The Early Stages of the Microstructural Development of the Colony Structure in Bi-2223 Tapes

The current protocol for processing (Bi,Pb)2Sr2Ca2Cu3010-(B i-2223) multifilamentary tapes involves the in situ formation of the primary phase from a suitable mixture of precursor phases. As such, the developments during the first few minutes of heat treatment determine to a large extent the efficiency of primary phase development, competing secondary phase development, texture evolution, and grain-to-grain connectivity. This work documents the development of the liquid phase, secondary phases, defects which may affect alignment and reaction kinetics, and the precipitation of Bi-2223 from the liquid phase.