Comparison of superconducting properties and residual resistivities of bronze processed Nb3Sn wires with Ta, Ti and Ni+Zn additives

Critical current densities up to 23 T measured on a series of 19 core Nb3Sn wires with Ta, Ti and Ni+Zn additions, prepared by the bronze route under identical conditions, show very similar results in the whole field range. After optimization, Jcin the A15 layer was determined to 6 × 10⁴A/cm²at 18 T, independent on the alloying element. Parallel to the increase of Jcat high fields, an enhancement of B*c2up to 26 to 27 T as well as a reduced strain sensitivity of Jcwith respect to unalloyed Nb3Sn wires were observed in all cases. On fully reacted filamentary tapes of m thickness and m width (obtained from the same starting material) an increase of the residual resistivity from cm for binary Nb3Sn to 35 - 40 μΩ cm for Ta alloyed Nb3Sn (4 at%) was found. The present data are the first direct indication for the increase of ρoin alloyed multifilamentary wires prepared by the bronze route. They furnish a strong evidence for the correlation between ρoand the enhancement of Bc2in alloyed Nb3Sn wires.