Magnetic domain observations have been used to clarify the relationship between metallurgical structure and the core loss, permeability, and magnetostriction of grain-oriented 3% Si-Fe. Both the prediction of domain structures based on anisotropy, magnetostatics, stress, etc., and the various methods of making domain observations are reviewed. Both static and dynamic domain structures are shown and used to illustrate the relationships among domain structure, metallurgical structure, and magnetic properties. Core losses are shown to depend on the domain wall spacing and mobility, which in turn are controlled by grain size, stress, and defect structure. The high field permeability ( B at H = 10 Oe) is related to the amount of flux closure structure present, which is determined by the misorientation of the grains in the material. Magnetostriction is caused entirely by the motion of 90° domain walls which are introduced during the formation of flux closure structure and by residual or applied stress.

Effect of Inclusions on Coercive Force of Iron

Magnetic properties and domain structure in grain-oriented 3% Si-Fe

Publisher Summary The chapter presents a study on ferromagnetic domain theory. The chapter presents a broad review of the physical principles of domain theory and of the crucial experiments which bear directly on the foundations of the subject of ferromagnetic domains. The chapter is organized in two stages. There is first an introductory survey, which describes the basic physical concepts of domain theory in general nonmathematical terms. The ideas are then developed in detail. The essential aspects of ferromagnetism are illustrated by the implications of the following experimental fact: It is possible to change the overall magnetization of a suitably prepared ferromagnetic specimen from a n initial value of zero (in the absence of an applied magnetic field) to a saturation value of the order of 1000 gauss, by the application of a field whose strength may be of the order of 0.01 oersted. This fact contains two significant observations: (1) it is possible in some cases to attain saturation magnetization by the application of a very weak magnetic field. (2) It is possible for the magnetization of the same specimen to be zero in zero (or nearly zero) applied field. The chapter discusses that domain structure is a natural consequence of the various contributions to the energy-exchange, anisotropy, and magnetic-of a ferromagnetic body. The chapter presents a discussion on coercive force, hysteresis, and reversible permeability, including reversible permeability and Barkhausen effect.

Effect of Inclusions on Coercive Force of Iron

Citations

Magnetic properties and domain structure in grain-oriented 3% Si-Fe

Ferromagnetic Domain Theory

Soft ferromagnetism in nanostructured mechanical alloying FeCo-based powders

Report on precipitation

Hard magnetic materials

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