日本金属学会誌

J. Japan Inst. Metals, Vol. 56, No. 7 (1992),
pp. 810-818

Model for Directional Solidification of YBa2Cu3Ox Superconducting Oxide

Yuichi Nakamura1, Teruo Izumi1, Yuh Shiohara1 and Shoji Tanaka1

1Superconductivity Research Laboratory, International Superconductivity Technology Center, Tokyo

Abstract:

The unidirectional solidification by a zone melt method was performed in order to clarify the solidification mechanism of YBa2Cu3Ox (123) superconducting oxides. The continuous growth of 123 crystals were obtained under the growth rate less than 3 mm/h. A sharp faceted interface of 123 crystals was observed in the sample grown at 1 mm/h and the volume of the 211 phase decreased drastically from liquid into 123 crystal across the interface. From these results, we concluded that the necessary solute for peritectic reaction (211+liq.→123) is provided through a liquid. Based on this idea, we considered the driving forces for diffusion in liquid between the 211 particle and the growing interface, and developed a unidirectional solidification model. From this growth model, we can predict the balanced velocity of 123 growth and the distributions of 211 particles trapped in 123 crystal, and this model is in good agreement with the experimental results.


(Received 1992/01/16)

Keywords:

YBCO superconductor, unidirectional solidification, zone melting method, peritectic reaction, undercooling, solidification model


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