Superconducting properties of rapidly heated and quenched Nb/sub 3/Ga wires

Stoichiometric Nb/sub 3/Ga with good long range ordering shows a high T/sub c/ above 20 K and a high H/sub c2/(4.2 K) above 30 T. However, high J/sub c/ had not yet been reported for any Nb/sub 3/Ga fabricated through various methods, which was preventing the development of practical Nb/sub 3/Ga conductors in the last 30 years. Recently we could overcome the problem through a promising combination of RHQ (rapid heating and quenching) treatment and microcomposite precursor wire of Nb and NbGa/sub 3/. Nb/sub 3/Ga layers were formed directly through the RHQ treatment. Post annealing at 600-800 (degree)C was very effective in improving the superconducting properties of the Nb/sub 3/Ga wire. The best values of T/sub c/ and B/sub c2/(4.2 K) of 19.7 K and 32 T were obtained, respectively. In addition the J/sub c/(4.2 K) values of Nb/sub 3/Ga layer at 20 T, 23 T, and 25 T were 370 A/mm/sup 2/, 250 A/mm/sup 2/ and 160 A/mm/sup 2/, respectively. These critical values are much higher than those of the commercialized (Nb,Ti)/sub 3/ Sn wire made through a bronze route.