In-situ Heating Investigation on Lattice Evolution of Zircaloy-4 during Its Oxidation Process

In-situ heating in the HRTEM using zircaloy-4 TEM thin foil specimen was carried out to investigate the oxidation behaviour of zirconium alloy at the initial stage, which provides a new view for the study of corrosion mechanism of zirconium alloys. The result shows that, the oxygen firstly is solid dissolved into the zirconium lattice to form oxygen-rich regions, and with the increasing of oxygen content, the deformation of the lattice increased and compressive strain is produced to promote the lattice modulation and the formation of the fcc structure ZrO sub-oxide. The sub-oxide is consisted of domains with similar crystal orientations and finally transformed to m-ZrO₂.