Study of powder density, Ag:superconductor ratio, and microhardness of BSCCO-2212 Ag-sheathed wires and tapes during wire drawing and rolling

摘要

Densification of Bi2Sr2CaCu2Ox (BSCCO-2212) powder cores in Ag-clad wires and tapes has been studied as a function of strain and initial packing density. Density was measured directly by etching away the silver and weighing the remaining core. A universal feature in both wires and tapes was the attainment of maximum densities (～80%) at intermediate strains of ～4. The linear correlation between microhardness and density found for round wires breaks down for rolled tapes, apparently because the core separates into dense locks separated by cracks.