Fabrication of superconducting Nb3Sn-Cu composites

A new process has been developed for the fabrication of multifilamentary composites of Nb3Sn in a Cu matrix. Dendritic Cu-Nb alloys are cast as 2.5-kg billets and extruded to a tube shape. The core of the tube is filled with a Sn–5 wt% Cu alloy, and the assembly is drawn to 0.015-cm-diam wire with no intermediate anneals. Reaction of the wire at 550 °C for two days gives a product suitable for magnets in the 8–14-T range.