  Zircaloy-4 (Zr-1.5%Sn-0.2%Fe-0.1%Cr wt. %) was electrochemically charged with
deuterium to create deuterides and subsequently analysed with atom probe
tomography and scanning transmission electron microscopy to understand
zirconium hydride formation and embrittlement. At the interface between the
hexagonal close packed (HCP) \alpha-Zr matrix and a face centred cubic (FCC)
\delta deuteride (ZrD1.5-1.65), a HCP \zeta phase deuteride (ZrD0.25-0.5) has
been observed. Furthermore, Sn is rejected from the deuterides and segregates
to the deuteride/\alpha-Zr reaction front.
