JPH04129111A - Method for manufacturing compound superconducting wire - Google Patents

Abstract

PURPOSE:To lower the strength of a Nb side, reduce the strength difference from element X to have well-balanced workability and improve workability as a whole by using a Vickers hardness 90 or below sheet made of Nb or its alloy. CONSTITUTION:A Nb plate of thickness 0.2mm and an Al foil of thickness 0.06mm are in piles with a copper rod of dia. 5mm as the center, wound together and inserted into a copper tube of outer dia. 18mm and inner dia. 16mm. After given drawing, 91 pieces of these are combined and inserted into a copper tube of outer dia. 18mm and inner dia. 16mm for drawing, to form a multicore superconductive wire. The Nb plate of Vickers hardness 90 or below is used to reduce the frequency of breakage during drawing into a small size and to improve workability. In this way, uniform transformation is allowed and wire material with optimum sizes of Nb and X can be manufactured, so that a Nb3X compound group superconductive wire can be obtained which has a high critical temperature and a high critical current density in a critical magnetic field, or a high magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a method for manufacturing a superconducting wire as a superconducting material for high magnetic fields of superconducting magnets used in nuclear fusion and other applications.

[Prior Art] Compound-based superconducting materials such as Nb3Al, Nb3Sn, and Nb3Ge are extremely hard and brittle compared to alloy-based superconducting materials such as Nb-Ti, and therefore are difficult to plastically work. For this reason, special methods such as ■bronzing method, ■in-situ method, ■powder metallurgy (PM) method, ■composite processing method, and ■jelly roll method are used to manufacture these Nb5X-based superconducting wires. There is. Among compound-based superconducting materials, Nb3At-based superconducting materials are said to have good critical current characteristics and strain resistance in high magnetic fields, and this Nb3At-based superconducting material can be manufactured by the above-mentioned manufacturing method called the jelly roll method. At this stage, it is said to be the closest to practical application. However, even with such a jelly roll method, wire drawability is not sufficient, and it is difficult to achieve multi-core or thin wire.

In order to solve such problems, Japanese Patent Application Laid-Open No. 2-14862
No. 0 proposes forming a through portion in a sheet made of Nb or an Nb alloy sheet, or a sheet made of element X or an alloy containing X, which is a compound that reacts with Nb and exhibits superconductivity.

[Problems to be Solved by the Invention] However, even with such a method, uniform composite processing is difficult. This difficulty in processing is due to Nb
This is believed to be because the sheet of metal or its alloy and the sheet of element X or its alloy have a large difference in strength and flexibility. For this reason, the above
No matter which manufacturing method is used, it is difficult to fully eliminate non-uniform deformation and process the wire into a thin wire. Therefore, it is known that there is an optimal value for the diameter (or thickness) and ratio of Nb and X from the viewpoint of critical temperature, critical magnetic field, and critical current density. Even if we try to process it, it results in non-uniform deformation, so the current situation is that such an optimal one cannot be obtained.

An object of the present invention is to provide a method for manufacturing a Nb5X compound-based superconducting wire that can solve these conventional problems and improve workability.

[Means for Solving the Problems] The manufacturing method of the present invention is based on the jelly roll method.
This is a method of manufacturing a compound-based superconducting wire by winding and laminating a sheet made of metal or Nb alloy and a sheet made of element X or an alloy containing element X, which reacts with Nb to form a compound exhibiting superconductivity. , a sheet made of Nb metal or Nb alloy is characterized in that it has a Vickers hardness of 90 or less.

Examples of the element X that reacts with Nb to form a compound exhibiting superconductivity include AU, Sn, and Ge.

The alloying elements contained in the Nb alloy and/or the alloy containing element X include Ti, Si, Hf, Ta, Zr, M
Examples include g or Be.

[Operations and Effects of the Invention] It is generally known that as impurities in a metal element increase, the number of dislocation pinning points increases and the strength increases. Conventionally, attempts have been made to take advantage of this phenomenon by adding impurities to the element X side and hardening it, thereby reducing the strength difference between Nb and X and improving workability. However, in such a method, even if the difference in strength between Nb and X can be reduced, the overall strength only increases;
No significant effect was observed in improving workability.

In this invention, the sheet made of Nb metal or Nb alloy has a Vickers hardness of 90 or less.

This lowers the strength on the Nb side, reduces the difference in strength with X, balances workability, and improves workability as a whole.

In this invention, the sheet made of Nb metal or Nb alloy has a Vickers hardness of 90 or less, but in order to lower the Vickers hardness, it is preferable to increase the purity of Nb and to perform heat treatment. For example, if a treatment such as annealing is performed at a stage as close to the final stage as possible, a product with low Vickers hardness can be obtained.

According to the manufacturing method of the present invention, it is possible to improve the workability in the composite state of Nb and ) wire rods can be manufactured. Therefore, it is possible to obtain an Nb5X compound-based superconducting wire that has a high critical temperature and a high critical current density in a critical magnetic field, that is, a high magnetic field.

[Example] A Nb plate with a thickness of 0.2 mm and an AU foil with a thickness of 0.06 mm were stacked, and the Nb plate and the AU foil were wound together around a copper rod with a diameter of 5 mm, and the outer diameter was 13 mm. Inner diameter 16mm
It was inserted into a copper pipe. After drawing the line, bundle 91 pieces,
Furthermore, the outer diameter is 18mm.

The wire was inserted into a copper tube with an inner diameter of 16 mm and drawn to obtain a multicore superconducting wire.

The Vickers hardness of the Nb plate is as shown in Table 1.
80 (Example 1), 70 (Example 2), 130 (Comparative Example 1), 110 (Comparative Example 2), and 95 (Comparative Example 3),
The final wire diameter of each is 2mm and 1m.
Table 1 shows the number of wire breaks when the wire was drawn to a length of 0.5 mm, 0.5 mm, and 0.3 mm.

(Margins below) As is clear from Table 1, Examples 1 and 2 using Nb plates with a Vickers hardness of 90 or less according to the present invention were more effective when drawn to a thinner wire diameter than Comparative Examples 1 to 3. The number of disconnections is small, and workability is improved.

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Claims (3)

[Claims] (1) According to the jelly roll method, a sheet made of Nb metal or Nb alloy and a sheet made of element A method for manufacturing a compound-based superconducting wire, wherein the sheet made of Nb metal or Nb alloy has a Vickers hardness of 90 or less. (2) The method for manufacturing a compound-based superconducting wire according to claim 1, wherein the element X is at least one selected from the group consisting of Al, Sn, and Ge. (3) The alloying elements contained in the Nb alloy and/or the alloy containing the element X are Ti, Si, Hf, Ta, and Zr.
2. The method for producing a compound-based superconducting wire according to claim 1, wherein the compound-based superconducting wire is at least one selected from the group consisting of , Mg, and Be.