How the crystallography and nanoscale chemistry of the metal/oxide interface develops during the aqueous oxidation of zirconium cladding alloys
How the crystallography and nanoscale chemistry of the metal/oxide interface develops during the aqueous oxidation of zirconium cladding alloys
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DOI：
10.1016/j.actamat.2012.09.021
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发表时间：
2012-12-01
期刊：
影响因子：
9.4
通讯作者：
Grovenor, C. R. M.
中科院分区：
文献类型：
--
作者：
Ni, N.;Hudson, D.;Grovenor, C. R. M.
在水冷核反应堆中，锆合金用作燃料包壳和组件部件的主要限制因素是水腐蚀和氢化。金属氧化物界面一直是以往研究的重点，但在复杂氧化过程的不同阶段，界面上存在什么仍然没有明确的认识。在此，我们报告了用最先进的仪器对几种不同时间腐蚀的锆合金的界面进行了系统的研究。我们发现在几乎所有的预转变样品中都可以观察到成分接近ZrO的薄中间氧化层，并且该层在预转变阶段变厚。就在动力学转变之前，亚氧化物的宽度发生了很大的变化，这表明动力学转变是一个非常局部的过程。跃迁后，亚氧化物一般不存在。在亚氧化物的位置，发现了不同的结构，包括一个未识别的相。饱和氧（类似于30at）。在（后期）转变前样品中，氧化物下方的金属区域最厚，而在转变后样品中，金属区域明显更薄。我们认为，亚氧化物本身不能作为保护层，并得出结论，它是相互连接的孔隙发展到金属-氧化物界面是氧化动力学转变的原因。(C) 2012材料学报Elsevier Ltd.出版。版权所有。
Aqueous corrosion and hydrogenation have become major limiting factors to the use of zirconium alloys as fuel cladding and assembly components in water-cooled nuclear reactors. The metal oxide interface has been a particular focus of previous research, but there is still no clear understanding of what is present at the interface at different stages of the complex oxidation process. We report here a systematic investigation using state-of-the-art instrumentation on the interfaces in several zirconium alloys corroded for different times. We have shown that thin intermediate oxide layers with compositions close to ZrO can be observed in almost all the pre-transition samples studied, and that this layer thickens during the pre-transition stage. Just before the kinetic transition, a large variation in the suboxide width was detected, suggesting that the kinetic transition is an extremely local process. After transition the suboxide was generally absent. In the suboxide locations different structures, including an unidentified phase, were found. The oxygen-saturated (similar to 30 at.% 0) metal regions found beneath the oxide are thickest in the (late) pre-transition samples and significantly thinner in the post-transition samples. We suggest that the suboxide cannot by itself act as a protective layer and conclude that it is the development of interlinked porosity down to the metal-oxide interface that is the reason for the transition in oxidation kinetics. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.