Development of Nb-Ti-Ta ternary alloy multifilamentary superconducting wire

The superconducting wire with approximately 10 /spl mu/m diameter filaments of Nb-41 wt%Ti-28 wt%Ta alloy was fabricated from our standard production billet. Critical current densities and upper critical fields after various heat treatments were measured in the temperature range of 4.2 K to 1.6 K. Thermo-mechanical treatments for /spl alpha/-Ti precipitates were optimized to improve critical current densities. A 27-strand Rutherford type cable having a large keystone angle was trial-fabricated using the optimized-processed wires. The achieved J/sub c/s were 1383 A/mm/sup 2/ (10 T and 1.9 K) and 602 A/mm/sup 2/ (12 T and 1.9 K). The fabricated wire was proved to have high homogeneity and good workability.