat-treated CuNb-enhanced niobium-tin wire with a size of φ0.8mm is obtained.

[0059] Step 5: subjecting the wire obtained in step 4 to an annealing heat treatment at 590° C. / 50 h to obtain a CuNb enhanced niobium-tin composite wire.

[0060] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0061] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for preparing a CuNb-enhanced niobium-tin composite wire, characterized in that: The following steps are involved:

1. Put the Sn alloy rod into the copper tube, and obtain the Cu / Sn single core rod after multiple stretching and cutting to a fixed length; 2. The Cu / Sn single core rod is loaded into a Nb alloy tube and then into a copper tube to obtain a tubular niobium-tin subcomponent blank, and the tubular niobium-tin subcomponent is obtained after multiple drawing, forming and cutting to size; 3. Bundling the tubular niobium-tin subcomponent and the CuNb single core rod into a copper tube to obtain a niobium-tin composite wire blank, and obtaining an unheat-treated CuNb enhanced niobium-tin wire after multiple drawing passes, wherein the CuNb single core rod is obtained by loading an oxygen source into a Nb alloy tube and then into a copper tube to obtain an oxygen-containing CuNb single core rod blank, and then drawing, forming and cutting to a fixed length; Fourth, subjecting the unheat-treated CuNb-enhanced niobium-tin wire to an annealing heat treatment to obtain a CuNb-enhanced niobium-tin composite wire.

2. The method for preparing the CuNb-enhanced niobium-tin composite wire according to claim 1, characterized in that: The Nb alloy tube described in step 2 is any one of Nb-Ti, Nb-Ta, Nb-Zr or Nb-Hf, wherein the addition amounts of Ti, Ta, Zr and Hf are all in the range of [0.5at.%, 5at.%].

3. The method for preparing the CuNb-enhanced niobium-tin composite wire according to claim 1, characterized in that: The oxygen source described in step three includes any one of SnO2, CuO, Cu2O, Nb2O5, ZrO2, and MoO2.

4. The method for preparing the CuNb-enhanced niobium-tin composite wire according to claim 1, characterized in that: The CuNb single core rod and the unheat-treated CuNb enhanced niobium-tin wire in step three both have a hexagonal structure.

5. The method for preparing the CuNb-enhanced niobium-tin composite wire according to claim 1, characterized in that: The temperature range of the heat treatment described in step 4 is [500°C, 590°C], and the heat treatment time is [3h, 50h].

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