Nb3Sn superconducting wires made with restacked-rod process (RRP®) were found to have a dramatically improved resilience to axial tensile strain when alloyed with Ti as compared to Ta. Whereas Ta-alloyed Nb3Sn in RRP wires showed permanent damage to its current-carrying capacity (Ic) when tensioned beyond an intrinsic strain as small as 0.04 %, Ti-doped Nb3Sn in RRP strands exhibit a remarkable reversibility up to a tensile strain of about 0.25 %, thus making Ti-doped RRP wires more suitable for high-field magnets used in particle accelerators and nuclear magnetic resonance applications where mechanical forces are intense. A strain cycling experiment at room temperature caused a significant drop of Ic in Ta-alloyed wires, but induced an increase of Ic in the case of Ti-doped strands. Whereas either Ti or Ta doping yields a similar enhancement of the upper critical field of Nb3Sn, the much improved mechanical behavior of Ti-alloyed wires clearly makes Ti a better choice over Ta, at least for the RRP wire processing technique.
Citation: Superconductor Science and Technology
Pub Type: Journals
Superconductors, Ternary Nb<sub>3</sub>Sn, Alloys, Strain, Irreversible Strain Limit, Strain Cycling, Fracture