The structural relaxation of a high-angle grain boundary at elevated temperatures was simulated by molecular dynamics with the use of a bicrystal model composed of 399 atoms. The system studied was a (36.9°) [001] tilt boundary with interatomic interactions given by the empirical Johnson potential for -Fe. In the presence of an extrinsic vacancy, the boundary structure was found to be stable up to temperatures of at least two-thirds the melting temperature. Vacancy jumps, confined preferentially to within the grain-boundary core, were observed. Also observed were the thermal activation of vacancy-interstitial pairs, and with increasing temperatures a variety of more complicated vacancy-jump sequences. The simulation data were relevant to the understanding of fast diffusion along grain boundaries.

Molecular-Dynamics Studies of Grain-Boundary Diffusion. I. Structural Properties and Mobility of Point Defects. Kwok, T., Ho, P.S., Yip, S.:  Physical Review B, 1984, 29[10], 5354-62