EFFECT OF AU AND MG ADDITION TO AG SHEATH ON MICROSTRUCTURE AND SUPERCONDUCTING PROPERTIES OF BSCCO-2223 TAPES

Ag-Mg, Ag-Pd-Mg, and Ag-Au-Mg alloys were investigated as alternative- sheath materials to pure Ag for powder-in-tube (PIT) processing of BSC CO-2223 tape. These alloys were extruded into hollow tubes (OD: 12.7 m m, ID: 9.5 mm, 200 mm long), and were investigated for sausaging effec t, microstructure, and compatibility (I, measurement) with 2223 BSCCO superconductor during the processing. The alloying of Au and Pd to Ag increased the resistivity but is not very effective in increasing the hardness. The addition of a small quantity of Mg to Ag-Au and Ag-Pd in creased the hardness significantly due to dispersion hardening. The us e of Ag-Au-Mg alloys as the sheath materials improved the uniformity o f BSCCO core;thickness and mechanical strength without any deteriorati on of superconductivity. Microstructural studies of the BSCCO-2223/Ag- Au-Mg tapes revealed a more dense and aligned BSCCO structure particul arly along the sheath-core interface.