Experimental determination and symmetry related analysis of orientation relationships in heterophase interfaces: A case study in the Zr-B system

Orientation relationships between phases in the Zr-B binary system were determined using electron diffraction. Heterophase interfaces were produced during the solidification of the eutectic (Zr-ZrB2) followed by phase transformation, i.e. allotropic transformation of zirconium, formation of ZrB by peritectoid transformation and stabilisation of a metastable Zr phase, chi Zr. Despite the complexity of the various phases and their transformation upon cooling, the experimental analysis of all the orientation relationships (cubic-hexagonal and hexagonal-hexagonal) found in this system yields only three sets of orientations characterised by the parallelism of low index planes and directions. Using symmetry considerations and group theory, it has been demonstrated that these orientations can be understood as the lowest energy configurations which can be produced from one single orientation formed at high temperature between beta Zr and ZrB2. Copyright (C) 1996 Acta Metallurgica Inc.