Calculation of fast pipe diffusion along dislocation stacking fault ribbon

The diffusion of an interstitial Si atom along an edge dislocation in Al is studied by using a quantummechanics/molecular-mechanics coupling method. It is found that the diffusing Si atom follows approximately a sinusoidal trajectory. The diffusion energy barrier along the partial dislocation core is in excellent agreement with the experimental value. We predict that the stacking fault ribbon could provide a fast pathway for diffusion which increases the diffusivity by 6-7 orders of magnitude comparing to the bulk value at 700 K. At the same temperature, the diffusivity along the stacking fault is found to be three to four orders of magnitude greater than that along the partial dislocation core.