Preparation method of superconducting composite long wire

Abstract

The invention discloses a preparation method of a superconducting composite long wire. The preparation method comprises the following steps: smelting Cu, Mn and a copper alloy to obtain a Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy pipe; an Nb cylinder and an NbTi rod are placed in the alloy pipe to be manufactured into a single core rod; combining the single-core rod and an oxygen-free copper rod in an oxygen-free copper pipe to obtain a secondary composite rod; combining the secondary composite rod and an oxygen-free copper rod in an oxygen-free copper pipe to obtain a third composite rod; and carrying out drawing treatment on the tertiary composite rod to obtain a tertiary superconducting composite wire. The alloy resistive matrix is obtained in an alloying mode, the long-line machining capacity of the copper-manganese-based niobium-titanium superconducting wire is improved under the condition that critical current density and alternating-current loss are not reduced, the oxidation resistance of a single-core rod is obviously improved, the thickness of an oxide layer after hot extrusion is obviously reduced, the scaling frequency is effectively reduced in the machining process, and the service life of the single-core rod is prolonged. The deformation uniformity of the superconducting core wire can be effectively improved, so that the critical current density is improved, and the efficiency and cost can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting wires, and particularly to a method for preparing a superconducting composite long wire. Background Art

[0002] The field of practical superconductivity is developing rapidly. Among them, in various large scientific devices, the fast-pulse superconducting accelerator magnet, as a core component, has the characteristics of high central magnetic field and high magnetic field change rate, which is likely to cause very high AC losses. Therefore, NbTi superconducting wires with high critical current density and low loss are required. Previously, a good match of high critical current density and low AC loss has been obtained by "replacing Cu with a CuMn alloy resistive matrix" and "designing a new superconducting wire structure". However, there are still problems in the processing of long wires for the wire, which severely limits the batch preparation and application of NbTi / CuMn / Cu wires. Generally, when the single length of a superconducting wire is greater than 1000 m, it can be considered that it has the ability to process long wires. Summary of the Invention

[0003] An embodiment of the present invention provides a method for preparing a superconducting composite long wire, which is used to solve the problem that the NbTi / CuMn / Cu wire in the prior art has problems in the processing of long wires, which severely limits the batch preparation and application of NbTi / CuMn / Cu wires.

[0004] On the one hand, an embodiment of the present invention provides a method for preparing a superconducting composite long wire, including: Melting Cu, Mn and any one of CrCu, CuFe, CuZr, CuAg and CuTi to obtain a Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube; Placing an Nb cylinder and an NbTi rod in the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube to make a single-core rod; Combining the single-core rod and an oxygen-free copper rod in an oxygen-free copper tube to obtain a secondary composite rod; Combining the secondary composite rod and the oxygen-free copper rod in the oxygen-free copper tube to obtain a tertiary composite rod; Performing drawing treatment on the tertiary composite rod to obtain a tertiary superconducting composite wire.

[0005] In a possible implementation manner, the melting of Cu, Mn and any one of CrCu, CuFe, CuZr, CuAg and CuTi to obtain a Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube includes: Using the Cu and the Mn plus any one of the CrCu, CuFe, CuZr, CuAg, and CuTi as raw materials, an initial Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube is obtained through vacuum induction melting, casting, heating, extrusion, drawing, and vacuum annealing; The obtained Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube is obtained by performing a solution treatment on the initial Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube.

[0006] In a possible implementation manner, placing an Nb cylinder and an NbTi rod inside the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube to make a single-core rod includes: Sealing one end of the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube with an alloy cover of the same material; The sealed Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube, the alloy cover of the same material at the other end of the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube, the Nb cylinder, and the NbTi rod are successively cleaned, assembled, degassed, vacuum electron beam welded, hot extruded, drawn, skived, hexagonal formed, and cut to size to obtain a single-core rod.

[0007] In a possible implementation manner, combining the single-core rod with an oxygen-free copper rod inside an oxygen-free copper tube to obtain a secondary composite rod includes: Cleaning the oxygen-free copper tube, the upper and lower covers of the oxygen-free copper tube, a plurality of the single-core rods, and a plurality of the oxygen-free copper rods; Arranging a plurality of the single-core rods in the oxygen-free copper tube according to the superconducting wire structure; Inserting the oxygen-free copper rods into the gaps between a plurality of the single-core rods to obtain a composite ingot; Performing degassing, vacuum electron beam welding, hot isostatic pressing, hot extrusion, drawing, skiving, and cutting to size on the composite ingot in sequence to obtain a secondary composite rod.

[0008] In a possible implementation manner, combining the secondary composite rod with the oxygen-free copper rod inside the oxygen-free copper tube to obtain a tertiary composite rod includes: Arranging a plurality of the secondary composite rods in the oxygen-free copper tube according to the superconducting wire structure; Inserting the oxygen-free copper rods into the gaps between a plurality of the secondary composite rods to obtain a tertiary composite ingot; Performing degassing, vacuum electron beam welding, hot isostatic pressing, hot extrusion, drawing, skiving, and cutting to size on the tertiary composite ingot in sequence to obtain a tertiary composite rod.

[0009] In a possible implementation, the process of drawing the triple composite rod to obtain a triple superconducting composite wire includes: Cold-drawing and aging heat treatment are performed on the triple composite rod to obtain a triple composite wire.

[0010] In a possible implementation, there are multiple passes in the cold-drawing.

[0011] A method for preparing a superconducting composite long wire in the present invention has the following advantages: (1) By alloying, a Cu-Mn-(Cr / Fe / Zr / Ag / Ti) resistive matrix is obtained and made into a tube for a single-core ingot sheathing tube, which can significantly improve the long-wire processing ability of copper-manganese-based NbTi superconducting wire without reducing the critical current density and increasing the AC loss, realizing batch application, and improving the yield and reducing the production cost.

[0012] (2) Compared with the previous NbTi / CuMn single-core rod, the oxidation resistance of the NbTi / Cu-Mn-(Cr / Fe / Zr / Ag / Ti) single-core rod is significantly improved, and the thickness of the oxide layer after hot extrusion is significantly reduced. During the processing, the number of peeling operations can be effectively reduced, which can not only effectively improve the deformation uniformity of the superconducting core wire and thus improve the critical current density, but also further save production time, increase efficiency and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0014] Figure 1 It is a flowchart of a method for preparing a superconducting composite long wire provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0016] Figure 1 It is a flowchart of a method for preparing a superconducting composite long wire provided by an embodiment of the present invention; an embodiment of the present invention provides a method for preparing a superconducting composite long wire, including: Smelt Cu, Mn and any one of CrCu, CuFe, CuZr, CuAg and CuTi to obtain a Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube; Place an Nb cylinder and an NbTi rod inside the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube to make a single-core rod; Combine the single-core rod and an oxygen-free copper rod inside an oxygen-free copper tube to obtain a secondary composite rod; Combine the secondary composite rod and the oxygen-free copper rod inside the oxygen-free copper tube to obtain a tertiary composite rod; Perform drawing on the tertiary composite rod to obtain a tertiary superconducting composite wire.

[0017] The step of smelting Cu, Mn and any one of CrCu, CuFe, CuZr, CuAg and CuTi to obtain a Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube includes: Use Cu, Mn and any one of CrCu, CuFe, CuZr, CuAg and CuTi as raw materials, and obtain an initial Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube through vacuum induction melting, casting, heating, extrusion, drawing, and vacuum annealing; Perform solution treatment on the initial Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube to obtain the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube.

[0018] The step of placing an Nb cylinder and an NbTi rod inside the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube to make a single-core rod includes: Seal one end of the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube with an alloy cap of the same material; Clean, assemble, degas, vacuum electron beam weld, hot extrude, draw, skin, hexagon form, and cut to length the sealed Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube, the alloy cap of the same material at the other end of the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube, the Nb cylinder, and the NbTi rod in sequence to obtain a single-core rod.

[0019] The step of combining the single-core rod and an oxygen-free copper rod inside an oxygen-free copper tube to obtain a secondary composite rod includes: Clean the oxygen-free copper tube, the upper and lower covers of the oxygen-free copper tube, multiple single-core rods, and multiple oxygen-free copper rods; Arrange multiple single-core rods according to the superconducting wire structure inside the oxygen-free copper tube; Insert the oxygen-free copper rod into the gaps between multiple single rods to obtain a composite ingot; Perform degassing, vacuum electron beam welding, hot isostatic pressing, hot extrusion, drawing, peeling, and sizing cutting on the composite ingot in sequence to obtain a secondary composite rod.

[0020] The combination of the secondary composite rod and the oxygen-free copper rod in the oxygen-free copper tube to obtain a tertiary composite rod includes: Arrange multiple secondary composite rods according to the superconducting wire structure in the oxygen-free copper tube; Insert the oxygen-free copper rod into the gaps between multiple secondary composite rods to obtain a tertiary composite ingot; Perform degassing, vacuum electron beam welding, hot isostatic pressing, hot extrusion, drawing, peeling, and sizing cutting on the tertiary composite ingot in sequence to obtain a tertiary composite rod.

[0021] The drawing process of the tertiary composite rod to obtain a tertiary superconducting composite wire includes: Perform cold drawing and aging heat treatment on the tertiary composite rod to obtain a tertiary composite wire.

[0022] There are multiple passes in the cold drawing.

[0023] Exemplarily, the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy is used as the resistive matrix of the low-loss superconducting wire, and the content ranges of alloying elements are as follows: the content of Mn element is 0.5% - 5%, the content of Cr or Fe or Zr or Ag or Ti element is 0.01% - 1%, and the balance is Cu. Among them, to ensure purity and content, the alloying elements are all added in the form of intermediate alloys such as MnCu, CuCr, CuFe, CuZr, CuAg, or CuTi; Before solution treatment, the microstructure of the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube is a recrystallized structure, and all the precipitated phases in the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy are redissolved into the matrix through solution treatment, aiming to re-regulate the precipitation of precipitated phases during the aging process. The solution parameters of the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube are as follows: the solution temperature is 800 - 1050 °C, the solution time is 1 - 5 h, and the cooling method is water cooling; The thicknesses of the components required for the single-core rod are as follows: the thickness of the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube is 15 - 60 mm, the thickness of the Nb cylinder is 0.5 - 2 mm, and the thickness of the NbTi rod is 100 - 300 mm. Finally, they are combined into the NbTi / Cu-Mn-(Cr / Fe / Zr / Ag / Ti) single-core rod, where Cu-Mn-(Cr / Fe / Zr / Ag / Ti) represents an alloy of Cu, Mn, and any one of CuCr or CuFe or CuZr or CuAg or CuTi, and NbTi / Cu-Mn-(Cr / Fe / Zr / Ag / Ti) represents a composite sheath structure of the NbTi rod and the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy; The hot extrusion processing parameters of the single-core rod are as follows: the extrusion temperature is 600 - 900 °C, the holding time is 2 - 8 h, and the extrusion ratio is 5 - 20. During the cold drawing process, skinning is only required 1 - 2 times; The hot isostatic pressing processing parameters of the secondary composite rod are as follows: the hot isostatic pressing temperature is 500 - 800 °C, and the holding time is 2 - 8 h; The hot extrusion processing parameters of the secondary composite rod are as follows: the extrusion temperature is 600 - 900 °C, the holding time is 2 - 8 h, and the extrusion ratio is 5 - 20; The aging heat treatment parameters of the tertiary composite wire are as follows: the aging temperature is 300 - 500 °C, the number of aging times is 2 - 8 times, the aging time for each time is 10 - 80 h, and the cooling method is furnace cooling.

[0024] In a possible embodiment, Example 1: Step 1, prepare a CuMnCr alloy tube with high oxidation resistance: Using a Cu source, an Mn source, and a CuCr master alloy as raw materials, a CuMnCr alloy tube is obtained through processes such as vacuum induction melting, casting, heating, extrusion, drawing, and vacuum annealing. The content range of alloying elements is as follows: the content of the Mn element is 0.5% - 5%, the content of the Cr element is 0.01% - 1%, and the balance is Cu. Subsequently, the CuMnCr alloy tube is subjected to a solution treatment to dissolve all the precipitated phases back into the matrix, and it is used as the initial tissue state for low-loss superconducting wires. The solution parameters are as follows: the solution temperature is 1050 °C, the solution time is 5, and the cooling method is water cooling; Step 2, prepare the NbTi / CuMnCr single-core rod: The thickness of the CuMnCr alloy tube is 60 mm, the thickness of the Nb cylinder is 2 mm, and the thickness of the NbTi rod is 300 mm. The CuMnCr alloy tube, upper and lower covers, high-purity Nb cylinder, and NbTi rod are successively cleaned, assembled, degassed, vacuum electron beam welded, hot extruded, multi-pass cold drawn with skinning, hexagonal forming, and cut to length, etc., to obtain the NbTi / CuMnCr single-core rod. The extrusion temperature is 900 °C, the holding time is 8 h, and the extrusion ratio is 15. During the cold drawing process, skinning is only required 1 - 2 times; Step 3, preparing the NbTi / CuMnCr / Cu secondary composite rod: Clean the oxygen-free copper tube and the upper and lower covers, as well as a specified number of NbTi / CuMnCr single-core rods and oxygen-free copper rods. Arrange the single-core rods in the oxygen-free copper tube according to the structural design, and fill the gaps in the oxygen-free copper tube with oxygen-free copper rods. Then, degas, vacuum electron beam weld, hot isostatic press, hot extrude, multi-pass cold draw combined with skinning, and cut to length for the composite ingot in sequence to obtain the NbTi / CuMnCr / Cu secondary composite rod. The hot isostatic pressing temperature is 800 °C, and the holding time is 8 h. The extrusion temperature is 800 °C, the holding time is 8 h, and the extrusion ratio is 15; Step 4, preparing the NbTi / CuMnCr / Cu tertiary composite wire: Clean the oxygen-free copper tube, the NbTi / CuMnCr / Cu secondary composite rod, and the oxygen-free copper rod. Arrange the NbTi / CuMnCr / Cu secondary composite rod in the oxygen-free copper tube according to the structural design, and use oxygen-free copper rods to fill the gaps in the oxygen-free copper tube. Combine cold drawing and multiple aging heat treatments to finally obtain the NbTi / CuMnCr / Cu tertiary composite wire. The aging temperature is 500 °C, the number of aging times is 6, the aging time for each time is 75 h, and the cooling method is furnace cooling.

[0025] In a possible embodiment, Embodiment 2: Step 1, preparing the CuMnFe alloy tube with high oxidation resistance: Using a Cu source, an Mn source, and a CuFe master alloy as raw materials, obtain the CuMnFe alloy tube through processes such as vacuum induction melting, casting, heating, extrusion, drawing, and vacuum annealing. The content ranges of alloying elements are as follows: the content of Mn element is 0.5% - 5%, the content of Fe element is 0.01% - 1%, and the balance is Cu. Subsequently, perform a solution treatment on the CuMnFe alloy tube to dissolve all the precipitated phases back into the matrix, and use it as the initial tissue state for low-loss superconducting wires. The solution parameters are as follows: the solution temperature is 1000 °C, the solution time is 4 h, and the cooling method is water cooling; Step 2, preparing the NbTi / CuMnFe single-core rod: The thickness of the CuMnFe alloy tube is 45 mm, the thickness of the Nb tube is 1.5 mm, and the thickness of the NbTi rod is 200 mm. Clean, assemble, degas, vacuum electron beam weld, hot extrude, multi-pass cold draw combined with skinning, hexagonal forming, and cut to length the CuMnFe alloy tube, the upper and lower covers, the high-purity Nb tube, and the NbTi rod in sequence to obtain the NbTi / CuMnFe single-core rod. The extrusion temperature is 850 °C, the holding time is 7 h, and the extrusion ratio is 13. Only 1 - 2 skinning operations are required during the cold drawing process; Step 3, preparing NbTi / CuMnFe / Cu secondary composite rods: Clean the oxygen-free copper tube and the upper and lower covers, as well as a specified number of NbTi / CuMnFe single-core rods and oxygen-free copper rods. Arrange the single-core rods in the oxygen-free copper tube according to the structural design, and fill the gaps in the oxygen-free copper tube with oxygen-free copper rods. Then, degas, vacuum electron beam weld, hot isostatic press, hot extrude, multi-pass cold draw combined with skinning, and cut to length for the composite ingot in sequence to obtain NbTi / CuMnFe / Cu secondary composite rods. The hot isostatic pressing temperature is 750 °C, and the holding time is 6 h. The extrusion temperature is 850 °C, the holding time is 7 h, and the extrusion ratio is 15; Step 4, preparing NbTi / CuMnFe / Cu tertiary composite wires: Clean the oxygen-free copper tube, NbTi / CuMnFe / Cu secondary composite rods, and oxygen-free copper rods. Arrange the NbTi / CuMnFe / Cu secondary composite rods in the oxygen-free copper tube according to the structural design, and use oxygen-free copper rods to fill the gaps in the oxygen-free copper tube. Combine cold drawing and multiple aging heat treatments to finally obtain NbTi / CuMnFe / Cu tertiary composite wires. The aging temperature is 450 °C, the number of aging times is 6, the aging time for each time is 30 h, and the cooling method is furnace cooling.

[0026] In a possible embodiment, Example 3: Step 1, preparing CuMnZr alloy tubes with high oxidation resistance: Using Cu source, Mn source, and CuZr master alloy as raw materials, obtain CuMnZr alloy tubes through processes such as vacuum induction melting, casting, heating, extrusion, drawing, and vacuum annealing. The content range of alloying elements is as follows: the content of Mn element is 0.5% - 5%, the content of Zr element is 0.01% - 1%, and the balance is Cu. Subsequently, perform solution treatment on the CuMnZr alloy tubes to dissolve all the precipitated phases into the matrix, and use it as the initial tissue state for low-loss superconducting wires. The solution parameters are as follows: the solution temperature is 1000 °C, the solution time is 4 h, and the cooling method is water cooling; Step 2, preparing NbTi / CuMnZr single-core rods: The thickness of the CuMnZr alloy tube is 30 mm, the thickness of the Nb tube is 1 mm, and the thickness of the NbTi rod is 150 mm. Clean, assemble, degas, vacuum electron beam weld, hot extrude, multi-pass cold draw combined with skinning, hexagonal forming, and cut to length for the CuMnZr alloy tube, upper and lower covers, high-purity Nb tube, and NbTi rod in sequence to obtain NbTi / CuMnZr single-core rods. The extrusion temperature is 850 °C, the holding time is 6 h, and the extrusion ratio is 13. Only 1 - 2 times of skinning is required during the cold drawing process; Step 3, Prepare the NbTi / CuMnZr / Cu secondary composite rod: Clean the oxygen-free copper tube and upper and lower covers, as well as a specified number of NbTi / CuMnZr single-core rods and oxygen-free copper rods. Arrange the single-core rods in the oxygen-free copper tube according to the structural design, and fill the gaps in the oxygen-free copper tube with oxygen-free copper rods. Then, degas, vacuum electron beam weld, hot isostatic press, hot extrude, multi-pass cold draw combined with skinning, and cut to length for the composite ingot in sequence to obtain the NbTi / CuMnZr / Cu secondary composite rod. The hot isostatic pressing temperature is 750 °C, and the holding time is 6 h. The extrusion temperature is 850 °C, the holding time is 7 h, and the extrusion ratio is 15; Step 4, Prepare the NbTi / CuMnZr / Cu tertiary composite wire: Clean the oxygen-free copper tube, NbTi / CuMnZr / Cu secondary composite rod, and oxygen-free copper rod. Arrange the NbTi / CuMnZr / Cu secondary composite rod in the oxygen-free copper tube according to the structural design, and use oxygen-free copper rods to fill the gaps in the oxygen-free copper tube. Combine cold drawing and multiple aging heat treatments to finally obtain the NbTi / CuMnZr / Cu tertiary composite wire. The aging temperature is 450 °C, the number of aging times is 6 times, the aging time for each time is 30 h, and the cooling method is furnace cooling.

[0027] In a possible embodiment, Example 4: Step 1, Prepare the CuMnAg alloy tube with high oxidation resistance: Use Cu source, Mn source, and CuAg intermediate alloy as raw materials to obtain the CuMnAg alloy tube through processes such as vacuum induction melting, casting, heating, extrusion, drawing, and vacuum annealing. The content range of alloying elements is as follows: the content of Mn element is 0.5% - 5%, the content of Ag element is 0.01% - 1%, and the balance is Cu. Subsequently, perform solution treatment on the CuMnAg alloy tube to dissolve all the precipitated phases back into the matrix, and use it as the initial tissue state for low-loss superconducting wire materials. The solution parameters are as follows: the solution temperature is 1000 °C, the solution time is 4 h, and the cooling method is water cooling; Step 2, Prepare the NbTi / CuMnAg single-core rod: The thickness of the CuMnAg alloy tube is 30 mm, the thickness of the Nb tube is 1 mm, and the thickness of the NbTi rod is 150 mm. Clean, assemble, degas, vacuum electron beam weld, hot extrude, multi-pass cold draw combined with skinning, hexagonal forming, and cut to length for the CuMnAg alloy tube, upper and lower covers, high-purity Nb tube, and NbTi rod in sequence to obtain the NbTi / CuMnAg single-core rod. The extrusion temperature is 850 °C, the holding time is 6 h, and the extrusion ratio is 13. Only 1 - 2 times of skinning is required during the cold drawing process; Step 3, preparing NbTi / CuMnAg / Cu secondary composite rods: Clean the oxygen-free copper tubes and upper and lower covers, as well as a specified number of NbTi / CuMnAg single-core rods and oxygen-free copper rods. Arrange the single-core rods in the oxygen-free copper tubes according to the structural design, and fill the gaps in the oxygen-free copper tubes with oxygen-free copper rods. Then, degas, vacuum electron beam weld, hot isostatic press, hot extrude, multi-pass cold draw with skinning, and cut to length for the composite ingot in sequence to obtain NbTi / CuMnAg / Cu secondary composite rods. The hot isostatic pressing temperature is 750 °C, and the holding time is 6 h. The extrusion temperature is 850 °C, the holding time is 7 h, and the extrusion ratio is 15; Step 4, preparing NbTi / CuMnAg / Cu tertiary composite wires: Clean the oxygen-free copper tubes, NbTi / CuMnAg / Cu secondary composite rods, and oxygen-free copper rods. Arrange the NbTi / CuMnAg / Cu secondary composite rods in the oxygen-free copper tubes according to the structural design, and use oxygen-free copper rods to fill the gaps in the oxygen-free copper tubes. Combine cold drawing and multiple aging heat treatments to finally obtain NbTi / CuMnAg / Cu tertiary composite wires. The aging temperature is 450 °C, the number of aging times is 6, the aging time for each time is 30 h, and the cooling method is furnace cooling.

[0028] In a possible embodiment, Embodiment 5: Step 1, preparing CuMnTi alloy tubes with high oxidation resistance: Using Cu source, Mn source, and CuTi master alloy as raw materials, obtain CuMnTi alloy tubes through processes such as vacuum induction melting, casting, heating, extrusion, drawing, and vacuum annealing. The content range of alloying elements is as follows: the content of Mn element is 0.5% - 5%, the content of Ti element is 0.01% - 1%, and the balance is Cu. Subsequently, perform solution treatment on the CuMnTi alloy tubes to dissolve all the precipitated phases into the matrix, and use it as the initial tissue state for low-loss superconducting wires. The solution parameters are as follows: the solution temperature is 800 °C, the solution time is 1 h, and the cooling method is water cooling; Step 2, preparing NbTi / CuMnTi single-core rods: The thickness of the CuMnTi alloy tube is 30 mm, the thickness of the Nb tube is 1 mm, and the thickness of the NbTi rod is 150 mm. Clean, assemble, degas, vacuum electron beam weld, hot extrude, multi-pass cold draw with skinning, hexagonal forming, and cut to length for the CuMnTi alloy tubes, upper and lower covers, high-purity Nb tubes, and NbTi rods in sequence to obtain NbTi / CuMnTi single-core rods. The extrusion temperature is 600 °C, the holding time is 2 h, and the extrusion ratio is 5. Only 1 - 2 skinning operations are required during the cold drawing process; Step 3, preparing the NbTi / CuMnTi / Cu secondary composite rod: Clean the oxygen-free copper tube and upper and lower covers, as well as a specified number of NbTi / CuMnTi single-core rods and oxygen-free copper rods. Arrange the single-core rods in the oxygen-free copper tube according to the structural design, and fill the gaps in the oxygen-free copper tube with oxygen-free copper rods. Then, degas, vacuum electron beam weld, hot isostatic press, hot extrude, perform multi-pass cold drawing combined with skinning, and cut to a specified length on the composite ingot in sequence to obtain the NbTi / CuMnTi / Cu secondary composite rod. The hot isostatic pressing temperature is 500 °C, and the holding time is 2 h. The extrusion temperature is 600 °C, the holding time is 2 h, and the extrusion ratio is 5; Step 4, preparing the NbTi / CuMnTi / Cu tertiary composite wire: Clean the oxygen-free copper tube, the NbTi / CuMnTi / Cu secondary composite rod, and the oxygen-free copper rod. Arrange the NbTi / CuMnTi / Cu secondary composite rod in the oxygen-free copper tube according to the structural design, and use oxygen-free copper rods to fill the gaps in the oxygen-free copper tube. Combine cold drawing and multiple aging heat treatments to finally obtain the NbTi / CuMnTi / Cu tertiary composite wire. The aging temperature is 300 °C, the number of aging times is 2 times, the aging time for each time is 10 h, and the cooling method is furnace cooling.

[0029] In a possible embodiment, the parameters of Comparative Example 1 are the same as those of Example 1, except that the alloy raw material in Comparative Example 1 is CuMn alloy.

[0030] In a possible embodiment, the parameters of Comparative Example 2 are the same as those of Example 2, except that the alloy raw material in Comparative Example 1 is CuMn alloy.

[0031] In a possible embodiment, the parameters of Comparative Example 3 are the same as those of Example 3, except that the alloy raw material in Comparative Example 1 is CuMn alloy.

[0032] Perform critical current and loss performance tests on the NbTi superconducting wires prepared in Examples 1-5 and Comparative Examples 1-3, and count the wire lengths of the superconducting wires. The results are summarized in Table 1: Table 1 Physical properties and wire lengths of low-loss NbTi superconducting wire materials under the same conditions in examples and comparative examples

[0033] As can be seen from Table 1, the low-loss NbTi superconducting wire prepared by the method of the present invention can significantly improve the long-wire processing ability of the low-loss NbTi superconducting wire, effectively improve the finished product rate of the superconducting wire, and greatly reduce the production cost without reducing the critical current density and loss performance. At the same time, it can improve the antioxidant performance of the single-core rod, reduce the number of skinning times, and improve the uniformity of the core wire deformation, thereby improving the critical current density of the superconducting wire.

[0034] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred examples as well as all changes and modifications that fall within the scope of the present invention.

[0035] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a superconducting composite long wire, characterized in that: include: Cu, Mn and any one of CrCu, CuFe, CuZr, CuAg and CuTi are smelted to obtain a Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube; Placing a Nb tube and a NbTi rod in the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube to form a single core rod; Combining the single core rod and the oxygen-free copper rod in an oxygen-free copper tube to obtain a secondary composite rod; Combining the secondary composite rod and the oxygen-free copper rod in the oxygen-free copper tube to obtain a tertiary composite rod; The tertiary composite rod is subjected to a drawing process to obtain a tertiary superconducting composite wire.

2. The method for preparing a superconducting composite long wire according to claim 1, characterized in that: The method of smelting Cu, Mn and any one of CrCu, CuFe, CuZr, CuAg and CuTi to obtain a Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube comprises: Using the Cu and the Mn plus any one of the CrCu, CuFe, CuZr, CuAg and CuTi as raw materials, through vacuum induction melting, pouring, heating, extrusion, drawing and vacuum annealing, an initial Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube is obtained; The initial Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube is subjected to a solid solution treatment to obtain the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube.

3. The method for preparing a superconducting composite long wire according to claim 2, characterized in that: The method of placing a Nb tube and a NbTi rod in the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube to form a single core rod comprises: One end of the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube is sealed by a cover made of the same alloy material; The Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube after sealing one end, the alloy cover of the same material at the other end of the Cu-Mn-(Cr / Fe / Zr / Ag / Ti) alloy tube, the Nb tube and the NbTi rod are sequentially cleaned, assembled, degassed, vacuum electron beam welded, hot extruded, drawn, stripped, hexagonally formed and cut to size to obtain a single core rod.

4. The method for preparing a superconducting composite long wire according to claim 3, characterized in that: The step of combining the single core rod and the oxygen-free copper rod in the oxygen-free copper tube to obtain a secondary composite rod comprises: Cleaning the oxygen-free copper tube, the upper and lower covers of the oxygen-free copper tube, the plurality of single core rods and the plurality of oxygen-free copper rods; Arranging a plurality of the single core rods in the oxygen-free copper tube according to the superconducting wire structure; Inserting the oxygen-free copper rod into the gap between the plurality of single core rods to obtain a composite ingot; The composite ingot is subjected to degassing, vacuum electron beam welding, hot isostatic pressing, hot extrusion, drawing, peeling and cutting to a fixed length in sequence to obtain a secondary composite rod.

5. The method for preparing a superconducting composite long wire according to claim 4, characterized in that: The step of combining the secondary composite rod and the oxygen-free copper rod in the oxygen-free copper tube to obtain the tertiary composite rod comprises: Arranging a plurality of the secondary composite rods in the oxygen-free copper tube according to the superconducting wire structure; Inserting the oxygen-free copper rod into the gap between the plurality of secondary composite rods to obtain a tertiary composite ingot; The tertiary composite ingot is subjected to degassing, vacuum electron beam welding, hot isostatic pressing, hot extrusion, drawing, peeling and cut-to-length cutting in sequence to obtain a tertiary composite rod.

6. The method for preparing a superconducting composite long wire according to claim 5, characterized in that: The drawing of the tertiary composite rod to obtain a tertiary superconducting composite wire comprises: The tertiary composite rod is subjected to cold drawing and aging heat treatment to obtain a tertiary composite wire.

7. The method for preparing a superconducting composite long wire according to claim 6, characterized in that: The cold drawing has multiple passes.

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