Cube textured tapes for use in YBa2Cu3O7–δ-coated conductor applications

Abstract

Abstract YBa2Cu3O7 is a high-temperature superconductor. Due to its complex lattice structure, belonging to the layered perovskite family, a strong biaxial texture of the grains is necessary to achieve technically relevant currents. In this paper, coarse-grained Ni, Ni-4at.% W, and electrolytic copper (E-Cu) obtained from swaged rods, and ultra-fine grained E-Cu produced by equal channel angular pressing, were thermo-mechanically processed. The development of the primary recrystallisation of the cube texture was studied and compared to determine the suitability of these materials as lattice-matched templates for coated conductor applications. Electron backscatter diffraction was performed to measure the texture and microstructure at various deformation levels and annealing temperatures. The texture sharpness formed in E-Cu with a coarse-grained starting microstructure proved superior, and it correlates with an anomaly observed in the temperature sensitivity of the flow stress in tensile tests, arising from crystal rotations.