Mew Method for manufacturing Ag-sheathed Bi-2223 superconducting tapes with uniform microsructure

摘要

Large variations of microstructure and hardness across the core width wre found in Ag-sheated Bi-2223 superconducting tapes. The relation between critical current density and deformation inhomogeneity during rolling and pressing were studied. It was shown that rolling and pressing make the oxide core deform inhomogeneously and lead to nonuniform microstructure over the cross section of the tapes, thus limit enhancement of overall Jc. Thereofore it is necessary to improve present fabrication techniques of tapes for obtaining uniform through thickness microstructure. Based on the this, we have developed a new technique to manufacture rectangular cross section tapes by hdrostatic extrusion. Experimental resulus showed that this method not only cused more uniform distribution of microstructure in the tapes, but also increased the density of oxide core.