Optimization of Nb3Sn

Considerable progress has been made in the fabrication of large quantities of Nb3Sn multifilamentary wires, and a number of small and large magnets have been produced successfully using these wires. However, demands for increased critical-current densities Jcin the medium magnetic field range (8-12 T) as well as at very high fields (16-20 T or greater) are now being made in order to reduce the cost and to increase the efficiencies of large machines (fusion reactors and high-energy particle accelerators). In order to help meet these demands, some improvements have recently been made in increasing Jcof Nb3Sn, e.g., Ti additions to Nb3Sn. In this presentation, the characterization of Nb3Sn for physical properties (resistivity, lattice parameter, chemical compositions at the grain boundaries and in the bulk, etc.) and for microstructural and chemical properties will be reviewed and those properties which are particularly important in producing high values of Jcwill be discussed.