Atomic insights into the oxidation behavior of NiAl alloys in oxygen environments: A ReaxFF molecular dynamics study

The oxidation behavior of alloys exhibits different oxidation kinetic mechanisms in different environments, but the atomic mechanisms behind the oxidation process are still vacant. In this work, the early oxidation behavior of the NiAl alloys under the synergistic effect of temperature and oxygen content was systematically investigated using the simulation method of Reactive Force Field Molecular Dynamics (ReaxFF-MD, RMD). The oxidation process of the alloys has been found to be seriously affected by the number of oxygen molecules, and the rise in both temperature and oxygen content increases the oxidized volume expansion rate and the oxygen consumption rate. The amount of oxygen content at low temperatures does not have much effect on the oxidative behavior, whereas the increase in the oxygen content at high temperatures promotes the charge transfer and the formation of vacancies, which results in the enhancement of the oxidation in the high temperature aerobic environment. The increase in temperature has also been found to lead to the increase in the surface roughness of the alloy, which reduces the adsorption capacity of oxygen on the alloy surface, thereby accelerating the rate of elemental diffusion.