Non-equilibrium processing of YBCO

123-phase formation in non-equilibrium conditions was investigated with respect to higher growth rates. Non-equilibrium was achieved by rapidly heating a BaCuO2-CuO-Y2O3 powder-mixture to temperatures slightly below the peritectic temperature T-p of the superconducting phase. In situ hot-stage SEM revealed the formation of a liquid-phase at temperatures exceeding 900 degrees C, in which nucleation phenomena were observed Samples heated to temperatures below T-p exhibited a microstructure similar to samples rapidly cooled to these temperatures from the 211+liquid regime. A homogeneous distribution of micron sized 211 inclusions inside 123 grains, which were in the millimeter range, could be achieved without any dopant The degree of undercooling determined both the final size and the number of 123 grains. The powder-mixture can be assumed to represent an undercooled melt.