Self-Diffusion in Grain Boundaries and Dislocation Pipes in Al, Fe, and Ni and Application to AlN Precipitation in Steel

Diffusion along microstructural defects, such as grain boundaries or dislocation pipes, is significantly faster than diffusion through an undisturbed crystal. The ratio of diffusion enhancement is 3-4 orders of magnitude close to the melting point and reaches up to several ten orders of magnitude close to room temperature. An assessment of literature shows a large scatter in the available data and emphasizes the need for representative mean values. Applying a least mean square fit to selected experimental information delivers temperature-dependent functions for the ratio of grain boundary and dislocation pipe to bulk diffusion, respectively. We demonstrate that application of the attained results in a computational framework for the kinetics of precipitation makes the predictive simulation possible for the evolution of particles located at dislocations and grain boundaries.