The initial oxidation of Zircaloy-4 in lithiated water under autoclave conditions as examined by TEM

TEM thin foil specimens prepared using Zircaloy-4 coarse-grained samples were corroded by autoclaving at 250 °C and 280 °C in lithated water for a short time exposure, and the initial oxidation process before the formation of ZrO2 was investigated by TEM. The results show a variation of the crystal structure along with the increase of oxygen contents at the initial oxidation stage. When the Zr/O atomic ratio reached 6-7, 3 and 1, a commensurable long period super-lattice 9a0-2H and sub-oxides with hcp and fcc ordered structure were formed. When the Zr/O atomic ratio was 0.8, monoclinic ZrO2 was detected.