Effect of processing defects on stress-strain-I_c for AgMg sheathed Bi-2212 tapes

Manufacture of multifilamentary BSCCO tapes involves rolling of billets to final form. In BSCCO-2212 tapes, one method used to control the microstructure and increase J_c is intermediate annealing during the deformation process. At times, small bubbles have been observed on the tapes after annealing. Although such bubbles do not remain at the end of fabrication, the question of possible effect on superconducting performance has been studied. The sections that had bubbles after annealing were marked and the fabrication process completed on the tape. After final reaction of the tape, comparisons of stress-strain-I_c for bubbled and nonbubbled sections were performed. Here we present electrical, mechanical and microstructural studies on bubbled and bubble-free sections of tape. It was found that sections with bubbles had lower I_c than sections with no bubbles, though both had similar onset of I_c degradation at ∼ 0.40%.