Bi-2223 Ag-Au-Mg alloy sheathed tapes with J, (77 K, 0 T) up to 28.5 kA/cm(
2) were fabricated by a controlled melting (CM) process. It was found that
the CM process is effective for eliminating weak links and improving the tr
ansport properties of Bi-2223 Ag-Au-Mg alloy sheathed tapes. The compressiv
e stress in the Ag alloy/oxide interface induced by the fast cooling is dec
reased due to the low thermal conductivity of the Ag-Au-Mg alloy sheath. Th
ere is no microcracking observed at the interface of the fast-cooled sample
. The microstructure analysis demonstrates that the Bi-2223 phase decomposi
tion is accelerated with the increase of the melting temperature. Too high
melting temperature may cause severe phase segregation, which is unrecovera
ble in the subsequent heat treatments. (C) 1999 Elsevier Science B.V. All r
ights reserved.