JPS6251112A - Al stabilized nb-ti superconductor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an N-stabilized Nb Ti superconducting wire for pulsed magnets.

<Conventional technology and its problems> Nuclear fusion poloidal magnets, energy storage magnets for power system stabilization, field magnets for generators, etc. are operated in pulses with repeated rapid excitation and demagnetization. As a result of this pulsed operation, repeated stress is applied to the wire. Therefore, it is essential that the superconducting wire for pulsed magnets has high fatigue strength.

However, N-stabilized Nb Ti ultrafine multifilamentary wire (M
The disadvantage of the method (in which many NbTi superconductors in the form of filaments are embedded in a matrix) is that its mechanical strength, particularly its fatigue strength, is low.

In order to improve the stability of the superconductor, N is added in the final process.
Because strain relief annealing is performed to soften the N, fatigue cracks occur from the surface of the wire and propagate to the inside, but fatigue cracks occur because the N on the surface is softened. This is because it is easier to wear and has lower fatigue strength.

<Means for Solving the Problems> In view of the above points, the present invention was discovered as a result of studies to obtain a /V stabilized ridge-T superconducting wire with high fatigue strength.

That is, the present invention is an N matrix Nb-T in which filamentary ridges TL alloy are embedded in A&71~Rix.
*In multifilamentary wire, the outer layer is TL1F8, l'In, c
r.

N-stabilized Nb characterized by being an N alloy containing 0.1 to 0.8% by weight of one type of element selected from (1)
-It aims to provide a TL superconducting wire.

<Effect> The present invention will be explained below with reference to the drawings.

As shown in the cross-sectional view in FIG. 1, this invention has a structure in which an Nb-TL filament 2 is embedded in an N matrix 1, and an N alloy layer 3 is provided as an outer peripheral layer of the N matrix. This is an R-TL superconducting wire.

And the A&alloy layer of 3 is ear, FB, 1, and Cr.

An A1 alloy containing 0.1 to 0.8% by weight of one type of element selected from (1) is used.

Here, Ti, Fe, I"tn, Cr, V contained in the N alloy
Setting the amount of the element to 0.1 to 0.8% by weight is 0.1
If it is less than 0.8% by weight, it will only increase the electrical resistance of the matrix and reduce the stability of the superconductor, but it will not have the effect of increasing fatigue strength.If it is more than 0.8% by weight, work hardening will increase and the wire will This is because the processability of /V decreases, and the diffusion of the third element into the /V matrix increases, increasing the electrical resistance of the matrix.

The thus obtained M-stabilized superconducting wire A of the present invention can be twisted into a shaped rectangular stranded wire as shown in FIG. 2(a) as a cross-sectional view, or as shown in FIG. 2(b). The superconducting wires A are twisted together and surrounded by a conduit tube 4 to form a bundle-type twisted wire, which can be used as a cable conductor.

<Example> Hereinafter, this invention will be explained in detail with reference to Examples.

Outer diameter 70, with the outermost layer made of N alloy with the composition shown in Table 1.
Inside the double tube consisting of a tube with a wall thickness of 2.5 tone and a tube with an outer diameter of 65Irvn and a wall thickness of 3#, the inner side is made of pure aluminum.
A composite billet was fabricated by densely packing 127 hexagonal wires and hexagonal wires coated with the ridge-T, evacuating the inside in a vacuum chamber, and electron beam welding copper lids on the top and bottom.

This was extruded using an extruder to have an outer diameter of 25 #φ.

Here, the cross-sectional area ratios of A&gold alloy pure # and Nb-Tj were set to 15%, 48%, and 31%, respectively.

Next, the extruded material was wire-drawn to a diameter of 3 shoes, annealed at 320° C. for 1 hour, and then fatigue strength was examined by a rotary bending fatigue test. The results are shown in Table 1, but the Nb Ti multifilamentary wire of A & matrix shown for comparison <Nb ”l
It was recognized that the fatigue strength was significantly improved compared to the cross-sectional area ratio of 37% and the number of filaments of 127.

Table 1 <Effects of the Invention> In this invention, by using the N alloy layer as the outer peripheral layer as described above, the outer peripheral layer of the wire rod is strengthened and the fatigue strength is increased. This is because the recrystallization temperature increases due to the M alloying of the outer peripheral layer, and even if the strain relief annealing of the N matrix is performed in the final step, the outer peripheral alloy layer remains in a work-hardened state.

When the superconducting wires of the present invention are twisted together and used as a cable conductor, in addition to the effect of increasing the fatigue strength mentioned above, it is also possible to obtain the effect of reducing electrical loss caused by a fluctuating magnetic field. It is. This is because alloying increases the electrical resistance of the outer peripheral layer, increases the effective resistance between the strands, and reduces the coupling current induced by the fluctuating magnetic field.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a superconducting wire of the present invention, and FIGS. 2(a) and 2(b) are sectional views of a cable conductor obtained by twisting the superconducting wires of the present invention. 1...N matrix 2...Nb-TL filament 3...N alloy layer Patent attorney Kazu 1) Showa 1, 2, 2 (b) 8

Claims (1)

[Claims] In an Al matrix Nb-Ti multifilamentary wire in which a filamentary Nb-Ti alloy is embedded in an Al matrix, the outer peripheral layer contains one type of element selected from Ti, Fe, Mn, Cr, and V at 0.1 to An Al-stabilized Nb-Ti superconducting wire characterized by being an Al alloy containing 0.8% by weight.