Development of cube textured Ni-5at.%W alloy substrates for YBCO coated conductor application using a powder metallurgy process

Abstract

In this paper, Ni-5at.%W alloy substrate for YBCO coated conductor was fabricated by a dry powder metallurgy process including powder compaction, cold isostatic pressing (CIP), cold rolling and annealing for recrystallization. Ni and W powders were ball-milled at this process for various times of 10, 30, 50 and 100 h in argon atmosphere. The rod-like Ni-W alloy compacts were sintered at 1150 degrees C for 1 h in 96%Ar-4%H-2 atmosphere. The sintered rods were cold rolling into thin tape of 70-90 pm thickness with 5% reduction at each path. The Ni-W alloy tapes were annealed at 800-1200 degrees C in an atmosphere of 96%Ar-4%H2 mixing gas for the development of cube texture. The tape with the best properties of low surface roughness, small grain size and strong cube texture was obtained at the condition annealed at 1200 degrees C using ball-milled powder for 30 min. The W addition to Ni improved the mechanical properties by solid solution hardening and inhibited grain growth for annealing heat treatment. The tapes were characterized by X-ray pole-figure, optical microscopy (OM), scanning electron microscopy (SEM) and scanning probe microscopy (SPM). (C) 2007 Elsevier B.V. All rights reserved.