Effects of Inclusions on the Sintering Behavior of YBa 2 Cu 3 O 6+ x

The sintering behavior of two types of heterogeneous compacts of YBa 2 Cu 3 O 6+ x was studied: (1) Soft agglomerates present in the starting powder were used to study the effect of rapidly densifying inclusions on the overall sample densification. In this case, the induced stresses caused severe cracklike damage in the sintered microstructure. (2) On the other hand, when nondensifying inclusions (same composition) were incorporated into the starting powder, no sintering damage was observed. Further, there was no retardation of densification or coarsening due to the presence of these dense inclusions, over a wide range of inclusion size. Several possibilities for this behavior are discussed, based on the distribution of stresses induced by differential sintering rates.