JPS6116139B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a compound-based superconducting wire. Intermetallic compound superconducting wires such as Nb ₃ Sn and V ₃ Ga have a structure in which a large number of compound core wires are embedded as continuous fibers in the matrix, but superconducting compounds originally have excellent superconducting properties. On the other hand, it is inherently brittle, with an elongation of less than 0.1%, making it vulnerable to mechanical tension and bending, resulting in poor reliability in wire manufacturing and coil winding operations, and cooling efficiency with liquid helium. It was also low.
In order to eliminate these drawbacks, we embed a large number of extremely fine and closely spaced discontinuous superconducting compound fibers into the matrix, and utilize a tunnel effect called the proximity effect or filament effect to bring the entire wire into a superconducting state. A discontinuous fiber compound superconducting wire material has been considered, but its superconducting properties are much lower than that of continuous fiber ultrafine multifilament wires, and it has not been put to practical use.

Taking Nb ₃ Sn compounds as an example, the following two manufacturing methods are typically considered for conventional discontinuous fiber compound superconducting wires.

The first method is to melt Cu and Nb, create an ingot with a structure in which Nb is scattered in the form of grains and needles in the Cu matrix, and then wire-draw the ingot, and the final dimension is Sn. This is a method in which Nb ₃ Sn is generated on the surface of a long Nb fiber by diffusing it from the surface.

The second method is to mix Nb and Cu powder, fill it into a Cu-based metal tube, and then wire-draw it to diffuse Sn from the surface in the final dimension, so that Nb ₃ is added to the surface of the Nb fiber. This is a method of generating Sn.

However, in the former method, the ratio of Nb to Cu is
If the concentration exceeds 25 vol%, melting and casting will be difficult and an ingot containing a high proportion of Nb, which is necessary for good superconducting properties, will not be obtained, and wire drawing after casting will also be extremely difficult, resulting in poor superconducting properties and manufacturing reliability. It was inferior to

On the other hand, in the latter method, commercially available Nb powder is difficult to form into fibers during wire drawing, so surface treatment is required for the Nb and Cu powder in advance, but this surface treatment is complicated and difficult, and during wire drawing. There are many disconnection accidents. As a result, only products with inferior superconducting properties and manufacturing reliability could be produced.

Therefore, the present invention provides a compound-based superconducting wire material in which a large number of discontinuous compound superconducting fibers are embedded in a metal wire, which has excellent mechanical ductility, good cooling efficiency, and excellent superconducting properties, and whose production is stable and easy. The purpose is to do so.

Next, to explain the present invention, first, Cu-based, Sn
A core wire made of at least one of the following metals as a matrix, Ga-based, Cu-Sn alloy-based, or Cu-Ga alloy-based, and in which the matrix is made of one of Nb-based or V-based metals. A composite multi-core wire is obtained which has a configuration in which a large number of the above are buried at equal intervals. Then, the composite multi-core wire is drawn to a length of about 100ths of a millimeter, and then cut to a length of about 1 mm to produce a short composite metal wire. Next, a large number of short composite wires are filled into a metal container or integrally formed by pressing to form an assembly. This aggregate is molded and sintered at a temperature between room temperature and 1050℃, or
A composite molded body is made by extrusion processing at a temperature of to obtain a wire rod. Through such processing, a wire rod in which a fiber structure of Nb-based or V-based metal is contained in the matrix is obtained. In addition, for the above composite molded body, Sn-based, Ga-based, Cu-based
-Sn alloy metal layers or Cu-Ga alloy metal layers are arranged in parallel, or the wire rod is coated with these metal layers by plating or the like. Next, the wire is heat-treated to diffuse the metal layer to obtain a superconducting wire.

When using a Cu-Sn alloy as the matrix metal, the concentration of Cu is 0.1 to 15wt% and the concentration of Sn is
It is suitable if it is 50 wt% or more, and when using a Cu-Ga alloy, it is suitable if the Cu concentration is 0.1 to 25 wt% and the Ga concentration is 50 wt% or more.
Furthermore, Cu-based, Cu-Sn alloy-based, and Cu-Ga alloy-based metals contain at least 0.1 to 50 wt% of at least one metal element such as Al, Pb, In, Ga, Mn, Mg, and Sn.
It may be contained.

On the other hand, Nb-based or V-based metals include Ga, Hf,
It may contain 0.1 to 50 wt% of at least one metal element such as Sn, Ta, and Zr.

In addition, in the above explanation, when making an aggregate with a large number of short composite wires, Cu-based, Cu-Sn alloy-based, Cu-based
-Ga alloy metal may be added in powder or fiber form.

Next, the present invention will be explained in more detail using Examples.

Example 1 Having a cross section as shown in Fig. 1, matrix 2
is Cu, and core wire 1 is Nb, with 19 equally spaced cores.
The Cu-Nb composite multifilament wire was drawn to a diameter of 0.24 mm.
At this time, the diameter and spacing of the Nb core wires are each 0.03 mm.
and 0.015mm. This wire was cut to a length of approximately 1 mm to obtain a short composite metal wire.
Next, the short composite metal wires were filled as densely as possible (filling rate of about 70%) into a Cu container with an outer diameter of 80 mm, an inner diameter of 72 mm, and a length of 100 mm to form an aggregate of short composite metal wires and used as a billet for extrusion. It was extruded to a diameter of 20 mm using a hot extruder at an extrusion ratio of 16.0 and an extrusion temperature of 700°C, and then cold drawn to a diameter of 0.3 mm. When the cross section of the wire is observed under a microscope, it becomes metallurgically integrated.
It had a structure in which Nb fibers stretched in the longitudinal direction were present in the Cu matrix, and the diameter and spacing of the Nb fibers were both 0.08 to 0.12 μm. Approximately on the surface of this wire
After depositing 20μm thick Sn by electroplating
By heat treatment at 700°C for 50 hours, Sn was diffused into the wire and Nb ₃ Sn was generated on the surface of the Nb fiber.

The critical current characteristics of the Nb ₃ Sn wire thus obtained were measured under various conditions in liquid helium. The measurements were performed while applying a bias magnetic field of 10 Tesla to the wire and applying strain due to bending to the Nb ₃ Sn wire. The results are shown in curve A in Figure 2. This figure shows measurements taken under the same conditions for comparison. The characteristics of a commercially available continuous fiber ultrafine multifilamentary wire (curve B) and a discontinuous fiber wire produced by a conventional method (curve C) are also described. According to the measurement results, the wire of the present invention has a critical current value at zero strain that is higher than that of the continuous fiber ultrafine multifilament wire, and maintains the critical current value at zero strain up to about 2% strain. , and the decrease is gradual even for higher distortions. On the other hand, the continuous fiber ultra-fine multifilament wire of curve B has a strain of 0.5
% or more, the critical current value decreases rapidly, and curve C
The conventional discontinuous fiber wire has a lower critical current value than the wire of the present invention for all strains. As described above, the wire according to the present invention has excellent superconducting properties and mechanical properties.

Example 2 A sample was prepared in the same manner as in Example 1. Length approx. 1
A short composite metal wire with a diameter of 0.18 mm, a parent phase of Cu, and a diameter and spacing of 37 Nb core wires of 0.01 mm and 0.006 mm, respectively, is placed as tightly as possible in a Cu container with an outer diameter of 80 mm, an inner diameter of 20 mm, and a length of 150 mm. The mixture was filled into an extrusion billet and extruded into a hollow pipe having an outer diameter of 20 mm and an inner diameter of 8 mm using a hot pipe extruder at an extrusion ratio of 19 and an extrusion temperature of 700°C. Through extrusion, the wire has a structure in which stretched Nb fibers are interspersed in a Cu matrix, and are metallurgically integrated. Next, a Sn rod with a diameter of 7.8 mm was inserted into the hollow part of this pipe, and a Ta pipe with an outer diameter of 22 mm and an inner diameter of 21 mm was inserted as a Sn diffusion barrier.
After covering a Cu pipe with an outer diameter of 33 mm and an inner diameter of 23 mm for stabilization, this was made into a rectangular wire of 0.8 x 1.6 mm by cold wire drawing. By applying heat treatment at 700℃ for 50 hours to the wire obtained in this way, the Sn placed in the center of the wire is diffused and Nb ₃ Sn is generated on the surface of the Nb stretched into a fibrous shape for stabilization. Nb ₃ Sn superconducting wire with a Cu layer of
The critical current characteristics of this material were measured under various conditions in liquid helium, and as a result, extremely good superconducting characteristics and mechanical characteristics were obtained as in Example 1.

Example 3 The matrix 3 has a cross section as shown in FIG.
A 19-core (Cu-Sn)-Nb composite multi-filament wire in which Cu-14wt%Sn was Cu-14wt%Sn and core wire 1 was Nb was drawn to a diameter of 0.24 mm. The diameter and spacing of the Nb core wires at this time are
They were 0.03mm and 0.015mm. This line has a length of about 1
A short composite metal wire was cut to a length of mm. A large number of these short composite metal wires are assembled to form a wire with a diameter of 80 mm.
After press-forming into a rod shape with a length of 150 mm and a length of 150 mm, it was extruded into a wire with a diameter of 25 mm using a hot extruder under extrusion conditions of an extrusion ratio of 10.2 and an extrusion temperature of 550°C. As a result of extrusion, the wire has a structure in which Nb stretched into fibers is scattered in a metallurgically integrated Cu-Sn alloy matrix. Next, a Ta pipe with an outer diameter of 27 mm and an inner diameter of 26 mm was added to this wire as a diffusion barrier, and for stabilization, a Ta pipe with an outer diameter of 34 mm and
A Cu pipe with an inner diameter of 28 mm was coated, and this was made into a wire rod with a diameter of 0.5 mm by repeating cold working and annealing at 400°C for 1 hour. By heat-treating the wire thus obtained at 700°C for 50 hours, Nb ₃ Sn is generated on the surface of the Nb stretched into fibers, resulting in a Nb ₃ Sn superconducting wire with a Cu layer for stabilization. The critical current characteristics were measured under various conditions in liquid helium, and as a result, very good superconducting characteristics and mechanical characteristics were obtained as in Examples 1 and 2.

Regarding this example, the Sn concentration of the parent Cu-Sn alloy in the composite metal wire is from 0.1 to 15 wt%, and from 50 to 100 wt%, which allows subsequent cross-section reduction processing, and other I couldn't process things.

Example 4 The matrix 4 has a cross section as shown in FIG.
is Cu-10wt%Sn-4wt%Ga, and the core wire 5 is Nb-
19-core (Cu−Sn−Ga)−(Nb−) with 4wt%Hf
Hf) Composite multi-filament wire was drawn to a diameter of 0.12mm. At this time, the diameter and spacing of the Nb-Hf core wires are each 0.015 mm.
and 0.008mm. This wire was cut to a length of approximately 1 mm to obtain a short composite metal wire. A large number of short composite metal wires are preformed using a hydraulic press, and then made into a bar shape with a diameter of 30 mm and a length of 100 mm.
Cu is continuously sintered by hot pressing in vacuum at °C, metallurgically integrated by this process.
-Nb stretched into fibers in the Sn-Ga alloy matrix
-A structure in which Hf alloy is scattered is obtained. Next, this was made into a wire rod with a diameter of 0.3 mm by repeating cold working and annealing treatment at 400°C for 1 hour. It was μm. The wire thus obtained was heat-treated at 700°C for 50 hours to generate (Nb-Hf) ₃ Sn on the surface of the Nb-Hf alloy fiber, and the critical current was measured under various bias magnetic fields in liquid helium. As a result, the critical current density was improved by about 20% in high magnetic fields of 12 Tesla or more compared to the wire without Hf and Ga added.

Example 5 Approximately 1 mm in length, prepared in the same manner as in Example 1.
A short composite metal wire with a diameter of 0.24 mm, Cu matrix, and 19-core Nb core wire diameter and spacing of 0.03 mm and 0.015 mm, respectively, and Cu powder with an average particle size of about 40 μm are mixed in a 7:1 ratio by volume.
After thoroughly mixing in the proportions of , the mixture was poured into a Cu container with an outer diameter of 80 mm, an inner diameter of 20 mm, and a length of 150 mm as tightly as possible to form an extruded billet using a hot pipe extruder at an extrusion ratio of 19 and an extrusion temperature of 900°C. After extruding into a hollow pipe shape with an outer diameter of 20 mm and an inner diameter of 8 mm, Sn
A rod was inserted, and a Nb ₃ Sn wire rod was obtained by cold working and heat treatment to generate Nb ₃ Sn. In this way, composite metal wire
Even when Cu-based metal powder was added and molded, a Nb ₃ Sn superconducting wire with good cold workability and excellent superconducting properties was obtained as in Example 1.

Example 6 About 1 mm in length, created in the same manner as in Example 1.
The diameter is 0.24mm, the matrix is Cu-18wt%Ga, and the diameter and spacing of the 19 V cores are 0.03mm and 0.015mm, respectively.
mm short composite metal wire is press-formed into a rod shape with a diameter of 80 mm and a length of 150 mm, and then extruded using a hot extruder.
10.2 It was extruded into a wire with a diameter of 25 mm at an extrusion temperature of 550°C. Through extrusion, the wire is metallurgically integrated.
The Cu-Ga alloy has a structure in which stretched V is scattered in the matrix. This wire was then repeatedly subjected to cold working and annealing at 400°C for 1 hour to obtain a diameter of 0.3 mm. At this time, the diameter and spacing of the V fibers were approximately 0.1 μm and 0.08 μm, respectively. Ta. The thus obtained wire was heat-treated at 650°C for 50 hours to produce V ₃ Ga on the surface of the V fiber, making it a V ₃ Ga superconducting wire. As a result of measuring the critical current characteristics under various conditions in liquid helium, it was found that Nb ₃ Sn A V ₃ Ga wire with extremely excellent superconducting properties and mechanical properties similar to the wire was obtained.

The compound superconducting wire and the method for manufacturing the _same according to the present invention have the same great _{effect on other compound wires such as V 3 Si} , Nb ₃ Al, etc. that are manufactured by the same method as the Nb 3 Sn and V 3 Ga wires.

Although the present invention has been explained with limited drawings and examples, its features can be summarized as follows: (1) A compound wire with excellent superconducting properties can be produced extremely easily and stably.

(2) It has excellent mechanical properties such as bending resistance and tensile resistance, and can significantly improve the shortcomings of conventional compound wires, which are weak against stress.

(3) It is extremely easy to attach a layer of high-purity Cu or Al, which is necessary to stabilize the wire and improve cooling efficiency with liquid helium.

(4) Due to its excellent mechanical properties, it is easy to manufacture a conductor in a shape with good cooling efficiency and to wind the coil, and it is possible to manufacture a highly reliable compound superconducting coil with excellent coil characteristics.

(5) Nb-based or V-based metal fibers with extremely small wire diameters can be easily produced, and the process is simpler than conventional continuous fiber ultrafine multifilament wires, resulting in extremely large economical effects on wire manufacturing.

(6) The range of application of compound-based superconducting wires will expand dramatically, making it possible to manufacture inexpensive high-field magnets.

Therefore, it is clear that all the drawbacks of conventional compound wire rods and methods for producing the same can be eliminated.

In carrying out the present invention, the materials Nb, V,
Adding non-toxic ingredients to Cu, Sn, Ga, Cu-Sn alloy, Cu-Ga alloy, etc.
- Changing the composition and mixing method of composite metal wires such as Nb, Cu-V, and the method of creating molded bodies, etc.
Although various modifications may be made, the features of the present invention are not impaired in any case.

[Brief explanation of the drawing]

FIG. 1, FIG. 3, and FIG. 4 are cross-sectional structural views of a composite metal wire in an embodiment of the present invention. Figure 2 shows the strain-critical current value relationship at 4.2K and 10 terraces in the embodiment of the present invention, where curve A is for the present invention and curves B and C are for the conventional one. FIG. In the drawing, 1 is Nb
2 is a Cu-based metal layer, 3 is a Cu-Sn alloy-based metal layer, 4 is a Cu-Sn-Ga alloy-based metal layer, and 5 is a Nb-based metal layer.
-Hf alloy metal layer. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A step of obtaining a composite multi-core wire in which a metal that can be easily deformed by processing is used as a matrix and a metal wire of either Nb type or V type is embedded in the matrix; A step of drawing the composite multifilamentary wire and then cutting it into short lengths to obtain a short composite multifilamentary wire, a step of performing a forming process on the short composite multifilamentary wires collected in large numbers, and a subsequent heat treatment. A compound characterized by sequentially performing a step of combining a Sn-based or Ga-based metal layer with the short composite multifilamentary wire after the forming process, and a step of performing a superconducting compound-forming heat treatment to produce a superconducting compound. A method for manufacturing superconducting wire. 2 The metal matrix that can be easily deformed by processing is Cu.
2. The method for producing a compound superconducting wire according to claim 1, wherein the wire is made of at least one of a Cu-Sn alloy, a Cu-Ga alloy, and a Cu-Ga alloy.