Effect of the sinter-forging deformation rate on properties of Bi-2223 current leads

The influence of the sinter-forging rate on the critical cur ren t density (J,) behaviour in an external field a n d on the contact resistance R, for Bi-2223 cur ren t leads has been investigated. The cur ren t leads were fabricated by a combination of Cold Isostatic Pressing (CIP) and sinter-forging methods with the thickness reduction rate ranging from 0% to 90%. The two silver contact terminals of each sample were also prepared during the sinter-forging. The results revealed that J, was strongly affected by the deformation rate of sinter-forging and reached a maximum of 725 A/cm2 a t a deformation rate of 80%. From the measurements of the external magnetic field dependence on J,, it was determined that sinter-forging could improve the J, behaviour in external fields, particularly in the regime below ~ O X ~ O ~ Tesla ( i.e., 10 mT). The measurements of the contact resistance R, were conducted for different t ranspor t currents a t 77 K. The results showed that the contact resistance for the samples with higher deformation rates became less dependent on the t ranspor t cur ren t over a range of 0.5 A to SO A.