Very high critical current density of bronze-processed (Nb,Ti)/sub 3/Sn superconducting wire

摘要

From the viewpoint of fabricability, the Sn content in the bronze matrix of bronze-processed Nb/sub 3/Sn wire is limited to below 15 wt%. This limitation results in a higher matrix-to-niobium ratio of bronze-processed Nb/sub 3/Sn wire than other high-Sn-content wires, such as the tube-processed Nb/sub 3/Sn wire. This is a reason why the non-Cu critical current density (J/sub C/) of the bronze-processed Nb/sub 3/Sn wire is lower than that of tube-processed Nb/sub 3/Sn wire. Therefore, increasing the Sn content in the bronze matrix and reducing the bronze ratio is the key to enhancing the non-Cu J/sub C/ of the bronze-processed Nb/sub 3/Sn wire. A bronze-processed Nb/sub 3/Sn superconducting wire with a Cu-16wt%Sn-0.2wt%Ti matrix was successfully fabricated on a production scale. The wire achieved a high non-Cu J/sub C/ of approximately 1000 A/mm/sup 2/ at 12 T and 4.2 K.