Influence of ternary additions and precipitation on the critical current density and other superconducting properties in Nb-65 wt. %Ti

The superconducting behavior of Nb-65 wt. %Ti and their ternary alloys with 1 wt. % Mo, Re, Si, Ta, V, and Zr was studied with regard to precipitation. Transmission electron microscopy studies were carried out to determine the size and distribution of the precipitates. In contrast to the commerical Nb-Ti superconductor the alloys show a quadratic dependence of the pinning force on the field close to the upper critical field. With a suitable precipitate size distribution but without workhardening these alloys display high current densities which are comparable with commercial Nb-Ti.