Fragility under shocking: molecular dynamics insights into defect evolutions in tungsten lattice

Tungsten has promising applications in high-radiation, high-erosion and high-impact environments. Laser peening is an effective method to enhance the surface mechanical properties of tungsten materials. However, the ultrafast dynamic mechanism of defect evolutions induced by laser shockwave in tungsten lattice is unclear. Here, we investigated the evolutions and interactions of various defects under ultrafast compressive process in tungsten lattice using molecular dynamic method. The results confirm the brittleness of tungsten and reveal that void can reduce the yield strain and strength of the tungsten lattice by accelerating defect mesh extension and promoting the dislocation nucleation around itself. Dislocation density is increased with compressive strain rate. Meanwhile, dislocation multiplication and motion reduce the elastic stage and play a dominant role during the plastic deformation of tungsten lattice. Additionally, void can disrupt the dislocation displacement and promote the pinning effect on dislocations by defect mesh extension.