| Title |
Microstructure of YBCO Superconductor Fabricated by Melt Spinning and Peritectic Reaction |
| Authors |
박수진(S . J . Park); 김선화(S . H . Kim); 박원욱(W . W . Park); 정형식(H . S . Chung) |
| Abstract |
YBa₂Cu₃O_(7-x) Preform was melted and solidified into ribbon shape via melt spinning process. The as-spun ribbon contains melt-decomposed phases of rod shaped 211 phase aligned to spinning direction and Ba, Cu-rich matrix. Superconducting 123 phase is formed by a heat treatment through reaction between the 211 phase and the matrix. The grain morphology of the 123 phase is very much dependent of the presence of liquid phase during the heat treatment. The highly aligned large grain structure with strong (00ℓ) peak obtained through peritectic transformation indicates that the 123 phase is predominantly grown from the rod shaped 211 phase through reaction at the interface with the matrix. Heat treatment below peritectic transformation temperature yielded equiaxed type grain structure, indicating the random nucleation and growth of 123 phase. In case of a bulk specimen prepared by conventional powder consolidation technique, sintering above peritectic transformation temperature produced large grain structures but with random orientations. This strongly indicates that the presence of liquid phase can improve grain structure by promoting grain growth but is not effective for aligning the grains during the 123 phase formation. |