Lorentz microscopy observations of a nanocrystalline Fe44Co44Zr7B4Cu1 alloy

Domain imaging of soft magnetic materials by transmission electron microscopy (TEM) is difficult due to the potentially saturating field of the microscope´s objective lens. Energy filtered Lorentz microscopy provides a low field, high resolution domain imaging solution for soft magnetic materials. This technique was successfully applied to a soft magnetic nanocrystalline alloy to examine the domain configurations in a thin foil sample. A sample with composition Fe₄₄Co₄₄ Zr₇B₄Cu₁ annealed at 650°C for one hour was examined. Both Foucault and Fresnel methods were used to develop a clear picture of the relationship between the microstructure and domain structure of this alloy. Magnetic domain maps were created showing some regions of the sample with irregularly shaped domains, which are characteristic of amorphous alloys. Other regions contained relatively large grains with the magnetization in a circular in-plane configuration (presumably due to shape anisotropy)