CRITICAL-CURRENT RESPONSE OF BSCCO TAPES IN TENSION

Uniaxial tension experiments were performed on monofilament Bi1.9Pb0.4 Sr2Ca2Cu3Ox (BSCCO)-silver and pure silver tapes. Nearly silver-free B SCCO tapes were also tested to study the influence of the silver phase . In situ measurements of the critical current density (J(c)) vs appli ed strain provided evidence for the strength and failure behavior of t he superconducting oxide core. Final rolling deformation was used as t he primary processing variable. BSCCO-Ag tapes exhibited strain tolera nce of up to 0.4% before the superconducting performance began to degr ade. The stress-strain response of a near silver-free core was typical of ceramics with brittle failure occurring after an elastic strain of 0.19%. Although not optimized, the yield strength and J, improved wit h greater final rolling deformation. Even greater strain tolerance is postulated by improving the structure and integrity of the oxide core and by increasing the residual compressive stress imposed on the core by the thermal expansion mismatch with the silver sheath.