ORIENTATION RELATIONSHIPS OF DELTA HYDRIDES IN ZIRCONIUM AND ZIRCALOY-4

The fundamental investigation reported here was motivated by the controversial and incomplete data for zirconium delta-hydride orientation relationships. For the studies, electron back scattered diffraction analysis (EBSD) was used. Formation of zirconium delta-hydrides and their bulk distribution in zirconium and Zircaloy-4 were investigated. On the basis of the grain boundary spectra and the analysis of microtexture, the orientation relationships between delta-hydrides and the alpha-Zr matrix were refined. It was found that almost all authors, who criticised each other for years, have established the correct relationships. Seven variants of delta-hydride accommodation in the zirconium matrix were summarised in the table of possible orientation relationships.