Fabrication and performance of multifilamentary Nb3Sn wires by the cable-in-tube approach

A newly developed method of fabricating multifilamentary composite wires, referred to as the cable-in-tube (CIT), is described. CIT eliminates a number of the conventional processing steps including straightening, hexing, bundling, extruding, HIP etc. CIT processing is particularly advantageous in the fabrication of economical and high performance internal-tin Nb₃Sn wires. Recent successes in fabricating internal-tin wires with high Nb filament content, and tin diffusion distances of 10-20 μm are discussed. Microstructure and superconducting properties of these wires are presented.