Plastic Deformation Mechanism for Nano-Polycrystalline Al/Mg Layered Composites

Abstract

Understanding the plastic deformation behaviour helps in optimising the mechanical properties of nano-polycrystalline layered composites, but analysing the deformation behaviour of composites at the atomic scale is a great challenge due to the current limited experimental conditions. This study employs the molecular dynamics (MD) method to comprehensively investigate the effects of various factors, such as grain sizes, strain rates and interlayer thicknesses of intermetallic compounds (IMCs), on the plastic deformation behaviour of nano-polycrystalline Al/Mg layered composites. The results indicate that the influence of grain size on deformation behaviour is governed by the strain rate, and an increase in grain size is inversely proportional to yield stress at low strain rates, whereas it is positively proportional to tensile stress at high strain rates. This phenomenon arises from the change in deformation mechanism from grain deformation to slip along grain boundaries in nano-polycrystalline Al/Mg layered composites as strain rate escalates. Additionally, an appropriate thickness of the intermediate layer contributes to the enhanced composite strength, while excessive thickness weakens its tensile strength, and the strengthening effect of the intermediate layer of IMCs diminishes at excessive strain rates. This research significantly enhances the understanding of the atomic-scale plastic deformation mechanism in Al/Mg composites, providing valuable insights for the preparation of high-quality layered composites.

Keywords: Nano-polycrystalline, Al/Mg layered composites, deformation mechanism, molecular dynamics, Intermetallic compounds