| 摘要 |
PROBLEM TO BE SOLVED: To cause no lowering of critical current density and no lowering of a residual resistance ratio by providing a niobium complex containing a niobium filament, stabilized copper of pure copper, a reinforcement and two layered diffusion preventing materials. SOLUTION: First and second diffusion preventing materials 3, 6 exist on the inner peripheral surface and the outer peripheral surface of a pipe of alumina dispersion-strengthened copper forming a reinforcement 5 respectively. The first diffusion preventing material 3 prevents lowering of critical current density due to reduction of Sn concentration in bronze by preventing Sn from being diffused from the bronze to the alumina dispersion-strengthened copper by heat treatment to produce Nb3Sn, the second diffusion preventive material 6 prevents unreacted Al in the alumina dispersion-strengthened copper from being diffused to stabilized copper, and accordingly these two layered diffusion preventing materials 3, 6 have role to maintain purity of the stabilized copper 4 respectively. The second diffusion preventing material 6 is required between the reinforcement 5 and the stabilized copper 4. The thickness of the stabilized copper 4 can be suppressed to a minimum by the diffusion preventing layers.
|
