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

Single-core and multifilamentary Nb
3
Sn composites with titanium addition to the matrix have been fabricated. The electron-probe microanalysis indicates that the titanium is more rapidly incorporated into the Nb
3
Sn 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 Nb
3
Sn composites. The titanium addition to the matrix remarkably increases the growth rate and J
c
in high fields of the Nb
3
Sn layer. The optimum amount of titanium addition to the matrix to produce the highest overall J
c
at 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 J
c
in high magnetic fields. An overall J
c
of about 2.7×10
⁴
A/cm
²
at 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.