Study of microstructures of Ag-sheathed (BiPbSrCaCuO) multifilamentary tapes in various stages of processing

Abstract

Microstructures of 27-filament (Bi, Pb)2Sr2Ca2Cu3O10+x (BPSCCO 2223) tape at various stages of repetitive rolling and sintering have been investigated using TEM and SEM. It was found that the dislocation density increases with increasing sintering time with the maximum dislocation density of 1012/cm2 achieved for tapes sintered for 220 h. The interface between Ag-sheath and oxide core was observed to be wavelike. Small irregular 2223 colonies and cracks in the oxide cores were often observed near the Ag-sheath/oxide core interface. Repetitively rolled and sintered specimen with a total sintering time of 220 h was observed to have optimum phase purity of 2223 phase. Prolonged sintering results in recrystallization of the 2223 grains, degrading the texture of the oxide core.