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Atomic origins of water-vapour-promoted alloy oxidation
Nature Materials ( IF 41.2 ) Pub Date : 2018-05-07 , DOI: 10.1038/s41563-018-0078-5
Langli Luo , Mao Su , Pengfei Yan , Lianfeng Zou , Daniel K. Schreiber , Donald R. Baer , Zihua Zhu , Guangwen Zhou , Yanting Wang , Stephen M. Bruemmer , Zhijie Xu , Chongmin Wang

The presence of water vapour, intentional or unavoidable, is crucial to many materials applications, such as in steam generators, turbine engines, fuel cells, catalysts and corrosion1,2,3,4. Phenomenologically, water vapour has been noted to accelerate oxidation of metals and alloys5,6. However, the atomistic mechanisms behind such oxidation remain elusive. Through direct in situ atomic-scale transmission electron microscopy observations and density functional theory calculations, we reveal that water-vapour-enhanced oxidation of a nickel–chromium alloy is associated with proton-dissolution-promoted formation, migration, and clustering of both cation and anion vacancies. Protons derived from water dissociation can occupy interstitial positions in the oxide lattice, consequently lowering vacancy formation energy and decreasing the diffusion barrier of both cations and anions, which leads to enhanced oxidation in moist environments at elevated temperatures. This work provides insights into water-vapour-enhanced alloy oxidation and has significant implications in other material and chemical processes involving water vapour, such as corrosion, heterogeneous catalysis and ionic conduction.



中文翻译:

水蒸气促进合金氧化的原子起源

水蒸气的存在,有意或不可避免的,对于许多材料应用至关重要,例如在蒸汽发生器,涡轮发动机,燃料电池,催化剂和腐蚀1,2,3,4中。从现象学上讲,人们已经注意到水蒸气会加速金属和合金的氧化5,6。然而,这种氧化背后的原子机理仍然难以捉摸。通过直接原位原子尺度透射电子显微镜观察和密度泛函理论计算,我们发现镍铬合金的水蒸气增强氧化与质子溶解促进的阳离子,铁离子的形成,迁移和聚集有关。阴离子空位。来自水解离的质子可以占据氧化物晶格中的间隙位置,因此降低了空位形成能并降低了阳离子和阴离子的扩散势垒,这导致了高温下在潮湿环境中的氧化作用增强。这项工作提供了有关水蒸气增强合金氧化的见解,并在涉及水蒸气的其他材料和化学过程中具有重要意义,

更新日期:2018-05-08
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