PROCESSING OF HIGH-PERFORMANCE Nb{sub 3}Sn WIRES THROUGH A NEW DIFFUSION REACTION USING Sn BASED ALLOYS

Tightly consolidated Sn‐Ta and Sn‐B based alloys have been prepared by the reaction among constituent metal powders at 750–775° C. Sn‐Ta and Sn‐B based alloys exhibit quite similar microstructures. A small amount of Ti addition seems to improve the bonding between Ta or B particles and Sn matrix. Nb3Sn wires have been fabricated by the Jelly Roll (JR) and Multi‐rod (MR) process using Sn based alloy sheet and rod, respectively. Thick Nb3Sn layers with nearly stoichiometric A15 composition are synthesized through a new diffusion mechanism between Nb and Sn based alloy. Bc2 (4.2 K)’s of 26.9 T (mid) and 26.5 T (mid) have been obtained in the JR and MR processed wires, respectively, using Sn‐Ta based alloy. These wires exhibit enough non‐Cu Jc to be used above 20 T and 4.2 K. Tc of JR wires using Sn‐B based sheet is 18.14 K (offset) which is slightly higher than that of wires using Sn‐Ta based sheet.