STRUCTURAL DEFECTS AND INTERNAL-STRESS FIELD DISTRIBUTION IN NANOCRYSTALLINE FE73.5CU1NB3SI13.5B9

The positron annihilation Doppler broadening technique and micromagnet ism method have been employed to investigate structural defects in nan ocrystalline Fe73.5Cu1Nb3Si13.5B9 alloy. The results show that the pre cipitation of alpha-Fe(Si) in the amorphous matrix involves few defect s at the early stage of crystallization, while at the second stage a l arge amount of defects associated with grain boundaries becomes domina nt. The pinning centers resulting from quasi-dislocation dipoles have an intense influence on the soft magnetic properties. In view of these structural defects, the optimum soft magnetic properties of nanocryst alline Fe73.5Cu1Nb3Si13.5B9 can be explained.