Molecular Dynamics Simulations of Aluminum Foams under Tension: Influence of Oxidation

For
materials with high surface-to-volume ratio and high oxygen
affinity, oxide layers will significantly change the material properties.
However, oxidation effects have not been studied for metal nanofoams,
which have many applications because of their light weight and high
stiffness. We use molecular dynamics simulations to show that oxidized
aluminum nanofoams possess significantly improved ductility without
reduction in tensile strength. The Al–O interface leads to
an increased defect nucleation rate at the oxide interface, preventing
localized deformation. At the same time, the enthalpy of mixing between
aluminium and oxygen decreases for increasing O concentrations, reaching
a minimum at the stoichiometric ratio of Al2O3, resulting in stabilized bonds and increased strength.