Superconducting Properties of V-Ti Alloys

The effects of alpha-Ti depositions, caused with the heat treatments at 300-500degC, were studied for various V-Ti alloys through measurements of T_c, I_c, and X-ray diffraction patterns. J_c increased with the alpha-Ti depositions for the V-Ti alloys with various Ti contents. The alpha-Ti depositions are very effective pinning centers in V-Ti alloys, being similar to those in Nb-Ti alloys. The maximum Tc of 8.2 K was obtained for the V-40at%Ti alloy annealed at 500degC for 2 hr, while the maximum B_irr(4.2 K) of 8.5 T was obtained for the V-(50-60) at%Ti alloys. J_c (4.2 K, and 6.5 T) of about 170 A/mm² was obtained for the V-45at%Ti alloy annealed at 500deg C for 4 hr. We also fabricated the V-Ti alloy multifilament;!!} wires in order to stabilize the alloy superconductors. The final cold-drawing after heat treatment at 400-450degC is effective on the improvements of T_c, B_irr, and J_c of the multifilamentary V-(40-45)at%Ti alloy wires. J_c(4.2 K, 6.5 T) of 200 A /mm² was obtained for the multifilamentary wire.