Kinetic Monte-Carlo simulations were used to investigate the migration of He-bubbles in body-centered cubic Fe, using the binding energies of point defects to a He-bubble and the migration energies of an Fe atom on bubble surface, both of which were obtained by molecular dynamics and molecular static calculations. This approach linking multiple simulation methods could remove the degrees of freedom for lattice vibrations effectively and permitted the successful performance of long-term simulations. When the equilibrium concentration of point defects in a matrix was assumed, a He-bubble could migrate by the surface diffusion mechanism and showed the Brownian motion. The diffusion coefficient of larger He-bubbles than about 0.8nm in diameter was proportional to d−4, where d was the bubble diameter. It was in good agreement with conventional continuum theory predictions.

Modeling of He-Bubble Migration in BCC Fe. K.Morishita, R.Sugano: Nuclear Instruments and Methods in Physics Research B, 2007, 255[1], 52-6