Current characteristics and microstructure in a multifilamentary Nb-37Ti-22Ta superconductor

The 210-filamentary superconductor based on Nb-37Ti-22Ta, wt.% alloy was obtained by using the electric arc melting and deformation processing. During alloy drawing we used four isochronal intermediate heat treatments at the temperature 425/spl deg/C. The total heat treatment duration was varied from 50 to 1000 hours. The true plastic strain value between heat treatments was 0.4 and after the final treatment was 3-5. The kinetics of phase transformation in the ternary alloy was investigated by the method of transmission electron microscopy. The J/sub c/ value increases with an increasing quantity of the precipitated alpha-phase in medium magnetic fields. The J/sub c/ (5 T, 4.2 K) value reaches 3000 A/mm/sup 2/ or more. In high fields, J/sub c/(10.4 T, 2.05 K) for the given superconductor was equal to 1600 A/mm/sup 2/. The parameters responsible for the shape of pinning force curve are determined for different treatment conditions.