JPH09153310A - High-strength superconducting wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the strength sufficiently withstanding a strong electromagnetic force by arranging a complex dispersedly arranged with Nb filaments at the center, covering it with a Ta diffusion barrier layer, and forming a layer of an Nb/Cu reinforcing material and stabilized copper on the periphery. SOLUTION: A complex 1 dispersedly arranged with Nb filaments in a Cu-Sn alloy matrix is arranged at the center, and it is covered with a Ta diffusion barrier layer 2. A layer 4 of an Nb/Cu reinforcing material 3 and stabilized copper is arranged on the periphery. For the cross sectional configuration, the cross sectional area ratio between (Nb/Cu reinforcing material + stabilizing copper) and (diffusion barrier + complex) is set to 1:6, and the cross sectional area ratio between stabilized copper and Nb-Cu reinforcing material is set to 1:2. The Nb filaments of the complex 1 are made of pure Nb, the cross sectional area ratio between bronze and the Nb filaments is set to 2:9, and the size of the filaments is set to 1.9μm. The strength sufficiently withstanding the strong electromagnetic force can be obtained for a superconducting magnet using a superconducting wire, and the reliable field magnet can be easily designed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength superconducting wire used for a superconducting magnet or the like, and more particularly to a Nb ₃ Sn-based superconducting wire.

[0002]

2. Description of the Related Art Nb ₃ Sn-based superconducting wire has a critical magnetic field characteristic of about 25T and is widely used for superconducting magnets having a magnetic field of 10T or more. However, Nb ₃ Sn
The compound-based conductive wire materials such as (1) have the drawback that their characteristics, particularly the critical current characteristics, deteriorate when they are subjected to mechanical strain.

In a superconducting magnet, an electromagnetic force always acts on the superconducting wire in the magnet due to the magnetic field of the magnet and a current flowing through the magnet, so that mechanical distortion occurs in the wire. For this reason, in the design of a superconducting magnet using Nb ₃ Sn-based superconducting wire, a complicated design that takes into account the characteristic change of the wire due to the action of electromagnetic force is required, and the appearance of a wire having high strength characteristics is awaited.

[0004] The superconducting magnet by a Nb ₃ Sn-based superconducting wire, for a long time at a temperature of 600~750 ℃ Nb ₃ S
It is finally formed by heat treatment for forming an n-based compound. After this treatment, the Cu-based alloy matrix, the diffusion barrier layer (diffusion barrier), and the stabilizing material layer excluding the Nb ₃ Sn compound filament of the general wire cross-sectional structure were softened, and sufficient strength could not be obtained.

On the other hand, as a measure for increasing the strength of Nb ₃ Sn based superconducting wire, a Cu / Nb composite material produced by an in situ method may be used as a reinforcing material in the cross section of the wire. Known (low temperature engineering, vol.2
8, No. 8, pp 446-451, 1993).

[0006]

In the above-mentioned conventional technique, in producing a Cu / Nb composite material used as a reinforcing material, it is necessary to melt and cast a Cu-Nb alloy. The factor that governs the strength of this reinforcing material is the Nb dendrite spacing during casting. This changes depending on conditions such as casting temperature, cooling rate, and concentration in the molten metal, and it is difficult to obtain a uniform cast material. That is, it is difficult to manufacture a reinforcing material having stable strength characteristics, and the strength characteristics of the superconducting wire material that is a composite of the reinforcing materials tend to vary.

Further, the volume ratio of Nb in the Cu / Nb composite material by the in situ method cannot be increased from the viewpoint of melt castability, so that there is a problem that the strength of the Cu / Nb composite material is limited. .

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a superconducting wire having stable strength characteristics and high strength characteristics.

[0009]

The essential point of the present invention is to use, as a reinforcing material for a superconducting wire, a laminated composite material in which at least one sheet material of Nb, Ta and V and a sheet material of Cu are alternately laminated. This is because the composite material produced as the base material was used.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION When at least one sheet material of Nb, Ta and V and a Cu sheet material are alternately laminated and extruded as a base material and subjected to surface reduction processing such as drawing and rolling, layered If the structure collapses and the volume ratio of Nb, Ta, V, etc. is high, Cu becomes, and if the volume ratio of Cu is high, Nb, Ta, V, etc. become dispersed fibrous and a kind of dispersion composite material is formed.
The strength of this dispersed composite material is very high, at room temperature 200
It is also possible to obtain strengths above 0 MPa.

The present invention applies this phenomenon, and since it is manufactured using a laminated composite of a sheet material such as Nb having a constant thickness and a Cu sheet material as a base material, Nb / Cu / Cu in the composite material is produced. The volume ratio is constant, and a reinforcing material with stable strength characteristics can be obtained. However, if the strength of the superconducting wire is compared with 0.2% proof stress and the strength of the superconducting wire is 1.5 times that of the superconducting wire without composite reinforcement, The volume ratio of Nb or the like to Cu in the material is preferably in the range of 5: 1 to 1: 5.

Such a reinforcing material is a sheet material such as Nb and C
Easily made by stacking u sheet materials into a sushi roll-shaped laminated composite, or by simply stacking both sheet materials in the plate thickness direction to form a composite laminated body and extruding, rolling, drawing or other surface-reducing processing. Can be manufactured.

This reinforcing material may be pre-processed and incorporated into the superconducting wire base material for extrusion or drawing, or may be incorporated into the superconducting wire base material as a laminated composite.
The reinforcing material may be processed into a superconducting wire.

As the Nb constituting such a reinforcing material, industrial pure Nb having a residual resistance ratio of 50 or more, or Tb.
An Nb-based alloy containing 5 atomic% or less of at least one element of a, V, Ti, Hf, and Zr can be applied as a sheet material and a winding core. Further, instead of Nb or Nb-based alloy, Ta or Ta-based alloy, V or V-based alloy can be used as a sheet material or core material, and the same effect can be obtained.

The other component Cu is industrial pure Cu, or Ni, Si, Zn, Fe, Mn, T.
A Cu-based alloy to which at least one element of i, Zr, Nb, Ta, and V is added by 30 wt% or less is applicable.

The superconducting wire which is compounded with such a composite material is not limited to Nb ₃ Sn-based materials, but Nb ₃ Al-based materials and Nb-Ti materials.
It is possible to improve the strength of these superconducting wires by applying them to the production of oxide-based and oxide-based materials.

[0017]

EXAMPLE An example of the present invention will be described. FIG. 1 shows wire diameters 0.
An outline of the cross-sectional structure of a 9 mm bronze Nb ₃ Sn-based superconducting wire is shown.

In this superconducting wire, a composite 1 in which a large number of Nb filaments are dispersed and arranged in a matrix of Cu-Sn alloy (bronze) is arranged at the center of the wire, and Ta is used as Ta.
And a Nb / Cu reinforcing material layer 3 and a stabilized copper layer 4 are arranged around the diffusion barrier layer 2.

The sectional structure is such that the sectional area ratio of (Nb / Cu reinforcing material + stabilized copper) and (diffusion barrier + composite material) is 1.6, and the area ratio of stabilized copper and Nb / Cu reinforcing material is 1. : It was set to 2. Further, the Nb filament in the composite 1 is pure Nb.
And the cross-sectional area ratio between the bronze and the Nb filament is 2.9.
And the filament size was 1.9 μm.

Table 1 shows the production specifications of the Nb / Cu reinforcing material used in Examples and Comparative Examples.

Nb is a pure Nb material for both the sheet material and the winding core, and oxygen-free copper was used for the Cu sheet. In Table 1, Comparative Example 3 is a wire having a cross-sectional structure that does not include a Nb / Cu reinforcing material.

[0022]

[Table 1]

FIG. 2 shows an outline of the laminating process of the laminated composite material which is the base material of the Nb / Cu reinforcing material. The winding core 5 made of Nb and having a diameter of 6 mm has the same width as the length thereof. The Cu sheet 6 and the Nb sheet 7 are wound in multiple layers to form a laminated composite.

The laminated composite thus obtained had an outer diameter of 28
A billet for extrusion was prepared by inserting it into a Cu tube having a diameter of 2 mm and an inner diameter of 24.6 mm. After this was processed by hydrostatic extrusion, it was further drawn to obtain a wire rod 9 having a hexagonal cross-sectional shape with a side length of 0.93 mm and a cross-sectional configuration as shown in FIG. In FIG. 3, 8 indicates a Cu layer which is a modification of the Cu tube.

After that, the wire 9 was cut to a predetermined length, the outer Cu layer 8 was removed in nitric acid, and it was used as a member for forming an Nb / Cu reinforcing material layer in an extrusion billet for Nb ₃ Sn superconducting wire. . The total workability of the Nb / Cu reinforcing materials in Examples and Comparative Examples is 6.9 × 10 ⁵ in terms of cross-sectional area ratio.

For each of the obtained wire rods, 650 ° C. × 20
After the Nb ₃ Sn-based compound forming heat treatment for 0 hours,
0.2% proof stress was measured by a uniaxial tensile test at 4.2K. Table 2 shows the results.

The tensile test was carried out under the conditions of a gauge length of 100 mm and a strain rate of 6 × 10 ^-4 , and the tensile stroke was defined as elongation.

[0028]

[Table 2]

From the results shown in Table 2, the 0.2% proof stress of Comparative Example 3 in which the Nb / Cu reinforcing material is not compounded is 102 MPa, whereas in each of the Examples, the proof stress is improved by 50% or more and 0.2%. It was found that in Example 2, about twice the value was obtained. On the other hand, Comparative Example 1 in which the volume ratio of Nb and Cu in the Nb / Cu reinforcing material 3 is Nb-rich side than 5: 1 and Comparative Example 2 in which Cu-rich side is 1: 5 are:
Both show higher values than Comparative Example 3, but it is understood that the strength is not sufficient.

FIG. 4 shows another example of Nb, Cu according to the present invention.
A method of forming a Nb / Cu reinforcing material layer by winding a sheet material is shown. Instead of molding the Nb / Cu reinforcing material into a shape as shown in FIG. 3 once and using it, a bronze / Nb composite material is provided in the barrier layer 42. 41 is built in, the Cu sheet 61 and the Nb sheet 71 are directly laminated on the outer periphery of the barrier layer 42 and wound up, and as shown in FIG. It was done.

FIG. 6 shows another example of the present invention. In this example, the Nb ₃ Sn-based superconducting wire having the cross-sectional structure shown in FIG. 5 is used as a sub-element 11, and a large number of these are arranged in a Cu matrix 10. In FIG. 6, 61 is bronze / N
b composite, 62 diffusion barrier, 63 Nb / Cu reinforcement, 64 stabilized Cu layer.

FIG. 7 shows another example of the present invention. This example is N
The b / Cu reinforcing material 73 is arranged in the center of the wire, and the diffusion barrier 72, the bronze / Nb composite 71, the diffusion barrier 75, and the stabilizing Cu 74 are sequentially arranged in concentric circles around the periphery of the wire. is there.

FIG. 8 also shows another example of the present invention. In this example, a wire consisting of a bronze / Nb composite 81 covered with a diffusion barrier 82 and a stabilizing Cu 85 is used as a sub-element 12, and a large number of it is arranged in a Cu matrix 10 around an Nb / Cu reinforcement 83. Is.

Nb / Cu at the center in the examples of FIGS.
The reinforcing materials 73 and 83 may be either an aggregate of wires having a hexagonal cross section shown in FIG. 3 or a laminated composite of Nb and Cu sheet materials.

[0035]

As is apparent from the above description, according to the present invention, it is possible to provide a high-strength superconducting wire having a strength that can sufficiently withstand a strong electromagnetic force in a superconducting magnet using a superconducting wire. As a result, Nb ₃
It is easy to design a high magnetic field magnet using an Sn-based superconducting wire, and it is possible to realize a highly reliable high magnetic field magnet.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a cross-sectional structure of a superconducting wire used in an example of the present invention.

FIG. 2 is a production schematic diagram of a laminated composite which is a base material for forming a Nb / Cu reinforcing material used in an example of the present invention.

FIG. 3 is a cross-sectional view of an Nb / Cu reinforcing material layer forming member used in an example of the present invention.

FIG. 4 shows Nb in another example of the superconducting wire according to the present invention.
The figure which shows the method of forming a / Cu reinforcement material layer.

FIG. 5 is a diagram showing a state in which the composite shown in FIG. 4 is combined with a copper pipe.

FIG. 6 is a cross-sectional view showing another example of the superconducting wire according to the present invention.

FIG. 7 is a sectional view showing another example of a superconducting wire according to the present invention.

FIG. 8 is a sectional view showing another example of a superconducting wire according to the present invention.

[Explanation of symbols]

 1, 61, 71 and 81 Bronze / Nb composite 2, 72, 75 and 82 Diffusion barrier 3, 63, 73 and 83 Nb / Cu reinforcement 4, 74 and 84 Stabilized Cu 5 Nb winding core 6, 46 Cu Sheet 7, 47 Nb Sheet 8 Cu layer 9 Wire rod 10 Cu matrix 11 Sub-element

Claims (6)

[Claims] 1. A wire material using a composite material formed of a laminated composite material in which a sheet material of Nb, Ta, V or an alloy based on a metal thereof and a sheet material of Cu or a Cu-based alloy are alternately laminated as a reinforcing material. A high-strength superconducting wire characterized by being compounded in the cross section of. 2. The volume ratio of Cu to Nb, Ta, V or an alloy based on these metals and Cu in the reinforcing material is 5: 1.
The high-strength superconducting wire according to claim 1, which is in the range of 1 to 5 3. The high-strength superconducting wire according to claim 1, wherein the reinforcing material is arranged in layers on the outer periphery of the superconducting filament group. 4. The high-strength superconducting wire according to claim 1, wherein the reinforcing material is arranged in layers on the outer periphery of the superconducting filament group in the sub-element. 5. The high-strength superconducting wire according to claim 1 or 2, wherein the reinforcing material is arranged in the center of the wire. 6. The high-strength superconducting wire according to any one of claims 1 to 5, wherein the superconductor is Nb3Sn-based.