Continuous Al5 Nb3Ge superconducting tapes via the amorphous state

Alloys of Nb75Ge24.5B0.5 were rapidly solidified into amorphous ribbons using the melt-spinning technique. After annealing continuous Al5 tapes were obtained with an average grain size of 30 nm. It was not possible to form a continuous tape by melt spinning directly into the Al5 structure since only brittle fragments were obtained. The amorphous annealed Al5 phase was close to stoichiometry with a lattice parameter of 0.514 nm and a superconducting transition temperature of 18 K. The critical current densities were 5×1010 and 8×108 A/m2 at magnetic fields of 0 and 15 T, respectively. This processing technique could be the initial step in the fabrication of multifilamentary Nb3Ge superconducting composites.