A phenomenological model on the deformation mechanism of YBa2Cu3O7−x+Ag2O composite

in situ, under the compaction load (compressive), it might lead to effective interparticle welding. Fig. 2 illustratres how the original Ag20 particles are joined to form clusters. The continuity of these particles leads to a continuous network in the bulk giving rise to the desirable structural integrity and strength in the "green" state. Furthermore, metallization facilitates plastic flow under the action of the compaction load, and thus improves the integrity by promoting the mechanical bridging and keying action. That metallization indeed took place was confirmed by the X-ray diffraction data obtained from the compacted billets. Density measurement of compacts also points in this direction. The densities of the compacted billets were determined experimentally by the Archimedes method and then compared with the theoretical density of a void-free aggregate of Ag20 + 1-2-3 of identical compositions. The results (Table I) are apparently absurd, approaching the theoretical density too closely or even surpassing it! However, it is readily appreciated that the "theoretical density" cannot be dependable because it altogether ignores the metallization phenomenon. Note that compacts with large initial volume fraction of Ag 20 more closely approach the so-called "theoretical density". This observation, evidently, lends credence to the explanation presented. This is also illustrative of the fact that data on "percentage theoretical density" can often be mis