Transient Oxidation Stages of Metals

9902863杨目标是对金属表面条件和杂质受到高度控制的氧化阶段有新的了解。对铜和铝进行了一系列协调的原位电子显微镜实验，解决了瞬时氧化中的公开问题，包括初始氧化物形成的动力学。在匹兹堡大学进行了样品制备、初步的异地表征和氧化实验，以及数据分析和建模。氧化的初始阶段之后，在伊利诺伊大学香槟分校材料研究实验室(UIUC)进行现场超高真空电子显微镜观察。与橡树岭国家实验室(ORNL)的腐蚀科学与技术(CS&amp；T)小组的密切互动是该项目不可或缺的一部分。目前，氧原子在金属表面的行为是通过表面技术来观察的，如低能电子衍射(LEED)和超高真空扫描隧道显微镜(UHV-STM)，其中表面受到高度控制，或者通过研究高温和低温下发生的宏观氧化物生长来观察氧原子在金属表面上的行为，在这些表面技术中，原子水平的表面清洁度是极其困难的。计划中的实验提供了弥合这两个极端之间差距的基本信息。%表面氧化过程在环境稳定性、高温腐蚀、电化学、某些催化反应和薄膜生长以及极端燃料反应中发挥着关键作用。关于氧与金属表面的相互作用和热力学稳定氧化物的宏观生长，人们已经知道了很多。然而，目前，氧化的瞬时阶段，从金属氧化物的成核到热力学上稳定的氧化物的形成，是一个具有科学挑战性和技术重要性的领域。

9902863YangThe goal is to gain new understanding of the stages of oxidation where metal surface conditions and impurities are highly controlled. A coordinated series of in-situ TEM experiments on copper and aluminum address open issues in transient oxidation, including the kinetics of initial oxide formation. Sample preparation, initial ex-situ characterization and oxidation experiments, as well as data analysis and modeling, are conducted at University of Pittsburgh. The initial stages of oxidation are followed by in-situ ultrahigh-vacuum transmission electron microscopy performed at the Materials Research Laboratory, University of Illinois at Urbana-Champaign (UIUC). Close interaction with the Corrosion Science and Technology (CS&T) Group at Oak Ridge National Laboratory (ORNL) is integral to this program. At present the behavior of oxygen atoms on metal surfaces are observed by surface techniques such as low energy electron diffraction (LEED) and ultra-high vacuum-scanning tunneling microscopy (UHV-STM), where the surfaces are highly controlled, or by studies of macroscopic oxide growth occurring at high and low temperatures, where surface cleanliness at the atomic level is extremely challenging to achieve. The planned experiments provide essential information that bridges the gap between these two extremes.%%%Surface oxidation processes play critical roles in environmental stability, high temperature corrosion, electrochemistry, certain catalytic reactions and thin film growth as well as extreme fuel reactions. Much is known about oxygen interaction with metal surfaces and about the macroscopic growth of thermodynamically stable oxides. At present, however, the transient stages of oxidation, from the nucleation of the metal oxide to the formation of the thermodynamically stable oxide, represent a scientifically challenging and technologically important area.***