| Some classes of ferromagnetic materials are composed of discrete single-domain particles embedded in a nonmagnetic matrix. Material systems fitting this description are conducive to computer modeling to predict magnetic response.;The magnetic behavior of such materials under the influence of an applied field depends upon the response of the individual particles (governed by magnetic anisotropy) and the texture (orientation alignments) of the particle assembly. While magnetization influenced by shape anisotropy has been thoroughly examined, response under combined crystal, shape, and stress anisotropy has only been proposed. Further, the concept of texture has typically been applied only to crystal orientations, but application to shape and stress orientation is conceivable.;This work establishes theoretical initial magnetization and hysteresis curves for such materials. It considers textured assemblies of particles having either cubic or hexagonal crystal structure, under the combined influences of crystal, shape, and stress anisotropy.;Two models establishing individual particle response were developed. The simplified two-dimensional model defines total particle energy with angular respect to the field. Minimizing this energy by differentiation establishes the magnetic vector position, or magnetization, for a given field. Switching occurs at the point of instability (an additional differentiation). Computer numerical methods are employed to solve for the vector positions where the derivatives are zero. The more accurate and computationally complex three-dimensional model uses computer numerical minimization methods to establish those vector positions yielding minimum energy.;A data input file provides texture and particle properties to the models. While texture was described by Gaussian (normal) distributions ranging from random to full alignment about a preferred orientation, other orientation distribution functions could easily have been accommodated. Distributions were transformed to a radial distribution to rotate the texture and establish it with respect to field direction. Distributions representative of wire and sheet texture were simulated. To evaluate the magnetic response of random distributions of cubic crystals, suitable texture representations were developed for use with the two-dimensional model.;Results obtained throughout were consistent with magnetization process understanding. Additionally, the methods adequately predicted the magnetic response of Lodex, the stress effect in Permalloy, and the impact of ferromagnetic impurities. |
