Mechanical properties and TEM studies on BPSCCO-2223-Ag composite tapes

The role of silver powder in the stress-strain-critical current relationship of BSPCCO tapes was investigated. The tapes were tested at 77 K and analysed using a TEM to understand the microstructure of the ceramic core in the tapes. The monolithic tapes had an average irreversible strain of 0.19% while the composite tapes with 30% (by volume) silver powder addition to the ceramic core had similar critical current capacity with an average irreversible strain of 0.47%. TEM studies indicate that the major difference between the monolithic and composite tapes is the dislocation density in the centre of the ceramic core. The monolithic tapes had a one order of magnitude higher dislocation density along the edges as compared with the centre of the core, while the composite tapes with the silver powder addition had uniform dislocation density across the entire core section. (author)