Thin films of the amorphous alloy were deposited by ion-beam sputtering of a composite target. Analogous to the melt-spun amorphous alloys of similar composition, the crystallization of the amorphous film occurred in 2 steps, but with a substantially reduced thermal stability. After completion of the first crystallization step, which started at 473K, the microstructure consisted of 12nm nanocrystals of body-centered cubic Fe, embedded in the grain boundary region of the remaining amorphous phase. At 673K, the remaining amorphous phase transformed into Fe2Zr. Self-diffusion measurements of Fe in the nanocrystalline state and in the parent amorphous state were carried out by using secondary ion mass spectroscopy depth profiling and neutron reflectivity techniques. In contrast to the case of finemet Fe73.5Si13.5B9Nb3Cu1 alloy, where significant enhancement of the diffusivity took place in the nanocrystalline state, the diffusivity in the nanocrystalline state - in the present case - was similar to that in the parent amorphous state. It was suggested that, in this system, atomic diffusion occurred mainly via grain boundary regions. The calculated values of the pre-exponential factor and the activation energy for diffusion were 10−14m2/s and 0.7eV.

Iron Self-Diffusion in Nanocrystalline FeZr Thin Films. A.Gupta, M.Gupta, U.Pietsch, S.Ayachit, S.Rajagopalanl, A.K.Balamurgan, A.K.Tyagi: Journal of Non-Crystalline Solids, 2004, 343[1-3], 39-47