Electromechanical properties of Ag/Bi2223 flat wire in a short thermocycle

Abstract

An independently oxidized AgMn alloy is used to gauge the overall tensile strength oftechnical Ag/Bi2223 composite flat wire through the contributions of individual constituentstrengthenings. Theoretical analysis based on the rule of mixtures shows similarity betweenmeasured and calculated curves of the composite at room temperature (RT) and 77 K. Theelastic modulus of the composite wire, deduced from initial and loading/unloading curves,is found to be around 95–98 GPa, while for Bi2223 filaments, the modulus of elasticity wasestimated to be 129 GPa. The effect of thermal cycling between RT and 77 Kon the electromechanical properties of the wire is also examined. The criticalcurrent is significantly reduced by tensile strain above 0.4% but not affected by theshort thermocycle when measured across different specimens. Finally, the relationbetween the fracture strain and the strain span of the Bi2223 filaments is found toaccommodate an intrinsic filament fracture strain of about 0.04–0.11% in the wire.