Superconducting Properties of V-Ti Alloys

Abstract

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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> , I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> , and X-ray diffraction patterns. J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">irr</sub> (4.2 K) of 8.5 T was obtained for the V-(50-60) at%Ti alloys. J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> (4.2 K, and 6.5 T) of about 170 A/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> , B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">irr</sub> , and J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> of the multifilamentary V-(40-45)at%Ti alloy wires. J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> (4.2 K, 6.5 T) of 200 A /mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> was obtained for the multifilamentary wire.