JPS6029166B2 - Manufacturing method of superconducting compound wire - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a superconducting compound wire.

It is well known that wires made by combining ultrafine wires of superconducting materials with good normal conductors at extremely low temperatures have excellent stabilizing properties as winding materials for superconducting equipment, and superconducting alloy wires with high plasticity such as NbTi have already been developed. It has been put into practical use.

However, since commonly known superconducting compounds such as Nbbn and V30a are mechanically fragile, it is not necessarily easy to make such ultra-fine wires into composite superconducting compounds. One conventional method for manufacturing superconducting compound wires is the method shown in FIG. In this method, as shown in FIG. 4. Insert the core material 2 made of Cu-Sn alloy. An example of normal conductivity at an extremely low temperature of K is to make an assembly surrounded by a coating material 3 of Cu. When this assembly is expanded and contracted and heat treated, Nb and Sn in the Cu-Sn alloy selectively react with each other on the inner surface of the tube material 1 (Cu is a mediating metal and does not participate in the reaction). is generated, and a superconducting compound shown in the cross-sectional view of FIG. 1b is obtained. This wire is bonded to Cu via the Nb remaining after the Nb3Sn reaction, but since this Nb is thin, the resulting wire has high thermal and electrical conductivity, and is stable when used with current. It also has excellent chemical properties. Further, this wire can be a multi-core wire with units of FIG. 1b.
However, a drawback of this conventional manufacturing method is that since the base metal is used in the form of a tube as a raw material, it is difficult to wire-draw the assembly, especially when the wire has a large number of cores.

This is mainly because breakage is likely to occur due to irregular deformation of the tube-shaped material, that is, the tube material, during the process of eliminating voids at the initial stage of wire drawing, and non-uniformity of wall thickness during the subsequent process. Therefore, it is difficult to expect that superconducting compounds produced using tubes as loss bodies will be made extremely fine. Another major drawback of this manufacturing method is that it is economically disadvantageous because it uses a tube made of a base metal such as Nb. These metals have higher melting points than general metals and are extremely susceptible to oxidation at high temperatures, so it costs a lot of money to process them into pipe materials compared to camphor wood, and they also cannot be made into long lengths like camphor wood. Since it is difficult to manufacture in terms of equipment, there are drawbacks such as a decrease in the manufacturing efficiency of superconducting compound wires. The manufacturing method of the present invention has been made with the object of providing an improved method that eliminates all the drawbacks of the conventional methods.

That is, this invention separates a layer consisting of a plurality of strands of a base metal containing a high melting point component of a superconducting compound from a reactive metal containing a low melting point component of the superconducting compound and a metal that is normal conductive at 4.20K. A combination body placed between the two is made, and this combination body is processed into an intermediate body, and then heat treated, or this intermediate body is further concentrated, processed, and then heat treated. This is a method for manufacturing a superconducting compound wire.
According to this method, the base metal is not used as a tube material as in the conventional method, but is used as a raw material, so the workability of the target wire is significantly improved, and a certain wire can be manufactured from a large number of ultra-fine superconducting compound core wires. It becomes easier to do so. In addition, it is clear that mulberry wood is cheaper than pipe material and can be made into the largest length, making it possible to mass-produce superconducting compound wires and having great economic advantages.

Next, one embodiment of the present invention will be described with reference to the drawings.
Figure 2 is a diagram showing a cross section of wire rods in an example in which the superconducting compound is NCSn.
A layer in which a plurality of Nb strips 5 are arranged is provided between a covering material 3 made of U and a core material 2 made of a Cu--Sn alloy to create an assembly having a structure in which the covering material and the core material are separated. It is desirable that the Nb twills be arranged as close to each other as possible, and the gaps may be further filled with comb materials of different thicknesses. Next, this assembly is extruded and processed into a wire shape by rolling, drawing, or wire drawing while adding intermediate sintering for work hardening of the Cu-Sn alloy to produce the intermediate shown in FIG. 2b. In this process of linear processing, the Nb material 5 undergoes plastic processing and deforms, and a kind of fitting connection occurs between the adjacent material to form a strongly connected layer, and the Cu covering material 3 and the Cu - It becomes a partition wall between the core material 2 of the Sn alloy. Processing into an intermediate is extremely easy, and is stable without uneven thickness or breakage as in the case of the Nb tube in the secondary method described above. Good processability from such an assembly to an intermediate is mainly due to the N stage in which the voids in the assembly disappear and the materials become close together.
This is probably because the bamboo wood in b slides against each other according to internal stress and balances, and no local extreme deformation occurs.
The details of the mechanism are still unclear. Even better workability and connectivity between the birch strips can be obtained if the Nb fibers 5 of the assembly are softened to some extent and used as anchors. Furthermore, if the intermediate body processed to the desired thickness is heated to a temperature of 600 to 100 mm, the Sn contained in the core material 2 of the Cu-Sn alloy will selectively react with the Nb of Ayamura, forming the superconducting compound 4. Generate wide Sn. The connections between the Nb bamboo materials are not necessarily chemically bonded, but the above-mentioned NCs are chemically generated by the above-mentioned selective reaction.
The Sn becomes a continuous tubular body and becomes a superconducting compound wire as shown in FIG. 2c. In the state of the intermediate, the partition wall consisting of the above arrangement of N materials internally encapsulates the Sn contained in the core material, that is, serves as a stopper for the diffusion of the Nb and Sn, and by controlling the heat treatment, the outer Cu coating is The contamination by Sn of No. 3 can be adequately prevented, and as a result, the above-mentioned high thermal and electrical conductivity of U is maintained on the outside.
In addition to Nb, the base metals constituting the combination of this example include Nb-Zr alloy (Zr=0.5-5W%), Nb-Ti
It can be made into an alloy (Ti=0.5 to 11 W%), and the generated N improves the current characteristics of the Sn superconducting compound.

The upper concentration limit of the alloy is the limit for the down-reduction processability of the structural assembly of this example. Also, Nb-Ta alloy (Ta=0.5~15
W%), Nb-V alloy (V=0.5 to 7W%) has high strength and is useful for improving workability. Heartwood 2 Cu
-A high Sn concentration in the Sn alloy is desirable in order to increase the absolute amount of Sn, but if it exceeds 16 W%, a uniform solid solution cannot be obtained and the ductility will not be extremely lost, and if it is below 2 W%, the Nb
Since the production rate of carbon is too slow to be practical, a range of 2 to 16 W% is appropriate. FIG. 8 is a diagram showing a multicore assembly in a manufacturing example of a multi-N Sn superconducting compound wire of the present invention, and shows an intermediate material corresponding to the assembly in FIG. 2a or the intermediate body in FIG. 2b. The figure shows a state in which a large number of Nos. 7 are gathered together, surrounded by a Cu outer covering material 6, and sealed for exhaust gas.

If this multi-core assembly is extruded at a temperature of 500 DEG to 800 DEG C., a multi-core intermediate containing many parts corresponding to the intermediate shown in FIG. 2b will be obtained. If this is cold drawn at a temperature of 250 to 600°C while adding intermediate phosphorus annealing as appropriate, and then heated in an argon stream, a tubular N
A multi-core superconducting compound wire containing a large number of QSn core wires is obtained. The diameter of the Nb blue wire at this time is usually 30 microns or less, and it can also be 1 micron, but this thickness depends on the diameter of the tubular layer formed by the base Nb bamboo material 5. can be controlled. The intermediate material 7 constituting the multi-core assembly may be the one in the state of the assembly shown in Figure 2a, but it is processed to eliminate the internal voids in advance, and the spaces between the Nb camphor wood are If an intermediate body with strengthened connection as shown in FIG. 2B is used, the Cu-Sn alloy and Cu will be completely blocked, which will be more effective. The multi-core superconducting compound wire can be manufactured by the same process as the single-core wire in the above example, and the wire has a structure in which the reactive metal and the normal conductive metal are separated by a plurality of base metal layers. This method of fabricating and heat-treating has common features, and it is easy to obtain wires in which ultrafine wires of superconducting compounds are embedded in a good conductor. FIG. 4 is a diagram showing an assembly in an example in which the superconducting compound is V30a, in which Cu-Ga alloy (Ga = 2 to 13 W%)
Between the coating material 10 and the core material 9 made of high purity Cu,
It is made by providing a plurality of layers of bamboo wood 8 made of V or V-Zr alloy (Zr=0.5 to 6 W%).

Here, the composition ranges of the Cu--Ga alloy and the V-Zr alloy are selected for the same reasons as the compositions of the Cu--Sn alloy and the Nb--Zr alloy in the previous example. This combination 250
If the wire is drawn using an appropriate intermediate pseudo-anchor at a temperature of ~550 pm and then heat treated at a temperature of 500 ~ 80 pm, the coating material 101 contains Ga and V or V-Zr alloy twill material. By this reaction, V3Ga is generated on the outside, and the core Cu is blocked by the V-Z alloy and is not exposed to Ga. The structure of the V3Ga superconducting compound wire made in this example is different from the structure of the example of the N-broad Sn superconducting compound wire in FIG. The basic meaning of the book being separated by a layer of metal base material remains the same. In addition, the tubular covering material 6 in Fig. 3 is made of Cu-G.
By inserting the assembled or processed intermediate material shown in FIG. 4 as the intermediate material 7 made of a-alloy, it is possible to easily create a multi-core V or a superconducting compound wire in the same way as the example of the N-Sn superconducting wire. Can be done.

The cross-sectional shape of the Nb bar material 5, which is the base metal of the assembly shown in FIG. 2a, is circular, and the material 8 of FIG. Any material can be used as long as the material can be plastically deformed to form interconnected continuous layers, and an ellipsoidal shape or a shape that fits from the beginning can also be effective.

However, a thin plate-shaped base metal is not suitable because the amount of plastic deformation is small and the bond between adjacent plates is incomplete, and the ratio of the shortest diameter to the longest diameter in the cross section of the twill material depends on the type of shape. Regardless, it is desirable that it be in the range of 1 to 1/10. FIG. 5 is a diagram showing the reactive metal core material used in another embodiment, in which the inner core material 11 made of a solid or powder of Sn or Sn-rich Su-Cn alloy (Sn=1 to 6%) is replaced with Cu. It is a composite body surrounded by an inner covering material 12 consisting of.

If the core material made of this hybrid is used in place of the core material 2 made of the Cu-Sn alloy shown in Fig. 2a, the constituent materials of this composite, Cu and Sn or the Su-Cn alloy, will cool as well as the Cu-Sn alloy. It does not harden and lose its ductility during processing, can be processed to the normally required thickness without an intermediate hammer, and can finally be made into a superconducting compound wire similar to that shown in FIG. 2c by heat treatment. It is clear that it is equally applicable to the production of multi-filament wires. However, the core material of this structure is an internal core material 11 made of Sn or Sn-Cu alloy, which has weak strength.
is reinforced with an internal coating material 12 of Cu,
If it is too thin, it will break, so the volume ratio of the inner covering material to the core material should be 20 to 5 mol. % is suitable for improving the integral wire manufacturing properties of the assembly. The invention has been described above with respect to a limited number of embodiments.

In the description of this invention, the term "base metal" refers to Nb, V, which are high melting point components of a superconducting compound, or alloys containing these metals as main components. The low melting point metal is a simple substance or alloy selected from Sn, Ga, AI, W, and Si, which are low melting point components of the superconducting compound, or a metal with an alloy or hybrid structure of these simple substances or alloys and Cu as a mediating metal. refers to 4. What is a normal conducting metal? Cu, which is a good electrical and thermal conductor at 〆K,
It is a metal selected from Ag and AI. Therefore, the method of this invention not only targets superconducting compound wires made of Nb3Sn and V30a, but also
, 1x) and other multicomponent superconducting compounds based on Nb and V. In addition, if the assembly shown in Fig. 3 or an intermediate processed from this is used as the intermediate material 7, and the process of focusing and processing is repeated, the number of superconducting compounds ○ can be further increased, and the number of superconducting compounds ○ can be further increased. It will be appreciated that the method of the present invention, carried out using an assembly or intermediate in which a normal metal and a reactive metal are separated by a layer comprising: As is clear from the above description, the present invention provides a layer consisting of an arrangement of a plurality of strands of a base metal containing a high melting point component of a superconducting compound, a reactive metal containing a low melting point component of the superconducting compound, and 4. At 20K, a normal conductive metal, which is a good electrical and thermal conductor, is separated and placed in the middle to form an assembly, and this assembly is processed into a rod shape and then heat treated.

Therefore, compared to the method using the above-mentioned base metal, more specifically, the Nb tubular body, a significant reduction in manufacturing cost and an improvement in productivity can be obtained, and the above-mentioned contamination due to Sn diffusion to Cu, for example, can be appropriately prevented and high It has the effect of stabilizing properties such as maintaining thermal and electrical conductivity.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1a and 1b are cross-sectional views of a material assembly and a superconducting compound wire, respectively, obtained by a conventional method. FIGS. 2a, 2b, and 2c are sectional views of an assembly, an intermediate, and a superconducting compound wire in an embodiment of the present invention, respectively.
3 and 4 are cross-sectional views of an assembly according to another embodiment of the present invention, and FIG. 5 is a cross-sectional view of a core material comprising a composite body according to another embodiment.
．． In the drawing, 1 is Nb tube material, 2 is Cu-S
n alloy core material, 3 is Cu covering material, 4 is Nb3Sn product, 5 is Nb material, 7 is intermediate material, 8 is V or V-
9 is a core material of Cu, 10 is a covering material of Cu--Ga alloy, and 11 is an internal core material. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A layer consisting of an array of a plurality of rods of a base metal containing a high melting point component of a superconducting compound is electrically heated at 4.2°K with a reactive metal containing a low melting point component of the superconducting compound. A superconductor characterized in that a normal conductive metal, which is a good thermal conductor, is separated from the other and placed in the middle to form an assembly, and this assembly is processed into a linear shape and then heat-treated to produce a superconducting compound. Method for manufacturing compound wire. 2. The superconductor according to claim 1, wherein the assembly is a bundle of a plurality of intermediate bodies each containing a layer in which a plurality of bars of the base metal are interconnected. Method for manufacturing compound wire. 3. Production of a superconducting compound wire according to claim 1 or 2, wherein the ratio of the shortest diameter to the longest diameter in the cross section of the base metal bar is in the range of 1 to 1/10. Method. 4. The base metal is Nb or Nb-Zr alloy (Zr concentration 0.5 to 5 w%), and the reaction metal is Cu-Sn alloy (Sn concentration 2 to 16 w%). A method for manufacturing a superconducting compound wire according to any one of claims 1 to 3. 5 The base metal is V or V-Zr alloy (Zr concentration is 0)
．． 5 to 6 w%), and the reactive metal is Cu-Ga alloy (G
The method for manufacturing a superconducting compound wire according to any one of claims 1 to 3, wherein the concentration of a is 2 to 13 w%). 6. The reactive metal consists of a hybrid body in which Sn solid or powder is externally coated with Cu, and the volume fraction of Cu in this composite body is 20 to 50 vol. % of the superconducting compound wire according to claim 4. 7. The method for producing a superconducting compound wire according to any one of claims 1 to 6, wherein the diameter of the core wire made of the superconducting compound contained in the superconducting compound wire is 1 to 30 microns. .