A method of fabricating a superconductor device includes providing a first metal layer on top of the substrate. An oxidation of a top surface of the first metal layer is rejected. A second metal layer is deposited on top of the second metal layer. A superconducting alloy of the first metal layer and the second metal layer is created between the first metal layer and the second metal layer. There is no oxide layer between the superconducting alloy and the first metal layer.

A precursor, which is a drawn wire product of a composite pipe, the composite pipe having: a composite wire group; a barrier layer; and a protective layer, wherein the composite wire group has: a plurality of tin wires each having at least one tin core being made of tin or a tin alloy, and a copper matrix which surrounds the at least one tin core; and a plurality of niobium wires each having a plurality of niobium cores being made of niobium or a niobium alloy, and a copper matrix which surrounds the plurality of niobium cores, the plurality of niobium wires being disposed such that each of the tin wires is surrounded by the niobium wires, the composite wire group contains titanium in an amount of from 0.38% by mass to 0.55% by mass.

An insulation-coated compound superconducting wire includes a compound superconducting wire having a compound superconducting part which includes a first matrix and a plurality of compound superconducting filaments containing compound superconducting phases, a reinforcing part disposed on the outer circumferential side of the compound superconducting part and includes a plurality of reinforced filaments, a second matrix and a second stabilizing material. A stabilizing part is disposed on at least one side among the inner circumferential side and the outer circumferential side of the reinforcing part. An electrical insulation part covers the outer circumferential surface of the compound superconducting wire, in which the insulation-coated compound superconducting wire has a critical current value (Ic) larger than that of the compound superconducting wire before being covered with the electrical insulation part.

In various embodiments, superconducting wires incorporate diffusion barriers composed of Nb alloys or Nb—Ta alloys that resist internal diffusion and provide superior mechanical strength to the wires.

A monofilament (100) for producing an Nb.sub.3Sn-containing superconductor wire (33) includes a powder core (1) with an Sn-containing powder, a reaction tube (3) composed of an Nb alloy that includes Nb and at least one further alloy component X. The powder core is disposed within the reaction tube. The monofilament also includes at least one source (4) for at least one partner component Pk. A respective source includes one or more source structures at a unitary radial position in the monofilament. The alloy component X and the partner component Pk form precipitates XPk on reaction annealing of the monofilament in which Sn from the powder core and Nb from the reaction tube react to produce Nb.sub.3Sn. The powder core is disposed in a moderation tube, which in turn is disposed within the reaction tube. This provides a monofilament for a powder-in-tube based Nb.sub.3Sn-containing superconductor wire with improved current carrying capacity.

In various embodiments, superconducting wires incorporate diffusion barriers composed of Nb alloys or Nb—Ta alloys that resist internal diffusion and provide superior mechanical strength to the wires.

In various embodiments, superconducting wires feature assemblies of clad composite filaments and/or stabilized composite filaments embedded within a wire matrix. The wires may include one or more stabilizing elements for improved mechanical properties.

The present invention provides: a compound superconducting twisted wire in which non-adhesiveness between compound superconducting strands or separation easiness after adhesion is improved while a strength against tension is improved to a degree to be equivalent to or stronger than that of a conventional compound superconducting twisted wire; and a rewinding method thereof. The compound superconducting twisted wire 1 of the present invention includes a plurality of compound superconducting strands 10 being twisted to form a twisted structure, in which each of the compound superconducting strands 10 includes a compound superconductor part 11, a reinforcing part 12 and a stabilizing part 13, in which the compound superconductor part 11 includes a plurality of compound superconducting filaments 15 and a first matrix 16, the compound superconducting filaments 15 each including a compound superconducting phase, in which the reinforcing part 12 is disposed on an outer circumferential side of the compound superconductor part, and comprises a plurality of reinforcing filaments 18 and a second matrix 19, in which the stabilizing part 13 is disposed on at least one side of an inner circumferential side and an outer circumferential side of the reinforcing part. In the compound superconducting twisted wire, a volume ratio of the reinforcing part relative to the compound superconducting strand is larger than a volume ratio of the compound superconductor part relative to the compound superconducting strand, or a metal layer 20 with a thickness of 2 μm or less is formed on a surface of the compound superconducting strand for preventing thermal fusion between the compound superconducting strands.

A subelement (1) for an Nb.sub.3Sn-containing superconductor wire includes an Sn-containing core (2), an inner matrix (5) which includes Cu and surrounds the Sn-containing core (2), a region (7) of mutually abutting Nb-containing rod elements (8, 30), which surrounds the inner matrix (5), where the Nb-containing rod elements (8, 30) are each configured with an Nb-containing core filament (9; 31) and a Cu-containing filament casing (10), an outer matrix (6) which includes Cu and surrounds the region (7) of Nb-containing rod elements (8, 30). The Sn-containing core (2) has a core tube (3) into which an Sn-containing powder (4) has been introduced, the Sn-containing powder (4) being in a compacted state. This provides a subelement for an Nb.sub.3Sn-containing superconductor wire which cost-effectively yields an improved superconducting current carrying capacity.

In various embodiments, superconducting wires incorporate diffusion barriers composed of Ta alloys that resist internal diffusion and provide superior mechanical strength to the wires.