Development of cube-textured Ni-W alloy substrates for YBCO-coated conductor

We fabricated pure Ni and Ni-W alloy substrates for YBCO-coated conductor applications and evaluated the effect of W in Ni on texture, grain size, grain boundary and surface morphology, and hardness of the substrates. Pure Ni, Ni-2at.%W, and Ni-5at.%W alloy substrates were prepared by plasma arc melting, cold rolling, and recrystallization heat treatment at various temperatures (700-1300 °C). Substrate texture was evaluated by pole-figure and microstructure and surface morphology were investigated by optical and atomic force microscopy (AFM). We observed that the Ni-W alloy substrates had stronger cube texture that was maintained at higher annealing temperatures than seen for the pure Ni substrate: Full-width at half-maximum of in-plane texture was 13.40° for the Ni substrate and 4.42-5.57° for the Ni-W substrate annealed at 1000 °C. In addition, the Ni-W substrate had smaller grain size, less thermal grooving, and higher hardness, compared to those of the pure Ni substrate, indicating that the presence of W in Ni effectively restricts grain growth and enhances thermal stability by strengthening the grain boundary in the Ni substrate.