Mechanical Properties of Magnesium–Zinc Functionally Graded Materials: Insights from Molecular Dynamics Simulations

The functionally graded materials (FGM) structures achieve a combination of high strength and ductility compared with uniform alloy structure. Mg–Zn FGM has great application value in many fields such as aerospace fields and microelectromechanical construction. The change of two metal components will also bring about the difference of mechanical properties and physical properties. Therefore, six functionally graded materials with different metal content ratios were established and analyzed by molecular dynamics simulation. Tensile,compression and nanoindentation simulation of FGM were carried out at three temperatures of 220, 300, and 420 K. The simulation results show that the alloy have multiple plastic deformation mechanisms such as dislocation slip, deformation twinning, phase transformation from hexagonal close-packed (HCP) to face-centered cubic (FCC), and grain boundary plastic behavior. It is found that the strengthening effect of the alloy is very obvious, and the Young’s modulus changes significantly under tensile and compressive conditions. In the nanoindentation simulation, the nanohardness increases first and then decreases. Through the comparative analysis of multiple sets of data, this study can provide help for the design of Mg–Zn alloy functionally graded materials with superior performance to a certain extent. It can also provide insights for the utilization of alloys with different components at different temperatures.