JP2001057118A - SUPERCONDUCTING WIRE OF Nb3Sn COMPOUND AND MANUFACTURE THEREOF - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cause no lowering of critical current density and no lowering of a residual resistance ratio by providing a niobium complex containing a niobium filament, stabilized copper of pure copper, a reinforcement and two layered diffusion preventing materials. SOLUTION: First and second diffusion preventing materials 3, 6 exist on the inner peripheral surface and the outer peripheral surface of a pipe of alumina dispersion-strengthened copper forming a reinforcement 5 respectively. The first diffusion preventing material 3 prevents lowering of critical current density due to reduction of Sn concentration in bronze by preventing Sn from being diffused from the bronze to the alumina dispersion-strengthened copper by heat treatment to produce Nb3Sn, the second diffusion preventive material 6 prevents unreacted Al in the alumina dispersion-strengthened copper from being diffused to stabilized copper, and accordingly these two layered diffusion preventing materials 3, 6 have role to maintain purity of the stabilized copper 4 respectively. The second diffusion preventing material 6 is required between the reinforcement 5 and the stabilized copper 4. The thickness of the stabilized copper 4 can be suppressed to a minimum by the diffusion preventing layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Nb ₃ Sn compound superconducting wire and a method for producing the same.

[0002]

2. Description of the Related Art At present, superconducting wires that have been put into practical use include those using a compound superconducting wire such as Nb ₃ Sn and Nb ₃ Al, and those using an alloy Nb—Ti superconducting wire. ing. Practical application to a power transmission cable and a superconducting coil capable of forming a strong magnetic field with little consumption of electric power by using these wires has been promoted.

[0003] As described above, a superconducting wire using a compound superconducting wire is formed by a bronze method using a Cu-based matrix to which Sn is added in advance, or an internal Sn using a Cu-based matrix in which Sn bars and Nb bars are arranged. Diffusion method, Nb
It is manufactured by inserting an Sn rod into a tube and using an Nb tube method using a Cu-based matrix.

As shown in the cross sectional view of FIG. 7, a Nb ₃ Sn compound superconducting wire to which the above-described bronze method is applied is composed of a plurality of Cu—Sn alloy (bronze) tubes 1 and each tube 1.
A niobium-bronze composite 10 composed of a Nb core wire (niobium filament) 2 embedded in each of them, and a diffusion preventing material 3 and a stabilizing material 4, for example, stabilizing copper, are arranged concentrically.

A superconducting wire having such a configuration is manufactured, for example, as follows. First, a large number of composites in which a Nb core wire 2 is embedded in a Cu—Sn alloy tube 1 are combined, and a diffusion preventing material 3 and a stabilizing material 4 are integrated. Then, the surface is reduced to a predetermined outer diameter by a swaging machine or the like. Apply processing. Thereafter, the Nb core wire 2 and the Sn in the niobium bronze composite 10 are subjected to a heat treatment at the Nb ₃ Sn generation temperature.
To form an Nb ₃ Sn superconductor layer on the outer peripheral side of the Nb core wire 2.

As described above, in the cross-sectional structure of the superconducting wire,
In order to maintain the stability at the time of superconductivity, the stabilizing copper 4 constituting the stabilizing material is always provided. However, the Sn in the adjacent niobium bronze composite 10 diffuses into the stabilizing copper 4 to stabilize the copper 4. Stabilized copper 4 and niobium
The diffusion preventing material 3 is provided between the anti-diffusion material 3 and the bronze composite 10.

A superconducting wire using a compound superconductor such as Nb ₃ Sn as described above has a disadvantage that the superconducting characteristics such as the critical current density decrease when a tensile force or bending strain is applied in the longitudinal direction. Have. For example, the tensile properties are 0.2% proof stress, only about 160MPa, and it cannot be adopted at all in the design and manufacture of high magnetic field magnets that apply a large tensile force of 160MPa or more to the wire due to high hoop force, which is a great difficulty for industrialization. Had become.

Recently, there has been an increasing demand for large-sized and high-field coils of 10 T or more, but it has been practically difficult to manufacture such coils.

Therefore, in order to improve mechanical properties such as tensile properties, a structure was manufactured in which, for example, alumina dispersion-strengthened copper, which hardly softens even at the Nb ₃ Sn generation temperature, was incorporated as a reinforcing material. The alumina dispersion-strengthened copper is a reinforced Cu alloy that is dispersion-strengthened by dispersing Al ₂ O ₃ particles in Cu in a range of about 1 to 2% by weight, for example, copper oxide powder and alumina powder. Obtained by subjecting a mixture of the above to reduction sintering. As a result, the tensile property was 260 MPa at a 0.2% proof stress, and the strength was greatly improved and improved as compared with the conventional art.

However, the Nb ₃ Sn formation heat treatment condition is 65
Since the time is as long as 240 hours at 0 ° C., the unreacted residual Al contained in the alumina dispersion strengthened copper diffuses into the stabilized copper, so that the purity of the stabilized copper is deteriorated and the residual resistance as a wire is reduced. The ratio becomes smaller.

That is, the electrical conductivity and the thermal conductivity of the stabilized copper deteriorate. In such a wire, when it transits to normal conduction, a large resistance generates a large amount of heat, and an accident occurs in which the superconducting wire burns out during energization.

As a countermeasure, the thickness of the stabilized copper is made sufficiently large to provide a region in which the stabilized copper is not diffused by Sn for a long heat treatment time, thereby maintaining the purity of the stabilized copper and maintaining the superconductivity. There is also a method for maintaining the stability as a line.

However, in this method, since the thickness of the stabilizing copper becomes too thick and the cross-sectional area of the wire increases, the weight of the wire wound as a magnet becomes considerably large, and the amount of refrigerant for cooling increases. And the necessity of a large-sized refrigerator has a drawback that it becomes practically difficult to handle. Further, since Sn in bronze diffuses into alumina dispersion-strengthened copper, the Sn concentration in bronze decreases, the amount of Nb3Sn decreases, and a new problem arises that lowers the superconductivity such as lowering the critical current density. I was

The present invention has been made to address such a problem, and even if a reinforcing material such as alumina dispersion strengthened copper is used for a compound superconductor, the critical current density and the residual resistance ratio are reduced. and its object is to provide a free Nb 3 _Sn compound superconducting wire and its manufacturing method.

[0015]

In order to achieve the above object, an invention according to claim 1 comprises a niobium bronze composite containing a niobium filament, a stabilized copper made of pure copper, a reinforcing material, An Nb ₃ Sn compound superconducting wire comprising two layers of a diffusion preventing material.

According to a second aspect of the present invention, there is provided a niobium filament containing a niobium filament.
A bronze composite, stabilized copper made of pure copper, a reinforcing material, and first and second diffusion preventing materials are arranged concentrically, and in the cross section, from the center to the outer peripheral side, An Nb ₃ Sn compound superconducting wire, wherein the niobium-bronze composite, the first diffusion preventing material, the reinforcing material, the second diffusion preventing material, and the stabilized copper are sequentially arranged.

According to a third aspect of the present invention, there is provided a niobium filament containing a niobium filament.
A bronze composite, stabilized copper made of pure copper, a reinforcing material, and first and second diffusion preventing materials are arranged concentrically, and in a cross section thereof, from the center toward the outer peripheral side. , The niobium-bronze composite, the first diffusion preventing material, the stabilized copper, the second diffusion preventing material, and the reinforcing material are arranged in this order in an Nb ₃ Sn compound superconducting wire.

According to a fourth aspect of the present invention, there is provided a niobium filament containing a niobium filament.
A bronze composite, stabilized copper made of pure copper, a reinforcing material, and first and second diffusion preventing materials are arranged concentrically, and in the cross section, from the center toward the outer peripheral side. , The stabilized copper, the first diffusion preventing material, the niobium-bronze composite, the second diffusion preventing material, and the reinforcing material are sequentially arranged, and the Nb ₃ Sn compound superconducting wire is characterized in that:

In order to achieve the above object, the invention according to claim 9 is based on a composite made of a Cu—Sn alloy containing niobium, a stabilized copper made of pure copper, a reinforcing material, and a two-layer diffusion preventing material. A first step of producing a member comprising:
A second step of reducing the surface of the member obtained in the step, and subjecting the member subjected to the surface reduction in the second step to a heat treatment.
_{And a third} step of forming a ₃ Sn layer. A method for producing an Nb ₃ Sn compound superconducting wire, comprising:

According to the invention corresponding to any one of claims 1 to 4 and claim 9, Nb _{3 is} provided by providing a diffusion preventing material between the reinforcing material and the stabilized copper adjacent to the reinforcing material. Since the diffusion of Sn in bronze and Al in alumina dispersion-strengthened copper generated by heat treatment for generating Sn can be suppressed, a practical and highly reliable Nb ₃ Sn compound superconductor without lowering of the residual resistance ratio or the critical current density. A wire and a method for manufacturing the wire can be provided.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a first embodiment of the Nb ₃ Sn compound superconducting wire according to the present invention. In this embodiment, a niobium-bronze composite 10 composed of an Nb core wire 2 and a Cu—Sn alloy (bronze) tube 1 containing the Nb core wire 2 is schematically shown in FIG.
And a diffusion prevention material (first diffusion prevention material) 3, a stabilized copper 4 made of pure copper, and a reinforcing material 5, and a second diffusion prevention material 6 is newly provided.

Specifically, the niobium bronze composite 10, the first diffusion preventing material 3, the reinforcing material 5, the second diffusion preventing material 6, the stabilized copper 4 are sequentially arranged concentrically.

The superconducting wire having such a configuration is manufactured as follows. First, an Nb rod is inserted into a bronze pipe having a Sn concentration of 10%, integrated with a swaging machine or the like, and molded into a rod having a regular hexagonal shape while reducing the surface to a predetermined shape. A large number of the regular hexagonal rods are bundled, inserted into a diffusion preventing member 3 made of, for example, a Ta tube, integrated again by a swaging machine or the like, and then formed into a reinforcing material 5, for example, into an alumina dispersion strengthened copper pipe. Insert and integrate.

Next, the diffusion preventing material 6 made of, for example, a Ta tube, which constitutes the second layer of the diffusion preventing material 6, is inserted, and integrated processing is performed by a swaging machine or the like. Finally, it is inserted into a pipe made of oxygen-free copper which becomes the stabilized copper 4 and integrated by a swaging machine or the like. FIG. 1 shows a cross section of the superconducting wire thus formed.

According to the embodiment described above, the diffusion preventing materials 3 and 6 are present on the inner peripheral surface and the outer peripheral surface of the pipe-shaped alumina dispersion strengthened copper constituting the reinforcing material 5, respectively. This 2
The following effects can be obtained by the diffusion preventing materials 3 and 6 of the layers. The diffusion preventing material 3 prevents the diffusion of Sn from bronze into alumina dispersion-strengthened copper by heat treatment for generation of Nb ₃ Sn, thereby preventing a decrease in critical current density due to a decrease in the Sn concentration in bronze. Has the role of preventing the unreacted Al in the alumina dispersion strengthened copper from diffusing into the stabilized copper and maintaining the purity of the stabilized copper 4.

The Nb3Sn formation heat treatment condition of 650 was used.
By providing the stabilized copper 4 with a thickness equal to or greater than the Sn diffusion distance by 240 hours, the diffusion preventing material 6 may not be required between the reinforcing material 5 and the stabilized copper 4. Increasing the thickness of the copper oxide 4 leads to an increase in the weight, and increases the design burden such as an increase in the structural support material, an increase in the refrigerant, an increase in the refrigeration capacity, and has a practical disadvantage. .

For this reason, a diffusion preventing material 6 is also required between the reinforcing material 5 and the stabilized copper 4. With this diffusion preventing layer, the thickness of the stabilizing copper 4 can be minimized to a necessary minimum, and it is possible to reduce the weight of the wire rod, reduce the refrigerant, and reduce the refrigeration capacity of the refrigerator. There is.

Therefore, when alumina dispersion strengthened copper is used to increase the strength of the superconducting wire, it is necessary to provide the above-mentioned diffusion preventing materials 3 and 6 on the inner and outer peripheral surfaces of the alumina dispersion strengthened copper. Become.

The diffusion preventing materials 3 and 6 constituting the diffusion preventing layer described above are not limited to the tantalum (Ta) used in the embodiment, but include niobium (Nb). Examples of the reinforcing material 5 used for reinforcement include an Nb-Cu alloy and Nb in addition to alumina dispersion strengthened copper.

Next, a specific example of the method for manufacturing a superconducting wire according to the present invention will be described.

First, a Cu—Sn having a Sn concentration of 10% was used.
An Nb rod having an outer diameter of 3 mm is inserted into an alloy (bronze) pipe (outer diameter 10.0 mm, inner diameter 3.2 mm), and integrated with a swaging machine or the like.

Since work hardening occurs during the integration process, 50
After softening by heat treatment at 0 ° C. for 60 minutes in argon gas, further processing is performed to form a hexagonal shape. This is 2
56 tubes, Ta tube (outer diameter 4
7 mm, inner diameter 45 mm). Next, it was connected to an alumina dispersion strengthened copper pipe (outer diameter 50 mm, inner diameter 47.2).
mm).

Further, it is inserted into a Ta tube (outer diameter: 52 mm, inner diameter: 50.3 mm) serving as a second diffusion prevention layer.

Finally, a stabilized copper pipe (outer diameter 55 mm,
After insertion into the inside diameter (52.3 mm), both ends are sealed by welding. These molded articles are extruded by a hot extruder at 500 ° C. to reduce the diameter, and further, the diameter reducing step using a swaging machine or the like and the softening step by heat treatment are repeated, whereby the superconducting wire of the present invention (wire diameter 2. 2 mm).

In order to make a comparison with the superconducting wire of the present invention formed in this way, in order to prevent only the diffusion of Sn from bronze into stabilized copper as in the case of the conventional wire,
A wire in which only one layer of the Ta diffusion preventing layer exists between the bronze matrix and the stabilized copper, that is, a wire in which only the Ta diffusion preventing material 3 of FIG. 1 exists and a wire in which only the Ta diffusion preventing material 6 exists Produced. Furthermore, a conventional wire having only the Ta diffusion preventing material 3 and a superconducting wire of the present invention were prepared by changing the thickness of the standardized copper, and the influence on the residual resistance ratio was examined.

These wires were heat-treated at 650 ° C. for 240 hours in a vacuum of 1.25 × 10 ^-5 torr. The results of measuring the critical current density and the residual resistance ratio of the wire of the present invention and the wire for comparison are shown in FIGS.

FIG. 2 shows the characteristics of the critical current density Jc [A / mm ² ] with respect to the magnetic field B [Tesla] in comparison with the present invention and the conventional example. 2 according to the invention
The critical current density characteristic with respect to the magnetic field of the superconducting wire provided with the diffusion prevention materials 3 and 6 of the layers is higher than the case where the diffusion prevention material 6 of one layer is provided between the stabilized copper and the reinforced copper as a comparative example. This shows the effectiveness of the present invention.

FIG. 3 shows the characteristics of the residual resistance ratio with respect to the heat treatment time in comparison between the present invention and the conventional example.
In the conventional example provided with one layer of the diffusion prevention material, the heat treatment time [H]
The residual resistance ratio tends to gradually decrease with the passage of time. However, in the wire structure of the present invention in which the two layers of the diffusion preventing materials 3 and 6 are provided, the residual resistance ratio hardly changes even when the heat treatment time is 240 hours or more. Shows the effectiveness of the present invention. In particular, a critical current density of 500 A / mm ² (4K,
It is generally said that a heat treatment of 240 hours or more is required for Nb3Sn wire in order to secure 12T) or more, and the residual resistance ratio in such a long time region is important.

FIG. 4 shows the results of a comparison between the case where the diffusion preventing material 3 as seen in the conventional example has one layer and the case where the diffusion preventing materials 3 and 6 of the present invention have two layers. Heat treatment at 650 ° C. for 24
Performed for 0 hours. Obviously, a high residual resistance ratio was obtained in the case of the present invention having two layers of the diffusion preventing material.

In each case, the effect on the residual resistance ratio was examined by changing the thickness of the stabilized copper. In the case of the two diffusion prevention layers as in the present invention, the first Al diffusion prevention layer provided between the stabilized copper and the alumina dispersion strengthened copper even if the thickness of the stabilized copper is as thin as 20 to 50 microns. Therefore, the purity of stabilized copper is 100% (resistivity just above critical temperature,
(Low value of 1.0 × 10 ⁻⁸ Ωcm) or more.

In the conventional example having one diffusion prevention layer, the residual resistance ratio was about 10 when the thickness of the stabilized copper was 50 μm or less, and 20-60 when the thickness was 60-100 μm.

With such a low residual resistance ratio, when the wire material changes from the superconducting state to the normal conducting state, it has a high resistance value (a resistivity just above the critical temperature: 1.0 × 10 ⁻⁶ Ωcm).
Joule heat is generated and burned out. That is, if only one Ta diffusion prevention layer is used, a superconducting coil manufactured by winding a wire is burned and cannot be used as a superconducting device.

FIG. 4 shows one layer of the Ta diffusion preventing material 3.
In only case, the change in the residual resistance ratio when the thickness of the stabilized copper was increased was also shown. In this case, at a thickness of 150 microns, the rate of contamination of the stabilized copper is reduced,
Although the residual resistance ratio becomes 105, on the other hand, it has a large drawback that the weight of the wire increases, which is not practical. In other words, the burden on the cooling system of the superconducting coil increases, resulting in a very large superconducting device.

Further, in addition to the specific examples shown in the figures, various wires having different ratios of the constituent parts of the present wire rod were manufactured. That is,
Niobium-bronze composite, stabilized copper made of pure copper, residual resistance ratio due to change in volume ratio of reinforcement, and whether long working as a superconducting wire is possible with each configuration, and whether a practical critical current density can be obtained Was examined. As a result, the niobium bronze composite, the stabilized copper composed of pure copper, and the reinforcing material can be processed into long wires at volume ratios of 30-70%, 10-30%, and 10-50%, respectively, and have a residual resistance. A good ratio of 100 or more was obtained.

If the niobium bronze complex is less than 30%, the amount of Nb ₃ Sn generated is small, and a sufficiently high critical current density cannot be obtained. If it is 70% or more, the amount of pure copper is small and the residual resistance ratio is small. If the amount of pure copper is 10% or less, the residual resistance ratio becomes about 10 and cannot be used. On the other hand, if it is 30% or more, the critical current density decreases and the amount of the reinforcing material also decreases, so that the strength also decreases. The amount of reinforcement should be 10-50% to obtain sufficient strength.

Further, the thickness of the Ta diffusion preventing layer was examined.
The wire was designed and manufactured with a thickness of 1-50 microns.
If the diameter is less than micron, it was found that the Ta layer was broken during the processing of the wire, and it was not possible to prevent the diffusion. From a practical point of view, a thickness of 5 microns or more is required to maintain continuity in the longitudinal direction.

According to the first embodiment described above, the superconductivity and the residual resistance ratio of the compound superconductor are maintained without reduction, and the mechanical strength characteristics are improved. The obtained Nb ₃ Sn compound superconducting wire is obtained.

That is, if the diffusion preventing material 3 is provided between the niobium bronze composite 10 having a large number of Nb core wires 2 and the reinforcing material 5 such as alumina dispersion strengthened copper, the S
Since the diffusion of n into the alumina dispersion strengthened copper is suppressed, the Sn concentration in the bronze does not decrease. Therefore, Sn and Nb
Reaction proceeds sufficiently, and an Nb ₃ Sn superconducting layer is formed on each Nb core wire 2, and the critical current density does not decrease.

Next, when a diffusion preventing material 6 is provided also between the reinforcing material 5, for example, the alumina dispersion strengthened copper and the stabilized copper 4,
Since the diffusion of unreacted Al in the alumina dispersion strengthened copper into the stabilized copper 4 is suppressed, the purity of the stabilized copper 4 is maintained, and the residual resistance ratio is a high value (the resistivity is as low as × 10 ⁻⁸ Ωcm). Value).

For this reason, the superconducting wire does not burn out due to low resistivity even if Joule heat is generated due to an unstable factor, and the reliability of the superconducting magnet can be improved.

In the embodiment of FIG. 1 described above, the structure of each member is, in order from the center of the wire to the outside, the niobium bronze composite 10, the first diffusion preventing material 3, the reinforcing material 5, the second material. The diffusion preventing material 6 and the stabilized copper 4 are used. Of course, since the purity of the stabilized copper 4 may be maintained by the diffusion preventing material, the following configuration is also effective.

That is, as shown in the schematic cross-sectional view of FIG. 5, the niobium bronze composite 1
0, a first diffusion preventing material 3, a stabilized copper 4, a second diffusion preventing material 6, and a reinforcing material 5 are sequentially arranged.

As shown in the schematic cross-sectional view of FIG.
The stabilizing copper 4, the first diffusion preventing material 3, the niobium bronze composite 10, the second diffusion preventing material 6, and the reinforcing material 5 are sequentially arranged from the center of the wire to the outer peripheral side.

As described above, FIG. 5 and FIG. 6 show that the stabilized copper 4 made of pure copper is made of, for example, the Ta diffusion preventing material 3,
6, a good residual resistance ratio of 100 or more could be obtained.

[0056]

As described above, according to the present invention,
Even if a reinforcing material such as alumina dispersion strengthened copper is used for the compound superconductor, it is possible to provide an Nb ₃ Sn compound superconducting wire which does not cause a decrease in critical current density or a decrease in residual resistance ratio, and a method for producing the same.

[Brief description of the drawings]

FIG. 1 shows a first example of an Nb ₃ Sn compound superconducting wire according to the present invention.
FIG. 2 is a cross-sectional view showing a schematic configuration of the embodiment.

FIG. 2 is a diagram showing characteristics of a critical current density with respect to a magnetic field of an Nb ₃ Sn compound superconducting wire according to the present invention and a conventional example.

FIG. 3 is a graph showing characteristics of a residual resistance ratio with respect to a heat treatment time using an Nb ₃ Sn compound superconducting wire according to the present invention and a conventional example.

FIG. 4 is a graph showing a change in a residual resistance ratio depending on a thickness of stabilized copper by an Nb ₃ Sn compound superconducting wire according to the present invention and a conventional example.

FIG. 5 shows a second example of the Nb ₃ Sn compound superconducting wire according to the present invention.
FIG. 2 is a cross-sectional view showing a schematic configuration of the embodiment.

FIG. 6 shows a _{third example} of the Nb ₃ Sn compound superconducting wire according to the present invention.
FIG. 2 is a cross-sectional view showing a schematic configuration of the embodiment.

FIG. 7 is a configuration diagram of a conventional Nb ₃ Sn compound superconducting wire having only one diffusion prevention layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cu-Sn alloy (bronze) tube 2 ... Nb core wire (niobium filament) 3 ... First diffusion preventing material 4 ... Stabilized copper 5 ... Reinforcing material 6 ... Second diffusion preventing material 10 ... Niobium bronze composite body

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Joru Yamada 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Hamakawasaki Plant (72) Inventor Tomoyuki Hattori 2, Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 Inside the Toshiba Hamakawasaki Plant (72) Inventor Tsutomu Kurusu 2-4 Suehirocho, Tsurumi-ku, Yokohama, Kanagawa Prefecture Inside the Keihin Works, Toshiba Corporation (72) Inventor Akira Murase Suehirocho, Tsurumi-ku, Yokohama, Kanagawa Prefecture 2-4-4 Toshiba Keihin Works Co., Ltd. (72) Inventor Yasuji Morii 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Toshiba Yokohama Works Co., Ltd. No. 1 Furukawa Electric Co., Ltd. (72) Inventor Shinichiro Meguro 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Sou Endo 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F-term (reference) 5G321 AA11 BA03 CA09 CA39 CA41 CA42 CA52 DC09

Claims (13)

[Claims] 1. Nb _{3 comprising} a niobium bronze composite containing a niobium filament, stabilized copper made of pure copper, a reinforcing material, and two layers of a diffusion preventing material.
Sn compound superconducting wire. 2. A niobium bronze composite containing a niobium filament, a stabilized copper made of pure copper, a reinforcing material, and first and second diffusion preventing materials are arranged concentrically. The niobium bronze composite, the first diffusion preventing material, the reinforcing material, the second diffusion preventing material, and the stabilizing copper are sequentially arranged from a center to an outer peripheral side in a cross section thereof. Characteristic Nb ₃ Sn compound superconducting wire. 3. A niobium bronze composite containing a niobium filament, a stabilized copper made of pure copper, a reinforcing material, and first and second diffusion preventing materials are concentrically arranged. In the cross section, the niobium bronze composite, the first diffusion preventing material, the stabilized copper, the second diffusion preventing material, and the reinforcing material are sequentially arranged from the center toward the outer peripheral side. An Nb ₃ Sn compound superconducting wire, characterized in that: 4. A niobium bronze composite containing a niobium filament, a stabilized copper made of pure copper, a reinforcing material, and first and second diffusion preventing materials are concentrically arranged. In the cross section, the stabilizing copper, the first diffusion preventing material, the niobium bronze composite, the second diffusion preventing material, and the reinforcing material are sequentially arranged from the center toward the outer peripheral side. An Nb ₃ Sn compound superconducting wire, characterized in that: 5. The reinforcing material is alumina dispersion strengthened copper, N
5. The Nb ₃ Sn compound superconducting device according to claim 1, wherein the Nb—Sn alloy is any one of Ta and Nb. line. 6. The volume ratio of the niobium bronze composite, the stabilized copper, and the reinforcing material is 30 to 70, respectively.
%, 10-30%, and 10-50% of Nb _{3 according} to any one of claims 1 to 4.
Sn compound superconducting wire. 7. The Nb _{3 according} to claim 1, wherein the thickness of the stabilized copper is 20 μm or more and 20-150 μm.
Sn compound superconducting wire. 8. The Nb ₃ Sn compound superconducting wire according to claim 1, wherein the thickness of the diffusion preventing material is 5 μm or more. 9. A first step of producing a composite made of a Cu—Sn alloy containing niobium, a stabilized copper made of pure copper, a reinforcing material, and a member made of a two-layer diffusion prevention material; A second step of reducing the surface of the member obtained in the second step, and a third step of subjecting the member reduced in the second step to heat treatment to form an Nb ₃ Sn layer. A method for producing an Nb ₃ Sn compound superconducting wire, comprising: 10. The method for manufacturing a Nb ₃ Sn compound superconducting wire according to claim 9, wherein said diffusion preventing material is one of Ta and Nb. 11. The reinforcing material is alumina-dispersion strengthened copper, N
b, Nb-Cu alloy, and the diffusion preventing material is T
The method for producing a Nb ₃ Sn compound superconducting wire according to claim 9, wherein the superconducting wire is any one of a and Nb. 12. The method for producing an Nb ₃ Sn compound superconducting wire according to claim 9, wherein the thickness of the stabilized copper is in the range of 20 μm or more and 20-150 μm. 13. The method for producing a Nb ₃ Sn compound superconducting wire according to claim 9, wherein the thickness of the diffusion preventing material is 5 μm or more.