Engineering the precompression of Bi,Pb(2223): the influence of the geometry of the metallic matrix on the mechanical properties of tapes

At relatively low tensile strain (/spl epsiv/) levels, Bi,Pb(2223) tapes show a strain insensitive plateau In their I/sub c/(/spl epsiv/) behavior. The "Irreversible I/sub c/ Reduction Model" explains this regime as due to the irreversible damage caused by the precompression of the ceramic filaments by the metal matrix. In this paper we investigate whether this damage occurs predominantly during the cool-down from the reaction temperature to room temperature, or during the cryogenic refrigeration. Furthermore, we present I/sub c/(/spl epsiv/) data on a range or tapes with different superconductor-to-matrix ratio and different tape geometry, showing how these factors influence the precompression. A modification of the "Irreversible I/sub c/ Reduction Model" is proposed to take into account "connected-grains" domains in the I/sub c/(/spl epsiv/) behavior.