Reactive diffusion in the roll bonded iron–aluminum system

The diffusion-controlled growth of iron aluminide (Fe2Al5) was studied on bulk Fe–Al solid state diffusion couples annealed for 10–90 min at 773–873 K. The layer growth kinetics was parabolic. The parabolic growth constants of the second kind for the exclusive growth of Fe2Al5 from the adjacent phases were calculated from the measurement on the Fe–Al diffusion couples. The rate constants of the second kind were in turn related to the diffusion properties of the aluminide. As a result, the interdiffusion coefficient, taking into account the diffusion of both elements, was obtained for Fe2Al5 phase. The resulting activation energy was 84.9 kJ mol− 1.