Fabrication of highly aligned YBa₂Cu₃O_7-δ-Ag melt-textured composites

Liquid phase processing techniques with slow cooling through the peritectic transformation have been utilized to fabricate bulk aligned 123-Ag composites. Coarse (∼30-40 μm) and fine (∼5-10 μm) particles of silver are distributed between and within the 123 grains. Although the processing temperatures employed are much higher than the melting point of silver, particles of silver are retained behind the advancing solid-liquid interface. The peritectic reaction occurs at the solid-liquid interface and the rate of the reaction is limited by diffusion between the two solid phases, hence the transformation invariably results in some unreacted phases. Ellipsoidal, Y₂BaCuO_itx particles varying in size from 10-25 μm are trapped within the 123 phase. In addition, regions of CuO and BaCuO₂ are present in the sample as separate phases. Silver particles are also dispersed in these insulating regions of the microstructure. The 123-Ag composites have superior mechanical properties compared to melt-textured stoichiometric 123 samples. A detailed study describing the effects of processing on the microstructureof these aligned composites is reported.