Atomistic simulation of the diffusion behavior in Al-Fe

Abstract

The diffusion behavior of the Al-Fe system was investigated by a classical molecular dynamics simulation for simulating the Al coating process on Fe. Two bulks were built as the model: one bulk contained Al atoms and the other was made from Fe atoms. The diffusion was studied at four different temperatures for 6 ns by utilizing a MEAM potential. The mean square displacement (MSD) and potential energy of Al and Fe atoms were recorded during the simulation. Fe atoms penetrated inside the Al lattice in low quantities and at a slower rate compared with the fast and large number of diffusing Al atoms that did not penetrate inside the Fe lattice. The diffusion coefficient was estimated by the fitting of the linear region from the MSD and time curves. The Arrhenius equation was used to find the activation energy and the frequency of attempts. The activation energy of Al was 0.83 eV, whereas that of Fe was 0.72 eV. The frequency of attempts for the Al and Fe atoms were 1.03×10-6and 5.83×10-8 m2/s, respectively. The diffusing mechanisms were studied, and it was found that the Fe atoms diffused into the Al lattice by the first-neighbor hopping mechanism. The potential energy of the Fe atoms increased as the Fe atoms penetrated the Al lattice.

Keywords

• Diffusion
• Molecular dynamics
• Mean square displacement
• Vacancy
• Activation energy