Fabrication of cold-rolled Ag-sheathed Bi(2223) tapes by a partial-melting process

The extensive work presented here reports a new method to fabrication of Bi-2223/Ag tapes by a partial-melting process in order to achieve good grain alignment and connection. This partial-melting process consists of three heating cycles. The green tapes require a first heat treatment at relative lower temperature in order to ensure 2212 phase forms sufficiently and prevent 2223 phase from formation. A short period of melt treatment at 860 °c for 15 minutes is applied at the second annealing. The pre-oriented 2212 phase transforms to the highly-aligned 2223 phase by sintering at 835 °c for 200h during the third heating cycle. The improvement of grain size and texture compared with the normally processed tapes has been achieved by this partial-melting process.