Open AccessEffect of lead content on phase evolution and microstructural development in Ag-clad Bi-2223 composite conductors
Author(s) -
N. Merchant,
V.A. Maroni,
Andreas Fischer,
Steve Dorris,
Wenguo Zhong,
N. Ashcom
Publication year - 1997
Language(s) - English
Resource type - Reports
DOI - 10.2172/446397
Subject(s) - texture (cosmology) , materials science , scanning electron microscope , phase (matter) , composite number , diffraction , microstructure , x ray crystallography , analytical chemistry (journal) , content (measure theory) , grain size , lead (geology) , electrical conductor , powder diffraction , crystallography , composite material , chemistry , image (mathematics) , optics , mathematical analysis , physics , mathematics , organic chemistry , chromatography , geomorphology , artificial intelligence , computer science , geology
A two powder process was used to prepare silver-sheathed monofilamentary Bi{sub 1.8}Pb{sub x}Sr{sub 1.98}Ca{sub 1.97}Cu{sub 3.08}O{sub y} (Bi-2223) tapes with varying lead contents, x, from 0.2 to 0.5. The resulting tapes were subjected to thermomechanical processing and then characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray analysis (EDX). Layered phase texture was accessed using image analysis software on scanned SEM micrographs. Transport currents were measured at 77 K and zero field by the four-probe method. It was found that tapes with low lead content (X = 0.2 and 0.25) showed incomplete conversion to Bi-2223, had small grain size and poor c-axis texture. Tapes having higher lead content (x = 0.4 and 0.5) also showed incomplete conversion and the presence of lead-rich secondary phases. Tapes with lead content x = 0.3 and 0.35 showed complete conversion to Bi-2223, and had the least amount of secondary phases, the best c-axis texture, and the highest transport current (j{sub c}). The carbon content of the precursor powder also had a strong influence on secondary-phase chemistry