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Overpressure (OP) processing influences the microstructure and critical current density (Jc) of Ag sheathed Bi-2223 tapes. SEM and mass density measurements show higher core density and fewer micro-cracks in OP tape than in 1 atm tape. The self-field critical current density, Jc (0 T, 77 K) in multifilamentary tapes was increased from 33.5 kA/cm2 with 1 atm processing (1 atm IR) to 48 kA/cm2 with OP processing (OP pressure = 148 atm) after the first heat treatment (OP HT1), and to 58.7 kA/cm2 with OP processing after intermediate rolling (OP IR). The corresponding values for Jc (0.1 T, 77 K) are 12.3 kA/cm2 (1 atm IR) to 18.2 kA/cm2 for OP HT1 and to 22.4 kA/cm2 for OP IR.
Date of Publication: June 2003