Symmetry analysis of interface triple junctions

The symmetry properties of triple junctions formed by crystal interfaces are presented using colour crystallography. Triple junctions are treated as composites of three crystals and are studied using the principle of superposition of symmetries. The conclusions are used for the understanding of the equivalences and invariances within one tricrystal composite and for studying such composites from the point of view of interfacial connectivity. A dissymmetrization procedure is established through which tricrystals equivalent by symmetry and their ways of coexistence can be found. Also, the relations between the symmetry properties of the tricrystal and those of the three bicrystals participating in the junction are given. Emphasis is placed on a particular class of composities that are termed variant constituted tricystals. In these, two out of three bicrystals belong to orientation variants of the same dichromatic pattern. Such composites are usual in polycrystals and can exhibit interesting symmetry properties. The ordinary symmetry and antisymmetry in the third bicrystal can be predicted using a given algorithm. Appropriate examples are given to illustrate the application of the analysis.