Powder-in-tube-processed multifilamentary Bi-(2223) tapes with silver-alloy sheaths

Superconducting Bi-(2223) multifilamentary tapes with Ag_100-x Y_x alloy sheaths, with Y=Cu, Mn and Pd, were made by the oxide-powder-in-tube technique. All resistivities of the Ag alloy sheaths exceed that of the pure Ag sheath by at least a factor of 2. The maximum resistivity was achieved for Ag₉₉Pd₁ with ρ_77K=1.3 μΩcm. Tapes sheathed by Ag₉₀Cu₁₀ exceed the critical current density, J _C, of pure Ag sheathed ones. J_C up to 26 kA/cm² were achieved by pressing Ag₉₀Cu₁₀ sheathed tapes during the thermo-mechanical-treatment, TMT. For thinner Ag₉₀Cu₁₀ sheathed tapes up to 31 kA/cm² were obtained employing flat rolling during TMT. Measured irreversibility lines of thin and thicker tapes with comparable J_C suggest, that thicker tapes have a larger pinning strength and a better grain texture but thinner ones a better grain-to-grain connectivity