Improvements in current-carrying capacities of Nb3Sn composites in high fields through titanium addition to the matrix

Single-core and multifilamentary Nb3Sn composites with titanium addition to the matrix have been fabricated. The electron-probe microanalysis indicates that the titanium is more rapidly incorporated into the Nb3Sn layer from the matrix than from the core. The titanium addition of less than 1.5 at.% to the matrix does not deteriorate the workability of the Nb3Sn composites. The titanium addition to the matrix remarkably increases the growth rate and Jcin high fields of the Nb3Sn layer. The optimum amount of titanium addition to the matrix to produce the highest overall Jcat 16 T was found to be about 0.8 at.% for the 160-core Nb/Cu-7at.%Sn-Ti composite wires. The simultaneous titanium addition to the core and to the matrix produces further improvement in Jcin high magnetic fields. An overall Jcof about 2.7×10⁴A/cm²at 16 T is obtained for the 370-core Nb-1.5at.%Ti/Cu-8at.%Sn-0.5at.%Ti composite wire reacted at 700°C for 200 h.