Structural Phase Transition of Single-Crystalline Iron under Shock Loading along the [110] Direction: Molecular Dynamics Simulations Based on Different Potential Functions

Single-crystal iron is a prototypical system for studying the dynamic behavior of metallic materials under shock loading, which is of great significance in high-pressure phase transition research due to its phase transformation mechanisms and mechanical response characteristics. In this work, molecular dynamics simulations were performed to investigate the mechanical response of single-crystal iron under shock loading along the [110] crystallographic direction. Three different potential functions (Ackland, Mishin, optimized MAEAM) were employed to examine differences in stress transmission, dislocation activity, and new phase formation, as well as to explore the coupling mechanisms between plasticity and phase transformation. The results indicate that the BCC-HCP phase transition pressure predicted by the Ackland potential (14.03 GPa) is closest to experimental data, with dynamically stable dislocation density, suggesting strong coupling between plasticity and phase transformation. In contrast, the Mishin potential exhibits sequential plasticity and phase transformation, while the optimized MAEAM potential predicts a higher phase transition pressure. Furthermore, all three potentials exhibit the same phase transformation mechanism: BCC compression followed by shear-induced stacking fault formation and subsequent reorientation.