HREM OF ARTIFICIAL GRAIN-BOUNDARIES IN BI-CRYSTALS AND TRI-CRYSTALS OBTAINED BY THE SOLID-PHASE INTERGROWTH PROCESS

Results of a HREM investigation of artificial grain boundaries (AGBs) in crystalline composites, obtained by solid-phase intergrowth of garn et crystals, are described. In bi-crystals with similarly oriented par ts AGB is not revealed. Small misalignment results in pseudo-periodic, flat defect formation inclined relative to the intergrowth interface. If parts are in different orientations, the AGB is even and flat. Tri ple joints are characterized by rotation of the crystal parts and chan ging of the junction geometry. The AGB in a bi-crystal formed from dif ferent types of garnets is wavy. AGB deformation in this case as well as in the case of tri-crystals could be explained by the different ela stic properties of its parts.