Abstract
An ultrasonic nondestructive evaluation technique was developed to monitor liquid-phase evolution during heat treatment of high-Tc superconductors. The liquid phase is essential for microstructural and phase development of superconductors and is important in fabricating conductors with high critical current density, Jc. Tapes were fabricated by a powder-in-tube process and then placed in a controlled-atmosphere furnace. During heat treatment, a magnetostrictive transducer launches a 140-kHz wave into the sample, and the relative change in acoustic velocity is then measured. A significant decrease in velocity was seen at the incongruent melting temperatures of Bi-based superconductors. In addition, Ag-clad tapes with Al2O3and NaCl cores were used to validate the measurement technique. Advantages of this approach over other thermal analysis methods include in-situ analysis of the final tape form, monitoring of isothermal liquid evolution, and control of volatile species such as Tl and Pb.
Original language | English (US) |
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Pages (from-to) | 1475-1478 |
Number of pages | 4 |
Journal | IEEE Transactions on Applied Superconductivity |
Volume | 5 |
Issue number | 2 |
DOIs | |
State | Published - Jun 1995 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering