NUCLEATION OF AN MTG YBA2CU3OY

The kinetics of the appearance of the superconducting 123 phase in par tially melted at 1200 degrees C YBCO samples has been studied in the t emperature range of low undercoolings from 1040 degrees C to 920 degre es C. An EDS analysis of the phases formed at different stages of the cooling of the melt has been performed and the experimental conditions for crystallization of 123 phase with finely dispersed 211 phase in i t have been established. The results have been interpreted in terms of the classical theory of nucleation and they have been applied to the MTG process for formation of highly textured YBa2Cu3Oy materials.