8. Diffusion and collective behavior of grain boundaries

Grain boundary diffusivity plays an important role in many properties of polycrystals. Neither the knowledge of average intergranular diffusivity nor that of individual diffusivities attached to certain types of joints can be used to approach the problem of the contribution of a set of joints to the material's behavior. As a first step towards engineering grain boundaries, we need to establish the distribution of diffusivities and the activation energies of intergranular diffusion in polycrystals.