Preparation of nickel substrates for coated conductors

Polycrystalline Ni has been used as a substrate for high-current, coated YB a2Cu3Ox superconductors. For many conductors, Ni is rolled to large deforma tion and annealed to produce a cube texture. In this study, Ni was rolled t o >95% reduction and annealed in 5% H-2/95% He at 300-1000 degrees C for va rious times. The resulting substrates were examined by scanning electron mi croscopy, X-ray and electron diffraction, and surface interferometry. Key d eterminations for the Ni were extent of in-plane and out-of-plane texture, surface smoothness, and grain size. The extent of texture was approximately independent of annealing temperature and increased slightly with annealing time. Annealing at temperatures >600 degrees C increased surface roughness , primarily due to grain-boundary grooving. Grain growth was fastest at 100 0 degrees C and was proportional to time to the 0.1 power.