Superconducting properties of powder metallurgically processed Ti‐alloyed Nb3Sn microcomposites

CuNb3Sn microcomposite wires with Ti additions have been produced by the hot‐powder‐metallurgical preparation method. The influence of the Nb3Sn filament diameter, heat treatment, and Ti addition on the superconducting properties are discussed on the basis of critical current densities (up to fields of 22 T), critical temperatures, as well as x‐ray microprobe analyses. Critical current measurements of Nb3Sn multifilamentary tapes indicate that filament/matrix interfaces are dominant flux pinning centers in these composites. When Ti is incorporated into the A15 phase, the upper critical field is enhanced by about 2 T with respect to unalloyed superconductors. A drastic improvement of the superconducting properties can be achieved by the utilization of larger Nb powder particles. In microcomposites prepared from larger Nb powder (100–300 μm), Bc2 is enhanced by about 3–4 T with respect to finer Nb powder (20–45 μm). Critical fields up to 21.4 T and critical current values of 1.2×104 A/cm2 at a magnetic fiel...