Role of crystal orientations and loading conditions on the microstructure evolution and void evolution dynamics in single crystal iron: An atomistic investigation

An understanding of void evolution dynamics is required to develop/improve fracture models at a high strain rate to predict spall fracture at the macroscale. We perform molecular dynamics simulations to explore the role of crystal orientations and loading conditions on the microstructure evolution and void evolution dynamics in single-crystal iron. We find that all the cases of crystal orientations show structural transformations consistent with experiments. The dominance of the nucleation and growth of voids is sensitive to the applied loading conditions and crystal orientations. Void growth dominates under uniaxial deformation, and void nucleation dominates under triaxial deformation. Peak tensile pressure, the amount of structural transformation, and overall void volume fraction are insensitive to the crystal orientations under triaxial deformation, while they are susceptible under uniaxial and biaxial deformations. The dislocation evolution, number of voids, and size distributions of voids are all very sensitive to the applied loading conditions and crystal orientations. A small percentage of voids accounts for the majority of the total volume of the voids.