| This article discussed a superficial nanometer processing to the zircaloy corrosion resistance performance influence. At frist a computation model of corrosion rate-grain size of nanocrystalline and ultra-fine Zircaloy-4 has been presented. The model is based on the Wagner's theory and the electron theory of solids. The conductivity, electronic mean free path and grain size of metal were considered. By this model, the corrosion rate of Zircaloy-4 under different temperature was computed. The results show that the corrosion resistance of nanocrystalline Zircaloy-4 is much superior to that of Zircaloy with coarse grain size. The corrosion rate constant and weight gain of nanocrystalline Zircaloy-4 decrease with the decrease of grain size. Compare to nanometer Zr-4 alloy corrosion test data in 400℃steam, the two tallies very well. So the refinement of grain size can remarkably improve the corrosion resistance of Zircaloy-4. The oxide film component .topography , surface roughness, grain size and stress distribution of nanocrystallization and coarse grain Zircaloy-4 alloy were observed though the XRD,SEM,AFM,TEM. The results show that the corrosion resistance of nanocrystalline Zircaloy-4 is much superior to that of Zircaloy-4 with coarse grain size, tallied with the model. For a surface nanometer and the ultra finer organization's zircaloy, its corrosion property influence factor not only includes the grain size, but also includes the alloy composition, the oxide film organization and the nature, the heat treatment technique, the surface condition, chemistry of reactor coolant, temperature of reactor coolant , heat flux through the cladding, irradiation effects and so on. Any one of these factors change will lead to corrosion property can be change. Therefore, this kind of research should be carried out carefully.
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