OBSERVATIONS BY LORENTZ MICROSCOPY OF MOVEMENTS OF MAGNETIC DOMAIN-WALLS IN AMORPHOUS FE78B13SI9 ALLOYS

The interaction between microstructure and magnetic domain configurati on has been studied in the Fe78B13Si9 amorphous alloy in as-quenched a nd partially crystallized states, using transmission electron microsco py in the Lorentz mode. TEM observations have been made in static and dynamic conditions under planar magnetic field applied in situ. The si ze of the domain structure in the as-quenched state is only slightly m odified by the onset of crystallization after annealing. The measured hysteresis loops in presence of various defects provide evidence of th e pinning effect between isolated domain walls and cracks and large pr ecipitates. When the defect density is high enough, alpha-Fe particles and precipitates can interact, without marked pinning, with DWs.