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CN-121483792-B - Low-loss tin source distributed Nb3Method for producing Sn wire

CN121483792BCN 121483792 BCN121483792 BCN 121483792BCN-121483792-B

Abstract

The invention belongs to the field of superconducting material preparation, and particularly relates to a preparation method of a low-loss tin source distributed Nb 3 Sn wire. According to the method, holes are drilled on an oxygen-free copper ingot in a hexagonal close packing or annular distribution mode, nb bars are filled into the holes, and a hexagonal CuNb composite bar is manufactured, and SnTi/Cu single core rods are prepared. And then assembling the CuNb composite rod and the SnTi/Cu single-core rod into an NbTa alloy tube in a hexagonal close-packed mode, coating the oxygen-free copper tube outside to form a final blank, stretching, twisting and finally stretching the final blank to obtain a stranded wire, and finally performing heat treatment to obtain the low-loss tin source distributed Nb 3 Sn wire. According to the invention, through optimizing tin source distribution and a core wire structure and combining low-temperature long-time heat treatment, nb 3 Sn crystal grain refinement is realized, high critical current density and low alternating current loss are effectively considered, and the method is suitable for high-requirement scenes such as high-field pulse magnets, fusion device polar field coils and the like.

Inventors

  • XIN YANG
  • LIU XIANGHONG
  • FENG YONG
  • LI JIANFENG
  • ZHANG PINGXIANG
  • GUO QIANG
  • WANG CHUNGUANG
  • HAN GUANGYU
  • LI PENGJU
  • CHEN JIANYA
  • CHEN JIAXU
  • LI ZHENG
  • YAN GUO

Assignees

  • 西安聚能超导线材科技有限公司

Dates

Publication Date
20260505
Application Date
20260109

Claims (5)

  1. 1. The preparation method of the low-loss tin source distributed Nb 3 Sn wire is characterized by comprising the following steps of: Drilling holes on an oxygen-free copper ingot in a hexagonal close packing or annular distribution mode to obtain a porous oxygen-free copper ingot, and filling the Nb rod into the porous oxygen-free copper ingot to obtain a CuNb composite rod with a hexagonal section and a copper ratio of 0.85-2.5, wherein the diameter of the holes is 5.0-15.0 mm, and the spacing of the holes is 1.0-5.0 mm; Step two, filling SnTi alloy rods into an oxygen-free copper pipe to prepare SnTi/Cu single core rod with a hexagonal or fan-shaped section and a copper ratio of 0.20-0.50, wherein the mass percentage of Ti in the SnTi alloy rods is 1.5-2.5%, and the balance is Sn; Step three, assembling the CuNb composite rods prepared in the step one and the SnTi/Cu single-core rods prepared in the step two into NbTa alloy tubes in a hexagonal close packing mode, and arranging oxygen-free copper tubes outside to prepare a final blank, wherein 6 CuNb composite rods are surrounded around each SnTi/Cu single-core rod except the edges, and 3 SnTi/Cu single-core rods and 3 CuNb composite rods are adjacent to each CuNb composite rod; Step four, stretching, twisting and re-stretching the final blank obtained in the step three to obtain Nb 3 Sn strands; and fifthly, carrying out heat treatment on the Nb 3 Sn stranded wire prepared in the step four, firstly, carrying out heat preservation at 210+/-10 ℃ for 40-60 hours, then carrying out heat preservation at 400+/-10 ℃ for 40-60 hours, and finally carrying out heat preservation at 610-630 ℃ for 150-250 hours to generate a Nb 3 Sn phase.
  2. 2. A low-loss tin source distributed Nb 3 Sn wire prepared by the preparation method according to claim 1, wherein the wire has a fine-scale Nb 3 Sn core wire array derived from a discretely distributed SnTi/Cu single core rod, and the Nb 3 Sn core wire array is isolated by a copper matrix, the low-loss tin source distributed Nb 3 Sn wire has a critical current density of no less than 1514A/mm 2 at 4.2K, 12T, and an ac loss of no more than 456mJ/cm 3 at a magnetic field variation of ± 3T.
  3. 3. The CuNb composite rod for preparing the low-loss tin source distributed Nb 3 Sn wire is characterized in that the CuNb composite rod is prepared by embedding Nb rods into an oxygen-free copper ingot, the cross section of the CuNb composite rod is hexagonal, the copper ratio is 0.85-2.5, the Nb rods are embedded into holes drilled on the oxygen-free copper ingot in a hexagonal close-packed or annular distribution mode, the diameter of the holes is 5.0-15.0 mm, and the spacing of the holes is 1.0-5.0 mm.
  4. 4. A final billet for the preparation of the low loss tin source distributed Nb 3 Sn wire of claim 2, wherein the final billet comprises an NbTa alloy tube, a CuNb composite rod and SnTi/Cu single core rod arranged in a hexagonal close-packed fashion in the NbTa alloy tube, and an external oxygen free copper tube.
  5. 5. Use of the low loss tin source distributed Nb 3 Sn wire of claim 2 in high field pulse magnets, fusion device polar field coils, or high energy physical detector magnets.

Description

Preparation method of low-loss tin source distributed Nb 3 Sn wire Technical Field The invention belongs to the field of superconducting material preparation, and particularly relates to a preparation method of a low-loss tin source distributed Nb 3 Sn wire. Background Nb 3 Sn is one of key materials in the field of high-field superconducting magnets, and is widely applied to high-energy physical devices, controllable nuclear fusion devices and next-generation high-field scientific instruments. The application scenes put stringent requirements on the superconducting materials, not only are high critical current density and upper critical field required under high magnetic field, but also low alternating current loss is required to be kept under alternating magnetic field conditions, so that the stability and energy efficiency of the magnet in pulse operation are ensured. Currently, the main production methods of Nb 3 Sn wire include bronze and internal tin. Although the alternating current loss of the wire rod prepared by the bronze method is relatively low, the process flow is long, the tin source is limited, and the critical current density is increased to face the bottleneck. While the internal tin method such as RRP can realize higher critical current density, the effective core wire size is larger, the superconducting phase grain structure is uneven, and the grain boundary and defects are more due to uneven tin source distribution and complex barrier layer structure. Under alternating magnetic field, the wire is easy to generate obvious magnetic flux jump and eddy current loss, and is difficult to meet the low-loss requirement of rapid pulse operation scenes such as a fusion device polar-to-field coil and the like. The existing Nb 3 Sn wire has outstanding contradiction between high critical current density and low alternating current loss, and becomes a key technical problem for restricting the large-scale application of the Nb 3 Sn wire in high-field pulse magnets. The novel Nb 3 Sn wire preparation process which can maintain the high critical current density and the high upper critical field characteristic and greatly reduce the alternating current loss is developed, and is a technical bottleneck to be broken through in the field of superconducting materials. Disclosure of Invention The invention aims to overcome the contradiction that the prior Nb 3 Sn wire is difficult to achieve between critical current density and alternating current loss, and provides a novel Nb 3 Sn wire preparation method which can not only maintain high critical current density, but also remarkably reduce alternating current loss. In order to achieve the above object, the present invention adopts the following technical scheme. In one aspect, the invention provides a method for preparing a low-loss tin source distributed Nb 3 Sn wire, which comprises the following steps: Drilling holes on an oxygen-free copper ingot in a hexagonal close packing or annular distribution mode to obtain a porous oxygen-free copper ingot, and filling the Nb rod into the porous oxygen-free copper ingot to obtain a CuNb composite rod with the copper ratio of 0.55-2.5; Step two, filling SnTi alloy rods into an oxygen-free copper pipe to prepare a SnTi/Cu single core rod with the copper ratio of 0.20-0.50; Step three, assembling the CuNb composite rod prepared in the step one and the SnTi/Cu single-core rod prepared in the step two into an NbTa alloy pipe in a hexagonal close packing mode, and arranging an oxygen-free copper pipe outside to prepare a final blank; Step four, stretching, twisting and re-stretching the final blank obtained in the step three to obtain Nb 3 Sn strands; And fifthly, carrying out heat treatment on the Nb 3 Sn strand prepared in the step four, wherein the heat treatment comprises heat preservation for 150-250 hours at 610-630 ℃ to generate a Nb 3 Sn phase. In the preparation method of the low-loss tin source distributed Nb 3 Sn wire, the diameter of the holes in the first step is 5.0-15.0 mm, and the spacing of the holes is 1.0-5.0 mm. Further, in the preparation method of the low-loss tin source distributed Nb 3 Sn wire, the mass percentage of Ti in the SnTi alloy rod is 1.5-2.5%, and the balance is Sn. Further, in the method for preparing the low-loss tin source distributed Nb 3 Sn wire, in the third step, except for the edges, 6 CuNb composite rods are wound around each SnTi/Cu single core rod, 3 SnTi/Cu single core rods and 3 CuNb composite rods are adjacent to each CuNb composite rod, each edge SnTi/Cu single core rod is in a fan shape or a hexagon shape, and each edge SnTi/Cu single core rod can be replaced by a CuNb composite rod. In a second aspect, the invention also provides the low-loss tin source distributed Nb 3 Sn wire prepared by the preparation method, the critical current density of the low-loss tin source distributed Nb 3 Sn wire under the conditions of 4.2K and 12T is not lower than 1514A/mm 2, and the alt