MICROSTRUCTURAL EVOLUTION OF Y123 AG COMPOSITES DURING SINTERING

The grain-growth kinetics of YBa2Cu3O7-x (Y123) and the coarsening kinetics of silver inclusions in Y123/Ag composites during sintering were investigated. The sintering was carried out in the temperature range 900-950-degrees-C. The addition of silver lowered the formation of a liquid phase and the grain growth of Y123 in Y123/Ag composites was thus enhanced at the beginning of sintering. However, as the effective silver content was increased, more silver inclusions became interconnected, and the grain growth kinetics and coarsening kinetics slowed down significantly. This may be due to the mass transportation paths progressively changing from the grain boundaries to interfacial boundaries as the amount of interconnected silver networks is increased. The grain growth kinetic constant was calculated and compared with other published data. Because the inclusion was ripened with the growth of matrix grains, the coarsening of silver inclusions was deduced to be a coalescence process.