Feasibility Study of Diffusion Welding of Microcomposite Copper-Niobium Conductors

The present research provides the results of an experimental study of diffusion-welded joints between Cu-Nb microcomposite conductors designed for potential application in electrical connections for magnetic systems. The joints were produced in the solid state using uniaxial diffusion bonding and glow-discharge diffusion welding with metal foil interlayers, which made it possible to avoid remelting the Cu-Nb conductor and limit the degradation of its filamentary microstructure. The effect of the interlayer materials on the microstructure, as well as on the mechanical and electrical properties of the joints, was evaluated. Among the configurations studied, the Cu-Ti-Cu interlayer provided the best combination of properties, with a tensile strength of 400 MPa, a yield strength of 220 MPa, an elongation of 2.5%, and an electrical conductivity of 51.6% IACS. Compared to the initial conductivity of the conductor (65.1% IACS), this corresponds to a reduction in conductivity of approximately 20.7%. The results demonstrate a clear trade-off between mechanical and electrical characteristics when using interlayers containing titanium. Thus, diffusion bonding using a glow discharge and foil interlayers is considered a promising approach for Cu-Nb conductor joints that are not directly exposed to the maximum magnetic and tensile forces generated in high-power solenoids.