Two axial rolling of Bi,Pb(2223) tapes under longitudinal stress

Control of precursor density during the deformation process of Bi,Pb(2223) tapes is crucial in order to achieve a good homogeneity of the filaments. W hen an excessive density is reached too early, the ceramic grains cannot lo nger slide properly, which results in an more pronounced sausaging. Two-axe s rolling is known to yield a higher homogeneity among the filaments. On th e other hand, the ceramic density increases much faster than during convent ional deformation processes. Therefore, we used the combination of two-axis rolling and longitudinal stress. We present density, texture and transport measurements both during the deformation process and after the heat treatm ent. Results clearly show an improvement in the control of microstructure r esulting in higher critical current densities in tapes deformed under longi tudinal stress compared to tapes deformed without stress. (C) 2001 Elsevier Science B.V. All rights reserved.