Enhancing performance of nitrogen diffusion in HCP and BCC titanium by diffusion temperature: Molecular dynamics simulation study

The diffusion coefficient of nitrogen atoms in HCP and BCC titanium was studied using molecular dynamics (MD) simulations. The modified embedded atom method was used to simulate the diffusion process of 900 nitrogen atoms placed at a hollow surface position of 18000 titanium atoms. The diffusion process was investigated at temperature range 600 to 1100 K in HCP titanium and at temperature range 1300 to 1800 K for BCC titanium, both with temperature intervals of 100 K. It was observed that the diffusion coefficient increases from 0.500×10-11 to 1.667×10-11 m2/s in HCP crystal and from 1.667×10-9 to 4.667×10-11 m2/s in BCC crystal. The diffusion activation energy values are 0.357 eV and 0.396 eV for HCP and BCC titanium, respectively. The simulation also shows that the diffusion depth of nitrogen atoms in the BCC structure is larger than that in the HCP structure. Some parameters of nitrogen diffusion behavior in the simulation results are better than the experimental data, thus making it happen in the near future.