A study was made of interstitial diffusion along twist grain boundaries by using the embedded atom method. Six (100) twist grain boundaries (8.79 to 43.6) were investigated. It was found that the interstitial formation energies were much lower (0.26 to 0.78eV) than in the bulk, while the migration energies were found to be comparable (0.01 to 0.24eV) to the bulk value of 0.09eV. A vacancy mechanism was favored in low-angle boundaries, while an interstitial mechanism was favored in high-angle boundaries. The variations in formation energy as a function of twist angle were partially explained in terms of a volume expansion of the grain boundary. The total diffusion rate, due to both mechanisms, was calculated. It agreed reasonably well with experimental data for Cu in polycrystalline Cu. The calculated diffusion rates for specific twist boundaries also agreed well with experimental measurements for Zn/Al.

Interstitial Diffusion along Twist Grain Boundaries in Cu. M.Nomura, J.B.Adams: Journal of Materials Research, 1995, 10[11], 2916-24