Preparation and Properties of NbTi–Nb₃Sn–NbTi Superconducting Joints

NbTi–Nb₃Sn–NbTi superconducting joints were fabricated by resistive welding. The microstructure and connecting status were estimated using an X-ray 3D microscopic imaging system online without destroying the joints. The microstructure and grain orientation maps of the Nb₃Sn bulk in the joints were tested by electron backscatter diffraction. The Nb₃Sn phase exhibited random orientation, and the grain boundaries were mainly composed of high-angle grain boundaries. The resistance of the joints was evaluated under different background fields. Results showed that the resistance was 3 × 10⁻¹³ Ω under the background field of 3 T.