Studies on Superplastically Deformed 123/Ag Composites
Author(s)
Goyal, A.
Wang, Z. L. (Zhong Lin)
Sun, Y. R.
Kroeger, D. M.
Thompson, J. R.
Chou, Y. T.
Yun, Y.
Harmer, A. P.
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Abstract
Composites containing 25 vol% Ag
were compressed at room temperature to over 110% at
850°C in air. Measurement of the strain rate sensitivity
yielded a value of 0.5, characteristic of superplastic
deformation. As deformed materials had sub-micron
grain size and significant c-axis texture parallel to the
pressing direction. TEM examination showed that the
grains were highly defected and that the grain
boundaries were clean. The T[subscript c] was however low with
an onset of 50K and a width of ~10K. Annealing studies
were carried out with an aim to "fully oxygenate" the
material and anneal out a minimal number of defects to
obtain higher transition temperatures, at the same time
retaining a significant defect density for enhanced fluxpinning.
Magnetization measurements were performed
after most anneals in order to evaluate intragranular
and intergranular properties. Results indicate the
presence of unusually high J [subscript c]'s at low temperatures
after the final anneal (T[subscript c] onset ~90°K). The
observations may be explained by highly superior
intragranular properties coupled with increased local
current loop size.
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Date
1995-05
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