Effect of core inhomogeneity on strain tolerance of Bi-2223 composite conductors

Abstract

Effects of bend strains on monocore Bi-2223 tapes were studied by transport measurements, magneto-optical imaging and electron microscopy. The strain tolerance of tapes that were sintered for 100 (uniform and well-textured microstructure with high I c ) and 50 h (nonuniform microstructure with low I c ) was evaluated. The strain tolerance of the 100-h sintered tape was superior to that of the 50-h sintered tape. We have shown that the observed strain tolerance is largely determined by the interplay of nonuniform strains and microstructural variation across the tape cross section, leading to nonuniform I c values. An explanation that accounts for an observed concentration of the critical-current density at the Ag/BSCCO interface was presented for the measured strain dependence of the retained I c .