Sputter deposition of Cu on Al, under intense bombardment of low-energy ions resulted in the formation of 2 interfacial zones. The mean diffusion coefficient effective in the formation of the first zone, ≤ 3 x 10-10cm2/s, was attributed to vacancy supersaturation. The results strongly suggested that by supplying the necessary energy for the formation of vacancies, the activation energy for diffusion could be reduced to the level of the enthalpy of migration, provided lifetimes of freely migrating defects were sufficiently long.

Enhanced Diffusion of Cu in Aluminium under Low-Energy Ion Bombardment. Z.Sternberg, M.Stupnisek: Europhysics Letters, 2005, 71[5], 757-62