Molecular dynamics simulation of the behavior of titanium under high-speed deformation

Abstract

We present molecular dynamics simulation to study the α–ω phase transformation in titanium under different conditions simulating high-energy impacts. We employed the interatomic potential developed within the N-body method, which predicts the stability of the ω phase and the stacking fault energy in the α phase in excellent agreement with the experimental and theoretical data. The latter is crucial for the correct description of the deformation mechanisms. The dependence of the beginning and mechanism of the α–ω transition process on loading conditions are derived. In particular, at the uniaxial compression along the [0001] direction at 300 K, the ω phase is localized in deformation bands within the α phase, and the α–ω transition is observed at a pressure of more than 3 GPa. With this type of deformation, the residual inclusions of the α phase remain in the ω phase volume. A similar deformation at a temperature of 700 K does not lead to the formation of the ω phase. Meanwhile, at the hydrostatic compression, the α–ω transition is restrained and at a pressure of 20 GPa is not observed. In the case of anisotropic three-axis deformation along the α–ω transition pathways proposed by Trinkle et al at a constant pressure of 20 GPa, the transition mechanism includes the formation of dislocations, followed by the transformation of the regions between the dislocations into the ω phase. The simulation results demonstrate good agreement with the experimental data and confirm the applicability of the employed interatomic potential for simulating the deformation of titanium.