STUDIES ON SUPERPLASTICALLY DEFORMED 123 AG COMPOSITES/

Composites containing 25 vol% Ag were compressed at room temperature t o over 110% at 850 degrees C in air, Measurement of the strain rate se nsitivity yielded a value of 0.5, characteristic of superplastic defor mation, As deformed materials had sub-micron grain size and significan t c-axis texture parallel to the pressing direction. TEM examination s howed that the grains were highly defected and that the grain boundari es were clean, The T-c was however low with an onset of 50K and a widt h of similar to 10K, Annealing studies were carried out with an aim to ''fully oxygenate'' the material and anneal out a minimal number of d efects to obtain higher transition temperatures, at the same time reta ining a significant defect density for enhanced flux-pinning, Magnetiz ation measurements were performed after most anneals in order to evalu ate intragranular and intergranular properties. Results indicate the p resence of unusually high J(c)'s at low temperatures after the final a nneal (T-c onset similar to 90 degrees K). The observations may be exp lained by highly superior intragranular properties coupled with increa sed local current loop size.