The effect of processing on the microstructure of Ag-sheathed Bi-2223 wires

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:43028

Miller, D J; Hu, J G; Kostic, P; Balachandran, U ^[1]; Haldar, P ^[2]

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1. Argonne National Lab., IL (United States)
2. Intermagnetics General Corp., Guilderland, NY (United States)

The effect of processing on the microstructure of long-length (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) wires has been evaluated using scanning and transmission electron microscopy. In particular, these studies have focused on the effect of the final heat treatment conditions on the microstructure of the wires and the corresponding variations in critical currents (I{sub c}). It is found that variations in I{sub c} for segments cut from various points along the length of a wire can be correlated with variations in the volume fraction and nature of second phases. Similar variations are observed between wires processed under different final annealing conditions. A common feature found in all of the wire segments with lower I{sub c} values was the presence of the Pb{sub 3}Sr{sub 2}Ca{sub 2}CuO{sub x} phase (Pb-3221). Microchemical analysis suggests that the formation of this phase leads to variations in the composition of the Bi-2223 grains. As a result, the wires which exhibit the Pb-3221 phase consist of an assemblage of grains with a range of transition temperatures based on composition. Thus, in these segments, the current carrying capacity of individual grains at 77K varies from very good to poor, and a significant reduction in the overall I{sub c} of the segment is observed.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 43028
• Report Number(s): CONF-9310224--; ISBN 0-87339-271-X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
BISMUTH OXIDES
CALCIUM OXIDES
COPPER OXIDES
CRITICAL CURRENT
EXPERIMENTAL DATA
FABRICATION
LEAD OXIDES
MICROSTRUCTURE
SILVER
STRONTIUM OXIDES
SUPERCONDUCTING COMPOSITES
SUPERCONDUCTING WIRES