JPH02288112A - Manufacture of nb3sn superconducting wire - Google Patents

Abstract

PURPOSE:To decrease a loss at the time of an AC current flow by forming a Cu alloy layer not containing Sn around a core to reduce the diameter so that a compound layer is not produced at a boundary portion between the core and the Cu alloy layer. CONSTITUTION:The periphery of a rod-like core 10 made up of Nb or Nb alloy is covered with a shell 11 whose outside is further covered with a shell 12 made up of Cu-Sn alloy, etc., to reduce the diameter of the whole of them to make a complex 13. Then, one magnetic element or more is added to Cu of t he shell 11 so that it is made up of Cu alloy not containing Sn. Further, a plurality of the complexes 13 are collected, and thereafter, they are housed in a shell 14 made up of Cu-Sn alloy, etc., and the reduction of their diameters is repeated. Thereby, troubles such as breaking of wire, etc., are prevented, and a Nb-Sn superconducting wire whose loss at the time of AC current flow is small can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for manufacturing Nb3Sn superconducting wires used in toroidal magnets for nuclear fusion reactors, magnets for particle accelerators, magnets for superconducting generators, and the like.

"Prior Art" Conventionally, a superconducting wire having a structure in which countless ultrafine N b3S n superconducting filaments are arranged inside a metal base made of a Cu alloy is known. To manufacture this Nb3Sn superconducting wire, first, as shown in Fig. 11, a plurality of composites formed by covering a core material l made of an Nb rod with a tube body 2 made of a Cu-Sn alloy are assembled. Then, it is inserted into a tube 3 made of a Cu-Sn alloy to reduce its diameter, thereby producing a primary strand 4 shown in FIG. 12.

Next, a plurality of these primary wires 4 are collected and inserted into a Cu-Sn alloy tube 5 as shown in FIG. 13 to reduce the diameter to create a cable wire 7 shown in FIG. 14. The strand 7 is subjected to a diffusion heat treatment to diffuse Sn to generate Nb3Sn superconducting filaments, thereby producing an Nb3Sn superconducting wire 8 (not shown in FIG. 15).

``Problems to be Solved by the Invention'' In the conventional method described above, the assembly of the strands and the diameter reduction process are repeated, so when the tube body 2°3.5 made of Cu-Sn alloy is used, the tube body 2 ．． Work hardening of a and s is significant and there is a risk of wire breakage. Therefore, in order to prevent wire breakage during processing, intermediate annealing treatment is repeatedly performed during processing, but this has the problem of complicating the process.

In addition, during the repeated intermediate annealing treatment, the Nb core material l
A brittle compound layer is formed at the interface between the Nb filament and the surrounding Cu-Sn alloy tube 2, and this compound layer may cause the Nb filament to undergo distorted deformation during diameter reduction processing. In addition, when manufacturing superconducting wire for AC, the diameter of the filament is sometimes reduced to 1 μm or less, but if the Nb filament is distorted as described above, it may break. This tends to occur, making diameter reduction processing difficult.

Furthermore, among the superconducting wires 8 manufactured by the above method, especially those manufactured for AC use, the diameter of the superconducting filaments is small, 1 μm or less, and the spacing between the superconducting filaments is small, so that adjacent ultra-fine There was a problem that the superconducting filaments tended to behave erratically as if they were just 61 filaments, and AC loss was likely to occur. Furthermore, when a superconducting wire for alternating current is manufactured and the filament diameter is reduced to 1 μm or less, there is a problem in that the critical current density decreases significantly in a high magnetic field region.

The present invention has been made to solve the above-mentioned problems. Therefore, the loss when AC current is applied is small, the critical current density is excellent in a high magnetic field region, and there is no disconnection during diameter reduction processing during manufacturing, and AC It is an object of the present invention to provide a method capable of manufacturing Nb5Sn superconducting wire which is excellent in use.

"Means for solving the problem" In order to solve the problem, the invention described in claim 1 has the following features:
A process of forming a composite comprising a core material made of Nb or a Nb alloy and a coating layer made of a Cu alloy containing a magnetic element but not containing Sn, and collecting a plurality of this composite to reduce the diameter. is repeated a necessary number of times to create a wire with a structure in which many filaments made of Nb or Nb alloy are embedded inside a Cu alloy base containing a magnetic element, and then this wire is heat-treated to form Nb, Sn superconducting filaments. is generated.

In order to solve the above problem, the invention described in claim 2 has the following features:
A composite comprising a core material made of Nb or a Nb alloy and a coating layer made of a Cu alloy containing a magnetic element and Ti but not Sn is formed, and a plurality of these composites are assembled to reduce the diameter. C containing magnetic elements and Ti
A wire having a structure in which a large number of filaments made of Nb or Nb alloy are embedded inside a u-alloy base is created, and then this wire is heat-treated to produce a Nb3Sn superconducting filament.

"Effect" Since a magnetic element is contained in the Cu alloy base in which superconducting filaments are dispersed, when Cooper electron bears seep out from the superconducting filament to the normal conductive metal base, the magnetic moment of the magnetic element causes When the pair is broken, the coupling current that attempts to flow into the alloy matrix between the superconducting filaments () when AC current is applied is suppressed, reducing AC loss.

Furthermore, since the Cu alloy base provided outside the core material does not contain Sn, the formation of a compound layer at the interface between the core material and the alloy base during processing is suppressed. Furthermore, since Ti is diffused into the metal base around the superconducting filament,
Critical current characteristics in the high magnetic field region are improved.

The present invention will be explained in more detail below.

Figures 1 to 7 show the actual process of applying the method of the present invention to a method for manufacturing Nb*Sn superconducting wire. , 1st
Rod-shaped core material 1 made of Nb or Nb alloy shown in the figure
Tube I made of Cu alloy with magnetic elements added to the outer periphery of 0
I, and further cover the outside with a tubular body 12 made of Cu-Sn alloy, etc., and reduce the diameter of the whole to form a composite body 1 as shown in FIG.
Create 3. In this composite body 13, a coating layer made of the constituent material of the tubular body 11 is formed around the core material lO.

The core material 1O is pure Nb, an Nb alloy added with Ti and Ta, or Sc, Ti, V, Cr, Mn, Fe.
.

Co, Ni, Sr, Y, Cb, Zr, Rh, Pd
, Ce, Pr, NdSm, Eu, Gd, Tb, Dy,
It is formed from an Nb alloy containing one or more magnetic elements such as Ho, Er, and Tm, or an alloy containing a magnetic element and Ti and Ta. When the core material IO contains Ti, the content m is preferably 0.5 to 2% by weight, and when it contains Ta, the content is preferably 0.5 to 4% by weight.

The tubular body 11 is made of a Cu alloy in which one or more of the magnetic elements mentioned above is added to Cu and does not contain Sn. Further, the tube body 11 may be formed from an alloy containing the magnetic element and Ti but not Sn.

The content of the magnetic element in the tube body 11 is preferably 0.5 to 5% by weight when the magnetic element is completely dissolved in solid solution with respect to the metal element constituting the metal base surrounding the superconducting filament. In the case of magnetic elements that may cause intermetallic compounds, the amount is preferably 0.1 to 0.5% by weight or less.

Furthermore, when using a metal base of Cu alloy as in this example, Mn and Ni etc. are completely dissolved in Cu, so when adding Mn or Ni, it is necessary to add 0.5 to 5%. It shall be. Further, when adding Ti to the Cu-Sn alloy, the content of In is preferably 0.1 to 0% by weight.

The tube body 12 is made of a Cu-Sn alloy, such as a Cu-8n alloy containing the magnetic element, or a Cu-8n alloy containing the magnetic element and Ti.
-Sn alloy or a Cu-Sn alloy containing Ti. The content of Sn in the tube body 12 is preferably 6 to 13% by weight.

Next, after a plurality of the composite bodies 13 are assembled as shown in FIG. 3, they are housed in a tube 14 made of a Cu-Sn alloy or the like, and the diameter is reduced to create a primary strand 15 as shown in FIG. 4. . The above magnetic element and Ti may be added to the tube body 14 used here.

Next, a plurality of the primary wires 15 are assembled and inserted into the tube body 16 as shown in FIG.
The next strand 17 is created. The tube body 16 used here is Cu
-Sn alloy or C added with the above magnetic element and Ti
A u-Sn alloy may also be used. When the diameter reduction process is repeated as described above, the tubular body If provided outside the core material IO is made of Sn.
is not included, so no compound layer is generated at the interface between the core material 10 and the tube body 11 when intermediate annealing is performed during the diameter reduction process. Therefore, the filament produced by the diameter reduction process will not be deformed into an irregular shape.

Subsequently, a diffusion heat treatment is performed in which the secondary wire 17 is heated at 500 to 800° C. for several tens of hours to several hundreds of hours. By performing this diffusion heat treatment, the Nb ultrafine filaments inside the secondary wire 17 are reacted with Sn to generate Nb3Sn superconducting filaments, and the Nb3Sn superconducting wire 20 shown in FIG. 7 can be obtained.

This superconducting wire 20 has a structure in which a large number of extremely thin Nb3Sn superconducting filaments are arranged inside a base made of a CuSn alloy containing a magnetic element. Further, when any of the core lO1 tubes 12, 14, and 16 contains Ti, a structure is obtained in which a large number of Nb3Sn superconducting filaments are arranged inside the alloy base containing Ti.

The superconducting wire 20 is cooled to an extremely low temperature using a coolant such as liquid helium. When AC current is applied, since the metal base contains a magnetic element, coupling loss occurring between the superconducting filaments can be reduced. Here, in a superconducting wire, coupling loss occurs between superconducting double filaments when AC current is applied.
From superconducting filaments with such a small diameter, electron pairs of superconducting electrons seep into the surrounding Cu-Sn alloy base side, and the bonding of electron pairs between adjacent superconducting filaments occurs. that it might be done. Therefore, if a magnetic element is contained in the Cu--Sn alloy base around the superconducting filament, pairs of Cooper electrons are broken by the magnetic moment of the magnetic element, making it difficult for coupling to occur, and AC loss is reduced. Also, N
b.

In the case of a structure in which Ti is diffused into the metal base around the Sn superconducting filament, Ti has the effect of improving the critical current density in the high magnetic field region of Nb5Sn, so the critical current density in the high magnetic field region of the obtained superconducting wire is reduced. Improves current density. In addition,
Is it possible to adjust the effect of improving the critical current density by changing the amount of Ti added? To adjust the amount of Ti added, adjust the amount of Ti contained in the core material 10, tube body 12, tube body 14, and tube body 16. This can be easily adjusted.

Note that the cable assembly process and the diameter reduction process performed in the above embodiments are not limited to two times, but may be performed three or more times.

FIG. 8 is for explaining an example in which the manufacturing method of the present invention is applied to the manufacturing method of a superconducting wire with a stabilizing material. A diffusion prevention layer 23 made of a metal material such as Ta or Nb is formed on the outer periphery of the stabilizing material 22 made of pure copper, and a coating layer 24 made of a Cu-Sn alloy or the like is further formed on the outer periphery to form a stabilized conductor. Create 25. Note that the coating layer 24 has i
'i or a Cu-Sn alloy containing a magnetic element.

Here, the diffusion prevention layer 23 is provided in order to prevent elements from diffusing to the stabilizing material 22 side and contaminating the stabilizing material 22 during the diffusion heat treatment performed in a later process. As the material, a metal material having a melting point of 800° C. or higher and having low reactivity to copper, such as Ta or Nb, is preferably used.

Next, a plurality of these stabilizing conductors 25 are assembled, and outwardly,
A plurality of primary strands 15 or secondary strands I7 used in the above example are further collected and bundled, inserted into a tube body 27 made of Cu, -Sn alloy, etc., and the diameter of this is reduced to form a strand. get the line. The tube body 27 is made of a magnetic element or Cu-containing Ti.
It may be formed from a Sn alloy. By subjecting the wire to heat treatment, a Nb3Sn superconducting wire with a stabilizing material can be produced.

In this superconducting wire, since the stabilizing material 22 provided in the center is prevented from being contaminated with Sn, the stabilizing material 22 is
The electrical resistance at extremely low temperatures becomes a sufficiently low value, and the stability of the superconducting wire becomes sufficiently high. Furthermore, since the structure combines the stabilizing material 22 at the center of the superconducting wire, it is possible to create a more compact structure compared to the case where a new stabilizing material is added to the outside of the superconducting wire. .

FIG. 9 is for explaining a second example in which the manufacturing method of the present invention is applied to the manufacturing method of a superconducting wire with a stabilizing material. A stabilizing conductor 25 equivalent to the stabilizing conductor 25 used in the above example is prepared.

Next, a plurality of these stabilizing conductors 25 are assembled and arranged in an inverted Y shape as shown in FIG. Or secondary strand I7
Collect a few more traces, insert them into a tube body 28 made of Cu-Sn alloy, etc., reduce the diameter of the whole to create a wire, and then heat treat it to produce a superconducting wire with a stabilizing material. be able to.

Note that the tube body 28 is made of a magnetic element or Cu containing Ti.
- It is preferable to form it from a Sn alloy.

FIG. 10 is for explaining a third example in which the manufacturing method of the present invention is applied to the manufacturing method of a superconducting wire with a stabilizing material. A stabilizing conductor is created by forming a diffusion prevention layer 31 made of a metal material such as , Ta, or Nb.

Once the diffusion prevention layer 31 is formed, the above-described primary strands 15 or secondary strands 17 are arranged and attached over its entire circumference. Once the strands are attached, Cu-
A tube body 33 made of Sn alloy or the like is placed over the tube as shown in FIG. 9, and then diameter-reduced to obtain a wire having a diameter equivalent to that of the superconducting wire to be obtained. Note that the tubular body 33 may be formed from a magnetic element or a Cu-Sn alloy containing Ti.

Next, if this wire is heat treated under the same conditions as described above, an Nb3Sn superconducting wire can be obtained.

"Example" A tube made of a Cu-1, Ovt%Mn alloy with an outer diameter of 12 mm and an inner diameter of 10IIlffl is attached to a NbO rod with a diameter of 9 mm, and then the tube is reduced to a diameter of 9 mm to create a composite material. Next, this composite material was mixed with Cu-8wt%S n-0,
Made of 5wt% Ti alloy, outer diameter 15mm, inner diameter 10mm
A composite body is obtained by inserting the composite body into a tube body and reducing the diameter to 0.58 mm while performing an intermediate annealing treatment at 450° C. for 2 hours.

Next, 547 pieces of this composite were collected and bundled, and Cu-8wt
%5n-0,5wt%Ti alloy with outer diameter 18 ml
11. It is inserted into a tube with an inner diameter of 16 mm, subjected to intermediate annealing treatment, and then subjected to diameter reduction processing to obtain a primary composite body with a diameter of 1.0+++ m. Next, collect 91 primary complexes and bundle them, C
The wire was inserted into an alloy tube made of a u-8.0 wt% 5n-0.5 wt% Ti alloy and had an outer diameter of 12 mm and an inner diameter of 11 mm, and was subjected to diameter reduction processing to obtain a wire with a diameter of 0.2 mm. In this wire, the diameter of the Nb filament buried inside was approximately 0.4 μm.

Next, heat treatment was performed at 600°C for 150 hours to remove N.
A superconducting wire was manufactured by reacting the filament of b with Sn to generate an Nb3Sn superconducting filament.

When the critical current density (Jc) of the Nb5Sn superconducting wire manufactured as explained above was constant at 1111 in a 10T magnetic field, Jc
= 600 A/mm' (total value of the wire rod) When measured in a magnetic field of 15 T, an excellent value of Jc = 200 A/mm'' (total value of the wire rod) was obtained.

"Effects of the Invention" As explained above, according to the present invention, Sn is formed around the core material.
We formed a Cu alloy layer that does not contain carbon dioxide and performed diameter reduction processing to prevent the formation of a compound layer at the boundary between the core material and the Cu alloy layer. Even when processed, the filament does not deform into an irregular shape. Therefore, even if an AC superconducting wire is manufactured by reducing the diameter to an ultra-fine filament of 1 μm or less, problems such as disconnection may occur in the Nb3Sn superconducting wire, which has uniformly shaped filaments. It can be manufactured without any

In addition, since the Cu alloy base surrounding the superconducting filament contains a magnetic element, even if bare superconducting electrons seep into the metal base around the superconducting filament when AC current is applied, the magnetism of the magnetic element will cause the electrons to The pair is broken, and the combined current can be suppressed when AC current is applied. Therefore, it is possible to obtain a Nb, Sn superconducting wire with low loss when AC current is applied.

Furthermore, Ti is added to the Cu alloy base around the superconducting filament.
In the case where Ti is contained, the Ti diffused into the Cu alloy base has the effect of improving the critical current density in the high magnetic field region.

[Brief explanation of the drawing]

Figures 1 to 7 are for explaining an example of the method of the present invention, in which Figure 1 is a sectional view showing a composite state of the core material and tube body, Figure 2 is a sectional view of the composite body, and Figure 3 is a sectional view of the composite body. The figure is a cross-sectional view showing the assembled state of the complex, Figure 4 is a cross-sectional view of the primary cable line, and Figure 5 is a cross-sectional view of the primary cable line.
6 is a sectional view of the secondary strands, FIG. 7 is a sectional view of the superconducting wire, and FIGS. 8 to 1O
The figures show an example in which the present invention is applied to a method for manufacturing a superconducting wire with a stabilizing material. Fig. 8 is a cross-sectional view for explaining the first example, and Fig. 9 is a cross-sectional view for explaining the second example. Figure 10 is a cross-sectional view for explaining the third example, and Figure 11 is a cross-sectional view for explaining the third example.
Figures 1 to 15 show an example of a conventional method for manufacturing superconducting wires. Figure 1t is a cross-sectional view showing the assembled state of a composite, Figure 12 is a cross-sectional view of a primary strand, and Figure 13 is a cross-sectional view of a primary strand. A sectional view showing the assembled state of the primary strands, FIG. 14 is a sectional view of the secondary strands,
FIG. 15 is a cross-sectional view of the superconducting wire. IO...core material, 11...pipe body (coating layer), 12...
Pipe body, 13...Composite, 15...Primary strand, 17...
・Secondary strand, 19... strand, 20... superconducting wire.

Claims (2)

[Claims] (1) Form a composite comprising a core material made of Nb or a Nb alloy and a coating layer made of a Cu alloy containing a magnetic element but not Sn, and aggregate a plurality of these composites and shrink them. A wire with a structure in which many filaments made of Nb or Nb alloy are buried inside a Cu alloy base containing a magnetic element is created by performing the necessary number of rounds of diameter processing, and then this wire is heat-treated to form a Nb_3Sn superconducting filament. A method for producing a Nb_3Sn superconducting wire, the method comprising: producing Nb_3Sn superconducting wire. (2) Form a composite comprising a core material made of Nb or a Nb alloy and a coating layer made of a Cu alloy containing a magnetic element and Ti but not Sn, and collect a plurality of these composites. A wire having a structure in which many filaments made of Nb or Nb alloy are embedded inside a Cu alloy base containing a magnetic element and Ti is created by performing diameter reduction processing a necessary number of times, and then heat-treating this wire. A method for producing a Nb_3Sn superconducting wire, the method comprising: producing a Nb_3Sn superconducting filament.