In the production of an internal-tin-processed Nb.sub.3Sn superconducting wire, the present invention provides a Nb.sub.3Sn superconducting wire that is abundant in functionality, such as, the promotion of formation of a Nb.sub.3Sn layer, the mechanical strength of the superconducting filament (and an increase in interface resistance), the higher critical temperature (magnetic field), and the grain size reduction, and a method for producing it. A method for producing a Nb.sub.3Sn superconducting wire according to an embodiment of the present invention includes a step of providing a bar 10 that has a Sn insertion hole 12 provided in a central portion of the bar 10 and a plurality of Nb insertion holes 14 provided discretely along an outer peripheral surface of the Sn insertion hole 12, and that has an alloy composition being Cu-xZn-yM (x: 0.1 to 40 mass %, M=Ge, Ga, Mg, or Al, provided that, for Mg, x: 0 to 40 mass %), a step of mounting an alloy bar with an alloy composition of Sn-zQ (Q=Ti, Zr, or Hf) into the Sn insertion hole 12 and inserting Nb cores into the Nb insertion holes 14, a step of subjecting the bar 10 to diameter reduction processing to fabricate a Cu-xZn-yM/Nb/Sn-zQ composite multicore wire with a prescribed outer diameter, and a step of subjecting the composite multicore wire to Nb.sub.3Sn phase generation heat treatment.

The stabilizer material for superconductor of the present invention is used for a superconducting wire, and the stabilizer material for superconductor includes a copper material, the copper material contains one kind or more of additive elements selected from Mg, Mn, Ti, Y, and Zr for a total amount of 3 ppm by mass or more and 100 ppm by mass or less, with the remainder being Cu and unavoidable impurities, the total concentration of the unavoidable impurities other than O, H, C, N, and S, which are gas components, is 5 ppm by mass or more and 100 ppm by mass or less, and compounds including one kind or more selected from MgS, MgSO.sub.4, MnS, TiS, YS, Y.sub.2SO.sub.2, and ZrS are present in the matrix.

The stabilizer material for superconductor of the present invention is used for a superconducting wire, and the stabilizer material for superconductor includes a copper material, the copper material contains one kind or more of additive elements selected from Mg, Mn, Ti, Y, and Zr for a total amount of 3 ppm by mass or more and 100 ppm by mass or less, with the remainder being Cu and unavoidable impurities, the total concentration of the unavoidable impurities other than O, H, C, N, and S, which are gas components, is 5 ppm by mass or more and 100 ppm by mass or less, and compounds including one kind or more selected from MgS, MgSO.sub.4, MnS, TiS, YS, Y.sub.2SO.sub.2, and ZrS are present in the matrix.

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

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

It is an object of the present invention to provide an MgB.sub.2 wire helping to achieve compatibility between the ease with which superconducting connection is effected and thermal stability. A superconducting wire according to the present invention includes: an elemental wire formed of MgB.sub.2; and a first metal not reacting with Mg. In a section orthogonal to the longitudinal direction of the superconducting wire, the region extending from the center of the superconducting wire to the installation position of the elemental wire is formed by the elemental wire and the first metal.

It is an object of the present invention to provide an MgB.sub.2 wire helping to achieve compatibility between the ease with which superconducting connection is effected and thermal stability. A superconducting wire according to the present invention includes: an elemental wire formed of MgB.sub.2; and a first metal not reacting with Mg. In a section orthogonal to the longitudinal direction of the superconducting wire, the region extending from the center of the superconducting wire to the installation position of the elemental wire is formed by the elemental wire and the first metal.

Various embodiments may include an electric conductor for producing a stator winding of a stator of an electric machine comprising: a plurality of filaments of a material normally conductive at 4.2 K; and a normally conductive matrix material. The plurality of filaments are embedded in the matrix material to form a monolithic composite. The matrix material is more electrically resistive than the filaments.

Various embodiments may include an electric conductor for producing a stator winding of a stator of an electric machine comprising: a plurality of filaments of a material normally conductive at 4.2 K; and a normally conductive matrix material. The plurality of filaments are embedded in the matrix material to form a monolithic composite. The matrix material is more electrically resistive than the filaments.

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