(Nb,Ta,Ti)(3)Sn multifilamentary wires using Osprey bronze with high tin content and NbTa/NbTi composite filaments

摘要

Several (Nb,Ta,Ti)(3)Sn multifilamentary wires with different Ti contents (up to 0.6 wt.%), but identical configuration have been processed using the bronze route and NbTa/NbTi composite filaments. The wires were manufactured by a sequence of three extrusion steps using a Cu 15.4 Sn Osprey bronze as matrix. The wires of 1.06 mm diameter with 14641 filaments of 4.4 mum size were reacted by various heat treatments, ranging from 600 to 730 degreesC. Critical current density (J(c)) measurements on samples in a coil geometry have been performed up to 17 T at 4.2 K, yielding to 195 A mm(-2) at 17 T. Upper critical magnetic fields (B-c2) up to 28.2 T were estimated by Kramer extrapolation. The variation of the critical temperature (T-c) as well as of the n factor were determined. The effect of various Ti contents was analyzed with respect to the various superconducting parameters, especially in view of applications at fields >20 T. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 6]