Characterization and properties of an advanced composite substrate for YBCO-coated conductors

Thin, biaxially textured Ni5W/Ni12W/Ni5W composite substrates for coated conductor applications have been fabricated. The particularity of this three-layer composite configuration resides in the elemental diffusion between the outer layer and the core layer. Due to the migration of elemental W, the diffusion layer in the as-annealed substrate becomes broader than that of the as-rolled substrate. The obtained tape has a sharp cubic texture on the Ni5W outer layers, and the volume fraction of cubic grains exceeds 98.8% (<10°) at the outer surfaces. In situ electron backscatter diffraction strain–stress analysis shows that the high-quality cubic texture was stable until elongations as high as 2%. The yield strength of the composite substrate approaches 240 MPa and its saturation magnetization at 77 K has been strongly reduced with respect to pure Ni and Ni5W substrates. The present results demonstrate that this advanced three-layer substrate is suitable for the epitaxial growth of the LZO buffer layers.