【作者】 石明华；

【导师】 张喜燕；

【作者基本信息】 广西大学 ， 材料物理与化学， 2007， 硕士

【摘要】 本文讨论了纳米化处理对锆合金的抗腐蚀性能的影响。首先在wagner理论和固体电子理论的基础上，将电导率与电子的平均自由程及晶粒尺寸的关系联系起来，建立了纳米及超细晶结构Zr—4合金腐蚀速率-晶粒尺寸关系模型，并结合锆合金的性质，模拟计算了不同温度下晶粒尺寸对锆合金腐蚀速率常数的影响，结果表明，与普通晶粒相比，纳米晶粒尺寸下锆合金的速率常数低于普通晶粒锆合金的速率常数，同时，随着纳米晶粒尺寸的减小锆合金的速率常数也降低，对比纳米Zr-4合金在673K水蒸气中的腐蚀试验数据，二者符合很好，显示出纳米化处理可以改善锆合金的腐蚀性能。其次通过XRD、SEM、EDS、AFM分析了纳米锆合金与粗晶锆合金在673K高温高压水的高压釜中腐蚀形成的氧化膜的成分、形貌、表面粗糙度、晶粒尺寸大小及氧浓度分布，发现纳米化改善了锆合金的耐腐蚀性能，与所建的模型符合。然而对于具有表面纳米及超细晶组织的锆合金来说，其腐蚀性能的影响因素不仅仅包括晶粒尺度，还包括合金成分、氧化膜的组织与性质、热处理工艺方法、表面状态、反应堆水化学、水冷却剂温度、通过包壳锆合金的热通量密度、辐照效应等等。而上述因素中的任何一个因素发生变化，都会导致材料腐蚀性能的改变。因此对于锆合金纳米化后腐蚀性能的研究，应该从全方位考虑，从而对锆合金的腐蚀性能有一个全方位的认识。更多还原

【Abstract】 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.更多还原