Structural defects and internal stress field distribution in nanocrystalline Fe73.5Cu1Nb3Si13.5B9

The positron annihilation Doppler broadening technique and micromagnetism method have been employed to investigate structural defects in nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloy. The results show that the precipitation of α-Fe(Si) in the amorphous matrix involves few defects at the early stage of crystallization, while at the second stage a large amount of defects associated with grain boundaries becomes dominant. 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 nanocrystalline Fe73.5Cu1Nb3Si13.5B9 can be explained. (orig.)