Numerical simulation of a magnetostatically coupled composite magnet

The demagnetization behavior of the hard-soft composite magnet has been simulated with a simple model in order to understand better the magnetization reversal of die-upset composite magnets fabricated from blends of Nd–Fe–B ribbons and coarse Fe powders. The calculations show that soft magnetic inclusions of any size can be fully magnetically coupled with the hard matrix by long-range magnetostatic interactions provided that the inclusions form layers perpendicular to the magnetization direction. Though the magnetostatic coupling along does not lead to enhanced hard magnetic properties of the composite magnets, it makes the full exchange coupling between the hard and soft phases unnecessary and, therefore, relaxes the strict requirements for the size of the soft inclusions. The combination of magnetostatic coupling and partial exchange coupling in a die-upset magnet with layered morphology may facilitate the development of anisotropic hard-soft composite magnets with properties superior to the single-phase permanent magnets.