JPS61279662A - Production of nb3sn multi-cored superconductive wire - Google Patents

Abstract

PURPOSE:To produce quickly a multi-cored Nb3Sn superconductive wire by dividing plural pieces of composite Cu-Nb composite wires by Cu to plural groups, disposing the wires to the outside periphery of Sn rods, housing the rods into a Cu pipe and subjecting the pipe to sectional area reducing working and heat treatment. CONSTITUTION:Plural pieces of the composite wires 2 formed by disposing many pieces of Nb filaments 2b into Cu matrixes 2a to the outside periphery of the rods 3 consisting of the Sn or Sn alloy rods 3a coated with Cu 3b are housed into the stabilized Cu pipe 6 via an Nb or Ta diffusion barrier 5 and the above-mentioned composite wires 2 are disposed in the spaces formed by dividing the spaces between the barrier 5 and plural pieces of the aggregated rods 3 by the Cu wires 4. The composite body 1 formed in the above-mentioned manner is subjected to the sectional area reducing working such as drawing, then to a diffusion heat treatment of Sn and heat treatment for forming Nb3Sn. The above-mentioned Cu wires 4 reduces the time for the diffusion heat treatment as the Sn diffusion path. The multi-cored Nb3Sn superconductive wire having the excellent workability and superconductive characteristic is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a superconducting wire, and particularly to a method for manufacturing a multicore Nb, Sn multicore superconducting wire using an internal diffusion method.

[Technical Background of the Invention] Conventionally, an internal diffusion method has been known as a method for producing a multicore Nb, 3 Sn superconducting wire. In this method, a 5N wire serving as a diffusion source and a large number of Nb wires are arranged in a Cu matrix, and a two-step heat treatment is performed after processing to form an NbHSn layer around or over the entire Nb wire. Usually, stabilized Cu is placed around the outer periphery of the Cu matrix with a diffusion barrier interposed therebetween.

The above heat treatments include (1) a heat treatment below 500 °C to diffuse 50 into the Cu matrix (first stage heat treatment), and (2) a heat treatment below 500 °C to form Nb,3Sn.
that's all.

Usually, heat treatment is carried out at around 700°C (second stage heat treatment), but in particular, the first stage heat treatment is usually carried out in a temperature range from just above the melting point of Sn to below the reaction temperature for Nb, Sn formation. Although the heat treatment time depends on the diameter and arrangement of the Nb filaments, it takes from several days to more than ten days. The reason why such a long heat treatment is required is that the heat treatment temperature is low and that the Sn diffusion path is close to the N
b This is because it is limited to the Cu matrix in the filament gap.

[Problems in the background art] The internal diffusion method described above has the advantage of not requiring intermediate annealing during processing, but the first step of Sn diffusion heat treatment takes a long time, and it is difficult to achieve sufficient homogeneity. If Sn is not diffused, the generation of Nb3Sn will be insufficient in the second stage heat treatment, resulting in a disadvantage that the superconducting properties will deteriorate.

[Object of the Invention] The present invention has been made to solve the above-mentioned difficulties, and by dividing the Nb filament group into a plurality of pieces using Cu, which serves as a diffusion path for Sn, the heat treatment time in the first stage is shortened. In addition, the eleventh objective is to improve the superconducting properties after the second stage heat treatment.

[Summary of the invention] The present invention provides the following features: C on the outer periphery of Sn or Sn alloy rod.
A plurality of composite wires in which a large number of Nb filaments are arranged in a u matrix are assembled, and the composite wires are housed in stabilized Cu9 via a diffusion barrier.The composite wire is subjected to a cross-section reduction process, and then Sn diffusion heat treatment and In the method of manufacturing a superconducting wire by applying heat treatment to generate Nb and 3Sn, the composite wire is arranged in a space divided into a plurality of spaces by Cu between a diffusion barrier and a Sn or Sn alloy rod. It is characterized by

The composite wire in the present invention is Cu covered r1. It is obtained by processing Nb rods into a regular hexagonal cross section, accommodating a large number of these rods in a Cu tube, and then further processing them into a regular hexagonal cross section.

On the other hand, the Sn or Sn alloy rod can be a Cu-coated rod, and by making it have the same cross-sectional shape as the above-mentioned composite wire, a plurality of composite wires can be closely spaced around the outer periphery of an arbitrary aggregate. It can be filled inside.

[Embodiments of the invention] An embodiment of the present invention will be described above.

[Example] FIG. 1 is a partial sectional view of a composite 1 used in the present invention, FIG. 2 is a sectional view of a composite wire 2 incorporated into this composite 1, and FIG. 3 is a sectional view of a composite wire 2 incorporated into the composite 1. It shows a cross-sectional view of a Cu-coated Sn rod 3, in which a composite 1 was manufactured by the method described above.

As shown in FIG. 2, 931 Nb filaments 2b are arranged in a Cu matrix 2a with a copper ratio of 1.0. As shown in FIG. 3, there is a composite wire 2 with a regular hexagonal cross section with a distance between parallel planes of 2.13+u+a, and a 15v wire with a %Sn composition of Sn rod 3a coated with Cu3b on the outer periphery of a Sn rod 3a with the same cross-sectional shape as this composite wire 2, as shown in FIG. A Cu-covered Jil S r+ rod 3 was manufactured by cold working. Furthermore, C with the same cross-sectional shape as composite wire 2
127 of the Cu-coated Sn rod 3.
Arrange 174 composite wires 2 on the outer periphery of the collection of books so that they are divided into 6 by Cu wires 4, and divide them into 2 mm thick T
Through pipe 5 of a, outer diameter 58mmφ, inner diameter 46mm
The complex was housed in a Cu vibro of φ to constitute a complex I.

This composite 1 is subjected to cross-sectional reduction processing such as swaging and wire drawing, so that the outer diameter is 1.0 + umφ and the filament diameter is 0.
．． After making a wire with a diameter of 9 μm and 144,300 filaments, it was subjected to S at 300°C for 3 days and at 450°C for 5 days.
First, N diffusion heat treatment was performed at 700°C for 60 hours.
b3 Nb3Sn with multi-core structure after heat treatment to generate Sn
Manufactured superconducting wire. The critical current value of this superconducting wire is 9
It was 60A at T.

[Comparative example] '15 m 91 b= s°t6a*K 1 (DA
I-jNk-1! iQ@°11.

The composite wire 4 shown in FIG. 4 is replaced with a composite wire 2, and the composite wire 7 shown in FIG.
Using the same processing method as 1°, the outer diameter was 1.0II11.
1Iφ, F-men outer diameter 0.9μmφ
, number of filaments 1 (i, 0.95 million a *A &
'<* f: * , °°°°0°58 nll *;
-11,0450'CX ] 05 B.

First, Sn diffusion heat treatment was performed at 700°C
A superconductor 14 conductor with a multi-core structure was produced by heat treatment to generate Nb3Sn+ between [:'1:]. The critical current value of this superconducting wire was 9T and 46A.

[Effects of the Invention] As described above, according to the method for manufacturing a Nb3Sn superconducting wire of the present invention, C is contained in the wire having the final wire diameter before heat treatment.
Since the Sn diffusion path made of U is provided, the Sn diffusion heat treatment time can be greatly shortened, and the processability is also excellent, and the superconducting properties after the heat treatment are also improved.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a composite used in the method of the present invention, FIGS. 2 and 3 are cross-sectional views of a composite wire and a Cu-coated Sn rod incorporated into this composite, respectively, and FIG.
The figure is a partial cross-sectional view of a composite in a comparative example. 1, 7...Compound 2...Compound line

Claims (1)

[Claims] 1. A plurality of composite wires in which a large number of Nb filaments are arranged in a Cu matrix are assembled around the outer periphery of a Sn or Sn alloy rod, and these are stabilized by Cu via a diffusion barrier.
The composite housed in the tube is subjected to cross-section reduction processing, and then S
In the method for manufacturing a superconducting wire by performing a diffusion heat treatment of n and a heat treatment for producing Nb_3Sn, the composite wire has carbon between a diffusion barrier and a Sn or Sn alloy rod.
A method for producing a Nb_3Sn multicore superconducting wire, characterized in that the Nb_3Sn multicore superconducting wire is arranged in a space divided into a plurality of spaces by u. 2. The method for manufacturing a Nb_3Sn multicore superconducting wire according to claim 1, wherein the Sn or Sn alloy rod is a Cu-coated rod. 3. Nb_3 according to claim 1 or 2, in which a plurality of Sn or Sn alloy rods are assembled.
A method for manufacturing Sn multicore superconducting wire. 4. The method for manufacturing a Nb_3Sn multicore superconducting wire according to claim 1, wherein the diffusion barrier is made of Nb or Ta.