Twinning dominated microstructural evolution in tungsten under impact loading

Under extreme conditions such as impact loads, the dominant mechanism of tungsten (W) deformation is not well understood, and this problem is crucial for the application of W in various industrial and mechanical applications. This study aims to reveal that problem by using molecular dynamics simulation with a model system featuring hat-shaped nanocrystalline W under impact loading at a velocity of 600 m/s. To assess the impact of different interatomic potentials, five commonly used potentials were compared and analyzed their influence on W's microstructural evolution during impact loading. The study uncovers that plastic deformation in nanocrystalline W predominantly occurs through the formation of deformation twins. These twins are generated at the surface, grain boundaries, or through twin-twin interactions, and they migrate via disconnection-mediated processes. These identified mechanisms contribute to both internal microstructural evolution and changes in surface morphology. Furthermore, it is observed that impact compression leads to crack propagation and dynamic recrystallization, aligning with previously established experimental results. These findings highlight variations that can be attributed to artificial effects while ensuring consistent dominant mechanisms. This research enhances the understanding of W's behavior under extreme conditions, providing valuable insights into its deformation mechanisms and microstructural evolution.