Magnetism, structure and the effects of thermal aging on (Fe/sub 1-x/Mn/sub x/)/sub 73.5/Si/sub 13.5/B/sub 9/Nb/sub 3/Cu/sub 1/ alloys

Amorphous alloys of (Fe/sub 1-x/Mn/sub x/)/sub 73.5/Si/sub 13.5/B/sub 9/Nb/sub 3/Cu/sub 1/, where x=0, 0.05, 0.10, 0.15, were prepared by vacuum melt-spinning. Anneals performed at or above the crystallization temperature led to the formation of a nanostructure where the primary phase is a body centered cubic or DO/sub 3/ FeSi phase embedded within an intergranular amorphous phase. The saturation induction of the x=0.05 alloy is 1.19 T, slightly lower than the parent alloy. Prolonged thermal aging led to an enhancement in the soft magnetic properties. This change occurs at soak times near 6000 s and corresponds to a decrease in the anisotropy and coercivity, and an increase in the remanent magnetization. EXAFS studies suggest that the Mn partitions during crystallization and thermal aging to the grain boundary regions may play an important role in enhancing the exchange coupling of the aged samples by increasing the Curie temperature of the amorphous intergranular phase.