A dynamic diffusion model was presented that could describe the parabolic and cubic behavior of the pre-transition oxidation kinetics of polycrystalline Zr in dry O during isothermal oxidation treatments at 573 or 623K. The model assumed that the processes of crystallization and grain growth during oxidation modified the O diffusion coefficient by decreasing the number of short-circuit paths in the oxide. The change in O diffusion coefficient was related to the time-at-temperature of each oxide layer that formed at the oxide/metal interphase boundary.

E.A.García: Journal of Nuclear Materials, 1995, 224[3], 299-304