Electromechanical properties of yttrium-barium-copper-oxide (YBCO) coatings on both pure Ni and Ni-5at.%W alloy rolling-assisted, biaxially-textured substrates (RABiTS) were investigated. The effect of transverse compressive stress on transport critical-current densities (Jc) was measured on samples at 76 K and self magnetic field. Transverse compressive stress can significantly degrade Jc in YBCO deposited on pure Ni RABiTS unless sufficient frictional support is provided to the sample or the substrate is given a work-hardening treatment. On the other hand, results obtained for YBCO on Ni-5at.%W alloy RABiTS show that the tolerance to transverse stress of these conductors are significantly improved. These electromechanical-property results are interpreted in terms of scanning-electron micrographs of the microstructure of the samples after electromechanical testing, as well as stress-strain characteristics measured on RABiTS substrates at 76 K. The tensile yield strength, Young's modulus, and proportional limit of elasticity of candidate RABiTS substrate materials were tabulated and compared.
Citation: IEEE Transactions on Applied Superconductivity
Pub Type: Journals
coated conductors, critical current density, mechanical properties, microstructure, RABiTS, strain, stress, YBCO