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

Abstract

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.