JP2001243844A - Method for producing Nb3Ge-based superconducting wire - Google Patents

Abstract

(57) [Summary] [Problem] To manufacture Nb3Ge-based superconducting wires without problems of deterioration of magnetic field current characteristics due to bending stress, magnetic instability, difficulty of compounding stabilizing material, and specialization of manufacturing equipment. Provide a way. Kind Code: A1 A heat treatment (i) is performed on a composite wire in which an Nb filament and a Cu—Ge alloy material are integrated to diffuse a Ge component from the Cu—Ge alloy material into the Nb filament. Rapid heating and rapid cooling (j)
To form a Nb-Ge solid solution in the filament, and then to a heat treatment (k) to obtain a Nb-Ge solid solution.
3 Ge is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an Nb3 Ge-based superconducting wire, and more particularly to a conventional Nb3G superconducting wire, such as a decrease in magnetic field current characteristics due to the action of bending stress or magnetic instability.
The present invention relates to a manufacturing method capable of solving various problems of an e-based superconducting wire.

[0002]

2. Description of the Related Art Before the discovery of copper oxide superconductors, Nb3 Ge has the highest critical temperature of 23 K among all materials having superconductivity, and has an upper critical magnetic field characteristic of 40 T or more. Therefore, it has been regarded as promising as a superconducting material for a high magnetic field magnet. But,
Since the Nb3 Ge compound has the property of being stabilized only at a high temperature of about 2000 ° C. in the phase diagram, its production involves very difficulties.

Conventionally, as a method for producing a Nb3 Ge superconducting wire, a molten Nb-Ge metal is sprayed onto a base tape and then quenched, or a film is formed on a heated base tape by a CVD method. Methods and the like have been tried, and according to the superconducting wire obtained by these methods,
It has been confirmed that the film exhibits high critical current density characteristics in a high magnetic field of 20 T or more.

[0004]

However, the conventional Nb3
According to the manufacturing method of the Ge-based superconducting wire, since the obtained superconducting wire has a structure in which the Nb3Ge layer is provided on the base tape, Nb3G is applied by bending strain stress applied at the time of magnet winding or the like.
e, there is a problem that the magnetic field current characteristics are deteriorated, and there is also a problem of magnetic instability due to generation of a flux jump in a low magnetic field due to the single-core structure. It has many problems, such as difficulty in production and the need for special manufacturing equipment.

[0005] Accordingly, an object of the present invention is to reduce the magnetic field current characteristics due to bending stress or the like, to cause magnetic instability, to make it difficult to combine a stabilizing material, and to avoid the problem of specializing a manufacturing apparatus.
An object of the present invention is to provide a manufacturing method capable of obtaining a b3Ge-based superconducting wire.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides Nb or Nb alloy (hereinafter simply referred to as Nb alloy).
The filament is inscribed, circumscribed, or inscribed and circumscribed, and a Cu—Ge alloy material is disposed thereon, and a heat treatment is performed on a composite wire obtained by integrating these materials.
-Diffusing the Ge component of the Ge alloy material into the filament, generating a Nb-Ge solid solution in the filament by subjecting the composite wire to rapid heating and quenching after the heat treatment, and then heating the composite wire. The present invention provides a method for producing an Nb3 Ge-based superconducting wire, characterized in that an Nb3 Ge compound is generated in the filament by the above method.

[0007] The above-mentioned composite wire is often manufactured by extruding and drawing a composite billet made of a combination of pipe materials, in which case the Cu-Ge alloy material diffuses Ge into the Nb filament. In order to make the Nb filament uniform, the Nb filament is located inside and outside. Specifically, a Cu—Ge alloy material is filled into an Nb pipe, and a composite billet is formed around the pipe by covering the pipe with a Cu—Ge alloy pipe, which is extruded and drawn to a predetermined size. To finish.

[0008] In the above heat treatment performed for diffusing the Ge component into the Nb filament, it is preferable to set the diameter of the Nb filament to 3 µm or less.
The Ge component is diffused by segregating Ge around the filament and part of the segregated Ge diffuses into the Nb filament. When the diameter of the filament becomes larger than 3 μm, Ge becomes the center of the filament. Nb3 Ge tends to deviate from the stoichiometry (Nb: Ge = 3: 1), making it difficult to secure predetermined superconducting characteristics. Therefore, the diameter of the Nb filament during the Ge diffusion process in the present invention is set to 3 μm or less in many cases.

As the above-mentioned rapid heating means, energization heating capable of instantaneously increasing the temperature is preferable. On the other hand, when the energization heating is employed, the Cu-Ge alloy material contains a third component such as Zn. Preferably. In the Cu-Ge alloy material after the diffusion of Ge into the Nb filament,
Although Cu having no reactivity with Nb remains, if the purity of Cu becomes high, current selectively flows to this portion during heating for energization, making it difficult to heat the core. Therefore, the inclusion of the third component such as Zn in the Cu—Ge alloy material leads to maintaining the electric resistance after diffusing Ge at a predetermined level, and is an effective means for guaranteeing electric heating. .

As another preferable means for ensuring the electric heating, there is a method of setting the amount of Ge in the Cu-Ge alloy material to be larger than that used for diffusion. The Ge component left over from diffusing into the Nb filament will maintain the electrical resistance of the remaining Cu, and thus the residual C
Selective current flow to u is prevented and a predetermined energized heating is ensured.

The heat treatment temperature for diffusing the Ge component into the Nb filament is 500 to 1,000 ° C.
On the other hand, the rapid heat treatment by energization or the like and the heat treatment for final Nb3 Ge generation are performed, for example, at about 2,000 ° C. and about 800 ° C., respectively.

[0012]

Next, an embodiment of a method for manufacturing an Nb3 Ge superconducting wire according to the present invention will be described. FIG.
Indicates a manufacturing procedure. First, Cu-3 at% is used.
Ge-5at% Zn alloy rod (diameter 9.7 mm, length 1
50mm) and Nb pipe (inner diameter 10mm, outer diameter 20m)
m, length 150mm) and Cu-3at% Ge-5at
% Zn alloy pipe (inner diameter 20.3mm, outer diameter 25m
m, 150 mm in length), and by combining them, a composite material shown in (a) was assembled in which the innermost layer was a bar 1, the intermediate layer was an Nb pipe 2, and the outermost layer was an alloy pipe 3. Next, a single billet was manufactured by attaching a copper plug and an iron plug to the front end and the rear end, respectively.

Next, in (b), this is subjected to extrusion and drawing to form a single hexagonal line having a hexagonal opposite side distance of 1.4 mm in the cross section, and the single hexagonal line is cut into a length of 150 mm. Into a Ta pipe (inner diameter 29 mm, outer diameter 32 mm, length 150 mm).
After filling 9 pipes, the outer circumference of the Ta pipe is covered with a Cu pipe (inner diameter 32.3 mm, outer diameter 36 mm, length 150 mm) to combine a single hexagonal wire 4, a Ta pipe 5, and a Cu pipe 6 (c). The sub-multi billet was manufactured by assembling the composite material and attaching a copper plug and an iron plug to a front end and a rear end of the composite material, respectively.

Next, in (d), the sub-multi billet is extruded and drawn to form a hexagonal wire having a hexagonal cross section of 1.4 mm in opposite side distance, and the obtained hexagonal wire is represented by (e). ), The Cu jacket was removed by immersing in a 150 mm length and immersed in an acid solution, and then 210 sub hexagonal wires thus obtained were Nb pipes (inner diameter 24 mm, outer diameter 28 mm, length 150 mm) and a Cu pipe (inner diameter 2) on an Nb pipe.
8.3 mm, outer diameter 32 mm, length 150 mm)
As a result, a composite material shown in (f) was assembled in which the innermost layer was a sub-hexagonal wire 7, the intermediate layer was an Nb pipe 8, and the outermost layer was a Cu pipe 9, and then a copper plug was attached to the leading and trailing ends, respectively. A multi billet was made by attaching an iron plug.

Next, in (g), the multi billet is subjected to extrusion and wire drawing to reduce the wire diameter to 0.8.
After the wire is drawn to a thickness of 2 mm, a twist (twist) is added in (h) and the copper jacket is removed by dipping in an acid solution (i).
A predetermined wire rod was obtained through the above steps. The diameter of the cylindrical Nb filament in this wire is about 1 μm, and the Nb filament is Cu-Ge-Z
A large number of filaments of about 0.5 μm diameter made of n alloy are incorporated. The total number of Nb filaments in this wire is
349 × 210 = 73,290 lines.

The above composite wire is then subjected to a heat treatment (j) at 600 ° C. × 100 hours in a vacuum, whereby Ge is diffused from the Cu—Ge—Zn alloy into the Nb filament. Next, in (k), a rapid heating by current heating (100 A × 0.1 second / 200 mm) and a rapid cooling immediately thereafter are performed to generate a Nb—Ge solid solution in the filament, and then the final step of (l) is performed. A heat treatment is performed, whereby Nb3 G
An e compound is formed.

FIG. 2 shows the magnetization of the wire rod obtained as described above.
It shows a temperature characteristic. The diamagnetism of the wire is 22.5
K, indicating that this wire is an excellent Nb3 Ge-based superconducting wire having a critical temperature characteristic of 22.5K. Further, according to the superconducting wire obtained as described above, since it is possible to form a round and composite structure, there is no problem of the magnetic field current characteristics of Nb3 Ge deteriorating due to the action of bending strain stress, and the magnetic flux due to flux jump in a low magnetic field is reduced. Since there is no problem of thermal instability and the alloy material or the like from which Ge has been removed can serve as a stabilizing material, the problem of difficulty in compounding a stabilizing material can be solved.

The manufacturing process is, as is clear from the above-described embodiment, the Ni mass conventionally produced in mass production.
It is based on a manufacturing mode similar to that of a Ti superconducting wire or an Nb3 Sn superconducting wire, so that an Nb3 Ge superconducting wire can be easily manufactured without requiring a special manufacturing apparatus.

[0019]

As described above, the Nb according to the present invention is
According to the method for producing a 3Ge-based superconducting wire, the Ge component of the Cu-Ge alloy material is diffused into the Nb filament by subjecting the composite wire material of the Nb filament and the Cu-Ge alloy material to heat treatment. After heat and quenching, a heat treatment for generating Nb3 Ge is performed to produce an Nb3 Ge-based superconducting wire. Therefore, as described above, the magnetic field current characteristics decrease due to bending stress and the like, magnetic instability, and stabilization. It is possible to manufacture a highly useful Nb3Ge-based superconducting wire without the difficulty of compounding the material and the problem of specializing the manufacturing apparatus.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a method for manufacturing an Nb3Ge-based superconducting wire according to the present invention.

FIG. 2 shows Nb3 Ge obtained by the embodiment of FIG.
Explanatory drawing which shows the characteristic of a system superconducting wire.

[Explanation of symbols]

 Reference Signs List 1 alloy rod (Cu-Ge-Zn) 2, 8 Nb pipe 3 alloy pipe (Cu-Ge-Zn) 4 single hexagonal wire 5 Ta pipe 6, 9 Cu pipe 7 sub hexagonal wire

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C22F 1/00 627 C22F 1/00 627 661 661A 691 691A 692 692A 1/08 1/08 B H01B 12/10 ZAA H01B 12/10 ZAA

Claims (6)

[Claims] 1. A Cu-Ge alloy material is inscribed, circumscribed, or inscribed and circumscribed on a filament of Nb or Nb alloy, and a heat treatment is performed on a composite wire obtained by unifying these Cu-Ge alloy materials. The Ge component of the Ge alloy material is diffused into the filament, and after the heat treatment, the composite wire is subjected to rapid heating and quenching to generate an Nb-Ge solid solution in the filament, and then heating the composite wire. Nb3 Ge compound is generated on the filament.
Manufacturing method of 3Ge superconducting wire. 2. The method according to claim 1, wherein the composite wire is made of Nb or Nb.
2. The Nb3 Ge according to claim 1, wherein the Nb3 Ge is formed by extruding and drawing a composite material in which a Cu-Ge alloy material is disposed inside and around an alloy pipe.
Of superconducting superconducting wire. 3. The method according to claim 1, wherein the heat treatment is performed with the diameter of the filament set to 3 μm or less. 4. The method according to claim 1, wherein the heat treatment is performed by applying a current to the composite wire. 5. The heat treatment according to claim 1, wherein the Cu—Ge alloy material is
5. The method for producing an Nb3 Ge-based superconducting wire according to claim 4, wherein the method is carried out by including a third component such as n. 6. The heat treatment is performed after the heat treatment.
5. The method for producing an Nb3 Ge-based superconducting wire according to claim 4, wherein the Cu-Ge alloy material is provided with a Ge concentration such that a Ge component remains in the Ge alloy material.