On the powder surface of oxygen-ordered ZrC0.6O0.4 obtained via isothermal heating of vacancy-ordered ZrC0.6 at 300 °C, an amorphous ZrC0.6O
y>0.4 layer in nanoscaled thickness is found to form if the heating lasts long enough. With the help of high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) measurements, the amorphous formation is recognized to originate from diffusion of superfluous oxygen atoms into Zr-tetrahedral centers in the surface area, thus leading to severe distortion of the lattice. In situ investigation of HRTEM, SAED, and electron energy loss spectra demonstrates that under electron irradiation of sufficient dose, the amorphous ZrC0.6O
y>0.4 layer transforms into a cubic ZrO2−x
layer with the same orientation as the underlying ordered ZrC0.6O0.4.