Fabrication of Nb3(Al,Ge) wires by using Al-Ge gas-atomized powder

As the starting material of Nb₃(Al,Ge) precursor wires, gas-atomized Al-Ge alloy powder is very promising because of the fine Ge particle dispersion in the alloy powder. The hardness of Al-Ge alloy is relatively small and well-balanced with that of the pure Nb. Therefore, no intermediate annealing is technically required for drawing a 7 × 220 × 233-core Nb/Al-Ge multifilamentary wire. Furthermore, excellent J_c-B performance without peak effects was obtained in the Nb₃(Al,Ge) tape specimens through the RHQ (rapid-heating/quenching) treatment. It may be caused by the synthesizing of A15 phases transformed from Nb-Al-Ge ternary supersaturated bcc phase. The present Nb₃(Al,Ge) tapes show a good agreement with Kramer´s scaling law described as F_p=A(B_c2)^2.14b^0.5(1-b)^1.46, where A is temperature and field independent, and b=B/B_c2.