(702a) Investigation of the Oxidation of Metal/Metal Oxide in the Corrosion Environment Using the Reaxff Reactive Force Field

A ReaxFF reactive force field description for Fe, Ni and Al metal and metal oxide and their interaction with oxygen has been developed. The force field parameters were trained against an extensive set of ab initial data including heats of formation and equation of state of varieties of bare metal, alloy and metal oxide. The potential developed here were validated using molecular dynamics simulations on relatively small systems (~1000atoms) addressing the process of Ni self diffusivity, Al/Fe impurity diffusivity in fcc Ni and O/H diffusivity in Al-Fe-Ni. Results from these studies agree with those from first principle calculations. Based on the force field parameters, we studied the surface segregation of different types of Al_xFe_yNi_(1-x-y) alloys and the adsorption of O₂ and subsequent oxidation process. Results of these studies will contribute to revealing the corrosion and aging of the material.

This project aims at closing the gap between atomistic-scale studies (e.g. Quantum Mechanics calculation) and experimental observations. The method will contribute to the development of reliable computational tools to predict the performance of novel Ni based superalloys in conditions relevance to advanced energy systems. Specifically, the large system sizes (>>1000 atoms) and large simulations times (>1 ns) will greatly enhance our capability to design and test materials in environment and time scales relevant to these systems.