JPH0660749A - Manufacture of nb3al-based multicore superconductive wire - Google Patents

Abstract

PURPOSE:To improve the processibility and stability of a Nb3Al-based superconductive wire with a multicore structure. CONSTITUTION:Two Nb sheets 1, 2, in one sides of which grooves 1a, 2a are formed respectively in parallel to each other and in a constant distance, are set so as to put the grooves 1a, 2a on the opposite to each other and Al wires 3 are put in the grooves and Cu sheets 4, 5 are put in the outside of the Nb sheets 1, 2. The obtained composite sheet is rolled and then coiled into a cylindrical shape, put in a Cu tube to give a composite body, and after the resulting composite body is extruded to decrease the cross-section surface area, it is heated at 800 deg.C or lower temperature to give a superconductive wire consisting of a Cu matrix and a large number of single wires put in the matrix.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a superconducting wire, and particularly to a Nb ₃ Al superconducting wire having a multi-core structure which is excellent in workability and can be thinned, and which is excellent in stability and superconducting characteristics. The present invention relates to improvement of manufacturing method.

[0002]

The superconducting material is [Prior Art] A15 type intermetallic compound, has excellent superconducting properties generally compared to an alloy-based superconducting material such as Nb-Ti alloy, in particular Nb ₃ Al
The critical temperature (Tc) and critical magnetic field than in the Nb3 Sn is (H _C
Although it has advantages such as high ₂ ) and excellent mechanical properties, stoichiometric Nb ₃ Al having excellent superconducting properties is difficult to form by diffusion reaction, and it is difficult to produce a long wire. .

That is, since Nb ₃ Al having a stoichiometric composition with excellent superconducting properties is stable only at high temperature and its generation rate is extremely low, it is difficult to diffuse and generate Nb ₃ Al by heat treatment at low temperature. is there. According to research on the diffusion process of Nb-Al alloys, the diffusion rate of Nb-Al is extremely low, and for example, Nb of several μm at around 800 ° C.
It is known that a very long diffusion time is required to form a ₃ Al layer.

However, if the diffusion distance between Nb and Al is made extremely small, grain boundary diffusion becomes dominant and the heat treatment conditions can be improved. Therefore, heat treatment at a temperature of 1000 ° C. or less makes it possible to obtain a practical level of superconductivity. It is possible to manufacture the material. Conventionally, from such a viewpoint,
Although the high magnetic field characteristics are slightly inferior to those of the melt quenching method,
A jelly roll method is known as a method for easily producing a long wire.

In this method, an Nb sheet and an Al sheet are laminated, rolled, inserted into a cylindrical sheath material, wire-drawn, and then heat-treated. For example, Nb
The sheet and the Al sheet are overlapped and wound on a Cu rod, inserted into a Cu pipe, and the Al sheet is drawn to a thickness of about 0.2 μm, and then heat treated at a temperature of 800 ° C. to obtain Tc = 15.6K. , Critical current density (Jc) = 10 ⁴ A
/ Cm ² Nb ₃ Al superconducting wire has been obtained (S. Cere
sala et al: IEEE Trans.on Magn.MAG-11 (1975) 263).

[0006]

In the above jelly roll method, since Nb and Al are adjacent to each other, a Nb ₃ Al layer is continuously formed by heat treatment.
Therefore, in the state of a single wire that is simply inserted into a cylindrical sheath material and subjected to wire drawing processing, the behavior of one filament is exhibited, the coupling loss becomes very large, and the stability becomes very poor. It cannot be used as a wire rod. For this reason, conventionally, a plurality of single wires are further inserted into a metal tube and subjected to a wire drawing process a plurality of times to make multiple cores, that is, by manufacturing a multi wire,
Solving this problem has been considered.

In this case, in order to improve the stability of the multi-wire, it is necessary to arrange a Cu tube outside the sheath material to manufacture a single wire. However, N as described above
The processing of b ₃ Al multi-wires is very difficult, and the production of long superconducting wires by this method has not been realized yet.
The present invention has been made to solve the above problems,
Nb of multi-core structure with improved workability, long length and excellent stability
_An object of the present invention is to provide a method for easily producing a ₃ Al superconducting wire.

[0008]

In order to achieve the above object, the method for producing a Nb ₃ Al multifilamentary superconducting wire according to the present invention comprises:
While arranging aluminum or aluminum alloy wires in parallel between the sheets of niobium or niobium alloy sheets, placing a copper sheet on the outside of the niobium or niobium alloy sheet, and subjecting this to rolling to produce a composite sheet, This composite sheet is rolled up and housed in a copper tube, then shaped into a predetermined shape by surface-reduction processing, and then heat-treated at a temperature of 800 ° C. or lower.

The Al (alloy) line in the present invention is arranged in parallel between two Nb (alloy) sheets. In this case, a line parallel to one or both of the Nb (alloy) sheets is formed. The Al (alloy) wire may be housed in this groove.

[0010]

With the above constitution, in the method of the present invention, C
Since Al or Al alloy wires are arranged in parallel between the Nb or Nb alloy sheets having the u sheet arranged on the outer side, it is possible to achieve multi-core and remarkably improve workability. Also, because Nb is arranged in the Cu matrix,
In addition to being excellent in stability, since the heat treatment is performed in a state where Nb and Al are close to each other, low-temperature treatment is possible like the jelly roll method.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view of a composite sheet of the present invention before rolling, wherein 1 and 2 are Nb sheets, 3 are Al wires and 4 and 5 are Cu sheets. Nb sheet 1,2
Grooves 1a and 2a are formed in parallel on one surface of the sheet at the same intervals. These Nb sheets 1 and 2 are arranged so that the grooves 1a and 2a face each other, and are formed by these grooves. The Al wire 3 is housed in the space, and the Nb sheet 1,
Cu sheets 4 and 5 are arranged on the outer side of 2.

The composite material 10 is rolled to form a composite sheet. Then, as shown in FIG. 2, the composite sheet 11 is lapped in a cylindrical shape and housed in a Cu tube 12 to form a composite body 13. Then this complex 13
After surface-reduction processing, heat treatment is performed at a temperature of 800 ° C. or less to manufacture a superconducting wire. In the above-mentioned composite material 10, the Al wire was housed in the groove formed in the two Nb sheets each having the Cu sheet arranged on the outer side. However, as shown in FIG. 3, the Al wire was housed in the Nb sheet 6 on one side. Groove 6 for
After forming a and accommodating the Al wire 3 in this groove, the Nb sheet 7 may be laminated thereon to form the composite material 20.

Further, as shown in FIG. 4, the Al wire 3 is housed in the grooves of two Nb sheets 8 and 9 in which grooves 8a and 9a are formed in parallel on one surface at equal intervals.
The composite material 30 may be formed by stacking the Nb sheets 8 and 9 so that the lines are alternately arranged with respect to the boundary surface H. still,
Cu sheets 4 and 5 are similarly arranged on the outer sides of the Nb sheets 6, 7, 8 and 9 of FIGS.

Specific Examples Hereinafter, examples of the present invention will be described. Thickness 0.2mm
0.1mm on one side of Nb sheet with a radius of 0.1mm
A semi-circular groove was formed. Two Nb with this groove
After stacking the sheets so that the positions of the respective grooves face each other, accommodating an Al wire having a diameter of 0.2 mm in the grooves and further disposing a Cu sheet having a thickness of 0.2 mm outside the two Nb sheets Then, this was rolled to manufacture a composite sheet having a thickness of 40 μm.

This composite sheet is lapped and wound to have an outer diameter of φ52.
The composite was formed by accommodating it in a Cu tube having a diameter of 41 mm and an inner diameter of 41 mm. This composite is subjected to hydrostatic extrusion processing to give a diameter of 33 m.
outer diameter φ0.5mm
After manufacturing the wire of (1), heat treatment was performed at 750 ° C. for 72 hours.

As a result of measuring Jc of the superconducting wire thus obtained, 4.8 × 10 ⁴ A / at 12T (Tesla)
The value was 4.5 × 10 ⁴ A / cm ² at cm ² and 15T. At this time, the filament diameter is about 0.1 μm in outer diameter.
Met.

[0017]

As described above, according to the method for producing a Nb ₃ Al multifilamentary superconducting wire of the present invention, the workability is remarkably improved. Therefore, the multifilamentation can be easily achieved by the same steps as the jelly roll method. In addition, it is possible to produce a superconducting wire which is excellent in stability and superconducting properties and which is suitable for alternating current by the low temperature treatment.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state before rolling of a composite sheet according to the present invention.

FIG. 2 is a sectional view showing a state in which the composite sheet of the present invention is housed in a metal tube.

FIG. 3 is a cross-sectional view showing another embodiment of the composite sheet before rolling in the present invention.

FIG. 4 is a sectional view showing another embodiment of the composite sheet before rolling in the present invention.

[Explanation of symbols]

 1, 2, 6, 7, 8, 9 ... Nb sheet 3 ... Al wire 4, 5 ... Cu sheet 1a, 2a, 6a, 8a, 9a ... Grooves 10, 20, 30 ... Composite material 11 ... Composite sheet 12 ... Cu Tube 13 ... Complex

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Haruhito Noro 2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki City Showa Electric Cable Co., Ltd. (72) Inventor Masaru Kawakami 2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi No. 1 Showa Electric Cable Co., Ltd.

Claims (2)

[Claims] 1. An aluminum or aluminum alloy wire is arranged in parallel between two niobium or niobium alloy sheets, and a copper sheet is arranged outside the niobium or niobium alloy sheet, and a rolling process is performed on the copper sheet. After manufacturing a composite sheet, the composite sheet is lapped and housed in a copper tube, then formed into a predetermined shape by surface-reduction processing, and then heat-treated at a temperature of 800 ° C. or less. _{3 A} method for manufacturing an Al multifilamentary superconducting wire. 2. The Nb ₃ Al multifilamentary superconducting wire according to claim 1, wherein the aluminum or aluminum alloy wire is arranged in a groove formed in at least one of niobium or niobium alloy sheet. Production method.