Interfacial Microstructures of Nb3Sn–NbTi Joints Fabricated via Resistive Welding

• Published in: Journal of low temperature physics 2024, Vol.214 (1-2), p.68-82
• Main Authors: Sun, Wanshuo, Cheng, Junsheng, Wang, Lei, Chen, Shunzhong
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Heat treatment; Low temperature physics; Magnetic Materials; Magnetism; Magnets; Microstructure; Niobium base alloys; Physics; Physics and Astronomy; Superconductivity; Welding
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-023-03008-7

Nb 3 Sn and NbTi superconducting joints were fabricated successfully via resistive welding technology. After long periods of heat treatment, Nb 3 Sn joints with a Nb 3 Sn block that surrounded Nb 3 Sn wires were prepared. The Nb 3 Sn block was welded together with the NbTi wires to form a joint without intermediate layers between them. The shortest path to conduct the superconducting current contributed to improving joint performance and reducing joint resistance. We investigated microstructural changes in Nb 3 Sn–NbTi superconducting joints. This type of joint has two interfaces: the interface between the Nb 3 Sn wires and the Nb 3 Sn block and the interface between the Nb 3 Sn block and the NbTi wires. Both interfaces are essential for conducting the superconducting current. We can improve our understanding of the underlying mechanism in the current path by investigating the microstructures of these joints. Results showed that Nb 3 Sn was welded together with NbTi, and the joint exhibited excellent performance. The resistance of the joint was lower than 2 × 10 −13 Ω under a background field of 1.25 T, which can meet most applications of Nb 3 Sn magnets.