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

The influence of the sinter-forging rate on the critical current density (J_c) behaviour in an external field and on the contact resistance R_c for Bi-2223 current leads has been investigated. The current 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_c was strongly affected by the deformation rate of sinter-forging and reached a maximum of 725 A/cm² at a deformation rate of 80%. From the measurements of the external magnetic field dependence on J_c. It was determined that sinter-forging could improve the J_c behaviour in external fields, particularly in the regime below 10×10^-13 Tesla (i.e. 10 mT). The measurements of the contact resistance R_c were conducted for different transport currents at 77 K. The results showed that the contact resistance for the samples with higher deformation rates became less dependent on the transport current over a range of 0.5 A to 50 A