Hitachi Cable, Inc.

Sh Copper Products Co., Ltd.

Morio Kimura

Yoshihide Wadayama

Kazuhiko Nakagawa

Katsumi Ohata

Masahiro Seido

Genzo Iwaki

A precursor for a NbSn superconductor wire to be manufactured by the internal diffusion method, includes a plurality of Nb-based single core wires, each of which includes a Nb-based core coated with a Cu-based coating including a Cu-based matrix, a plurality of Sn-based single core wires, each of which includes a Sn-based core coated with a Cu-based coating including a Cu-based matrix; and a cylindrical diffusion barrier including Ta or Nb, in which the plurality of Nb-based single core wires and the plurality of Sn-based single core wires are regularly disposed, wherein the plurality of Nb-based single core wires include Nb-based single core wires having a Cu/Nb ratio of 0.4 or more, wherein the Cu/Nb ratio is a cross sectional area ratio of the Cu-based coating to the Nb-based core.

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A precursor for a NbSn superconductor wire to be manufactured by the internal diffusion method. The precursor includes Nb-based single core wires, Sn-based single core wires, and a cylindrical diffusion barrier made of Ta or Nb. Each Nb-based single core wire includes a Nb-based core coated with a Cu-based coating made of a Cu-based matrix. Each Sn-based single core wire includes a Sn-based core coated with a Cu-based coating made of a Cu-based matrix. The Nb-based single core wires and the Sn-based single core wires are regularly disposed in the diffusion barrier. The Nb-based single core wires includes at least two kinds of Nb-based single core wires having different Cu/Nb ratios and the Cu/Nb ratio is a cross sectional area ratio of the Cu-based coating to the Nb-based core.

A method of producing a NbSn superconducting wire rod includes forming a wire rod comprising Nb, Sn and Cu, and having a mole ratio of the Sn expressed as ax+b(1&#x2212;x), where 0.25&#x2266;x&#x2266;0.8, 0.3&#x2266;a&#x2266;0.4 and 0.02&#x2266;b&#x2266;0.1, and x and 1&#x2212;x are prescribed as a mole ratio of the Nb and a mole ratio of the Cu, respectively, to a total of a mole number of the Nb and a mole number of the Cu, and heating the wire rod to produce NbSn from the Sn and the Nb. By the heating of the wire rod, a Cu&#x2014;Sn alloy is produced from the Sn and the Cu, concurrently with the NbSn produced from the Sn and the Nb.

An NbSn-based superconductive wire which, when used in a superconductive magnet, manifests sufficient strength also against force along the radius direction in operating the magnet and reveals little deterioration in properties due to mechanical strain ascribable to the force along the radius direction is provided. An NbSn-based superconductive wire comprising a bronze/filament aggregate obtained by placing a lot of niobium (Nb) or niobium alloy filaments in a copper (Cu)-tin (Sn)-based alloy matrix, wherein said niobium or niobium alloy filament constituting the bronze/filament aggregate' is a composite filamentobtained by combining with a filament reinforcing material having mechanical strength under temperature not more than room temperature after thermal treatment for producing an NbSn-based superconductive compound, larger than the mechanical strength of the niobium or niobium alloy.

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Kasumigaura, Japan

Morio Kimura