Orientation dependence of structural transition in fcc Al driven under uniaxial compression by atomistic simulations

By molecular dynamics simulations employing an embedded atom method potential, we have investigated structural transformations in single crystal Al caused by uniaxial strain loading along the [001], [011] and [111] directions. We find that the structural transition is strongly dependent on the crystal orientations. The entire structure phase transition only occurs when loading along the [001] direction, and the increased amplitude of temperature for [001] loading is evidently lower than that for other orientations. The morphology evolutions of the structural transition for [011] and [111] loadings are analysed in detail. The results indicate that only 20% of atoms transit to the hcp phase for [011] and [111] loadings, and the appearance of the hcp phase is due to the partial dislocation moving forward on {111}_fcc family. For [011] loading, the hcp phase grows to form laminar morphology in four planes, which belong to the {111}_fcc family; while for [111] loading, the hcp phase grows into a laminar structure in three planes, which belong to the {111}_fcc family except for the (111) plane. In addition, the phase transition is evaluated by using the radial distribution functions.