JPH0227620A - Manufacture of superconductive wire rod of nb3al series - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method for manufacturing Nb5Al-based superconducting wire, which is known to have a high critical temperature and critical magnetic field, and is particularly suitable for use in superconducting generators, etc. Use a method that allows superconducting wire to be obtained.

"Prior Art" As a method for manufacturing Nb5A+-based superconducting wire having a high critical temperature and high critical magnetic field, the method described below with reference to FIGS. 10 to 17 is conventionally known.

First, as shown in Figure 1O, a core material 2 made of Nb is inserted into a tube l made of At to create a composite 3, and the diameter of this composite 3 is reduced by extrusion and wire drawing. 11th
A compound line 4 shown in the figure is created. Next, a plurality of composite wires 4 are assembled and inserted into a tubular body 5 made of Al as shown in FIG. 12, and further reduced in diameter to obtain a secondary composite wire 6 shown in FIG. 13.

Next, as shown in FIG. 14, a plurality of the secondary composite wires 6 are assembled and inserted into a tube body 7 made of At, and further subjected to diameter reduction processing to obtain a tertiary composite wire 8 shown in FIG. 15. Next, as shown in FIG. 16, a plurality of these cubic compound lines 8 are collected to form
b or into the diffusion prevention tube 9 made of Ta, and then C
By inserting the wire into the tube lO consisting of N, further reducing the diameter to obtain a wire with the desired diameter, and applying diffusion heat treatment to heat this wire to 700 to 1000°C, the N shown in Fig. 17 is obtained.
b. Al superconducting wire 11 can be obtained.

This superconducting wire 11 has a structure in which a core 12 in which Nb and Al superconducting filaments are dispersed is covered with a diffusion prevention layer 13 made of Ta or Nb and a stabilizing base material 1i 114 made of Cu.

“Problem to be Solved by the Invention” When manufacturing the superconducting wire 11 using the manufacturing method described above, Nb
The core material 2 made of As this process is repeated, the Nb core materials, which have been reduced in diameter and become filament-like, become closer to each other inside the Al base, and as they are brought closer together, the Nb filaments are further reduced in diameter, resulting in non-uniform deformation of the Nb filaments. , heterogeneous Nb3Al
There was a problem with filaments being generated. Also, Nb.

Diffusion heat treatment performed to generate Al filaments is performed by heating to a temperature higher than the melting point of Al (660°C), so a phenomenon occurs in which Nb filaments approach each other in molten At during the diffusion heat treatment, resulting in Nb There was a problem in that the arrangement of the filaments became non-uniform, and as a result, the arrangement of the Nb and Al filaments also became non-uniform.

The present invention has been made to solve the above problems,
Nb + Al superconducting material conductive wire method that allows uniformly distributed superconducting filaments with a well-defined shape, allows free control of the ratio of Nb and Al in the wire, and facilitates processing. The purpose is to provide

"Means for Solving the Problems" In order to solve the above problems, the present invention provides a Nb base material in which storage parts such as grooves or through holes are formed in the length direction,
The storage portion is made of an Al alloy or pure Al containing one or more elements selected from Ag, Sj, Ga, and Ge.
A composite is created by inserting a core material consisting of NbffAl superconducting intermetallic compound by inserting a core material of It is something that generates.

"Operation" Because the At core material is combined with the Nb base material, which is harder than Al, to reduce the diameter, the At core materials inserted into the storage part of the Nb base material do not come close to each other during composite processing. The At core material is uniformly reduced in diameter during composite processing. Since the Al filament, which becomes molten during the diffusion heat treatment, is stored in the storage section of the Nb filament, which does not melt during the diffusion heat treatment,
The distance between the Al filaments is maintained at a predetermined distance, resulting in Nb5A! The filament spacing is also uniform.

"Example" Figures 1 to 8 are for explaining an example of the present invention. In order to manufacture a superconducting wire, a rod-shaped base material 20 made of Nb shown in Figure 1 is used. Prepare this base material 2
One or more groove portions (accommodating portions) 21 are formed along the length direction of the base material 20 on the outer periphery of the base material 20. Subsequently, each groove portion 21 is filled with pure Al.
A composite body 23 is created by inserting a core material 22 consisting of the following material as shown in FIG. The material constituting the core material 22 is A.
An Al alloy obtained by adding 111 or more selected from among g, Si, Ga, and Ge to Al may be used. These elements are known to improve the critical current characteristics of NbaA,l in the high magnetic field region, and when these elements are added, the Nb5
The critical current characteristics of the At superconducting filament in a high magnetic field region can be improved.

Next, the composite body 23 is covered with a tube body 24 made of Nb as shown in FIG.
A tube body 25 made of i-alloy or Cu-Be alloy is placed over the tube, and further diameter-reduced processing is performed to create a composite wire 26 shown in FIG. 5.

Next, as shown in FIG. 6, a plurality of composite wires 26 are gathered together, and then inserted into a diffusion prevention tube 27 made of Ta or Nb, and further covered with a tube body 28 made of pure Cu on the outside.
The following composite 30 is obtained. Next, this secondary composite 30 is subjected to diameter reduction processing until it has a diameter equivalent to that of the target superconducting wire to obtain a wire 31 shown in FIG. This wire rod 31 is composed of a core part 32 having a structure in which an Al filament is arranged inside a base made of Nb, and a diffusion prevention layer 33 and a stabilizing layer 34 that cover this core part 32. The Nb base inside the core 32 is partitioned into a plurality (seven in this embodiment) by a boundary layer formed by reducing the diameter of the tubular body 25 shown in FIG. This strand 31 is created by repeatedly performing diameter reduction processing after compounding the Al core material 22 with the base material 20 made of Nb, which is harder than At.
After the diameter reduction process, the mutual spacing between the Al filaments is kept uniform.

Next, this strand 31 is subjected to diffusion heat treatment in which the wire is heated to 700 to 1000°C to diffuse Al in the Al filament and react with surrounding Nb, thereby producing a Nb3Al superconducting intermetallic compound filament as shown in FIG. Superconducting wire B can be obtained.

Since the superconducting wire B manufactured as described above is manufactured by performing diffusion heat treatment on the wire 31 in which the Al filaments are uniformly arranged, the Nb3Al superconducting filaments are also uniformly arranged. Therefore, superconducting wire B with excellent properties can be obtained.

In addition, the generated NbffAl superconducting filament is N
This Nb base is divided into a plurality of parts by a boundary layer formed by processing the material constituting the tube body 25.

Therefore, when a high-resistance metal material such as a Cu-Ni alloy or a Cu-Be alloy is used for the material constituting the tube body 25, a boundary layer made of these alloys will reduce the coupling current that is about to occur between the superconducting filaments. Therefore, superconducting wire B with less AC loss can be obtained. Furthermore,
When an Al alloy containing one or more elements among Ag, Si, Ga, and Ge is used as the material constituting the core material 22, it is possible to improve the critical current characteristics of the Nb1Al filament in the high magnetic field region. There is an effect that can be done. In addition, when manufacturing the superconducting wire B by the above-mentioned method, W formed on the base material 20
By appropriately adjusting the size and number of 1t21 and changing the size and number of core material 22 inserted therein, the ratio of Al and Nb contained in the strand 31 can be changed, so the desired amount of N can be changed.
b. Al can be generated, and superconducting wire B with desired characteristics can be manufactured.

Superconducting wire B manufactured as described above has excellent critical current characteristics in a high magnetic field region, and has a structure in which uniformly processed Nb1Al superconducting filaments are uniformly dispersed inside a highly hard Nb base. It also has high mechanical strength. Therefore, this superconducting wire B can sufficiently withstand use as an alternating current wire in a superconducting generator or the like.

In the above embodiment, an example was explained in which the groove portion 21 was formed as a storage portion in the Nb base material 20, but as shown in FIG. (Three in this example) may be formed, and after inserting the core material 22 made of Al into each through hole 21a, diameter reduction processing may be performed to manufacture the superconducting wire. However, the method of forming the through hole 21a in the base material 20° may not be possible if the diameter of the base material 20° is small. In this respect, if the composite is performed by forming the WIt 21 on the rod-shaped base material 20 and inserting the core material 22 as described above, the base material 20 becomes 1
Even if the diameter is 0 mm or less, it can be easily carried out. In addition, when forming the through hole 21a and combining the core material 22, it is possible to use a base material 20' with a large diameter, but in that case, hot extrusion processing is performed for diameter reduction processing. The need arises. In this respect, if the method of forming the grooves 2I in the base material 20 starts from a small diameter base material 20, the diameter reduction process can be performed only by cold working.

Furthermore, in the above embodiment, an example was explained in which the step of gathering the compound lines 26 is performed only once, but the compound lines 26
After gathering a plurality of wire rods 6 and reducing the diameter to form a wire rod, the step of gathering a plurality of wire rods may be performed one or more times.

"Manufacturing example" Diameter 7. Four grooves each having a U-shaped cross section and a depth of 2.2 mm were formed at 90° intervals by cutting on the outer periphery of a rod-shaped Nb base material of 0 mm in diameter over the entire length of the Nb base material.

Next, a round wire-shaped core material made of an A i3 at%Ag alloy with a diameter of 2.0 mm was inserted into the groove of the Nb base material, and the whole was further reduced to an outer diameter of 10 m5. It is inserted into a Nb tube with an inner diameter of 8 mm, and further outside it is an outer diameter 15III1 made of Cu-10% Ni alloy.
No. 11 was covered with a tubular body having an inner diameter of 12 mm, and wire drawing was performed to obtain a composite wire with a diameter of 1.0 mm. Next, 91 of these composite wires were bundled into a Cu-10%Ni wire with an outer diameter of 13 mm and an inner diameter of 12+a.
After being inserted into a tube made of alloy, it is reduced in diameter to 1.0m.
m strands were created. Next, 91 of these wires were bundled and inserted into a tube made of Cu10%Ni alloy with an outer diameter of 13111111% and an inner diameter of 12 mm, and then a Nb tube with an outer diameter of 15 mm and an inner diameter of 14 m+m was placed on the outer periphery, and an outer diameter of 20+++n+,
An oxygen-free steel pipe with an inner diameter of 16 mm was placed over the wire and wire drawing was performed to obtain wires with a diameter of 0.5 mm.

The obtained wire was heated at 750°C in an Ar gas atmosphere.
A diffusion heat treatment was performed in which the wire was heated for 24 hours to generate a Nb and Al superconducting intermetallic compound filament, thereby obtaining a superconducting wire.

When we measured the superconducting properties of this superconducting wire, we found that it was 10T.
At 4.2 K in a magnetic field of
This superconducting wire exhibited an excellent value of 1.5 x 10 'A/am''. Also, this superconducting wire exhibited an excellent value of critical temperature Tc = 17. Furthermore, the inside of this superconducting wire was examined using X-ray diffraction. Upon investigation, it was confirmed that Al5 type Nb5Al superconducting compound filaments were produced.

"Effects of the Invention" As explained above, the present invention has the advantage that Nb, which has higher hardness than Al,
Since the diameter is reduced by combining Al or Al alloy core material with the base material, the core materials inserted into the storage part of the Nb base material do not come close to each other during composite machining, and the core materials are uniformly distributed during composite machining. The diameter can be reduced to Therefore, the diffusion heat treatment has the effect of producing uniformly deformed Nb5A+ superconducting filaments. Furthermore, since the Al or Al alloy filaments that become molten during the diffusion heat treatment are housed in the Nb filaments that do not melt during the diffusion heat treatment, the spacing between the Nb3Al filaments is maintained at a predetermined spacing. Therefore, uniformly dispersed Nb
There is an effect that a long and uniform superconducting wire having a 3Al superconducting filament can be manufactured. In addition, by adjusting the number and size of storage parts formed in the Nb base material to desired values, the ratio of Nb and Al can be adjusted to a desired value, which has the effect of controlling the amount of Nb5Al produced. . Furthermore, it is possible to produce a superconducting wire with high mechanical strength in which Nb3Al superconducting filaments are dispersed inside the Nb base, which is harder than At. Therefore, by carrying out the present invention, it is possible to obtain a superconducting wire having high mechanical strength and excellent superconducting properties suitable for use in superconducting power generators.

[Brief explanation of the drawing]

Figures 1 to 7 are for explaining one embodiment of the present invention. Figure 1 is a cross-sectional view of a Nb base material, and Figure 2 is a Nb base material with a storage section formed with an Al core. Fig. 3 is a cross-sectional view showing the Nb tube covered with the Nb base material, Fig. 4 is a cross-sectional view showing the Nb tube covered with the metal tube, and Fig. 5 is the cross-sectional view showing the Nb tube covered with the metal tube. A cross-sectional view of a composite wire, Figure 6 is a cross-sectional view showing the assembled state of the composite wire, Figure 7 is a cross-sectional view of the wire, Figure 8 is a cross-sectional view of the superconducting wire, and Figure 9 is another example of Nb base material. 10 to 17 are for explaining the conventional example, FIG. 10 is a sectional view of the compound wire, FIG. 11 is a sectional view of the compound wire after diameter reduction, and FIG. 12 is a sectional view showing the compound wire after diameter reduction. The figure is a cross-sectional view showing the assembled state of compound lines, Figure 13 is a cross-sectional view of a secondary compound line,
Figure 4 is a sectional view showing the assembled state of secondary composite wires, Figure 15 is a sectional view of tertiary composite wires, Figure 16 is a sectional view showing the assembled state of tertiary composite wires, and Figure 17 is a cross-sectional view of superconducting wires. FIG. 0...Nb base material, 21...Groove (storage part), 2...
・Core material, 23...Composite, 31...Element wire, 2...
Core portion, 33... Diffusion prevention layer, 4... Stabilization layer, 20
′...Nb base material, 1a... Through hole (storage part).

Claims (1)

[Claims] A long Nb base material in which storage parts such as grooves or through holes are formed in the longitudinal direction is prepared, and Ag, Si, and G are placed in the storage parts.
A core material made of an Al alloy or pure Al containing one or more elements selected from a and Ge is inserted to create a composite, and after a plurality of these composites are assembled, diameter reduction processing is performed. 1. A method for producing a Nb_3Al-based superconducting wire, comprising: forming a strand using a strand, and then subjecting the strand to a diffusion heat treatment to generate a Nb_3Al superconducting intermetallic compound.