Diffusion behavior of helium in titanium and the effect of grain boundaries revealed by molecular dynamics simulation

Cheng Gui-Jun¹, Fu Bao-Qin^{2, †,}, Hou Qing², Zhou Xiao-Song¹, Wang Jun²

Ensemble-averaged MSD (⟨R²⟩) along the x, y, and z axes as a function of time (Δt) at T = 900 K for He (a) and He₂ (b) in bulk Ti. The diffusion coefficient (half of the slope of the fitted line) is anisotropic (D_zz > D_xx ≈ D_yy).