The effect of wire drawing and cold rolling on the precursor 2212 phase texture and its subsequent influence on the (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ texture in Ag-clad tapes

We have studied the effect of wire drawing and cold rolling on the texture development of precursor (Bi,Pb)2Sr2CaCu20x(2212) phase and its influence on the subsequent (Bi,Pb)2Sr2Ca2Cu30y(2223) phase texture in Ag-clad tapes. A mixture of (Bi,Pb)2Cu04and SrCaCu03powders having an overall 2223 composition was reacted to form the 2212 phase at different stages of deformation. X-ray diffraction peak height analysis was used to quantify the 2212 texture F2212= I(OOS)/[I(OO8)+I(115)] at various oxide filament thickness. Wires containing powder reacted to the 2212 phase prior to loading into a Ag tube had F2212≈0.3 after drawing. This texture increased to F2212=0.7 upon rolling. Two other composites reacted to the 2212 phase immediately after drawing, and after being drawn and partially rolled, had worse initial textures, but improved during rolling to FzZl2≈0.7. Samples reacted to 2212 after rolling was complete had F2212≈0.35. The results indicate that the 2212 texture reaches a maximum value of F2212≈0.7 and remains at that level upon subsequent rolling. Samples of filament thickness ≈80 μm were then reacted to form 2223. For the samples which contained 2212 that had received at least some mechanical deformation, the 2223 phase formed with a texture factor F2223> 0.9, while the tape that contained 2212 formed after rolling developed a 2223 texture of only F2223≈0.75. The results show that there is a substantial texture enhancement upon reaction to 2223, which could be the result of either the 2223 formation mechanism or geometrically constrained grain growth.