JPH10125147A - Oxide superconducting wire material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxide superconducting wire material durable to tensile stress of 20kg/mm<2> or more required in production of a large magnet or a high magnetic field magnet and having high critical current density. SOLUTION: A first stabilized matrix 2 directly covering a filament 1 made of an oxide superconductor is made of silver or a silver alloy containing the amount and the kind of metal which do not deteriorate the superconducting characteristics of the filament 1. The silver alloy is Ag-Sb alloy containing 0.2-0.7 atomic percent Sb. A second stabilized matrix 3 covering the first stabilized matrix 2 is made of Ag-Mn alloy containing 1.0-8.0 atomic percent Mn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an oxide superconducting wire, and more particularly to an oxide superconducting wire having a high critical current density and a high mechanical strength suitable for applications such as magnets.

[0002]

2. Description of the Related Art As a method of manufacturing an oxide superconductor, for example, there is a method of performing plastic working and heat treatment in a state where a powder of an oxide superconductor or a raw material thereof is filled in a metal sheath. By this process, the powder in the metal sheath is sintered into a superconductor. This method is called a powder-in-tube method, and is advantageously applied, for example, when manufacturing a long superconducting wire. The obtained wire can be applied to power cables and various coils.

[0003] In the powder-in-tube method, a sheath filled with powder undergoes plastic working such as drawing and rolling. When pure silver is used as the sheath, the strength of silver is relatively low, so that it is impossible to apply an ideal compressive force to the powder in one plastic working. Further, when performing heat treatment for sintering an oxide superconductor on a wire using a pure silver sheath, a temperature higher than the softening temperature of silver is used, so that the silver after sintering has low strength. For this reason, when handling the obtained wire or forming a coil from the wire, there is a problem that excessive strain is likely to be applied and superconducting characteristics such as critical current density are likely to be deteriorated.

Japanese Patent Application Laid-Open No. 2-8335 discloses 1-10a
A sheath for producing an oxide superconducting wire made of an Ag alloy pipe containing t% Mn is disclosed. Such an alloy has a higher hardness than Ag. The publication is 1 to 10 at%
By using an Ag-Mn alloy pipe containing Mn as the sheath for powder filling, a thinner than the Ag sheath can be used, so that wire drawing can be facilitated, and the oxide superconductor It is described that recovery of oxygen deficiency of the lactobacillus is easy. The publication also states that this sheath is suitable as a sheath for a stretching method in which intermediate annealing at 100 to 300 ° C. is performed every time the cross-sectional compression ratio becomes 2 to 50. However, the sheath containing such a high concentration of Mn has a temperature of 800 ° C. to 9 ° C. due to sintering of the oxide superconductor.
Reacts with superconductors in a process requiring a high temperature of 00 ° C. and significantly degrades superconductivity. The publication does not mention any means for preventing the deterioration of the superconducting characteristics.

Summary of General Lectures of Autumn Meeting of the Japan Institute of Metals, 19
In October 1987, p236 also used Ag as a sheath material in the Y-Ba-Cu-O-based powder-in-tube method.
-2 at% Mn and Ag-5 at% Mn are disclosed.
However, the prior art using these sheaths is also 800-
It is not suitable for heat treatment at 900 ° C., and particularly when producing a bismuth-based oxide superconducting wire, it is difficult to obtain a high critical current density by the conventional technique.

Japanese Patent Application Laid-Open No. 5-74233 discloses the use of a silver alloy which is hardened by dispersing an oxide or is hardenable as a material for directly covering an oxide ceramic superconductor. As specific examples of silver alloys, the publication discloses that 0.1 to 0.25% by weight of Mg and 0.1 to 0.
Ag-Mg-Ni alloy containing 25% by weight of Ni and A
g-noble metal-Mg-Ni alloy, and Mn and Ni
Ag-Mn- having a total content of 0.5 to 1.5% by weight.
A Ni alloy and an Ag-noble metal-Mn-Ni alloy are disclosed. For example, in the case of an Ag-Mg-Ni alloy, heat treatment generates magnesium oxide particles in the alloy. Also,
A method of preparing a Bi-2212 / Ag alloy composite tape by a doctor blade method is disclosed (NOMURA
Others, “Properties of Bi ₂ Sr ₂ CaCu ₂ O _X / A
g-Alloy Composite Tapes ", Advances in Supercon
ductivity VI, Proceedings of the 6th International
Symposium on Superconductivity (ISS'93), October
26-29, 1993, Hiroshima, Vol. 2, p715-718). The proceedings are based on Au as a silver alloy that is brought into direct contact with the Bi-2212 oxide superconductor.
Ag-Au alloy containing at%, Cu is 0.026-
Ag-Cu alloy containing 2.6 at%, Ag- (Mg, N) having a total content of Mg and Ni of 0.036 to 1.3 at%.
i) alloy, and 0.16 at% and 0.40 at%
Ag-Mn alloys each containing 0.1% Mn. Among the components contained in the silver alloy described above, M
g, Ni, Cu and Mn have high reactivity with the oxide superconductor and cannot be contained in large amounts. On the other hand, with these limited contents, it is difficult to obtain a wire having high mechanical strength suitable for a large magnet or a high magnetic field magnet. In addition, Au contributes little to the improvement of mechanical strength compared to other components, and is expensive.

Japanese Patent Application Laid-Open No. 4-292816 discloses a method of manufacturing a bismuth-based oxide superconducting wire by a powder-in-tube method. Disclosed is the use of a silver alloy that does not lower the critical temperature of the body and an outer layer made of a metal having higher rigidity than the inner layer. This publication describes an Ag-Pd alloy containing 2 to 30% of Pd as a specific example of a highly rigid metal. However, in order to significantly improve the mechanical strength of the wire, a higher Pd content of 5% or more is required, and the cost is high.

Japanese Patent Application Laid-Open No. Hei 8-171822 discloses that, in an oxide superconducting wire, a stabilizing metal covering an oxide superconducting filament includes a first portion directly covering the filament and a second portion covering the first portion. Disclosed is that the first portion comprises and prevents the components of the second portion from diffusing into and reacting with the oxide superconducting filament. The publication discloses silver, as a specific example of the first part,
An Ag-Sb alloy, an Ag-Zr alloy, an Ag-Ti alloy and an Ag-Au alloy are described, while a specific example of the second portion is Ag-M containing 0.01 to 1 at% Mn.
n alloy, 1 to 30 at% Au and 0.01 to 1 at
-Au-Mn alloy containing 0.01% to 5% of Mn
Ag-Sb alloy containing t% Sb, 1-30 at% A
Ag-A containing u and 0.01 to 5 at% Sb
u-Sb alloy, Ag- containing 0.01 to 3 at% of Pb
Pb alloy, 1 to 30 at% Au and 0.01 to 3a
Ag-Au-Pb alloy containing t% Pb, 1-30 at
% Au and 0.01 to 3 at% Bi-
Au-Bi alloy, Ag containing 0.01 to 3 at% Bi
-Bi alloy, Ag-Mg alloy, Ag-Ni alloy, Ag-
Mg-Ni alloys and Ag-Zr alloys are described.
However, the structure disclosed in the publication has room for further improvement. In particular, further improvement in mechanical strength of the oxide superconducting wire has been desired. When a large magnet or a high magnetic field magnet is manufactured using an oxide superconducting wire, the wire must withstand a tensile stress of 20 kg / mm ² or more. As described above, when the added amount of the alloy component is increased to withstand such tensile stress, the superconductor reacts with the added metal, and the superconducting characteristics, particularly, the critical current density, are remarkably reduced. On the other hand, when the amount of the added metal element is adjusted so as not to lower the superconducting characteristics, the resistance to mechanical strain decreases. Development of a wire having higher mechanical strength without deteriorating superconductivity has been desired.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an oxide superconducting wire which satisfies both excellent superconducting properties, especially high critical current density and high mechanical strength.

A further object of the present invention is to provide an oxide superconducting wire having mechanical strength at a level practical for a large magnet or a high magnetic field magnet and exhibiting excellent superconducting properties.

[0011]

SUMMARY OF THE INVENTION The present invention provides an oxide superconducting wire comprising a filament made of an oxide superconductor and a stabilizing matrix covering the filament, wherein the stabilizing matrix directly covers the filament. And a second part covering the first part.
The present invention provides that the first portion is made of a material selected from the group consisting of silver and a silver alloy containing a metal of an amount and kind that does not deteriorate the superconducting property of the filament;
And the second part is Mn of 1.0 at% to 8.0 at%.
Characterized by comprising an Ag-Mn alloy containing
In the wire of the present invention, the first portion prevents the component of the second portion from reacting with the filament portion to degrade the superconducting characteristics, and the second portion is more mechanical than the first portion. The target strength is high.

In the present invention, the first portion is 0.2 at%.
It is particularly preferable to be made of an Ag-Sb alloy containing Sb of up to 0.7 at%. In the Ag-Sb alloy, it is particularly preferable that at least a part of Sb in the solid solution is precipitated as oxide particles in order to impart high mechanical strength to the wire.

On the other hand, the first portion can be silver. At present, silver is a more preferable material from the viewpoint of high superconducting properties.

According to the present invention, in order to obtain a wire having a mechanical strength more suitable for a large magnet or a high magnetic field magnet, an Ag-Mn alloy containing 1.0 at% to 8.0 at% Mn is used in the second portion. Used. In this alloy, if at least a part of Mn in the solid solution is precipitated as oxide particles, the mechanical strength of the wire is further increased.

Although the present invention is preferably applied to a multifilamentary superconducting wire having a plurality of filaments, it may be applied to a monofilamentary superconducting wire. The present invention particularly relates to Bi-Pb-Sr-Ca
-Cu-O system or the like is preferably applied to the wire using a bismuth-based oxide superconductor, among others (Bi, Pb) ₂ Sr ₂
Bismuth-based 22 such as Ca ₂ Cu ₃ O _10-X (0 ≦ X <1)
It is preferably applied to a wire using a 23 oxide superconducting phase as a filament.

According to the present invention, when the applied magnetic field is zero at the temperature of liquid nitrogen, it has a critical current density of 25,000 A / cm ² or more and a critical current density for a tensile stress of 20 kg / mm ^2. A wire that does not decrease can be provided.

In the present specification, "at%" indicating the concentration is used.
Stands for atomic percentage, i.e., the ratio of a particular atom to the total number of atoms in the composition or mixture (percentage).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The wire according to the present invention includes a single-core wire or a multi-core wire having a structure in which a filament made of an oxide superconductor is embedded in a stabilizer. The form of the wire is not particularly limited, and a round wire or a tape-like wire can be provided according to the present invention. The tape-shaped wire is a preferred form from the viewpoint of high orientation of the superconductor crystal. The oxide superconductor includes, for example, an yttrium-based, bismuth-based, or thallium-based oxide superconductor. The present invention can be preferably applied particularly to a bismuth-based ceramic superconductor. The wire rod of the present invention can be manufactured through the processes of firing and pulverizing the raw material powder of the oxide superconductor, filling the powder into the stabilizing material sheath, plastic working, and sintering. In the preparation of the raw material powder, powders of oxides or carbonates of the elements constituting the superconductor are mixed at a predetermined mixing ratio and sintered, and then the sintered product is ground to obtain the raw material powder. The sheath filled with the powder can be formed from silver or a silver alloy as described below.
For the plastic working, wire drawing, swaging, rolling and the like are used. After plastic working, the resulting wire is, for example, about 800 ° C. to about 900 ° C., preferably about 840 ° C.
Sintering at a temperature of ８850 ° C. allows the superconductor in the sheath material to obtain high orientation and high critical current density. In the case of manufacturing a multifilamentary wire, a plurality of wires obtained after wire drawing are fitted and subjected to plastic working and sintering. In the process described above, a combination of plastic working and sintering can produce a nearly single superconducting phase with high orientation. For example, the filament of the tape-shaped superconducting wire produced by this process has a substantially uniform superconducting phase over the length of the tape wire, and the c-axis of the superconducting phase is oriented substantially parallel to the thickness direction of the tape wire. . Further, the crystal grains in the filament have a flake shape extending in the longitudinal direction of the tape wire, and the crystal grains are strongly bonded to each other. The flake-like crystal grains are stacked in the thickness direction of the tape wire. Although the size of the tape-shaped superconducting wire is not particularly limited, for example, the width is 1.0 mm to 1 mm.
0 mm, preferably 2 mm to 6 mm, thickness 0.05 mm
１1 mm, preferably 0.1 mm to 0.4 mm.

1 to 3 show specific examples of the oxide superconducting wire according to the present invention. 1 and 3 show a specific example of a multifilamentary wire,
FIG. 2 shows a specific example of a single core wire. FIG.
In the cross section of the tape-shaped oxide multi-core superconducting wire shown in (a), the plurality of filaments 1 are directly covered with the first stabilizing material 2. The first stabilizer is silver or filament 1
Made of a silver alloy containing an amount and type of metal that does not deteriorate the superconducting characteristics of the alloy. The first stabilizer 2 includes:
It is covered with a second stabilizing material 3 made of an Ag—Mn alloy containing 0 at% to 8.0 at% of Mn. The second stabilizer 3 mainly contributes to the improvement of the mechanical strength of the wire. On the other hand, the first stabilizing material 2 prevents the components of the second stabilizing material 3 from reacting with the portion of the filament 1 to prevent the superconducting properties from deteriorating. FIG. 1B shows an example of a round line. The plurality of filaments 11 made of an oxide superconductor
The first stabilizer 12 is directly covered with the second stabilizer 13. The compositions and functions of the first stabilizer and the second stabilizer are the same as those in FIG. In the tape-shaped single core wire shown in FIG. 2A, the filament 21 is first covered with the first stabilizing material 22, and further covered with the second stabilizing material 23. In the case of the round wire shown in FIG.
And then covered with a second stabilizing material 33. FIG.
In the tape-shaped line shown in (a), the portion 40 composed of the filament 41 and the first stabilizing material 42 covering the filament 41 is the second line.
Has a structure dispersed in the stabilizing material 43. That is, the second stabilizer exists between the plurality of stabilizers covering each filament. Also in the round wire shown in FIG. 3B, the portion 50 composed of the filament 51 and the first stabilizing material 52 covering the filament 51 is the second stabilizing material 5
3 are dispersed.

In the wire rod of the present invention, the portion composed of the filament and the first stabilizing matrix directly covering the filament mainly retains excellent superconducting characteristics, and the second stabilizing matrix covering the filament mainly retains the superior superconductivity. Provides mechanical strength. The first portion in the stabilization matrix suppresses the reaction between the second portion and the filament, and maintains high superconducting properties of the filament portion. At present, silver is the best material that does not substantially react with the oxide superconductor during the sintering process of the wire and allows sufficient diffusion of oxygen into the superconductor. Therefore, it is important that the first portion be made of silver or a silver alloy containing a metal of an amount and type that does not deteriorate the superconducting characteristics of the filament.
When a silver alloy is used for the first portion, attention must be paid to the type and amount of alloy components from the viewpoint of superconducting characteristics. For example, in the case of an Ag-Au alloy, Au is 30a.
Even if it is contained up to about t%, the superconducting properties do not deteriorate. Therefore, the Au content of the Ag-Au alloy is 3
0 at% or less is preferable, and 10 at% or less is more preferable. In the case of an Ag-Mn alloy, the Mn content is 0.1
Even at%, the critical current density of the filament is reduced. Therefore, an Ag-Mn alloy is not so preferable as the first part. When the Ag-Mn alloy is used for the first portion, the content of Mn is desirably 0.01 at% or less. In the case of an Ag—Cu alloy, even a small amount of Cu of 0.02 at% can cause a decrease in critical current density. Therefore, an Ag-Cu alloy is not preferable as the first portion.

As a result of the study by the present inventors, it has become clear that an Ag-Sb alloy is more preferable as the silver alloy used for the first portion. In the case of an Ag-Sb alloy, the content of Sb can be made relatively high, and the mechanical strength of the wire can be improved to some extent even in the first portion. Further, the oxide particles can be dispersed in the solid solution of the Ag-Sb alloy by the oxidation of Sb during the heat treatment.
Such oxide particles can further improve the strength of the alloy. Furthermore, the present inventors have studied the Ag—Sb alloy from both viewpoints of improving mechanical strength and maintaining a high critical current density.
It has been clarified that an Ag-Sb alloy containing 0.7 at% Sb is most suitable for satisfying both characteristics. As shown in the examples described later, 1 to 8 at% of M
When combining an Ag-Mn alloy containing n and an Ag-Sb alloy, the range of the Sb content is 0.2 to 0.7 at%.
Is suitable. If the content of Sb is less than 0.2 at%, it will be difficult to significantly improve the mechanical strength of the first portion. On the other hand, when the content of the Sb alloy is 0.
If it exceeds 7 at%, it becomes difficult to obtain a higher critical current density, especially a critical current density of 25,000 A / cm ² or more at the temperature of liquid nitrogen. Sb is 0.2 to 0.7
By combining an Ag-Sb alloy containing at% and an Ag-Mn alloy containing 1 to 8 at% of Mn, both a dramatic improvement in mechanical strength and a high critical current density can be achieved.

In the wire of the present invention, the stabilizing matrix ratio of the first portion (cross-sectional area of the first portion / cross-sectional area of the filament in the stabilizing matrix) is, for example, 0.5.
To 2, preferably 0.7 to 1.5. First
By setting the matrix ratio of the portion within this range, the filament can be sufficiently protected and a high critical current density can be obtained.

In the present invention, an Ag-Mn alloy containing 1 to 8 at% Mn is used for the second portion covering the first portion in the stabilization matrix. In the present invention, the second
By using this alloy in the portion of No. 5, the mechanical strength of the wire could be further improved without causing a reduction in the critical current density as in the prior art. When the content of Mn is less than 1 at%, it becomes difficult to obtain a resistance to a stress of 20 kg / mm ² or more required for a wire material, particularly for a magnet without lowering the critical current density. On the other hand, when the content of Mn exceeds 8 at%, the alloy becomes excessively hard and brittle, and it becomes difficult to perform sufficient processing together with the first portion. From the viewpoint of combination with the first portion, Mn of 1 to 8 at% is appropriate.

The second part in the matrix compensates for the mechanical strength that the first part alone is insufficient, and gives the wire a higher mechanical strength. The second part has significantly higher mechanical strength than the first part. The present inventors have studied various alloys suitable for the second part, and found that from the viewpoints of improvement in mechanical strength, workability and excellent superconducting properties, 1 to 8
Ag-Mn alloys containing at% Mn were found to be more suitable. This silver alloy can be subjected to plastic working while maintaining its shape even after heat treatment for sintering the oxide superconductor, for example, heat treatment at a high temperature of 800 to 900 ° C. In addition, this alloy can generate a Mn oxide having a melting point of 900 ° C. or more in a base material by oxidation during heat treatment. Oxide precipitation further increases the mechanical strength of the alloy.

In the wire of the present invention, the matrix ratio of the second portion (cross-sectional area of the second portion in the matrix / cross-sectional area of the filament) is preferably, for example, 0.2 to 4.5, and 0.5 to 4.5. 3.5 is more preferred. By setting the matrix ratio of the second portion to this range, it is possible to improve mechanical strength while maintaining high workability.

Therefore, the stabilization matrix ratio of the wire according to the present invention (the stabilization matrix of the first part and the second
Of the cross-sectional area of the stabilization matrix / cross-sectional area of the filament) is preferably 0.7 to 5, for example.
To 4 are more preferable. In the present invention, the stabilization matrix is divided into a portion that mainly maintains the superconductivity and a portion that mainly improves the mechanical strength. With this composite structure,
The strength of the wire can be remarkably improved compared to the related art while keeping the size of the wire and the stabilizing matrix ratio (cross-sectional area of the stabilizing matrix / cross-sectional area of the superconductor) as before. Therefore, high strength and excellent superconducting characteristics can be obtained with a compact size wire rod as in the conventional case. According to the present invention, a magnet or the like can be manufactured without using a conventionally required reinforcing material. If no reinforcing material is used, the overall critical current density of the product is substantially increased, and higher performance can be obtained in applied products such as magnets.

The compounding of the stabilizing matrix described above can be easily performed, for example, in the production of a multifilamentary superconducting wire. In the production of a multifilamentary wire, a raw material powder of an oxide superconductor is filled in a first metal sheath, and after plastic working, a strand is obtained. A plurality of the obtained wires are bundled and filled in the second metal sheath, and a multi-core wire can be prepared through plastic working and heat treatment. At this time, silver or a silver alloy for maintaining high superconducting characteristics is provided in the first sheath, and Ag-containing 1 to 8 at% of Mn is contained in the second sheath.
If each of the Mn alloys is used, the structure according to the present invention can be easily obtained. In the case of manufacturing a single-core wire, a raw material powder is filled in a sheath having a first portion inside and a second portion outside, or a wire covered with the first portion is placed in a second sheath. Compounding can be performed by fitting into the inside.

In the present invention, oxide particles can be precipitated for the alloy components in the first portion and the second portion. Such oxide particles can be precipitated in the first portion and the second portion by, for example, a heat treatment for sintering the oxide superconductor in a wire rod manufacturing process. On the other hand, a metal sheath in which oxide particles are previously deposited may be used. In this case, the metal sheath for filling the raw material powder and / or the metal sheath for fitting the element wire is heat-treated in advance, so that the metal sheath reinforced by the oxide is obtained. By using such a metal sheath, the compression density of the raw material powder can be further improved, and a higher critical current density can be obtained.

[0029]

【Example】

Example 1 Bi ₂ O ₃ , PbO, SrCO ₃ , CaCO ₃ , CuO
By using, Bi: Pb: Sr: Ca: Cu = 1.8:
A powder having a composition ratio of 0.4: 2.0: 2.0: 3.0 was blended. The obtained powder was subjected to a heat treatment at 700 ° C. for 12 hours and then at 800 ° C. for 8 hours.
A time heat treatment was further performed. After each heat treatment, the formulation was milled in a ball mill. The powder obtained by the pulverization was heat-treated at 800 ° C. for 2 hours and degassed, and then filled in a pipe having an outer diameter of 12 mmφ and an inner diameter of 10.5 mmφ. Table 1 shows the materials used for the filling pipe. After the pipe filled with the powder was drawn to 1.02 mmφ, the obtained wire was cut to prepare 61 wires. The obtained 61 wires are bundled to form an outer diameter of 12 mmφ and an inner diameter of 9 mmφ.
Pipe. Table 1 shows the materials used for the fitting pipe.
Shown in After the pipe filled with the wire was drawn to 1.15 mmφ, it was rolled to a thickness of 0.24 mm. After the obtained tape-shaped wire was subjected to a heat treatment at 845 ° C. for 50 hours, it was cooled to room temperature in a furnace. Then, the obtained wire rod is again subjected to rolling to a thickness of 0.2 mm,
Heat treatment was performed at 840 ° C. for 50 hours to obtain an oxide superconducting wire. Twelve kinds of wires as shown in Table 1 were obtained by changing the material of the powder filling pipe and the fitting pipe. The critical current density of the obtained wire was measured in liquid nitrogen by a DC four-terminal method. Further, a tensile test was performed in liquid nitrogen, and the stress Tε (kg
/ Mm ² ). Table 1 shows the measurement results together with the material of the pipe.

[0030]

[Table 1]

Sample No. 1 as a comparative example was used. As is clear from the results of 1 to 7, when Ag or Mn alloy having a low content of silver or Mn is used for the fitting pipe, high mechanical strength cannot be obtained. In addition, 0.
When a silver alloy containing 2 at% Mn was used, a high critical current density could not be obtained. In addition, 1.0a
When a silver alloy containing t% Sb and a silver alloy containing 0.98 at% Mn were combined, a high critical current density could not be obtained. On the other hand, the sample No. 8 ~
Looking at the results of No. 12, it was found that the critical current
It is understood that a wire rod capable of withstanding a stress of kg / mm ² or more was obtained. In particular, according to the present invention, a wire having a critical current density of 25,000 A / cm ² or more, and more preferably 30,000 A / cm ² or more when the applied magnetic field is zero at the temperature of liquid nitrogen can be obtained.

Example 2 Sample No. 1 shown in Example 1 was used. Alloy pipe of the same material as 12
Was used. Before filling the powder and before mating,
Each alloy pipe is exposed to air at 600 ° C for 100 hours.
And heat-treated. Same as Example 1 except for the above steps
A wire rod was produced. About the obtained wire, in liquid nitrogen
The critical current density was measured by a DC four-terminal method. further
Performs tensile test in liquid nitrogen, lowering critical current density
The stress Tε that starts to be measured was measured. As a result of the measurement, the criticality of the wire rod
Current density is 31,000 A / cm ^TwoAnd the critical stress T
ε is 32.0 kg / mm^TwoMet. Therefore, the alloy
Preliminary heat treatment of the pipe to precipitate oxide particles
Wire with higher critical current density and mechanical strength
It was found that wood was obtained.

[0033]

As described above, according to the present invention, it is possible to provide a wire that can satisfy both high critical current density and excellent mechanical strength. Therefore, the present invention can provide a high-performance wire rod that can withstand a stress of 20 kg / mm ² or more required for a full-scale class magnet or the like and has a high critical current density.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one specific example of a wire according to the present invention.

FIG. 2 is a cross-sectional view schematically showing another specific example of the wire according to the present invention.

FIG. 3 is a cross-sectional view schematically showing another specific example of the wire according to the present invention.

[Explanation of symbols]

1, 11, 21, 31, 41, 51 filament 2, 12, 22, 32, 42, 52 first stabilization matrix 3, 13, 23, 33, 43, 53 second stabilization matrix

Claims (8)

[Claims] 1. An oxide superconducting wire comprising a filament made of an oxide superconductor and a stabilizing matrix covering the filament, wherein the stabilizing matrix comprises a first portion directly covering the filament, A second portion covering the first portion, wherein the first portion is made of a material selected from the group consisting of silver and a silver alloy containing a metal of an amount and type that does not deteriorate the superconducting properties of the filament. Wherein the second portion comprises Mn of 1.0 at% to 8.0 at%.
Wherein the first portion prevents a component of the second portion from reacting with the filament portion to degrade superconductivity, and the second portion has An oxide superconducting wire having higher mechanical strength than the first portion. 2. The method according to claim 1, wherein the first portion is 0.2 at% to 0.7 at%.
The oxide superconducting wire according to claim 1, comprising an Ag-Sb alloy containing at% Sb. 3. The oxide superconducting wire according to claim 2, wherein in the Ag—Sb alloy, at least a part of Sb in the solid solution is precipitated as oxide particles. 4. The oxide superconducting wire according to claim 1, wherein said first portion is made of silver. 5. The oxide superconductivity according to claim 1, wherein at least a part of Mn in the solid solution is precipitated as oxide particles in the Ag—Mn alloy. wire. 6. The oxide superconducting wire according to claim 1, wherein the wire is a multi-core wire having a plurality of the filaments. 7. The oxide superconducting wire according to claim 1, wherein the oxide superconductor is a bismuth-based oxide superconductor. 8. At a liquid nitrogen temperature, in a state where an applied magnetic field is 0, it has a critical current density of 25,000 A / cm ² or more and a critical current density does not decrease with a tensile stress of 20 kg / mm ^2. The oxide superconducting wire according to any one of claims 1 to 7, which is characterized in that: