Comparative characterization of Cu-Ni substrates for coated conductors

Three Cu100-xNix alloys, with x = 23, 33 and 45 at.% Ni, have been evaluated for use as substrates for coated conductors on the basis of measurements of their microstructure, crystallographic texture and hardness. It is found that high-temperature annealing after heavy rolling generates strong cube textures in each investigated alloy. For all of these alloys an increase in the annealing temperature from 800 to 1000 degrees C strengthens the cube texture and reduces the fraction of high angle grain boundaries. In the Cu-23 at.% Ni and Cu-33 at.% Ni alloys annealed at 1000 degrees C for 1 h, the fraction of the cube texture approaches 100% and the fraction of high angle boundaries is less than 4%. These two alloys are however very soft in the annealed condition. The cube texture in the Cu-45 at.% Ni substrate is slightly weaker than in the two other alloys, but this substrate is considerably harder, which makes it better suited for large scale production of superconducting tapes. (C) 2014 Elsevier B. V. All rights reserved.