Optimal reduction in rolling Ag-sheathed Bi-2223 multifilamentary tapes

The difference in mechanical deformation of the cladding material and ceramic superconductor during cold working of Ag-sheathed Bi-based superconducting composite tapes has been analysed. From this, a optimal rolling procedure has been developed in order to improve the uniformity of the tapes by gradually increasing the reduction per pass during rolling. Using this technique, a uniform stress was achieved within the tapes which improved both the transverse and longitudinal filament interfacial homogeneity and reduced the sausaging effect. An improved and more uniform Jc was observed in long-length tapes fabricated using this procedure than in those fabricated using a non-optimized route. (author)