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

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 ( at 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.