Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 18 No. 5 October 2008|
（1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University,Xi’an 710072, China;
2. Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China）
Abstract:The infiltration-growth process was used as an alternative to conventional melt processing techniques for the preparation of bulk YBa2Cu3O7−x(Y123) with finely dispersed small size Y2BaCuO5(Y211) particles. Bulk YBCO superconductors with uniformly distributed particles of micron-sized Y211 were prepared by the directional infiltration and growth(DIG). The microstructure changes of the Y211 particles at various stages of processing were studied. About 70% of Y211 particles are under 1 μm in the final sample. The different stopped growth mechanism of this material along the c axis and ab plane was discussed. Undercooling and viscosity lead to tanglesome thick boundary layer. So the Y123 growth along c axis is stopped. Yttrium lack in front of the ab plane is the main reason why the growth stops at this direction.
Key words: infiltration; superconductor; Y211; YBCO