| The resistance corrosion of nanocrystallization Zircaloy-4 alloy in autoclave at 673K steam has been discussed in this paper in the following ways.In the first, It measured the thickness of oxide film of as-received Zircaloy-4 alloy and nanocrystallization Zircaloy-4 alloy by metallurgical microscope, plotted their oxide film growth kinetics curve in 400℃, and discussed the resistance corrosion of nanocrystallization Ziracloy-4 alloy. The results indication that the corrosion transition time of nanocrystallization Zircaloy-4 alloy reached about 100 days, which was delayed than Zircaloy-4 alloy; and the growth rate of Zircaloy-4 was more quickly than nanocrystallization Zircaloy-4 alloy with the corrosion process. The results indicated the oxide film growth rate of nanocrystallizaion Zircaloy-4 had relation with the percentage of tetragonal-Zirconia.It studied on oxide phases, evolution of phases, lattice variation of tetragonal-Zircnia and monoclinic-Zircnia, cell volume, prefer orientation of grains and the stress-influence atc. by X-ray diffraction. The results indication that the tetragonal-Zirconia' s cell volume of nanocrystallization Zircaloy-4 alloy reduced in the process of corrosion, the tetragonal-Zirconia of nanocrystallization Zircaloy-4 alloy was in the high compressed stress; And the interface of oxide/metal in the oxide film of nanocrystallization Zircaloy-4 alloy was in high compressed stress. These results were advantageous to stable the tetragonal-Zirconia, delayed the process of phase transformation, postponed the corrosion transition, and reduced the oxidation rate.EDS observed the anion ion vacancy diffusion of oxygen ion and oxide growth in the corrosion process. The results of oxygen distribution of as-received Zircaloy-4 alloy and nanocrystallizaion Zircaloy-4 alloy showed, after compact oxide film formation, oxygen ion diffused in oxide film of as-received Zircaloy-4 alloy more quickly than in nanocrystallization Zircaloy-4 alloy.Union these discussion results indication that the resistance corrosion of nanocrystallizaion Zircaloy-4 alloy was more excellence than as-received Zircaloy-4 alloy in autoclave at 673K steam. This paper showed the corrosion resistance improvement of nanocrystallization Zircaloy-4 alloy had relation with the percentage of tetragonal-Zirconia, the stress of tetragonal-Zirconia and the high compressed stress of oxide film. However about the corrosion resistance mechanism of nanocrystallizaion Zircaloy-4 alloy should be researched and discussed in the further.
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