Nb3Sn superconducting wire fabricated by bronze process and precursor therefor

摘要

A precursor used for making a Nb3Sn superconducting wire by a bronze process includes an aggregate obtained by bundling (A) a plurality of superconducting composite elements, each including one or a plurality of Nb or Nb-based alloy filaments disposed in a Cu-Sn-based alloy matrix and (B) a plurality of reinforcing composite elements, each including one or a plurality of Ta or Ta-based alloy filaments disposed in a Cu-Sn-based alloy matrix; a diffusion barrier layer; and stabilizing copper. The ratio of the cross-sectional area of the Ta or Ta-based alloy filaments disposed in the reinforcing composite elements to the cross-sectional area of the precursor wire is 2% to 15%. The reinforcing composite elements are present at a position in a range of 0.7D to 0.9D in the radial direction, where D is an outer diameter of the precursor wire.