The diffusion mechanism in Ni3Al, over grain boundaries of tilt <111> and <100> type, was studied using the method of molecular dynamics. It was found that grain boundary diffusion represented a combination of three principal mechanisms: the migration of atoms along the nuclei of grain boundary dislocations, a cyclic mechanism near to the nuclei and the formation of a chain of displaced atoms from one dislocation nucleus to the nucleus of another one. The diffusional mobility of Ni atoms was essentially higher than the mobility of Al atoms. Grain boundary slipping and intergrain slipping were also observed during deformation of the bicrystal.

Diffusion Mechanisms near Tilt Grain Boundaries in Ni3Al Intermetallide. Starostenkov, M.D., Sinyaev, D.V., Rakitin, R.Y., Poletaev, G.M.: Solid State Phenomena, 2008, 139, 89-94