HOT-ROLLING OF SILVER-SHEATHED BI(2223) TAPES

Silver-sheathed Bi(2223) tapes have been prepared using a newly developed hot-roll apparatus where the rolls can be heated up to 850-degrees-C. At 77 K and 0 T, a critical current density of 18 000 A/cm2 has been measured on tapes after hot rolling at 800-degrees-C. Microstructural analyses and X-ray diffraction have been performed. The field dependence and the anisotropy of the critical current were investigated at 77 K. The hot-rolled tapes show a higher density and better grain alignment compared to cold-rolled tapes. The critical current density at 77 K and 1 T is 3500 A/cm2, i.e., it decreases by a factor of 5 with respect to the value in zero field. This is a considerable improvement compared to the published data on cold-rolled tapes where this factor is almost 7 for our reference tape and between 8 and 12 in the published data.