Abstract
Accurate prediction of oxide structure has long been a major challenge in corrosion science, and is becoming increasingly important for advanced nanomanufacturing. Although high-temperature corrosion is a relatively well-established field of study, it is still based on classical models such as Wagner’s model, which lack consideration at the microstructural level. Therefore, these models are less accurate in explaining earlier stages of oxidation and cannot predict how factors such as surface orientations, defects, and boundaries affect the oxidation process. This is because experimental tools capable of observing this decisive early-stage oxidation have formerly been unavailable, and success in generating a predictive understanding requires the integrated efforts of a diverse group of researchers. Developments involving in situ environmental TEM (ETEM) have demonstrated the great promise of this capability. However, methods for analyzing the in situ data to extract meaningful information are challengin. Here we present in situ ETEM experiments, with advanced data analysis and correlated theoretical simulations, to investigate the initial stages of Cu oxidation, from the missing-row Cu-O surface reconstruction, oxide nucleation to its monolayer-by-monolayer island growth. These dynamic experimental atomic-scale observations, correlated with multiscale simulations, provide critical and fascinating new insights into the initial oxidation mechanisms of metals and alloys.
*The authors acknowledge funding from National Science Foundation (NSF) grants DMR-1410055, DMR-1508417, DMR-1410335, and CMMI-1905647, as well as support from Hitachi-High-Tech and technical assistance from the Nanoscale Fabrication and Characterization Facility (NFCF) in the Petersen Institute of Nano Science and Engineering (PINSE) at the University of Pittsburgh. This research used the Electron Microscopy facility of the Center for Functional Nanomaterials (CFN), which is a U.S. Department of Energy Office of Science User Facility, at Brookhaven National Laboratory under Contract No. DESC0012704. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE’s National Nuclear Security Administration under contract DE-NA-0003525.
