Multifilamentary wires based on binary NbTi and ternary NbTiTa alloys

For optimization of critical current density at high fields multifilamentary wires based on binary NbTi and ternary NbTiTa alloys with 12.3, 14.0 and 20.4 wt. % Ta have been produced by several heat treatment regimes, which differed by prestrain, number, duration and temperature of aging. The results are presented on superconducting properties of the conductors at 4.2 and 2.2-1.85 K. It is shown that the lower Ta content in alloy, the steeper j c = f(H) dependence, when using identical heat treatment. Critical current density at high field for NbTiTa conductors can be improved by use of more soft heat treatment, than for NbTi based wires.