Phase Development In Partial-Melt Processing Of Silver-Clad Bi2.15sr1.83ca1.02cu2ox Tapes

Ag-clad Bi2.15Sr1.83Ca1.02Cu2Ox tapes were fabricated by the powder-in-tube method and heated in air to maximum temperatures of 880-895 degrees C. The tapes were characterized by differential thermal analysis, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction. Microstructures of tapes that were heated at 885-895 degrees C were similar, and, at a given temperature, remained stable for up to 1.0 h, which was the longest time used. The most significant microstructural features in specimens quenched fi om the melt were voids of up to approximate to 400 mu m in diameter. CuO was a minor phase in the melt, but grew significantly upon cooling to become the major nonsuperconducting phase when solidification was complete.