Bi-2212 phase formation process in multifilamentary Bi-2212/Ag wires and tapes

摘要

We investigated phase formations of multifilamentary Bi-2212/Ag wires during the heat-treatment. We carried out systematic quenching experiments. In the partial-melting process in pure O/sub 2/, when heating rate was 10/spl deg/C/h, melting of filaments was started from central filaments and spread to the edge-located filaments. However, when heating rate was 5/spl deg/C/h, melting of filaments was caused uniformly. In the partial-melting process in 8% O/sub 2/ also, melting of filaments occurred caused uniformly. Phase identification indicates that the existing alkaline earth cuprate was 2:1 alkaline earth cuprate in 8% O/sub 2/ while alkaline earth cuprate was 14:24 alkaline earth cuprate in pure O/sub 2/. These results showed effect of O/sub 2/ partial pressure in filaments. In the slow solidification process, the Bi-2212 phase grew up greatly and broke through the silver matrix in pure O/sub 2/, but the grain growth was suppressed in 8% O/sub 2/, resulting in the suppressing of bridging of Bi-2212 filaments.