Analysis of stress-strain behavior in Bi2223 composite tapes

Tensile test was carried out for Bi2223/Ag/Ag alloy composite tapes at RT, 77 and 7 K. Two yielding points are observed in the stress-strain curves. From the stress-strain behavior of the components and critical current (I-c) as a function of tensile strain, it was found that the microscopic reason for these yieldings is attributed to yielding of Ag alloy and fracture of Bi2223, respectively. The strain at the second yielding has temperature dependence and it becomes larger with decreasing measured temperature. From the thermo-mechanical analysis, it can be explained by temperature dependence of compressive residual strain of Bi2223. Reversible recovery of I-c was found during loading-unloading test. The relationship between the reversible strain limit and the intrinsic strain of Bi2223 was discussed. (C) 2004 Elsevier B.V. All rights reserved.