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

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 O₂, when heating rate was 10°C/h, melting of filaments was started from central filaments and spread to the edge-located filaments. However, when heating rate was 5°C/h, melting of filaments was caused uniformly. In the partial-melting process in 8% O₂ also, melting of filaments occurred caused uniformly. Phase identification indicates that the existing alkaline earth cuprate was 2:1 alkaline earth cuprate in 8% O₂ while alkaline earth cuprate was 14:24 alkaline earth cuprate in pure O₂. These results showed effect of O₂ partial pressure in filaments. In the slow solidification process, the Bi-2212 phase grew up greatly and broke through the silver matrix in pure O₂, but the grain growth was suppressed in 8% O₂, resulting in the suppressing of bridging of Bi-2212 filaments.