New Nb_3Al-based A15 multifilamentary wires with high J_c in high fields

摘要

When Nb/Al-X (X = Ge or Cu) microcomposite precursor wires were rapidly heated and quenched, disordered Nn_3Al-based A15-phase filaments formed. With annealing at 750-800 deg C, their superconducting properties improved drastically. The Nb_3Al-based A15 wire, with Ge or Cu added, showed a maximum value of T_c = 19.4 or 18.2 K, and that of H_(c2) (4.2 K) = 39.5 or 28.7 T, respectively, which are higher than the maximum values of T_c = 17.9 K and H_(c2) (4.2 K) = 25.8 T for the rapid heating, quenching and transforming (RHQT)-processed Nb_3Al wire without additional elements. In addition, the new superconductors showed higher JC than that of the RHQT-processed Nb_3Al multifilamentary wire in high fields.