Strain effects on the critical current of Bi-2223/Ag tape

Publisher Summary This chapter discusses tensile and bending tests on Bi-2223/Ag tapes to study the effect of the strain on the I c of HTS (High temperature superconducting) tapes. HTS tapes can be regarded as a typical two component composites consisting of a brittle oxide core, which is composed of ceramic material, covered by a ductile layer. The I c reduction in strained HTS tapes is irreversible. The explanation for this is that the stress or strain will lead to the appearance and propagation of the micro-cracks, and degrade the I c of HTS tapes. The conductor's critical current (I c ) keeps nearly constant when the tensile strain is lower than a critical value. As tensile strain increases, I c decreases slowly at the beginning, and then degrades sharply near 0.3% of strain. Degradations of I c caused by the bending strain are in good agreement with the tensile testing results. Synchrotron radiation shows that the degradation of I c is related directly with propagation of micro-crack in the oxide layer under tensile tests.