Approach to saturation in textured soft magnetic materials

Abstract

A model has been developed for calculating the anisotropic magnetic properties of soft magnetic materials with the objective of accounting for variations in permeability in textured materials. The model in its current form takes account of the rotation of the magnetization direction in each domain of a textured polycrystal and, thus, is applicable to large applied fields. The magnetization direction is determined by minimizing the sum of the magnetocrystalline anisotropy energy and the energy of interaction between the applied field and local magnetization. Examples are given of the application to idealized textures, such as fiber textures, in which all grains share a common axis parallel to the sheet normal (ND). The cube fiber (〈100〉‖ND) has the highest permeability at any applied field, followed by a randomly oriented polycrystal, with the gamma fiber (〈111〉‖ND) having the lowest permeability. Two further examples are given of textured steel sheets, often referred to as “nonoriented electrical steels,” intended for use as laminations in rotating electrical machinery. In one case, the two samples show that a random texture is preferable to one in which the rolling texture is retained. The second example demonstrates the importance of a particular texture component, the Goss or 〈001〉{110}, for producing an anisotropic permeability.