Microstructure and Domain Imaging of Magnetic Materials
A major portion of microstructural analysis of magnetic materials has centered on examination of optical, electron, and scanning probe metallographic techniques. This article reviews the methods pertaining to the microstructural examination of bulk magnetic materials, including microscopy techniques specific to magnetic materials (e.g., domain imaging), with specific examples where possible. It includes metallographic sample preparation procedures, followed by descriptions of microstructures of bulk magnetic materials. Information on magnetically soft materials, permanent magnets, magnetism and magnetic domains is also included. Finally, the article discusses microscopy techniques unique to magnetic materials characterization. Techniques used in the study of magnetic domain structures (microstructure) include the magneto-optical Kerr method, the Faraday method, and the Bitter technique. Scanning electron microscopy (magnetic contrast Types I and II), scanning electron microscopy with polarization analysis, Lorentz transmission electron microscopy, and magnetic force microscopy are also examined.