Development of cube textured Ni-W alloy tapes using powder metallurgy along with high energy ball milling for HTS coated conductors

摘要

Ni based alloys have received considerable attention as the substrates for HTS coated conductors due to improved mechanical properties and reduced magnetization. Powder metallurgy is one of the promising processes for the fabrication of long alloy textured substrates. In this paper, Ni-3 at. percent W alloy substrates were prepared by using high purity metal powders as starting materials. The Ni and 3 at. percent W powder mixture was high energy ball milled for different periods, isostatically pressed, sintered, rolled and texture annealed. The high energy ball milling process made the powders mix uniformly and the grain sizes decrease significantly, which led to higher boundary energy and residual strain energy. The longer ball milling period resulted in a finer grain size and sharper texture in the substrate, which were confirmed by EBSD and SEM analysis. SEM and AFM observations indicate the surface of textured Ni-3 at. percent W substrates is smooth and the roughness value (R_(rms)) is about 1.126 nm, which is suitable for deposition of buffer layers.