Fe diffusion in nanocrystalline alloys and the influence of amorphous intergranular layers

Fe-59 tracer diffusion is used as a highly structure-sensitive tool for pro bing the interface structure and residual amorphous intergranular phases in nanocrystalline (n-) Fe90Zr10 produced by crystallization of melt-spun amo rphous ribbons. Analyses of Fe-59-diffusion profiles show the existence of two types of interfaces. In the one type the diffusivities are low; the oth er type acts as fast diffusion paths like conventional grain boundaries in alpha-Fe. In accordance with positron-annihilation and hydrogen-site spectr oscopy of the interfacial structure on n-Fe90Zr10, the slow diffusion proce ss may indicate the presence of amorphous intergranular layers similar as r ecently found for n-Fe73.5Si13.5B9Nb3Cu1. (C) 1999 Acta Metallurgica Inc.