Molecular Dynamics Simulation of the Unidirectional Tensile Properties of Single-Crystal Magnesium with Central Holes
摘要
In this study, molecular dynamics simulations combined with the embedded atom method were employed to investigate, at the atomic scale, the tensile properties and deformation mechanisms of single-crystal magnesium containing spherical voids under different tensile orientations ([0001], [10_10]and [11_20]) at 300 K and a strain rate of 2 × 109 s−1. The results indicate that the tensile behavior of void-containing single-crystal magnesium exhibits pronounced anisotropy, and the formation and evolution of deformation bands differ significantly across crystal orientations. For the [0001] orientation, the elastic modulus and yield strength reach the highest values, and the energy barrier for initiating plastic deformation is also the largest. The dominant deformation mechanism involves dislocation motion, accompanied by the nucleation of twins and, occasionally, the appearance of stacking faults. For the [10_10] orientation, deformation bands first emerge around the void, followed by severe void necking, which leads to an increasing number of deformation bands. Subsequently, stacking faults and microcracks are generated. The propagation and coalescence of these microcracks eventually cause fracture and material failure. For the [11_20] orientation, microcracks perpendicular to the tensile direction develop inside the crystal. These cracks gradually coalesce with the void and extend toward the upper and lower periodic boundaries. Ultimately, the cracks propagate to the crystal edges, resulting in fracture and failure.