Direct In-situ TEM Observation Of Modification Of Oxidation By The Injected Vacancies For Ni-4Al Alloy Using A Microfabricated Nanopost
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Vacancy injection and selective oxidation of one specie in bimetallic alloy at high temperature is a well-known phenomenon. However, detailed understanding of the behavior of the injected vacancies and consequently their behavior and effect on oxidation remains elusive. The current research examines the oxidation of high-purity Ni doped with 4.1 at% Al using in-situ transmission electron microscopy (TEM). Experiments are performed on nanoposts fabricated from solution-annealed bulk material that are essentially single crystal samples. Initial oxidation is observed to occur by multi-site oxide nucleation, formation of an oxide shell followed by cavity nucleation and growth at the metal/oxide interface. One of the most interesting in-situ TEM observations is the formation of a cavity that leads to the faceting of the metal on (111) surface and subsequent oxidation occurring by an atomic ledge migration mechanism on the faceted metal surface. Further, it is directly observed that metal atoms diffuse through the oxide layer to combine with oxygen at the outer surface of the oxide. The present work indicates that injection of vacancies and formation of cavity will lead to a situation where the oxidation rate is essentially controlled by the low surface energy plane of the metal, rather than by the initial terminating plane at the metal surface exposed to the oxidizing environment.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1212241
- Report Number(s):
- PNNL-SA-110747; 48670; KP1704020
- Journal Information:
- ACS Applied Materials and Interfaces, Vol. 7, Issue 31; ISSN 1944-8244
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
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