The fabrication and properties of Nb3Sn superconductors by the solid diffusion process

It has been demonstrated that the superconducting compound Nb3Sn can be produced at the interface of Nb and a Cu-Sn alloy when the composite is heat treated at the proper reaction temperature. This method of Nb3Sn preparation was also shown to be particularly suited to the fabrication of (a) Nb3Sn multifilamentary composite wires for dc and low frequency applications and (b) low ac loss Nb3Sn tapes for 60 Hz applications. The fabrication method and superconducting properties of Nb3Sn composite conductors made by this process are reviewed and the metallurgical aspects of the process are discussed. Since practical applications of these composites requires large, high current conductors, methods of producing compound conductors such as cables and braided ribbons which include strengthening and stabilizing components are also discussed and some preliminary results of high current conductors are presented.