The effect of Ti addition on critical parameters and transport properties of quaternary (Nb,Ta,Ti)3Sn wires

The addition of Ti and/or Ta to commercial multifilamentary Nb 3 Sn wires is commonly used to increase their upper critical field, and thus the critical current density at high fields. We have compared the critical parameters ( T c and B c2 ) and the critical current densities J c at 17 and 21 T for several multifilamentary quaternary (Nb,Ti,Ta) 3 Sn wires prepared by the bronze route process. The goal of this work is to establish a correlation between the Ti content and the superconducting properties ( T c , B c2 , J c ) of these wires. We have found that Ti additions do not lead to a further increase of T c and B c2 in quaternary (Nb,Ta,Ti) 3 Sn wires with respect to ternary (Nb,Ta) 3 Sn wires. On the other hand, the highest J c was measured in quaternary (Nb,Ta,Ti) 3 Sn wires (1.5 at.% Ti with respect to the Nb–7.5% Ta cores), where Ti was added to the bronze matrix. It was found that the wire configuration has only a small effect on T c and B c2 .