The Effect of Strain Rate and Temperature on the Mechanical Behavior of Al/Fe Interface Under Compressive Loading

Abstract

Molecular dynamics (MD) is employed to simulate the mechanical response of Al/Fe interface under compression at extreme conditions of seven temperatures and four strain rates ranging between 150 K and 900 K and 5.0 × 10⁷ s⁻¹ and 1.0 × 10¹⁰ s⁻¹, respectively. Stress–strain histories show two distinct yield stress points for simulations at temperatures below 500 K, which tend to merge into one as the temperature increases. Microstructural simulations show nucleation of dislocations, which occur in the bulk of the aluminum region, is associated with the first yield point. In the iron region, dislocations nucleate at the Al/Fe interface and are associated with the second yield point. The incoherent interface employed in these simulations contributes to the heterogeneous nucleation in iron by creating a defected area favorable for this nucleation from the aluminum side. MD generated data show that the two yield stresses and the consequent flow stress decrease with increasing temperature for all strain rates and fit a thermally activated model function of strain rate. The competing mechanisms between dislocation motion and phonon drag driven deformation are also simulated and modeled. The flow stress of the interface was found to fall midway between Zerilli–Armstrong models of the two materials constituting it, whereas the relaxation in Fe followed similar trend to what is reported in the literature.