Long-length processing of BSCCO-2223 tapes made by using Ag alloys sheath

To improve the smoothness of BSCCO/Ag interface as well as to increase strength and resistivity, we have fabricated various compositions of Ag-Mg alloy, Ag-Au alloy, Ag-Pd-Mg alloy, and Ag-Au-Mg alloy. These sheath alloys were evaluated for hardness, resistivity, and microstructure to find out alternative candidate to pure Ag for sheath materials in powder-in-tube (PIT) processing of BSCCO-2223 tapes. For a long-length process, these sheath alloys were extruded into commercial size (OD:12.7 mm, ID:9.5 mm, 200 mm long) of hollow tube, and were investigated for sausaging effect, microstructure, and compatibility (Ic measurement) with 2223 BSCCO superconductor during processing. The alloying of Au and Pd increased resistivity but is not very effective in Increasing hardness. Addition of small quantity of Mg to Ag-Au and Ag-Pd increased hardness significantly due to dispersion hardening. Microstructural studies of BSCCO-2223/Ag-Au-Mg tapes revealed a more dense and aligned BSCCO structure.