The effects of additives to the Cu-Nb melt on the high field properties of in situ multifilamentary Nb3Sn wires

In Situ multifilamentary superconducting Cu-30 wt % Nb wires have been produced with small admixtures of Al, Zn, Be or Ta. The resulting 0.25 mm diameter wires have been processed with an external plating of Sn, diffused and reacted. The measured high field Jcvalues are compared to Cu-30 wt % Nb-Sn without additives, and correlated with measured values of Tc, the fraction of Nb transformed to Nb3Sn, residual tin concentration in the matrix, and reaction time and temperature. Compared to Cu-30 wt % Nb wires without additives, the critical currents of those containing additives are comparable if the prestress is removed.