On the mechanical response and intermetallic compound formation in Al/Fe interface: molecular dynamics analyses

Molecular Dynamics (MD) simulations were used to investigate the mechanical response and interfacial mixing of Al/Fe system loaded in uniaxial compression at a constant strain rate of 5 x 10⁷ s^-1 and five temperatures (150, 300, 500, 700, and 900 K). During the simulations, the temperature was kept below the melting temperature of aluminium (similar to 933 K) so that stress assisted solid-state mixing is examined. For that purpose, the accuracy of the Al-Fe.eam.fs potential was validated though static simulations of pure Al and Fe crystals separately. Then, the mechanical response of Al/Fe system under compression was simulated. The onset of nucleation of dislocations in both materials was observed shortly after relaxation. Under the employed conditions of compression and temperature, the simulations revealed that dislocations movements were accompanied by significant interfacial mixing. Considering that temperature and stress are two factors that drive atoms out of their stable positions, it was found that large stresses have a more pronounced effect on this movement. Even at relatively low temperatures, the aluminium and iron atoms exhibited significant interfacial mixing under externally applied high compressive stress. Radial distribution function (RDF) computations for the Al and Fe atoms at the interface suggest that mixing in the solid-state resulted in the formation of FeAl intermetallic compound (CsCl crystal structure). (author)