Ferromagnetic Domain Structures in Cementite

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Abstract
By means of transmission electron microscopy, ferromagnetic domain structures have been studied in thin cementite (Fe3C) particles embedded in a ferrite matrix. In general, the domain structure was found to consist of parallel strips alternately magnetized along the positive and negative direction of the easy axis of magnetization [001]. By means of selected‐area electron diffraction the orientation of the cementite particles relative to the foil surface was determined. The domain walls lie in the (100) plane of the cementite lattice, and the width of the domains, as a function of angle between easy axis and normal to foil, agrees very well with the model of Malek and Kambersky. At the cementite‐ferrite interface domains of closure frequently occurred in the ferrite, but were never found in the cementite. The width of the (Bloch) domain walls is roughly 100 Å, in reasonable agreement with the theoretical width computed for bulk cementite.