Polytype structures in Zr-Cr-Fe laves phase

Abstract

Hexagonal polytype structures (H) have been found in ZrCr 2 and Zr(CrFe) 2 Laves phases in both bulk stoichiometric alloys and in precipitates in Zircaloy-4. Rhombohedral polytype structures (R) were found in both Zircaloy-4 and Zr-1.15wt.%Cr-0.1wt.%Fe alloys where the Laves phase is in the form of a precipitate. Good agreement was obtained with respect to possible polytype structures between the diffraction patterns and lattice fringe images in electron microscopy. A comparison of observed and calculated relative diffraction intensities show the polytype structures to be of the 6H, 8H, 12H and 14H modifications.