JP4009167B2 - Powder method Nb (3) Sn superconducting wire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a Nb ₃ Sn superconducting wire produced by a powder method, and particularly to a powder method Nb ₃ Sn superconducting wire useful as a material for a superconducting magnet for generating a high magnetic field.
[0002]
[Prior art]
Among the fields in which superconducting wire is put to practical use, superconducting magnets used in high-resolution nuclear magnetic resonance (NMR) analyzers have higher resolution as the generated magnetic field increases. There is a tendency.
[0003]
As a superconducting wire used for the superconducting magnet for generating a high magnetic field, a Nb ₃ Sn wire is put into practical use, and the bronze method is mainly used for manufacturing this Nb ₃ Sn superconducting wire. In this bronze method, a plurality of Nb base materials are embedded in a Cu-Sn base alloy (bronze) matrix and drawn to form the Nb base material as a filament, and a plurality of these filaments are bundled to form a wire group. No, it is buried in copper for stabilization (stabilized copper) and drawn. This is a method of generating a Nb ₃ Sn compound phase at the interface between the Nb-based filament and the matrix by heat-treating the wire group at 600 to 800 ° C. (diffusion heat treatment) (for example, see Non-Patent Document 1). However, this method has a drawback in that there is a limit to the Sn concentration that can be dissolved in the bronze, the thickness of the Nb ₃ Sn layer to be formed becomes thin, and the high magnetic field characteristics are not good.
[0004]
On the other hand, as a method for producing an Nb ₃ Sn superconducting wire, a powder method is also known in addition to the bronze method. As this powder method, an Nb and Sn intermediate compound powder is filled in a Nb sheath as a core material, and a heat treatment is performed after processing to generate an Nb ₃ Sn phase at the interface between the core material and the Nb sheath. It has been known. In addition, as a new powder method, Ta-Sn alloy powder is filled into a Nb or Nb-based alloy sheath as a core material and heat-treated after processing, so that there is no limit on the amount of Sn, and it is thicker than the bronze method and ECN method It has been shown that since a Nb ₃ Sn phase can be generated, a superconducting wire excellent in high magnetic field characteristics can be obtained (for example, see Patent Document 1).
[0005]
By the way, in general, a superconducting wire needs to have a thin superconducting filament diameter in order to remove and stabilize the heat even if partial heat generation occurs in the wire. An ultrafine multifilamentary wire containing many filaments is desirable. Actually, in the bronze method, a wire having thousands to tens of thousands of Nb ₃ Sn filaments has been put into practical use. The starting material of the ultra-fine multi-core wire is a single-core wire containing one Nb core, Nb sheath or Nb-based alloy sheath, or a sub-multi material containing several wires, which are bundled into a composite, which is extruded, drawn or rolled It can be obtained by reducing the diameter by, for example
[0006]
In the powder method (Patent Document 1), only the superconducting properties of a short prototype material having a single-core filament can be evaluated, and an improved multi-core method for a superconducting wire produced by the Ta-Sn powder method is used. The reality is that realization of a multi-core wire having stable superconducting properties by providing is eagerly desired.
[0007]
[Non-Patent Document 1]
K. Tachikawa Filamentary A15 Superconductors, Plenum Press (1980) p1
[Patent Document 1]
Japanese Patent Laid-Open No. 11-250749
[Problems to be solved by the invention]
In the powder method proposed so far, there is no problem when the single core wire is reduced in diameter, but when the single core wire is bundled into a composite to reduce the diameter to produce a multi-core wire, Since the formability is poor, uniform processing is difficult, and the Nb sheath or Nb-based alloy sheath may be damaged during processing, which has the problem of affecting the superconducting properties.
[0009]
Further, when the cross section of the wire after the final diffusion heat treatment is analyzed, surplus Sn component remains in the vicinity of the core center, and the ratio of the Nb ₃ Sn reaction region in the total cross-sectional area remains small, and the Sn component In addition, it cannot be said that a Ta component effective for improving high magnetic field characteristics is effectively utilized.
[0010]
Furthermore, the powder core portion and Nb ₃ Sn phase portion which is an intermetallic compound becomes brittle after diffusion heat treatment, since only Nb or Nb-based alloy sheath only do not contribute to wire strength, Nb ₃ Sn wire of the above method the bronze process There is a problem that the strength is insufficient. In addition, when subjected to bending strain after the heat treatment, the influence on the Nb ₃ Sn phase is increased, and the superconducting characteristics are greatly deteriorated. These are problems to be solved when the wire is used in a magnet.
[0011]
The present invention has been made under such circumstances, and its purpose is to improve the strength as a wire, to exhibit excellent superconducting characteristics, and even when strain is introduced, the superconducting characteristics are improved. The object is to provide a powder Nb ₃ Sn superconducting wire that does not cause deterioration.
[0012]
[Means for Solving the Invention]
The Nb ₃ Sn superconducting wires of the present invention which could achieve the above object, the powder a Nb ₃ Sn superconducting wire produced by the method of making a superconducting wire using, consisting of Nb or Nb-based alloy sheath One or a plurality of cores made of Nb or Nb-based alloy are disposed therein, and at least one metal of Ta, Nb and Ti is formed in a space formed between the sheath and the core It has a gist in that a wire material obtained by filling an alloy powder with Sn, an intermetallic compound powder, or a mixed powder and reducing the diameter thereof is used as a primary superconducting wire.
[0013]
The object of the present invention is to fill a pipe-shaped member made of Nb or an Nb-based alloy with an alloy powder, an intermetallic compound powder or a mixed powder of at least one of Ta, Nb and Ti with Sn. One or a plurality of wire rods that have been reduced in diameter are arranged in a sheath made of Nb or an Nb-based alloy, and at least one of Ta, Nb, and Ti is formed in a space formed between the sheath and the wire rod. This can also be achieved by an Nb ₃ Sn superconducting wire prepared by using a wire material obtained by filling an alloy powder, intermetallic compound powder or mixed powder of a seed metal and Sn and reducing the diameter thereof as a primary superconducting wire.
[0014]
As the powder used in the powder method Nb ₃ Sn superconducting wire of the present invention, it is also preferable to use a powder further containing Cu as a constituent element.
[0015]
Use a wire in which one or more primary superconducting wires used in the superconducting wire as described above are embedded in a Cu matrix, or a wire in which a plurality of wires embedded in the Cu matrix are further embedded in a Cu matrix. used can also be prepared powder method Nb ₃ Sn superconducting wire of the present invention can be a multi-sinkers were superconducting wire by such configuration.
[0016]
In addition, a composite layer is formed by disposing a barrier layer for preventing the diffusion of Sn to the outside during the diffusion process for forming the Nb ₃ Sn phase on the outer periphery of the various superconducting wires as described above, and further disposing a Cu sheath on the outer periphery. Even if this composite is used, the powder method Nb ₃ Sn superconducting wire of the present invention can be produced.
[0017]
Furthermore, the superconducting wire of the present invention can be produced using a superconducting wire or composite in which a Cu sheath is interposed between the sheath made of the Nb or Nb-based alloy and the powder. In the case of a wire rod, Nb or an Nb-based alloy can be processed more uniformly during diameter reduction processing.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have studied from various angles in order to achieve the above object. As a result, the present inventors have found that the above object can be achieved with the powder method Nb ₃ Sn superconducting wire produced using various superconducting wires or composites having the above-described configuration, and the present invention has been completed. The configuration of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a schematic cross-sectional view showing a configuration example of a primary superconducting wire used in the present invention, in which 1 is a core material made of Nb or Nb-based alloy, 2 is a sheath made of Nb or Nb-based alloy, 3 Indicates a raw material powder, 4 indicates a Cu sheath, and the primary superconducting wire 10 of the present invention is constituted by these members. In the primary superconducting wire 10, one or a plurality of core materials 1 made of Nb or Nb base alloy are arranged in a sheath 2 made of Nb or Nb base alloy, and a space formed between the sheath and the core material. It is a wire rod in which the raw material powder 3 is filled and the diameter thereof is reduced.
[0020]
The raw material powder 3 used at this time contains at least one metal of Ta, Nb, and Ti and Sn as components, and the form thereof may be any of alloy powder, intermetallic compound powder, or mixed powder. . Of the components contained in the raw material powder 3, Sn reacts with Nb or an Nb-based alloy arranged around it to form an Nb ₃ Sn phase. However, components such as Ta, Nb and Ti contain Nb ₃ Promotes the formation of the Sn phase, or exerts an effect of reacting with Sn to become a superconductor. The content of the Sn component in the raw material powder 3 is preferably about 20 to 75 atomic%. When the Sn content is less than 20 atomic%, the Nb ₃ Sn phase becomes thin, the superconducting characteristics deteriorate, and 75 If it exceeds atomic%, Sn will evaporate during diffusion heat treatment and voids are formed, which causes a decrease in strength and superconducting properties. In addition, even if this raw material powder 3 takes any form, it is preferable that the average particle diameter is 150 micrometers or less (100 mesh under) from a viewpoint of improving the reactivity at the time of heat processing.
[0021]
In addition, it is effective that the raw material powder 3 contains a Cu component as necessary. This Cu component exhibits the effect of reducing the diffusion heat treatment temperature. That is, the optimum reaction temperature (diffusion heat treatment temperature) when the Cu component is not contained in the conventional powder method is 900 to 925 ° C., whereas the optimum reaction temperature of the bronze method is about 650 to 850 ° C. When the heat treatment is performed as described above, the superconducting properties may be deteriorated due to excessively large crystal grains. However, the optimum heat treatment temperature can be lowered by adding a Cu component to the raw material powder, and as a result, the crystal grains are refined. High characteristics in the Nb ₃ Sn superconducting wire can be realized. In order to exert such an effect, the Cu content in the raw material powder is preferably 0.3% by mass or more. However, if the Cu content becomes too large, Cu is an impurity with respect to the produced Nb ₃ Sn. Therefore, the upper limit is preferably about 30% by mass.
[0022]
By performing a diffusion heat treatment using the primary superconducting wire 10 as shown in FIG. 1, Nb in the sheath and Sn in the raw material powder react to form an Nb ₃ Sn phase, thereby obtaining the superconducting wire of the present invention. It is done. In such a configuration, since the core material 1 made of Nb or Nb-based alloy is in the state of the powder, the strength of the entire wire is increased as compared with the conventional wire, and the sheath 2 made of Nb or Nb-based alloy is damaged. It will be difficult, and disconnection can be avoided as much as possible. In addition, by arranging the core material in the vicinity of the Sn component in the powder core (core part), the diffusion distance of Sn atoms is shortened, and the core material is embedded in the powder so that Nb or Nb in contact with the powder The surface area of the base alloy will increase, and the critical current can be increased by increasing the proportion of the Nb ₃ Sn reaction layer in the total cross-sectional area of the wire.
[0023]
In addition, according to the superconducting wire of the present invention, since the Nb ₃ Sn phase is dispersed and generated in each part, the thickness of the Nb ₃ Sn phase in each part becomes thin and it is difficult to crack, and cracks are partly formed. Even if it enters, the remaining Nb ₃ Sn phase can compensate for the effect, so even if the wire material after diffusion heat treatment is distorted, the effect on the Nb ₃ Sn phase is reduced, preventing deterioration of superconducting properties. Will be able to do. In consideration of these actions, the area ratio of the core material 1 and the raw material powder 3 (core material: raw material powder) is preferably about 1: 0.1 to 7.
[0024]
FIG. 2 is a schematic cross-sectional view showing another configuration example of the primary superconducting wire used in the present invention, in which 5 is a pipe-shaped member made of Nb or an Nb-based alloy, 6 and 8 are raw material powders, and 7 is Nb or A sheath made of an Nb-based alloy, 9 is a Cu sheath, and the primary superconducting wire 11 of the present invention is constituted by these members. The primary superconducting wire 11 basically has the same structure as the primary superconducting wire 10 shown in FIG. 1 except that a wire rod filled with a raw material powder in the pipe-like member 5 is used instead of the core material. Is similar.
[0025]
In such a configuration, the pipe-like member 5 performs the same function as the core material 1 and further increases the surface area of the Nb or Nb-based alloy in contact with the raw material powders 6 and 8 than the primary superconducting wire 10 shown in FIG. By doing so, the generation area of the Nb ₃ Sn phase can be increased. In addition, when the pipe-shaped member 5 made of Nb or an Nb-based alloy is present inside the raw material powder 8 as shown in FIG. 2, the Sn component in the raw material powder 6 is 8 parts of the raw material powder even if the member is broken during processing. In other words, it does not diffuse to the Cu sheath and is not wasted as in the case of a conventional wire, so that the generation of the Nb ₃ Sn phase is not affected.
[0026]
The primary superconducting wires 10 and 11 shown in FIGS. 1 and 2 are subjected to diffusion heat treatment to obtain a superconducting wire exhibiting desired characteristics. The primary superconducting wires 10 (FIG. 1) and 11 ( 2) and the primary superconducting wires 10 and 11, except for the Cu sheaths 4 and 9, the wire material (FIGS. 3 and 4) in which one or a plurality of wires are embedded in the Cu matrix 12 is used. The powder method Nb ₃ Sn superconducting wire of the present invention can also be produced by using a superconducting wire in which a plurality of buried wires are further embedded in a Cu matrix. With such a configuration, the number of cores (for example, a primary superconducting wire) can be increased. Can be a superconducting wire having a number of up to about 10,000). In addition, this Cu matrix also exhibits an effect of magnetically stabilizing the Nb ₃ Sn phase.
[0027]
Further, a barrier layer (for example, an Nb layer) for preventing the diffusion of Sn to the outside during the diffusion process for forming the Nb ₃ Sn phase is disposed on the outer periphery of the various superconducting wires as described above, and a Cu sheath is further disposed on the outer periphery thereof. The powder method Nb ₃ Sn superconducting wire of the present invention can be produced even if the composite is constituted by using the composite.
[0028]
Furthermore, in the superconducting wire of the present invention, it can be prepared using a superconducting wire or composite in which a Cu sheath is interposed between the sheath made of the Nb or Nb-based alloy and the raw material powder. In the superconducting wire, the Nb or Nb-based alloy sheath can be processed more uniformly during the diameter reduction processing.
[0029]
Note that the sheaths 2 and 7 (FIGS. 1 and 2) made of Nb or Nb-based alloy used in the present invention may be finally tubular, for example, a thin sheet of Nb or Nb-based alloy may be rolled up. Moreover, what was made into the tubular form by welding them is employable.
[0030]
Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are not of a nature that limit the present invention, and any design changes may be made in accordance with the gist of the present invention. It is included in the technical scope.
[0031]
【Example】
Example 1
Ta powder of 325 mesh or less and Sn powder are mixed so that the atomic ratio is 6: 5 (Ta: Sn), and Cu powder of 325 mesh or less is further mixed with this mixed powder with respect to the total amount of powder after mixing. The mixture was added and mixed to 2% by mass. This mixed powder was put in an alumina crucible and reacted in a vacuum of 1.33 × 10 ⁻³ Pa at 950 ° C. for 20 hours to produce a Ta—Sn—Cu alloy fine powder.
[0032]
Next, an Nb-4.0 atom% Ta alloy core material having an outer diameter of 2 mm is arranged at the center of the sheath made of Nb-4.0 atom% Ta alloy having an outer diameter of 8 mm and an inner diameter of 5 mm. This is filled with the Ta-Sn-Cu alloy fine powder prepared earlier (in the space formed between the sheath material and the core material), and a 1.0 mm square square cross-section wire (primary superconducting wire) by a groove roll ). At this time, as a comparative material, Ta-Sn-Cu alloy powder was filled without disposing the core material in the sheath, and processed into a 1.0 mm square square cross-section wire with a groove roll.
[0033]
Both wires were subjected to diffusion heat treatment at 800 ° C. for 80 hours to obtain superconducting wires. The cross section of the comparative Nb ₃ Sn wire is shown in FIG. 5 (drawing metal electron micrograph), but Sn outflow occurs in a part of the Nb-4.0 at% Ta alloy sheath (other than the end of the wire). Admitted. This is thought to be because the sheath was thinned unevenly due to insufficient strength during processing.
[0034]
On the other hand, the cross section of the superconducting wire of the present invention material is shown in FIG. 6 (drawing metal electron micrograph), but in the Nb-4.0 atomic% Ta alloy sheath, the outflow of Sn other than the end of the wire is I was not able to admit.
[0035]
After these Nb ₃ Sn superconducting wires are plated with Cu, the critical current density (critical current Ic in a magnetic field (external magnetic field) of 14 to 17 T in liquid helium (4.2 K) is obtained by removing the cross-sectional area of the wire. When the value divided by Jc) was measured, the following values were obtained.
[0036]
[Measured value of critical current density Jc]
(1) Invention material 523A / mm ² (14T), 481A / mm ² (15T), 461A / mm ² (16T), 445A / mm ² (16.5T), 419A / mm ² (17T)
(2) Comparative material 107A / mm ² (16T), 89A / mm ² (17T)
For example, the Jc when the external magnetic field is 17 T is 89 A / mm ² for the comparative material and 419 A / mm ² for the inventive material, and the actual material obtained by the conventional bronze method is 200 A / mm for the inventive material. ^The characteristics were significantly higher than ² . The relationship between the external magnetic field B and the critical current density Jc is shown in FIG. In FIG. 10, the critical current density Jc of the Cu—Sn base alloy (Sn content: 14 mass%) is also shown.
[0037]
For each superconducting wire, the bending strain dependence of the critical current Ic was evaluated by the ratio (Ic / Ic ₀ ) with the critical current Ic ₀ when the strain was zero. The results are shown in FIG. 11, and it is understood that the Ic decreases rapidly in the comparative material, but the decrease rate of Ic is greatly suppressed in the present invention material.
[0038]
Example 2
A Ta—Sn—Cu alloy fine powder produced in the same manner as in Example 1 was filled into a pipe-shaped member made of Nb-4.0 at% Ta alloy having an outer diameter of 8 mm and an inner diameter of 5 mm, and 2 by a groove roll. It was processed into a wire rod having a square section of 0.0 mm square. Thereafter, the wire was swaged to obtain a wire having a circular cross section (hereinafter, this wire is referred to as “processed wire”).
[0039]
Next, the processed wire is placed in the center of a separately prepared sheath of Nb-4.0 atomic% Ta alloy having an outer diameter of 8 mm and an inner diameter of 5 mm. In the space to be formed), the Ta—Sn—Cu alloy fine powder produced in Example 1 was filled and processed into a 1.0 mm square square cross-section wire with a groove roll.
[0040]
This wire was subjected to a diffusion heat treatment at 800 ° C. for 80 hours to obtain a superconducting wire. A cross section of the obtained superconducting wire is shown in FIG. 7 (drawing-substitute metal electron micrograph). As in the case of Example 1 (example of the present invention), no outflow of Sn was observed except at the end of the wire. It was.
[0041]
With respect to this superconducting wire, when the critical current density Jc in a magnetic field (external magnetic field) of 17 to 24 T was measured in the same manner as in Example 1, the following values were obtained. These values are also shown in FIG.
[0042]
[Measured value of critical current density Jc]
559A / mm ² (17T), 167A / mm ² (22T), 92A / mm ² (23T), 46A / mm ² (24T), 21A / mm ² (25T)
In addition, for this superconducting wire, the bending strain dependence of the critical current Ic was investigated in the same manner as in Example 1. The results are also shown in FIG. 11, and it can be seen that the decrease rate of Ic is significantly suppressed as compared with the comparative material.
[0043]
Example 3
Seven cores made of Nb with an outer diameter of 0.8 mm are bundled and arranged in the center of a sheath made of an Nb-4.0 atomic% Ta alloy with an outer diameter of 8 mm and an inner diameter of 5 mm. The Ta-Sn-Cu alloy fine powder produced in Example 1 was filled in a space formed between the sheath and the Nb core material, and processed into a wire having a 1.4 mm square square cross section by a groove roll.
[0044]
This wire was subjected to a diffusion heat treatment at 800 ° C. for 80 hours to obtain a superconducting wire. The cross section of the obtained superconducting wire is shown in FIG. 8 (drawing-substitute metal electron micrograph). As in the case of Example 1 (example of the present invention), no outflow of Sn was observed except at the ends of the wire. It was.
[0045]
With respect to this superconducting wire, when the critical current density Jc in a magnetic field (external magnetic field) of 15 to 25 T was measured in the same manner as in Example 1, the following values were obtained. These values are also shown in FIG.
[0046]
[Measured value of critical current density Jc]
^{264A / mm 2 (15T),} 261A / mm 2 (15.5T), 259A / mm 2 (16T), 256A / mm 2 (16.5T), 253A / mm 2 (17T), 240A / mm 2 (18T ), 200A / mm ² (20T), 166A / mm ² (21T), 130A / mm ² (22T), 91A / mm ² (23T), 45A / mm ² (24T), 20A / mm ² (25T)
In addition, for this superconducting wire, the bending strain dependence of the critical current Ic was investigated in the same manner as in Example 1. The results are also shown in FIG. 11, and it can be seen that the decrease rate of Ic is clearly suppressed as compared with the comparative material.
[0047]
Example 4
Prepare a Cu sheath with an outer diameter of 53 mm and an inner diameter of 49 mm and a screw-in type Cu lid, and evenly open 31 dents with an inner diameter of about 5 mm and a depth of about 3 mm in the Cu lid. 31 Nb-4.0 atomic% Ta alloy cores of 5 mm were inserted and held, and the cores were arranged uniformly in the Cu sheath. This is filled with Ta-Sn-Cu alloy fine powder prepared in the same manner as in Example 1, and the other lid is applied. Further, the outer periphery of the Nb sheet is 0.2 mm thick and the outer diameter is 59 mm. (Nb sheath), and this was loaded into a Cu billet (stabilized copper) having an outer diameter of 68 mm and an inner diameter of 60 mm to obtain a composite.
[0048]
This composite was processed by extrusion and wire drawing until the outer diameter became 2.0 mm, and the obtained wire was subjected to diffusion heat treatment at 800 ° C. for 80 hours to obtain a superconducting wire. A cross section of the obtained superconducting wire is shown in FIG. 9 (drawing metallurgical micrograph). Nb _{3 at the} boundary between the Nb sheet and the Cu sheath, and at the boundary between the Nb-4.0 atomic% Ta alloy core and the powder core. Sn phase was uniformly generated.
[0049]
With respect to this superconducting wire, the critical current density Jc in a 17 T magnetic field (external magnetic field) was measured in the same manner as in Example 1. As a result, it was 300 A / mm ² , which exceeded the conventional bronze normal wire. In addition, for this superconducting wire, the bending strain dependence of the critical current Ic was investigated in the same manner as in Example 1. The results are also shown in FIG. 11, and it can be seen that the decrease rate of Ic is remarkably suppressed.
[0050]
【The invention's effect】
The present invention is configured as described above, improves the strength as a wire, exhibits excellent superconducting characteristics, and does not cause deterioration of superconducting characteristics even when strain is introduced. A powder method Nb ₃ Sn superconducting wire was realized.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a structural example of a superconducting wire used in the present invention.
FIG. 2 is a schematic sectional view showing another configuration example of the superconducting wire used in the present invention.
FIG. 3 is a schematic sectional view showing still another configuration example of the superconducting wire used in the present invention.
FIG. 4 is a schematic cross-sectional view showing another configuration example of the superconducting wire used in the present invention.
5 is a drawing-substitute metallurgical micrograph showing a cross section of the superconducting wire (comparative material) obtained in Example 1. FIG.
6 is a drawing-substitute metallurgical micrograph showing a cross section of the superconducting wire (material of the present invention) obtained in Example 1. FIG.
7 is a drawing-substitute metallurgical micrograph showing a cross section of the superconducting wire (material of the present invention) obtained in Example 2. FIG.
8 is a drawing-substitute metallurgical micrograph showing a cross section of the superconducting wire (material of the present invention) obtained in Example 3. FIG.
9 is a drawing-substitute metallurgical micrograph showing a cross section of the superconducting wire (material of the present invention) obtained in Example 4. FIG.
FIG. 10 is a graph showing the relationship between Jc characteristics of Nb ₃ Sn superconducting wires obtained in Examples 1 to ₃ and an external magnetic field.
FIG. 11 is a graph showing a comparison of the bending strain dependence of Nb ₃ Sn superconducting wires obtained in Examples 1 to 4;
[Explanation of symbols]
1 Core material 2 made of Nb or Nb base alloy, 7 Sheath 3, 6, 8 raw material powder 4, 9 Cu sheath 10, 11 made of Nb or Nb base alloy Primary superconducting wire 12 Cu matrix

Claims (7)

An Nb ₃ Sn superconducting wire manufactured by a method of producing a superconducting wire using powder, wherein one or a plurality of cores made of Nb or Nb base alloy are arranged in a sheath made of Nb or Nb base alloy And filling the space formed between the sheath and the core with an alloy powder, intermetallic compound powder or mixed powder of at least one metal of Ta, Nb and Ti with Sn, A powder-processed Nb ₃ Sn superconducting wire, characterized in that it is produced as a primary superconducting wire using a diameter-reduced wire. An Nb ₃ Sn superconducting wire manufactured by a method of producing a superconducting wire using powder, and a pipe-shaped member made of Nb or an Nb-based alloy and at least one metal of Ta, Nb and Ti One or a plurality of wire rods filled with Sn alloy powder, intermetallic compound powder or mixed powder and reduced in diameter are placed in a sheath made of Nb or Nb-based alloy, and formed between the sheath and the wire rod. The space is filled with an alloy powder, intermetallic compound powder or mixed powder of at least one metal of Ta, Nb and Ti and Sn, and a wire rod obtained by reducing the diameter is produced as a primary superconducting wire. powder method Nb ₃ Sn superconducting wire is characterized in that which is. The powder method Nb ₃ Sn superconducting wire according to claim 1 or 2, wherein the powder further contains Cu as a constituent element. A powder-processed Nb ₃ Sn superconducting wire produced by using a wire in which one or more primary superconducting wires according to any one of claims 1 to 3 are embedded in a Cu matrix. A powder method Nb ₃ Sn superconducting wire produced by using a wire in which a plurality of the wires according to claim 4 are further embedded in a Cu matrix. A barrier layer for preventing the diffusion of Sn to the outside during the diffusion process for forming the Nb ₃ Sn phase is disposed on the outer periphery of the superconducting wire according to any one of claims 1 to 5, and a Cu sheath is disposed on the outer periphery thereof. Then, a powder method Nb ₃ Sn superconducting wire, which is a composite produced by using the composite. The powder method Nb according to any one of claims 1 to 6, wherein the powder method Nb is produced using a primary superconducting wire or a composite in which a Cu sheath is interposed between a sheath made of the Nb or Nb-based alloy and powder. ₃ Sn superconducting wire.

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