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

An independently oxidized AgMn alloy is used to gauge the overall tensile strength of technical Ag/Bi2223 composite flat wire through the contributions of individual constituent strengthenings. Theoretical analysis based on the rule of mixtures shows similarity between measured and calculated curves of the composite at room temperature (RT) and 77 K. The elastic 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 was estimated to be 129 GPa. The effect of thermal cycling between RT and 77 K on the electromechanical properties of the wire is also examined. The critical current is significantly reduced by tensile strain above 0.4% but not affected by the short thermocycle when measured across different specimens. Finally, the relation between the fracture strain and the strain span of the Bi2223 filaments is found to accommodate an intrinsic filament fracture strain of about 0.04-0.11% in the wire