【作者】 刘年富；

【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】 本文主要从以下几个方面来研究组织纳米化Zr-4合金在673K高压釜过热蒸汽中的耐腐蚀性能。首先利用金相显微镜测量普通Zr-4合金与组织纳米化Zr-4合金的氧化膜的厚度，绘制它们在400℃腐蚀的氧化膜生长动力学曲线，从而分析纳米化Zr-4合金的耐腐蚀性能。实验结果表明，纳米化Zr-4合金的腐蚀转折时间比普通Zr-4合金的腐蚀转折时间滞后，达到了100天左右；普通Zr-4合金的氧化膜生长速率要比纳米Zr-4合金的氧化膜的生长速率大。实验结果分析表明，纳米化Zr-4合金的氧化膜生长速率与氧化膜内的四方结构氧化锆的含量有关。利用X射线衍射（XRD）方法研究纳米结构与普通Zr-4合金氧化膜的物相，相的演变，t-ZrO₂以及m-ZrO₂相的晶格常数，晶胞体积，晶粒的择优取向以及应力的影响等因素。实验结果表明，纳米Zr-4合金的t-ZrO₂相的晶胞体积随着腐蚀进行处于降低过程，纳米Zr-4合金的t-ZrO₂处于比较大的压应力状态；纳米Zr-4合金氧化膜内的氧化膜／金属界面处存在的高压应力，这些将有利于稳定t-ZrO₂相，延缓相变的进程，推迟腐蚀转折的发生，从而降低氧化速率。使用EDS方法研究腐蚀过程中氧离子的阴离子空位扩散和氧化物生长情况。从氧元素在普通Zr-4合金与纳米化Zr-4合金中的分布的结果表明，在致密氧化膜形成后的腐蚀过程中，氧离子在普通粗晶Zr-4合金氧化膜中的扩散快于在纳米晶Zr-4合金氧化膜中的扩散。结合几个实验的研究分析结果证明了在673K高温过热蒸汽的高压釜中，纳米化Zr-4合金的耐腐蚀性能要比普通Zr-4合金的耐腐蚀性能好。本文表明，纳米化Zr-4合金耐腐蚀性能的提高与氧化膜内四方氧化锆的含量、四方氧化锆的应力状态以及氧化膜内的高压应力有直接的关系。而关于纳米化Zr-4合金耐腐蚀性能机理仍有待进一步的实验研究和分析。更多还原

【Abstract】 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.更多还原