Powder metallurgy processed Nb/sub 3/Sn(Ta) wire for high field NMR magnets

Powder metallurgy together with a multi-tin core approach was used to fabricate industrial scale lengths of Ta alloyed Nb/sub 3/Sn wire. The wire produced high critical currents (I/sub c/) along with high critical current densities (J/sub c/) at fields up to 20 tesla and 4.2 K. The wire was produced for a program funded by Battelle Pacific Northwest. One objective of the program was to compare various commercially available wires for applications in high field NMR magnets. The 1.5 mm diameter PM wire compares well with other wires tested in the program. More than 250 m of the 1.5 mm diameter wire was used to fabricate a superconducting model coil. The coil exhibited an I/sub c/ equal to that of a short sample. The performance of the Ta doped wire examined here was lower than those of similar PM wires which were produced earlier using Ti doping. Diffusion dynamics of the tin inside the wire was studied at various stages of heat treatment and was correlated to the properties of the wire.<>