Structural differences between the nanocrystalline Fe86Zr7B6Cu1 and Fe73.5Si13.5B9Nb3Cu1 alloys

The initial permeability, density and microstructure are compared as a func tion of the annealing temperature for nanocrystalline Fe86Zr7B6Cu1 and Fe73 .5Si13.5B9Nb3Cu1 alloys. In the optimum annealed state where the initial pe rmeability is the maximum, flat disc-shaped bcc-Fe(Zr) grains were observed by transmission electron microscopy in Fe86Zr7B6Cu1 in contrast to equiaxe d bcc-Fe(Si) grains in Fe73.5Si13.5B9Nb3Cu1. X-ray diffraction revealed a p referred orientation of the bce grains and large internal stresses in the n anocrystalline Fe86Zr7B6Cu1 alloy. All these observations may partly contri bute to the fact that in the optimum annealed state, the initial permeabili ty is much higher for Fe73.5Si13.5B9Nb3Cu1 than for Fe86Zr7B6Cu1 (C) 1999 A cta Metallurgica Inc.