TEM STUDY OF AG-CLAD BI-BASED (2223)MULTIFILAMENTARY TAPES IN VARIOUSSTAGES OF PROCESSING

The microstructures of 27-filament BPSSCO 2223 tapes in various heat t reatment stages have been studied by using TEM. The density of disloca tions in the tapes sintered for initial 60 h is very low. It increases to 10(11)/cm(2) at grain boundaries and 10(8)/cm(2) in the grains for the tapes sintered for 140 h with an intermidiate rolling. An average dislocation density of 10(12)/cm(2) at the grain boundaries is attain ed for the tapes sinterd for 220 h with two intermidiate rollings. Fut her rolling and annealing cause misarrangement of (001) atomic planes 2223 grains and subgrain boundaries in 2223 colonies. The results indi cate that the repetitive rolling and sintering for 220 h is the optimu m process for fabrication of tape since it shows the maximum dislocati on density and optimum phase purity of 2223 phase.