Nb3sn superconducting wire precursor, and nb3sn superconducting wire
Patent Information
- Application Number
- JP2025528012
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Priority Date
- 2023-06-22
- Filing Date
- 2024-06-14
- Publication Date
- 2024-12-26
AI Technical Summary
Existing methods for producing Nb3Sn superconducting wires face limitations in critical current density due to solid solubility constraints and mechanical strain, particularly in high-field applications, and suffer from wire drawability and workability issues when incorporating reinforcing elements.
A superconducting wire precursor configuration featuring a cylindrical stabilized copper layer, a Sn diffusion barrier layer, and a specific arrangement of Nb-based superconducting element wire precursors within a Cu-based alloy matrix, which includes reinforcing filaments and sub-elements, helps mitigate axial tensile and radial compressive stresses, enhancing mechanical strength and workability.
This configuration effectively suppresses decreases in critical current density and protects the superconducting filaments from damage during processing, resulting in high-quality Nb3Sn wires with improved mechanical strength and manufacturability for high-field applications.
Abstract
Description
Precursor for Nb3Sn superconducting wire and Nb3Sn superconducting wire
[0001] The present disclosure relates to Nb ３ Sn superconducting wire precursor and Nb ３ This relates to Sn superconducting wire.
[0002] Conventionally widely used Nb ３ The manufacturing method of Sn superconducting wire is to heat treat a wire having a structure in which a plurality of Nb filaments are embedded in a Cu-Sn-based alloy (bronze) matrix, and to diffuse the Sn in the bronze matrix into the Nb filaments, thereby forming the Nb superconducting phase. ３ There is a bronze process that produces Sn.
[0003] However, in the bronze process, there is an upper limit (solubility limit) to the Sn concentration that can be dissolved in bronze, so the Nb that can be produced ３ There is a limit to the area of Sn, and as a result, there is a limit to the improvement of the critical current density Jc of the superconducting wire.
[0004] In addition, Nb ３ In addition to the bronze process, there is also a method called the internal diffusion process for manufacturing Sn superconducting wires. In the internal diffusion process, a wire having a structure in which Nb-based alloy filaments and Sn-based alloy filaments are embedded in a Cu-based alloy matrix is heat-treated, so that Sn in the Sn-based alloy filaments is diffused into the Nb-based alloy filaments, and Nb is formed at the interface between the Nb-based alloy filaments and the Cu-based alloy matrix. ３ Sn is produced.
[0005] The internal diffusion method is not affected by the solid solubility limit of Sn in Cu-Sn based alloys, which is a problem in the bronze method. ３ The area where Sn is generated can be increased, and a high critical current density Jc can be obtained. In addition, the internal diffusion method can increase the Sn concentration compared to the bronze method, so high-quality Nb ３ Sn can be produced.
[0006] In addition, Nb ３ Regarding Sn, regardless of its manufacturing method, the critical current density Jc is ３ It is known that Sn is sensitive to mechanical strain.３ When Sn is used in a high magnetic field magnet, the critical current density Jc decreases due to distortion caused by electromagnetic force, and therefore, improvement in mechanical strength is required.
[0007] Nb produced by internal diffusion method ３ Methods proposed to improve the strength of Sn superconducting wire include placing a reinforcing metal core in an Nb element wire (see, for example, Patent Document 1) and replacing part of the element wire with a reinforcing element wire (see, for example, Patent Document 2).
[0008] However, in the method of providing a reinforcing metal core in an Nb element wire as in Patent Document 1, the deterioration of wire drawing processability due to the difference in mechanical properties between the Nb element wire and the reinforcing metal core, and the resulting deterioration of the superconducting filament shape cannot be ignored.
[0009] Furthermore, with regard to the method of replacing part of the element wire with reinforcing element wire as in Patent Document 2, the deterioration of workability due to the reinforcing element wire, which is difficult to work with, being dispersed within the superconducting filament, and the complication of the manufacturing process due to adding the reinforcing element wire to the element wire cannot be ignored.
[0010] Furthermore, in recent years, the development of experimental reactors aimed at realizing high-performance large accelerators and nuclear fusion reactors has been progressing, and there is a need for superconducting wires that have a high critical current density Jc and good manufacturability during stranding processing. However, as described above, conventional techniques have not adequately met these needs.
[0011] JP 2017-142898 A JP 2010-135215 A
[0012] The object of the present disclosure is to provide a Nb alloy for producing a superconducting wire rod having high mechanical strength, which can suppress a decrease in critical current density Jc due to axial tensile stress and radial compressive stress, and can also suppress damage to a superconducting filament precursor due to twisting and rolling processes. ３ Sn superconducting wire precursor and Nb ３ The object of the present invention is to provide a Sn superconducting wire.
[0013] [1] A superconducting element group precursor including a cylindrical stabilizing copper layer provided on an outer periphery, a cylindrical first Sn diffusion barrier layer provided inside the stabilizing copper layer, and a superconducting element group precursor housed inside the first Sn diffusion barrier layer, wherein the superconducting element group precursor includes a plurality of Sn-based element wires and a plurality of Nb-based superconducting element wire precursors, wherein the plurality of Sn-based element wires include a first stabilizing matrix made of Cu or a Cu-based alloy and one or more Sn-based filaments embedded in the first stabilizing matrix and made of Sn or a Sn-based alloy, and the plurality of Nb-based superconducting element wire precursors include a second stabilizing matrix made of Cu or a Cu-based alloy and one or more Nb-based superconducting element wire precursors embedded in the second stabilizing matrix. and / or a third stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing sub-elements embedded in the third stabilizing matrix and having a plurality of Nb-based reinforcing filaments made of Nb or an Nb-based alloy, a fourth stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based superconducting sub-element precursors embedded in the fourth stabilizing matrix and having a plurality of Nb-based superconducting filament precursors made of Nb or an Nb-based alloy and having a diameter larger than that of the Nb-based reinforcing filaments. ３ Precursor for Sn superconducting wire. [2] The Nb ３ In each of the plurality of Nb-based superconducting element wire precursors, in a cross section perpendicular to the axial direction of the Sn superconducting wire precursor, an Nb-based reinforcing filament assembly in which the plurality of Nb-based reinforcing filaments are aggregated is arranged in the center, and an Nb-based superconducting filament assembly precursor in which the plurality of Nb-based superconducting filament precursors are aggregated is arranged on the periphery. ３ [3] The Nb-based superconducting element wire precursor is a precursor for a Sn superconducting wire. ３The Nb superconducting wire precursor according to [2] above further comprises a second Sn diffusion barrier layer formed between the Nb-based reinforcing filament assembly and the Nb-based superconducting filament assembly precursor in a cross section perpendicular to the axial direction of the precursor. ３ [4] The Nb ３ In a cross section perpendicular to the axial direction of the Sn superconducting wire precursor, the plurality of Nb-based superconducting sub-element precursors and the plurality of Sn-based element wires are arranged in the center of the superconducting element group precursor, and the plurality of Nb-based strengthened sub-elements are arranged on the outer periphery of the superconducting element group precursor. ３ [5] The precursor for a Sn superconducting wire according to any one of [1] to [4] above, wherein the first Sn diffusion barrier layer is made of a pure metal or alloy containing Ta or Nb. ３ [6] A precursor for a Sn superconducting wire, comprising: a cylindrical stabilizing copper layer provided on an outer periphery; a cylindrical first Sn diffusion barrier layer provided inside the stabilizing copper layer; and a superconducting element group housed inside the first Sn diffusion barrier layer, wherein the superconducting element group comprises a plurality of Nb-based superconducting element wires, and the plurality of Nb-based superconducting element wires comprise a second stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing filaments and Nb-based reinforcing filaments embedded in the second stabilizing matrix and made of Nb or an Nb-based alloy. ３ and / or a third stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing sub-elements embedded in the third stabilizing matrix and having a plurality of Nb-based reinforcing filaments made of Nb or an Nb-based alloy; a fourth stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing sub-elements embedded in the fourth stabilizing matrix and having a compound superconducting phase made of Sn and having a diameter larger than that of the Nb-based reinforcing filaments. ３ and a plurality of superconducting sub-elements each having a compound superconducting phase made of Sn and each having a plurality of superconducting filaments having a diameter larger than that of the Nb-based reinforcing filaments. ３[7] The Nb superconducting wire according to [6] above, wherein the first Sn diffusion barrier layer is made of a pure metal or alloy containing Ta or Nb. ３ Sn superconducting wire.
[0014] According to the present disclosure, a Nb alloy for producing a superconducting wire rod having high mechanical strength can be obtained, which can suppress a decrease in critical current density Jc due to axial tensile stress and radial compressive stress, and can also suppress damage to the superconducting filament precursor due to twisting and rolling processes. ３ Sn superconducting wire precursor and Nb ３ It is possible to provide a Sn superconducting wire.
[0015] FIG. 1 shows the Nb ３ 2 is a cross-sectional view showing an example of a precursor for a Sn superconducting wire according to the first embodiment; ３ 3 is a cross-sectional view showing another example of an Nb-based superconducting element wire precursor constituting a precursor for an Sn superconducting wire. ３ Nb superconducting wire precursor obtained by heating ３ Fig. 4 is a cross-sectional view showing an Nb-based superconducting element wire obtained by heating the Nb-based superconducting element wire precursor of Fig. 2. Fig. 5 is a cross-sectional view showing an Nb-based superconducting element wire of a second embodiment. ３ 6 is a cross-sectional view showing an example of a precursor for a Sn superconducting wire. ３ Nb superconducting wire precursor obtained by heating ３ FIG. 2 is a cross-sectional view showing a Sn superconducting wire.
[0016] Hereinafter, a detailed description will be given based on an embodiment.
[0017] As a result of extensive research, the present inventors have found that Nb ３ In the precursor for the Sn superconducting wire, a plurality of Nb-based superconducting element wire precursors constituting the superconducting element group precursors housed inside the diffusion barrier layer are configured to have a predetermined structure, thereby ３ Nb obtained by heat treating precursor for Sn superconducting wire ３The inventors have discovered that Sn superconducting wire has high mechanical strength, which can suppress the decrease in critical current density Jc caused by axial tensile stress and radial compressive stress, and can also suppress damage to the superconducting filament precursor due to twisting and rolling processes, and have completed the present disclosure based on this finding.
[0018] Nb in the embodiment ３ The Sn superconducting wire precursor includes a cylindrical stabilizing copper layer provided on the outer periphery, a cylindrical first Sn diffusion barrier layer provided inside the stabilizing copper layer, and a superconducting element group precursor housed inside the first Sn diffusion barrier layer. The superconducting element group precursor includes a plurality of Sn-based element wires and a plurality of Nb-based superconducting element wire precursors. The plurality of Sn-based element wires include a first stabilizing matrix made of Cu or a Cu-based alloy, and one or more Sn-based filaments made of Sn or a Sn-based alloy embedded in the first stabilizing matrix. The plurality of Nb-based superconducting element wire precursors include a second stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing filaments and a plurality of Nb-based superconducting filament precursors having a diameter larger than that of the Nb-based reinforcing filaments, each made of Nb or an Nb-based alloy and embedded in the second stabilizing matrix; and / or a third stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing sub-elements having a plurality of Nb-based reinforcing filaments made of Nb or an Nb-based alloy and embedded in the third stabilizing matrix, and a fourth stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based superconducting sub-element precursors having a plurality of Nb-based superconducting filaments made of Nb or an Nb-based alloy and embedded in the fourth stabilizing matrix.
[0019] In addition, Nb ３The Sn superconducting wire comprises a cylindrical stabilizing copper layer provided on the outer periphery, a cylindrical first Sn diffusion barrier layer provided inside the stabilizing copper layer, and a superconducting element group housed inside the first Sn diffusion barrier layer. The superconducting element group comprises a plurality of Nb-based superconducting element wires. The plurality of Nb-based superconducting element wires comprises a second stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing filaments and Nb-based reinforcing filaments embedded in the second stabilizing matrix and made of Nb or an Nb-based alloy. ３ and / or a third stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing sub-elements having a compound superconducting phase made of Sn and a plurality of superconducting filaments having a diameter larger than that of the Nb-based reinforcing filaments, the third stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing sub-elements having a plurality of Nb-based reinforcing filaments made of Nb or a Nb-based alloy embedded in the third stabilizing matrix, a fourth stabilizing matrix made of Cu or a Cu-based alloy, and a fourth stabilizing matrix made of Nb ３ The superconducting subelements have a compound superconducting phase made of Sn and have a plurality of superconducting filaments with a diameter larger than that of the Nb-based reinforcing filaments.
[0020] (First embodiment) FIG. 1 shows the Nb ３ 1 is a cross-sectional view showing an example of a precursor for a Sn superconducting wire; ３ The cross-sectional view of the precursor 1 for Sn superconducting wire is ３ 1 is a cross section perpendicular to the axial direction (longitudinal direction) of the precursor 1 for a Sn superconducting wire. ３ The Sn superconducting wire precursor 1 includes a cylindrical stabilizing copper layer 10 , a cylindrical first Sn diffusion barrier layer 20 , and a superconducting element group precursor 30 .
[0021] Nb ３ The stabilizing copper layer 10 constituting the precursor 1 for the Sn superconducting wire is cylindrical, and ３ The stabilizing copper layer 10 is provided on the outer periphery of the Sn superconducting wire precursor 1, and covers the first Sn diffusion barrier layer 20 from the outside. The stabilizing copper layer 10 is made of Cu or a Cu alloy.
[0022] Nb ３The first Sn diffusion barrier layer 20 constituting the precursor 1 for a Sn superconducting wire has a cylindrical shape and is provided inside the stabilizing copper layer 10. The first Sn diffusion barrier layer 20 is preferably made of a pure metal or alloy containing Ta or Nb.
[0023] The first Sn diffusion barrier layer 20 is made of Nb ３ During the heat treatment for producing the compound superconducting phase 73 made of Sn, the Sn in the Sn-based filaments 42 is prevented from diffusing into the stabilizing copper layer 10 and bronzing the stabilizing copper layer 10, thereby preventing a decrease in superconducting properties such as the residual resistivity ratio, and also reacting with the Nb-based superconducting filament precursor 53 to form Nb ３ The amount of Sn necessary for generating Sn is held inside the first Sn diffusion barrier layer 20 .
[0024] Nb ３ The superconducting element group precursor 30 constituting the Sn superconducting wire precursor 1 is housed inside the first Sn diffusion barrier layer 20. The superconducting element group precursor 30 includes a plurality of Sn-based element wires 40 and a plurality of Nb-based superconducting element wire precursors 50.
[0025] Each of the plurality of Sn-based element wires 40 includes a first stabilizing matrix 41 and one or more Sn-based filaments 42. The first stabilizing matrix 41 is made of Cu or a Cu-based alloy. The Sn-based filaments 42 are made of Sn or a Sn-based alloy and are embedded in the first stabilizing matrix 41. By carrying out a heat treatment for generating a compound superconducting phase 73 (described later), Sn in the Sn-based filaments 42 reacts with an Nb-based superconducting filament precursor 53 in the Nb-based superconducting element wire precursor 50 to form Nb ３ The compound superconducting phase 73 is made of Sn. ３ In the Sn superconducting wire 2, when the Sn-based element wire 40 is heat treated, Sn diffuses, so that the Sn-based filaments 42 no longer exist as filaments, turn bronze, and become partially hollow.
[0026] In Figure 1, an example is shown in which each of the multiple Sn-based element wires 40 has only a single Sn-based filament 42, but it may also have only multiple Sn-based filaments 42, or it may have a mixture of a single Sn-based filament 42 and multiple Sn-based filaments 42.
[0027] Each of the plurality of Nb-based superconducting element wire precursors 50 includes a second stabilizing matrix 51, a plurality of Nb-based reinforcing filaments 52, and a plurality of Nb-based superconducting filament precursors 53. The second stabilizing matrix 51 is made of Cu or a Cu-based alloy. The plurality of Nb-based reinforcing filaments 52 and the plurality of Nb-based superconducting filament precursors 53 are both made of Nb or an Nb-based alloy and are embedded in the second stabilizing matrix 51.
[0028] The diameter of the Nb-based superconducting filament precursor 53 is larger than the diameter of the Nb-based reinforcing filament 52. For example, the diameter of the Nb-based reinforcing filament 52 is 0.04 μm or more and 0.30 μm or less, and the diameter of the Nb-based superconducting filament precursor 53 is 1 μm or more and 10 μm or less.
[0029] In addition, Nb ３In a cross section perpendicular to the axial direction of the Sn superconducting wire precursor 1, the ratio of the total area of the plurality of Nb-based reinforcing filaments 52 to the area of an Nb-based reinforcing filament assembly 52a in which the plurality of Nb-based reinforcing filaments 52 are aggregated is smaller than the ratio of the total area of the plurality of Nb-based superconducting filaments 52 to the area of an Nb-based superconducting filament assembly precursor 53a in which the plurality of Nb-based superconducting filament precursors 53 are aggregated. For example, the ratio of the total area of the plurality of Nb-based reinforcing filaments 52 to the area of the Nb-based reinforcing filament assembly 52a is 0.1 or more and 0.5 or less, and the ratio of the total area of the plurality of Nb-based superconducting filament precursors 53 to the area of the Nb-based superconducting filament assembly precursor 53a is 0.6 or more and 0.9 or less. Here, the Nb-based reinforcing filament assembly 52a is defined as including a plurality of Nb-based reinforcing filaments 52, as well as a second stabilizing matrix 51 present between the plurality of Nb-based reinforcing filaments 52, but not including any second stabilizing matrix 51 that is not sandwiched between the plurality of Nb-based reinforcing filaments 52. Also, the Nb-based superconducting filament assembly precursor 53a is defined as including a plurality of Nb-based superconducting filament precursors 53, as well as a second stabilizing matrix 51 present between the plurality of Nb-based superconducting filament precursors 53, but not including any second stabilizing matrix 51 that is not sandwiched between the plurality of Nb-based superconducting filament precursors 53.
[0030] By carrying out a heat treatment for generating the compound superconducting phase 73 described later, all or part of the Nb-based superconducting filament precursor 53 reacts with Sn diffused from the Sn-based filament 42 to form Nb ３ A filament-shaped compound superconducting phase 73 made of Sn is formed.
[0031] In this way, by providing a plurality of Nb-based reinforcing filaments 52 in the Nb-based superconducting element wire precursor 50, Nb ３ Sn superconducting wire precursor 1 and Nb ３ The Sn superconducting wire has high mechanical strength against axial tensile stress. ３ The decrease in the critical current density Jc of the Sn superconducting wire can be suppressed.３ Sn superconducting wire precursor 1 and Nb ３ When a radial compressive stress is applied to the Sn superconducting wire, the second stabilizing matrix 51 in the portion where the Nb-based reinforcing filaments 52 are embedded, in other words, the second stabilizing matrix 51 in the Nb-based reinforcing filament aggregate 52a, is preferentially deformed. Therefore, the superconducting filaments are less damaged during twisting and rolling, and the Nb ３ In this way, damage to the superconducting filament precursor due to twisting or rolling can be suppressed, and therefore the superconducting filaments are protected. ３ The Sn superconducting wire can exhibit a high critical current density Jc.
[0032] Furthermore, both the Nb-based reinforcing filament 52 and the Nb-based superconducting filament precursor 53 are made of Nb or an Nb-based alloy, which makes it possible to avoid deterioration in workability due to adjacent members with different mechanical properties.
[0033] As shown in FIG. ３ In a cross section perpendicular to the axial direction of the Sn superconducting wire precursor 1, in each of the plurality of Nb-based superconducting element wire precursors 50, it is preferable that an Nb-based reinforcing filament assembly 52a in which a plurality of Nb-based reinforcing filaments 52 are aggregated is arranged in the center, and an Nb-based superconducting filament assembly precursor 53a in which a plurality of Nb-based superconducting filament precursors 53 are aggregated is arranged on the periphery. In this case, the annular Nb-based superconducting filament assembly precursor 53a arranged around the entire periphery of the Nb-based superconducting element wire precursor 50 covers the periphery of the Nb-based reinforcing filament assembly 52a arranged in the center of the Nb-based superconducting element wire precursor 50. With this configuration, the Nb ３ The heat treatment for generating the compound superconducting phase 73 made of Sn is performed ３ When the Sn superconducting wire precursor 1 is subjected to the treatment, the Sn diffused from the Sn-based filaments 42 reacts preferentially with the plurality of Nb-based superconducting filament precursors 53, thereby forming high-quality Nb. ３ The Sn compound superconducting phase 73 is easily formed.
[0034] FIG. 2 shows the Nb ３ 2 is a cross-sectional view showing another example of an Nb-based superconducting element wire precursor constituting a precursor for an Sn superconducting wire. ３ In a cross section perpendicular to the axial direction of the Sn superconducting wire precursor 1, the Sn superconducting wire precursor 1 preferably further comprises a second Sn diffusion barrier layer 54 made of a pure metal or alloy containing Ta or Nb, which is provided between the Nb-based reinforcing filament assembly 52a and the Nb-based superconducting filament assembly precursor 53a. In this case, the second Sn diffusion barrier layer 54 completely covers the periphery of the Nb-based reinforcing filament assembly 52a. The second Sn diffusion barrier layer 54 is cylindrical, and the Nb ３ The Sn superconducting wire precursor 1 has a ring shape in a cross section perpendicular to the axial direction.
[0035] In the configuration shown in FIG. 2, during the heat treatment for generating the compound superconducting phase 73 described later, Sn in the Sn-based filaments 42 diffuses into the Nb-based reinforcing filament aggregates 52a and reacts with the Nb-based reinforcing filaments 52, resulting in the formation of Nb. ３ In other words, even if heat treatment is performed, the formation of Nb, which has low tensile strength, from the Nb-based reinforcing filaments 52 is further suppressed. ３ Suppresses the reaction with the compound superconducting phase made of Sn. ３ Sn superconducting wire precursor 1 and Nb ３ This can further suppress the reduction in mechanical strength of the Sn superconducting wire against tensile stress in the axial direction.
[0036] Next, Nb ３ The heat treatment for generating the compound superconducting phase 73 made of Sn is performed ３ Nb obtained by applying to the precursor 1 for Sn superconducting wire ３ The Sn superconducting wire 2 will be described. ３ The precursor for Sn superconducting wire 1 is heated to form Nb ３ 4 is a cross-sectional view showing an Sn superconducting wire 2. Fig. 4 is a cross-sectional view showing an Nb-based superconducting element wire 70a obtained by heating the Nb-based superconducting element wire precursor 50a of Fig. 2.
[0037] As shown in FIG.３ Nb, which is a heating product of the precursor 1 for Sn superconducting wire ３ The Sn superconducting wire 2 includes a cylindrical stabilizing copper layer 10 , a cylindrical first Sn diffusion barrier layer 20 , and a group of superconducting elements 60 .
[0038] Nb ３ The stabilizing copper layer 10 and the first Sn diffusion barrier layer 20 of the Sn superconducting wire 2 are made of Nb ３ The structure is the same as that of the stabilizing copper layer 10 and the first Sn diffusion barrier layer 20 of the precursor 1 for a Sn superconducting wire.
[0039] The superconducting element group 60 is housed inside the first Sn diffusion barrier layer 20. As shown in FIGS. 3 and 4, the superconducting element group 60 includes a plurality of Nb-based superconducting element wires 70, 70a.
[0040] Each of the plurality of Nb-based superconducting element wires 70, 70a includes a second stabilizing matrix 51 made of Cu or a Cu-based alloy, a plurality of Nb-based reinforcing filaments 52 made of Nb or an Nb-based alloy, and a plurality of superconducting filaments 80. The plurality of Nb-based reinforcing filaments 52 and the plurality of superconducting filaments 80 are both embedded in the second stabilizing matrix 51.
[0041] Each of the plurality of superconducting filaments 80 is made of Nb ３ The superconducting filaments 80 have a compound superconducting phase 73 made of Sn. The diameter of the superconducting filaments 80 is larger than the diameter of the Nb-based reinforced filaments 52. For example, the diameter of the Nb-based reinforced filaments 52 is 0.04 μm or more and 0.30 μm or less, and the diameter of the superconducting filaments 80 is 1 μm or more and 10 μm or less.
[0042] In addition, Nb ３In a cross section perpendicular to the axial direction of the Sn superconducting wire 2, the ratio of the total area of the plurality of Nb-based reinforced filaments 52 to the area of an Nb-based reinforced filament assembly 52a in which the plurality of Nb-based reinforced filaments 52 are aggregated is smaller than the ratio of the total area of the plurality of superconducting filaments 80 to the area of a superconducting filament assembly 80a in which the plurality of superconducting filaments 80 are aggregated. For example, the ratio of the total area of the plurality of Nb-based reinforced filaments 52 to the area of the Nb-based reinforced filament assembly 52a is 0.1 or more and 0.5 or less, and the ratio of the total area of the plurality of superconducting filaments 80 to the area of the superconducting filament assembly 80a is 0.6 or more and 0.9 or less. Here, the superconducting filament assembly 80a is defined as including the plurality of superconducting filaments 80 and second stabilizing matrices 51 present between the plurality of superconducting filaments 80, but excluding second stabilizing matrices 51 that are not sandwiched between the plurality of superconducting filaments 80.
[0043] 3 and 4 show Nb-based superconducting element wires 70 and 70a manufactured by the internal diffusion method. ３ Sn superconducting wire precursor 1 to Nb ３ When heat treatment is performed to generate the compound superconducting phase 73 made of Sn, Sn diffused from the Sn-based filament 42 reacts with Nb on the surface of the Nb-based superconducting filament precursor 53, and the compound superconducting phase 73 is formed by the reaction of Nb ３ Sn filaments can be produced. ３ The Sn superconducting wire 2 does not have the Sn-based filaments 42. ３ The heat treatment of the Sn superconducting wire precursor 1 is carried out in an inert gas atmosphere such as argon or nitrogen.
[0044] 3 and 4 show examples in which the Nb-based superconducting element wires 70 and 70a have central portions of Nb-based superconducting filament precursors 53 remaining without reacting with Sn present in the superconducting filaments 80. However, depending on the amount of Sn contained in the Sn-based filaments 42 and the diameter size of the Nb-based superconducting filament precursors 53, the Nb-based superconducting filament precursors 53 may not be present in the superconducting filaments 80, i.e., the superconducting filaments 80 may consist of a compound superconducting phase 73.
[0045] Thus, Nb ３ The Sn superconducting wire 2 has high mechanical strength against tensile stress in the axial direction because the Nb-based superconducting element wires 70, 70a are provided with a plurality of Nb-based reinforcing filaments 52. ３ When a compressive stress in the radial direction is applied to the precursor 1 for a Sn superconducting wire, the second stabilizing matrix 51 in the portion where the Nb-based reinforcing filaments 52 are embedded is preferentially deformed. ３ Nb during twisting and rolling of Sn superconducting wire precursor 1 ３ Since the superconducting filaments 80 of the Sn superconducting wire 2 are less damaged, a decrease in the critical current density Jc can be suppressed. ３ Even if the precursor 1 for the Sn superconducting wire is subjected to twisting or rolling, the Nb ３ The Sn superconducting wire 2 can exhibit a high critical current density Jc.
[0046] Furthermore, both the Nb-based reinforcing filament 52 and the Nb-based superconducting filament precursor 53 are made of Nb or an Nb-based alloy, which makes it possible to avoid deterioration in workability due to adjacent members with different mechanical properties.
[0047] In addition, Nb ３ As with the precursor 1 for Sn superconducting wire, the Nb ３In a cross section perpendicular to the axial direction of the Sn superconducting wire 2, in each of the plurality of Nb-based superconducting element wires 70, 70a, it is preferable that an Nb-based reinforcing filament assembly 52a where a plurality of Nb-based reinforcing filaments 52 are gathered is arranged in the center, and a superconducting filament assembly 80a where a plurality of superconducting filaments 80 are gathered is arranged on the periphery. In this case, the annular superconducting filament assembly 80a arranged around the entire periphery of the Nb-based superconducting element wires 70, 70a covers the periphery of the Nb-based reinforcing filament assembly 52a arranged in the center of the Nb-based superconducting element wires 70, 70a. With this configuration, the Nb ３ Since Sn diffused from the Sn-based filaments 42 of the Sn superconducting wire precursor 1 reacts preferentially with the plurality of Nb-based superconducting filament precursors 53, Nb ３ The Sn superconducting wire 2 is made of high-quality Nb ３ It has a Sn compound superconducting phase 73 .
[0048] Nb ３ The Sn superconducting wire 2 has high superconducting properties, strength against axial tensile stress, and resistance to deformation of the superconducting filaments due to radial compressive stress. ３ The Sn superconducting wire 2 is suitably used as a superconducting wire constituting a high-magnetic field superconducting magnet used in large accelerators, nuclear fusion reactors, analytical devices, and the like.
[0049] According to the first embodiment described above, Nb ３ In the precursor for the Sn superconducting wire, a plurality of Nb-based superconducting element wire precursors constituting the superconducting element group precursors housed inside the diffusion barrier layer are configured to have a predetermined structure, thereby ３ Nb obtained by heat treating precursor for Sn superconducting wire ３ Sn superconducting wire can have high mechanical strength, which can suppress the decrease in critical current density Jc caused by axial tensile stress and radial compressive stress, and can also suppress damage to the superconducting filament precursor due to twisting and rolling processes.
[0050] (Second embodiment) FIG. 5 shows the Nb ３FIG. 2 is a cross-sectional view showing an example of a precursor for a Sn superconducting wire.
[0051] In the following embodiment, the Nb ３ Sn superconducting wire precursor and Nb ３ The same components as those of the Sn superconducting wire are denoted by the same reference numerals, and redundant explanations will be omitted or simplified.
[0052] Nb in the second embodiment ３ The Nb-based superconducting element wire precursor 50b of the Sn superconducting wire precursor 1a and the Nb ３ The Nb-based superconducting element wire 70b of the Sn superconducting wire 2a is the same as that of the Nb-based superconducting element wire 70b of the first embodiment except that the configuration of the Nb-based superconducting element wire 70b is different. ３ Sn superconducting wire precursor 1 and Nb ３ The configuration is basically the same as that of the Sn superconducting wire 2. Therefore, the different configuration will be mainly described here.
[0053] As shown in FIG. 5, in the second embodiment, Nb ３ The Sn superconducting wire precursor 1a includes a cylindrical stabilizing copper layer 10, a cylindrical first Sn diffusion barrier layer 20, and a superconducting element group precursor 30. The superconducting element group precursor 30 includes a plurality of Sn-based element wires 40 and a plurality of Nb-based superconducting element wire precursors 50b.
[0054] The plurality of Nb-based superconducting element wire precursors 50 b include a plurality of Nb-based strengthening sub-elements 55 and a plurality of Nb-based superconducting sub-element precursors 57 .
[0055] Each of the plurality of Nb-based reinforcing sub-elements 55 includes a third stabilizing matrix 56 and a plurality of Nb-based reinforcing filaments 52. The third stabilizing matrix 56 is made of Cu or a Cu-based alloy. The plurality of Nb-based reinforcing filaments 52 are made of Nb or an Nb-based alloy and are embedded in the third stabilizing matrix 56.
[0056] Each of the plurality of Nb-based superconducting subelement precursors 57 has a fourth stabilizing matrix 58 and a plurality of Nb-based superconducting filament precursors 53. The fourth stabilizing matrix 58 is made of Cu or a Cu-based alloy. The plurality of Nb-based superconducting filament precursors 53 are made of Nb or an Nb-based alloy and are embedded in the fourth stabilizing matrix 58.
[0057] A third stabilizing matrix 56 of the Nb-based reinforced subelement 55 is provided with a plurality of Nb-based reinforced filaments 52, but is not provided with Nb-based superconducting filament precursors 53. A fourth stabilizing matrix 58 of the Nb-based superconducting subelement precursor 57 is provided with a plurality of Nb-based superconducting filament precursors 53, but is not provided with Nb-based reinforced filaments 52. In other words, the Nb-based reinforced filaments 52 and the Nb-based superconducting filament precursors 53 are provided in different subelements (subelement precursors).
[0058] Nb ３ As with the precursor 1 for Sn superconducting wire, Nb ３ In the Sn superconducting wire precursor 1a, the diameter of the Nb-based superconducting filament precursors 53 embedded in the fourth stabilizing matrix 58 is also larger than the diameter of the Nb-based reinforcing filaments 52 embedded in the third stabilizing matrix 56. For example, the diameter of the Nb-based reinforcing filaments 52 is 0.04 μm or more and 0.30 μm or less, and the diameter of the Nb-based superconducting filament precursors 53 is 1 μm or more and 10 μm or less.
[0059] In addition, Nb ３In a cross section perpendicular to the axial direction of the Sn superconducting wire precursor 1a, the ratio of the total area of the plurality of Nb-based superconducting filaments 52 to the area of the Nb-based reinforcing filament assembly 52a in which the plurality of Nb-based reinforcing filaments 52 are aggregated is smaller than the ratio of the total area of the plurality of Nb-based superconducting filaments 52 to the area of the Nb-based reinforcing filament assembly 52a in which the plurality of Nb-based reinforcing filaments 52 are aggregated. For example, the ratio of the total area of the plurality of Nb-based reinforcing filaments 52 to the area of the Nb-based reinforcing filament assembly 52a is 0.1 or more and 0.5 or less, and the ratio of the total area of the plurality of Nb-based superconducting filament precursors 53 to the area of the Nb-based superconducting filament assembly precursor 53a is 0.6 or more and 0.9 or less. ３ The Nb-based reinforcing filament assembly 52a in the Sn superconducting wire precursor 1a is defined as including a plurality of Nb-based reinforcing filaments 52 and a third stabilizing matrix 56 present between the plurality of Nb-based reinforcing filaments 52, but not including any third stabilizing matrix 56 that is not sandwiched between the plurality of Nb-based reinforcing filaments 52. ３ The Nb-based superconducting filament assembly precursor 53a in the Sn superconducting wire precursor 1a is defined as including a plurality of Nb-based superconducting filament precursors 53, as well as a fourth stabilizing matrix 58 present between the plurality of Nb-based superconducting filament precursors 53, but not including any fourth stabilizing matrix 58 that is not sandwiched between the plurality of Nb-based superconducting filament precursors 53.
[0060] By carrying out a heat treatment for generating the compound superconducting phase 73 described later, all or part of the Nb-based superconducting filament precursor 53 reacts with Sn diffused from the Sn-based filament 42 to form Nb ３ A filament-shaped compound superconducting phase 73 made of Sn is formed.
[0061] In this way, by providing a plurality of Nb-based reinforcing filaments 52 in the Nb-based superconducting element wire precursor 50b, Nb ３ Sn superconducting wire precursor 1a and Nb ３ The Sn superconducting wire has high mechanical strength against tensile stress in the axial direction.３ Sn superconducting wire precursor 1 and Nb ３ When a radial compressive stress is applied to the Sn superconducting wire, the third stabilizing matrix 56 in which the Nb-based reinforcing filaments 52 are embedded, in other words, the third stabilizing matrix 56 of the Nb-based reinforcing filament assembly 52a, is preferentially deformed. Therefore, the superconducting filaments are less damaged during twisting and rolling, and the Nb ３ In this way, damage to the superconducting filament precursor due to twisting or rolling can be suppressed, and therefore the superconducting filaments are protected. ３ The Sn superconducting wire can exhibit a high critical current density Jc.
[0062] Furthermore, both the Nb-based reinforcing filament 52 and the Nb-based superconducting filament precursor 53 are made of Nb or an Nb-based alloy, which makes it possible to avoid deterioration in workability due to adjacent members with different mechanical properties.
[0063] In addition, Nb ３ In a cross section perpendicular to the axial direction of the Sn superconducting wire precursor 1a, it is preferable that the plurality of Nb-based superconducting subelement precursors 57 and the plurality of Sn-based element wires 40 are arranged in the center of the superconducting element group precursor 30, and the plurality of Nb-based strengthened subelements 55 are arranged on the outer periphery of the superconducting element group precursor 30. In this case, the plurality of Nb-based strengthened subelements 55 arranged in an annular shape around the entire outer periphery of the superconducting element group precursor 30 cover the periphery of the plurality of Nb-based superconducting subelement precursors 57 and the plurality of Sn-based element wires 40 arranged in the center of the superconducting element group precursor 30. With this configuration, the Nb ３ The heat treatment for generating the compound superconducting phase 73 made of Sn is performed ３ When the Sn superconducting wire precursor 1a is applied, Sn diffused from the Sn-based filaments 42 of the Sn-based element wire 40 reacts preferentially with the plurality of Nb-based superconducting filament precursors 53, thereby forming high-quality Nb ３ The Sn compound superconducting phase 73 is easily formed.
[0064] Next, Nb ３ The heat treatment for generating the compound superconducting phase 73 made of Sn is performed ３ Nb obtained by applying to the precursor 1a for Sn superconducting wire ３ The Sn superconducting wire 2a will be described. ３ The precursor for Sn superconducting wire 1a is heated to form Nb ３ FIG. 2 is a cross-sectional view showing a Sn superconducting wire 2a.
[0065] As shown in FIG. ３ Nb, which is a heat product of the precursor 1a for Sn superconducting wire ３ The Sn superconducting wire 2 a includes a cylindrical stabilizing copper layer 10 , a cylindrical first Sn diffusion barrier layer 20 , and a group of superconducting elements 60 .
[0066] The superconducting element group 60 includes a plurality of Nb-based superconducting element wires 70b. The plurality of Nb-based superconducting element wires 70b includes a plurality of Nb-based strengthened sub-elements 55 and a plurality of superconducting sub-elements 77.
[0067] Nb ３ The Nb-based strengthening sub-element 55 of the Sn superconducting wire 2a is made of Nb ３ The structure is the same as that of the Nb-based strengthening sub-element 55 of the Sn superconducting wire precursor 1a.
[0068] Each of the plurality of superconducting subelements 77 includes a fourth stabilizing matrix 58 and a plurality of superconducting filaments 80. The fourth stabilizing matrix 58 is made of Cu or a Cu-based alloy. The plurality of superconducting filaments 80 are embedded in the fourth stabilizing matrix 58.
[0069] Each of the plurality of superconducting filaments 80 is made of Nb ３ The third stabilizing matrix 56 has a compound superconducting phase 73 made of Sn. The diameter of the superconducting filaments 80 is larger than the diameter of the Nb-based reinforcing filaments 52 embedded in the third stabilizing matrix 56. For example, the diameter of the Nb-based reinforcing filaments 52 is 0.04 μm or more and 0.30 μm or less, and the diameter of the superconducting filaments 80 is 1 μm or more and 10 μm or less.
[0070] In addition, Nb ３In a cross section perpendicular to the axial direction of the Sn superconducting wire 2a, the ratio of the total area of the plurality of Nb-based reinforced filaments 52 to the area of an Nb-based reinforced filament assembly 52a in which the plurality of Nb-based reinforced filaments 52 are aggregated is smaller than the ratio of the total area of the plurality of superconducting filaments 80 to the area of a superconducting filament assembly 80a in which the plurality of superconducting filaments 80 are aggregated. For example, the ratio of the total area of the plurality of Nb-based reinforced filaments 52 to the area of the Nb-based reinforced filament assembly 52a is 0.1 or more and 0.5 or less, and the ratio of the total area of the plurality of superconducting filaments 80 to the area of the superconducting filament assembly 80a is 0.6 or more and 0.9 or less. ３ The superconducting filament assembly 80a in the Sn superconducting wire 2a is defined as including a plurality of superconducting filaments 80, as well as a fourth stabilizing matrix 58 present between the plurality of superconducting filaments 80, but not including any fourth stabilizing matrix 58 that is not sandwiched between the plurality of superconducting filaments 80.
[0071] The third stabilizing matrix 56 of the Nb-based reinforced sub-element 55 is provided with a plurality of Nb-based reinforced filaments 52 but is not provided with a superconducting filament 80. The fourth stabilizing matrix 58 of the superconducting sub-element 77 is provided with a plurality of superconducting filaments 80 but is not provided with an Nb-based reinforced filament 52. In other words, the Nb-based reinforced filaments 52 and the superconducting filaments 80 are provided in different sub-elements.
[0072] 6 shows a Nb-based superconducting element wire 70b manufactured by the internal diffusion method. ３ Sn superconducting wire precursor 1a and Nb ３ When heat treatment is performed to generate the compound superconducting phase 73 made of Sn, Sn diffused from the Sn-based filament 42 reacts with Nb on the surface of the Nb-based superconducting filament precursor 53, and the compound superconducting phase 73 is formed by the reaction of Nb ３ Sn filaments can be produced. ３ The Sn superconducting wire 2a does not have the Sn-based filament 42. ３The heat treatment of the Sn superconducting wire precursor 1a is carried out in an inert gas atmosphere such as argon or nitrogen.
[0073] 6 shows an example in which the Nb-based superconducting element wire 70b has the central portion of the Nb-based superconducting filament precursor 53 remaining without reacting with Sn present in the superconducting filament 80. However, depending on the amount of Sn contained in the Sn-based filament 42 and the diameter size of the Nb-based superconducting filament precursor 53, the Nb-based superconducting filament precursor 53 may not be present in the superconducting filament 80, i.e., the superconducting filament 80 may consist of a compound superconducting phase 73.
[0074] Thus, Nb ３ The Sn superconducting wire 2a has a high mechanical strength against tensile stress in the axial direction because the Nb-based superconducting element wire 70b includes a plurality of Nb-based reinforcing filaments 52. ３ When a radial compressive stress is applied to the Sn superconducting wire precursor 1a, the third stabilizing matrix 56 in which the Nb-based reinforcing filaments 52 are embedded is preferentially deformed. ３ Nb during twisting and rolling of Sn superconducting wire precursor 1a ３ The damage to the superconducting filaments 80 of the Sn superconducting wire 2a is small, and the Nb ３ The reduction in the critical current density Jc of the Sn superconducting wire 2a can be suppressed. ３ Even if the Sn superconducting wire precursor 1a is subjected to twisting or rolling, ３ The Sn superconducting wire 2a can exhibit a high critical current density Jc.
[0075] Furthermore, both the Nb-based reinforcing filament 52 and the Nb-based superconducting filament precursor 53 are made of Nb or an Nb-based alloy, which makes it possible to avoid deterioration in workability due to adjacent members with different mechanical properties.
[0076] In addition, Nb ３ As with the Sn superconducting wire precursor 1a, Nb ３In a cross section perpendicular to the axial direction of the Sn superconducting wire 2a, it is preferable that the plurality of superconducting subelements 77 and the plurality of Sn-based element wires 40 are arranged in the center of the superconducting element group 60, and the plurality of Nb-based reinforced subelements 55 are arranged on the outer periphery of the superconducting element group 60. In this case, the plurality of Nb-based reinforced subelements 55 arranged in an annular shape around the entire outer periphery of the superconducting element group 60 cover the periphery of the plurality of superconducting subelements 77 and the plurality of Sn-based element wires 40 arranged in the center of the superconducting element group 60. With this configuration, Sn diffused from the Sn-based filaments 42 reacts preferentially with the plurality of Nb-based superconducting filament precursors 53, so that Nb ３ The Sn superconducting wire 2a is made of high-quality Nb ３ It has a Sn compound superconducting phase 73 .
[0077] According to the second embodiment described above, even if the Nb-based reinforced filaments 52 and the superconducting filaments 80 are provided in different sub-elements, the Nb ３ Nb obtained by heat treating precursor for Sn superconducting wire ３ Sn superconducting wire can have high mechanical strength, which can suppress the decrease in critical current density Jc caused by axial tensile stress and radial compressive stress, and can also suppress damage to the superconducting filament precursor due to twisting and rolling processes.
[0078] In the first embodiment, the Nb-based superconducting element wire precursors 50 and 50a are provided. ３ In the second embodiment, a Nb-based superconducting element wire precursor 50b is shown. ３ Although the precursor 1a for Sn superconducting wire is shown, Nb ３ The Sn superconducting wire precursor may include at least one of the Nb-based superconducting element wire precursor 50, the Nb-based superconducting element wire precursor 50a, and the Nb-based superconducting element wire precursor 50b. ３The precursor for the Sn superconducting wire may include two types, namely, an Nb-based superconducting element wire precursor 50 and an Nb-based superconducting element wire precursor 50a, or may include three types, namely, an Nb-based superconducting element wire precursor 50, an Nb-based superconducting element wire precursor 50a, and an Nb-based superconducting element wire precursor 50b.
[0079] In the first embodiment, the Nb-based superconducting element wires 70 and 70a are used. ３ In the second embodiment, the Sn superconducting wire 2 is shown, and in the second embodiment, the Nb superconducting element wire 70b is shown. ３ Although the Sn superconducting wire 2a is shown, the Nb ３ The Sn superconducting wire may include at least one of the Nb-based superconducting element wire 70, the Nb-based superconducting element wire 70a, and the Nb-based superconducting element wire 70b. ３ The Sn superconducting wire may include two types of Nb-based superconducting element wire 70 and Nb-based superconducting element wire 70a, or three types of Nb-based superconducting element wire 70, Nb-based superconducting element wire 70a, and Nb-based superconducting element wire 70b.
[0080] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure.
[0081] Next, examples and comparative examples will be described, but the present disclosure is not limited to these examples.
[0082] Example 1: Nb superconducting element wire precursor 50 as shown in FIG. ３ The present invention relates to a precursor for a Sn superconducting wire and a Nb superconducting element wire 70 as shown in FIG. ３ An Sn superconducting wire was produced.
[0083] First, a Sn-Ti rod (Sn-1.7 wt% Ti, diameter 24.5 mm) was inserted into a copper tube (oxygen-free copper, outer diameter 30.0 mmφ, inner diameter 24.5 mmφ) and drawn several times to form a Sn-based element wire with a flat length of 2.24 mmH.
[0084] In addition, a Nb rod (pure Nb, diameter 24.3 mm) was inserted into a copper tube (oxygen-free copper, outer diameter 27.5 mm, inner diameter 24.5 mm) and drawn multiple times to form a hexagonal Nb-based superconducting filament wire with a face-to-face length of 1.71 mmH.
[0085] In addition, an Nb rod (pure Nb, diameter 103.0 mmφ) was inserted into a copper tube (oxygen-free copper, outer diameter 214.0 mmφ, inner diameter 103.7 mmφ), extruded, and then drawn and stripped multiple times to form an Nb-based reinforced filament primary hexagonal wire with a face-to-face length of 13.4 mmH.
[0086] Next, 109 of the above-mentioned Nb-based reinforced filament primary hexagonal wires were inserted into a copper tube (oxygen-free copper, outer diameter 214.0 mmφ, inner diameter 166.0 mmφ), and the tube was subjected to HIP (hot isostatic pressing), external cutting, extrusion, and further subjected to multiple wire drawing and peeling processes to form an Nb-based reinforced filament secondary hexagonal wire with a face length of 1.71 mmH.
[0087] Next, 37 of the above-mentioned Nb-based reinforced filament secondary hexagonal wires and 114 of the above-mentioned Nb-based superconducting filament hexagonal wires were inserted into a copper tube (oxygen-free copper, outer diameter 27.5 mmφ, inner diameter 24.5 mmφ) in an arrangement such that the aggregate of the Nb-based reinforced filament secondary hexagonal wires was surrounded by the aggregate of the Nb-based superconducting filament hexagonal wires. After HIP and external cutting, the tube was extruded and further drawn several times to form an Nb-based superconducting element wire with a face length of 2.24 mmH.
[0088] Next, 19 of the Sn-based element wires and 36 of the Nb-based superconducting element wires were inserted into a copper tube (oxygen-free copper, outer diameter 30.0 mmφ, inner diameter 20.0 mmφ) in an arrangement such that the Sn-based element wires were not adjacent to each other, and after CIP (cold isostatic pressing) and external cutting, a Nb superconducting element wire with a diameter of 0.6 mmφ was drawn multiple times. ３ A precursor for Sn superconducting wire was formed. ３ In the precursor for the Sn superconducting wire, the diameter of the Nb-based superconducting filament precursor was larger than the diameter of the Nb-based reinforcing filament.
[0089] Next, the obtained Nb ３For Sn superconducting wire precursor, Nb ３ To produce a compound superconducting phase consisting of Sn, the alloy was subjected to a heat treatment of heating at 210°C for 6 hours, followed by heating at 350°C for 18 hours, then heating at 480°C for 28 hours, then heating at 570°C for 180 hours, and then heating at 665°C for 200 hours. ３ Sn superconducting wire was obtained. ３ In the Sn superconducting wire, the diameter of the superconducting filaments was larger than the diameter of the Nb-based reinforcing filaments.
[0090] The obtained Nb ３ The Sn superconducting wire had high mechanical strength, which could suppress the decrease in critical current density Jc caused by axial tensile stress and radial compressive stress, and could also suppress damage to the superconducting filament precursor due to twisting and rolling processes.
[0091] Example 2: Nb-based superconducting element wire precursor 50a as shown in FIG. ３ The precursor for the Sn superconducting wire and the Nb superconducting element wire 70a as shown in FIG. ３ An Sn superconducting wire was produced.
[0092] First, a Sn-Ti rod (Sn-1.7 wt% Ti, diameter 24.5 mm) was inserted into a copper tube (oxygen-free copper, outer diameter 30.0 mmφ, inner diameter 24.5 mmφ) and drawn several times to form a Sn-based element wire with a flat length of 2.24 mmH.
[0093] In addition, a Nb rod (pure Nb, diameter 24.3 mm) was inserted into a copper tube (oxygen-free copper, outer diameter 27.5 mm, inner diameter 24.5 mm) and drawn multiple times to form a hexagonal Nb-based superconducting filament wire with a face-to-face length of 1.71 mmH.
[0094] In addition, an Nb rod (pure Nb, diameter 103.0 mmφ) was inserted into a copper tube (oxygen-free copper, outer diameter 214.0 mmφ, inner diameter 103.7 mmφ), extruded, and then drawn and stripped multiple times to form an Nb-based reinforced filament primary hexagonal wire with a face-to-face length of 13.4 mmH.
[0095] Next, 109 of the above-mentioned Nb-based reinforced filament primary hexagonal wires were inserted into a copper tube (oxygen-free copper, outer diameter 214.0 mmφ, inner diameter 166.0 mmφ), and the tube was subjected to HIP, external cutting, and then extrusion processing. Further, multiple wire drawing and peeling processing were performed to form a Nb-based reinforced filament secondary hexagonal wire with a face length of 1.71 mmH.
[0096] Next, a 0.1 mm thick Nb foil was wrapped around 19 of the above-mentioned Nb-based reinforced filament secondary hexagonal wires twice around a copper tube (oxygen-free copper, outer diameter 27.5 mmφ, inner diameter 24.5 mmφ), and a wire assembly in which 114 of the above-mentioned Nb-based superconducting filament hexagonal wires were arranged around the Nb foil was inserted into the tube, and the tube was subjected to HIP and external cutting, followed by extrusion processing, and further wiredrawing processing multiple times to form an Nb-based superconducting element wire with a face length of 2.24 mmH.
[0097] Next, 19 of the Sn-based element wires and 36 of the Nb-based superconducting element wires were inserted into a copper tube (oxygen-free copper, outer diameter 30.0 mmφ, inner diameter 20.0 mmφ) in an arrangement such that the Sn-based element wires were not adjacent to each other, and after CIP and external cutting, a Nb superconducting element wire with a diameter of 0.6 mmφ was drawn multiple times. ３ A precursor for Sn superconducting wire was formed. ３ In the precursor for the Sn superconducting wire, the diameter of the Nb-based superconducting filament precursor was larger than the diameter of the Nb-based reinforcing filament.
[0098] Next, the obtained Nb ３ For Sn superconducting wire precursor, Nb ３ To produce a compound superconducting phase consisting of Sn, the alloy was subjected to a heat treatment of heating at 210°C for 6 hours, followed by heating at 350°C for 18 hours, then heating at 480°C for 28 hours, then heating at 570°C for 180 hours, and then heating at 665°C for 200 hours. ３ Sn superconducting wire was obtained. ３ In the Sn superconducting wire, the diameter of the superconducting filaments was larger than the diameter of the Nb-based reinforcing filaments.
[0099] The obtained Nb ３The Sn superconducting wire had high mechanical strength, which could suppress the decrease in critical current density Jc caused by axial tensile stress and radial compressive stress, and could also suppress damage to the superconducting filament precursor due to twisting and rolling processes.
[0100] Example 3: Nb-based superconducting element wire precursor 50b as shown in FIG. ３ The precursor for the Sn superconducting wire and the Nb superconducting element wire 70b as shown in FIG. ３ An Sn superconducting wire was produced.
[0101] First, a Sn-Ti rod (Sn-1.7 wt% Ti, diameter 24.5 mm) was inserted into a copper tube (oxygen-free copper, outer diameter 30.0 mmφ, inner diameter 24.5 mmφ) and drawn several times to form a Sn-based element wire with a flat length of 2.24 mmH.
[0102] Furthermore, an Nb rod (pure Nb, diameter 24.3 mm) was inserted into a copper tube (oxygen-free copper, outer diameter 27.5 mm, inner diameter 24.5 mm) and drawn multiple times to form a hexagonal Nb-based superconducting filament wire having a face-to-face length of 1.71 mmH. Next, 151 of the above-mentioned hexagonal Nb-based superconducting filament wires were inserted into a copper tube (oxygen-free copper, outer diameter 27.5 mm, inner diameter 24.5 mm), subjected to HIP and external cutting, and then extruded. Further, an Nb-based superconducting subelement wire having a face-to-face length of 2.24 mmH was formed by drawing multiple times.
[0103] Furthermore, a Nb rod (pure Nb, diameter 103.0 mm) was inserted into a copper tube (oxygen-free copper, outer diameter 214.0 mm, inner diameter 103.7 mm), extruded, and then subjected to wiredrawing and scalping multiple times to form a primary hexagonal Nb-based reinforced filament wire with a face-to-face length of 13.4 mmH. Next, 109 of the above primary hexagonal Nb-based reinforced filament wires were inserted into a copper tube (oxygen-free copper, outer diameter 214.0 mm, inner diameter 166.0 mm), subjected to HIP and external cutting, extruded, and further subjected to wiredrawing and scalping multiple times to form a secondary hexagonal Nb-based reinforced filament wire with a face-to-face length of 1.71 mmH. Next, 151 of the above-mentioned Nb-based reinforced filament secondary hexagonal wires were inserted into a copper tube (oxygen-free copper, outer diameter 27.5 mmφ, inner diameter 24.5 mmφ), and the tube was subjected to HIP, external cutting, extrusion, and further wiredrawing multiple times to form an Nb-based reinforced sub-element wire with a face-to-face length of 2.24 mmH.
[0104] Next, seven of the Sn-based element wires, 30 of the Nb-based superconducting sub-element wires, and 18 of the Nb-based reinforced sub-element wires were inserted into a copper tube (oxygen-free copper, outer diameter 30.0 mmφ, inner diameter 20.0 mmφ) in such a way that the Sn-based element wires were not adjacent to each other and the Nb-based reinforced sub-element wires were positioned on the outer periphery of the element wire assembly. After CIP and external cutting, a Nb-based superconducting sub-element wire with a diameter of 0.6 mmφ was obtained by wiredrawing several times. ３ A precursor for Sn superconducting wire was formed. ３ In the precursor for the Sn superconducting wire, the diameter of the Nb-based superconducting filament precursor was larger than the diameter of the Nb-based reinforcing filament.
[0105] Next, the obtained Nb ３ For Sn superconducting wire precursor, Nb ３ To produce a compound superconducting phase consisting of Sn, the alloy was subjected to a heat treatment of heating at 210°C for 6 hours, followed by heating at 350°C for 18 hours, then heating at 480°C for 28 hours, then heating at 570°C for 180 hours, and then heating at 665°C for 200 hours. ３ Sn superconducting wire was obtained. ３ In the Sn superconducting wire, the diameter of the superconducting filaments was larger than the diameter of the Nb-based reinforcing filaments.
[0106] The obtained Nb ３ The Sn superconducting wire had high mechanical strength, which could suppress the decrease in critical current density Jc caused by axial tensile stress and radial compressive stress, and could also suppress damage to the superconducting filament precursor due to twisting and rolling processes.
[0107] 1, 1a Nb ３ Precursor for Sn superconducting wire 2, 2a Nb ３ Sn superconducting wire 10 stabilizing copper layer 20 first Sn diffusion barrier layer 30 superconducting element group precursor 40 Sn-based element wire 41 first stabilizing matrix 42 Sn-based filament 50, 50a, 50b Nb-based superconducting element wire precursor 51 second stabilizing matrix 52 Nb-based reinforcing filament 52a Nb-based reinforcing filament assembly 53 Nb-based superconducting filament precursor 53a Nb-based superconducting filament assembly precursor 54 second Sn diffusion barrier layer 55 Nb-based reinforcing sub-element 56 third stabilizing matrix 57 Nb-based superconducting sub-element precursor 58 fourth stabilizing matrix 60 superconducting element group 70, 70a, 70b Nb-based superconducting element wire 73 compound superconducting phase 77 superconducting sub-element 80 superconducting filament 80a Superconducting filament assembly
Claims
1. A cylindrical stabilizing copper layer provided on the outer periphery, a cylindrical first Sn diffusion barrier layer provided inside the stabilizing copper layer, and a superconducting element group precursor housed inside the first Sn diffusion barrier layer, the superconducting element group precursor comprising a plurality of Sn-based element wires and a plurality of Nb-based superconducting element wire precursors, the plurality of Sn-based element wires comprising a first stabilizing matrix made of Cu or a Cu-based alloy and one or more Sn-based filaments embedded in the first stabilizing matrix and made of Sn or a Sn-based alloy, the plurality of Nb-based superconducting element wire precursors comprising a second stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing filaments and a plurality of Nb-based superconducting filament precursors having a diameter larger than that of the Nb-based reinforcing filaments, the plurality of Nb-based reinforcing filaments being embedded in the second stabilizing matrix and made of Nb or a Nb-based alloy, and / or a third stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcement subelements having a plurality of Nb-based reinforcement filaments made of Nb or a Nb-based alloy embedded in the third stabilizing matrix; a fourth stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based superconducting subelement precursors having a plurality of Nb-based superconducting filament precursors made of Nb or a Nb-based alloy and having a diameter larger than that of the Nb-based reinforcement filaments embedded in the fourth stabilizing matrix; ３ Precursor for Sn superconducting wire.
2. The Nb ３ 2. The Nb-based superconducting element wire precursor according to claim 1, wherein in a cross section perpendicular to the axial direction of the Sn superconducting wire precursor, in each of the plurality of Nb-based superconducting element wire precursors, an Nb-based reinforcing filament assembly in which the plurality of Nb-based reinforcing filaments are aggregated is disposed in the center, and an Nb-based superconducting filament assembly precursor in which the plurality of Nb-based superconducting filament precursors are aggregated is disposed on the outer periphery. ３ Precursor for Sn superconducting wire.
3. The Nb-based superconducting element wire precursor is ３ The Nb superconducting wire precursor according to claim 2, further comprising a second Sn diffusion barrier layer, which is provided between the Nb-based reinforcing filament assembly and the Nb-based superconducting filament assembly precursor in a cross section perpendicular to the axial direction of the precursor, and is made of a pure metal or alloy containing Ta or Nb. ３ Precursor for Sn superconducting wire.
4. The Nb ３ 2. The Nb-based superconducting subelement precursors according to claim 1, wherein in a cross section perpendicular to the axial direction of the Sn superconducting wire precursor, the plurality of Nb-based superconducting subelement precursors and the plurality of Sn-based element wires are arranged in the center of the superconducting element group precursor, and the plurality of Nb-based strengthened subelements are arranged on the outer periphery of the superconducting element group precursor. ３ Precursor for Sn superconducting wire.
5. The Nb of claim 1, wherein the first Sn diffusion barrier layer is made of a pure metal or alloy containing Ta or Nb. ３ Precursor for Sn superconducting wire.
6. A cylindrical stabilizing copper layer provided on the outer periphery, a cylindrical first Sn diffusion barrier layer provided inside the stabilizing copper layer, and a group of superconducting elements housed inside the first Sn diffusion barrier layer, the group of superconducting elements comprising a plurality of Nb-based superconducting element wires, the plurality of Nb-based superconducting element wires comprising a second stabilizing matrix made of Cu or a Cu-based alloy, and a plurality of Nb-based reinforcing filaments and Nb-based reinforcing filaments made of Nb or a Nb-based alloy embedded in the second stabilizing matrix. ３ and / or a third stabilizing matrix made of Cu or a Cu-based alloy and a plurality of Nb-based reinforcing sub-elements having a compound superconducting phase made of Sn and a diameter larger than that of the Nb-based reinforcing filaments embedded in the third stabilizing matrix and made of Nb or a Nb-based alloy, a fourth stabilizing matrix made of Cu or a Cu-based alloy and a plurality of Nb-based reinforcing sub-elements having a compound superconducting phase made of Sn and a diameter larger than that of the Nb-based reinforcing filaments embedded in the fourth stabilizing matrix and made of Nb. ３ and a plurality of superconducting subelements having a compound superconducting phase made of Sn and a plurality of superconducting filaments having a diameter larger than that of the Nb-based reinforcing filaments. ３ Sn superconducting wire.
7. The Nb of claim 6, wherein the first Sn diffusion barrier layer is made of a pure metal or alloy containing Ta or Nb. ３ Sn superconducting wire.