Precursor for manufacturing Nb
A precursor for manufacturing a Nb 3 Sn superconducting wire according to the present invention includes a mono-element wire including a Sn or Sn-based alloy core disposed at the, a Cu or Cu-based alloy matrix and a plurality of Nb or Nb-based alloy filaments surrounding the Sn or Sn-based alloy core, and a diffusion barrier layer and a stabilizing copper layer surrounding the Cu or Cu-based alloy matrix. In a final shape after a reduction process, the average diameter of the Nb or Nb-based alloy filaments is set to 5 μm to 30 μm, and the average distance between the Sn or Sn-based alloy core and the Nb or Nb-based alloy filaments nearest the Sn or Sn-based alloy core is set to 100 μm or less.
1. A precursor for manufacturing a Nb 3 Sn superconducting wire by an internal Sn process, the precursor comprising:
a multi-element wire having a center portion including a plurality of mono-element wires;
each of said plurality of mono-element wires having a Cu or Cu-based alloy matrix into which an Sn or Sn-based alloy core is embedded, and having a plurality of Nb or Nb-based alloy filaments surrounding the Sn or Sn-based alloy core, said plurality of Nb or Nb-based alloy filaments configured to have an average distance from the outer diameter of the Sn or Sn-based alloy core of 100 μm or less; and at least one of said plurality of Nb or Nb-based alloy filaments configured to have a distance from the outer diameter of the Sn or Sn-based alloy core of 50 μm or less; and said plurality of Nb or Nb-based alloy filaments having an average diameter of 5 μm to 30 μm, and a diffusion barrier layer surrounding said plurality of Nb or Nb-based alloy filaments; and
a stabilizing copper layer surrounding each of said mono-element wires.
2. The precursor according to claim 1 , wherein the plurality of Nb or Nb-based alloy filaments is disposed in the Cu or Cu-based alloy matrix so as not to contact each other, and the distance between the respective Nb or Nb-based alloy filaments is 0.05 to 0.30 times as large as the average diameter of the filaments.
3. A Nb 3 Sn superconducting wire wherein the precursor according to claim 1 is heat-treated to form a Nb 3 Sn superconducting phase.