Fabrication of Nb3Al and Nb3(Al,Ge) superconducting composite tapes by electron beam irradiation

Nb3Al and Nb3(Al,Ge) superconductors were synthesized using continuous electron beam irradiation on powder metallurgy processed Nb-Al and Nb-Al-Ge composite tapes. Transition temperatures Tc(onset) of 18.5 and 20.2 K were obtained for Nb-Al and Nb-Al-Ge tapes respectively, which indicated that nearly stoichiometric Al5 compounds were formed. Critical current density Jc (for reacted area) is nearly constant at fields above 15 T, with excellent values of ∼2×104 A/cm2 at 23 T and 4.2 K for both tapes. The excellent Jc’s as well as the easy scale-up procedure indicate that electron beam irradiation is promising for the fabrication of practical Nb3Al and Nb3(Al,Ge) superconductors, which can generate extremely high fields of ∼25 T.