Stress Dependence of Hysteresis Loss on Iron-Based Soft Magnetic Materials

Abstract

Magnetic properties of soft magnetic materials under stress are important, however, they have not been fully understood. We have studied on a magnetization process of soft magnetic materials, electrical steel sheets and nanocrystalline alloys, under stress, by investigating DC magnetization curves. As well known, a hysteresis loss of electrical steel sheets increases under compression. We found that the hysteresis loss of nanocrystalline alloys does not depend on stress. In this paper, experimental results and an interpretation on the loss mechanism were described. We have interpreted the magnetization process under compression as follows: magnetic domains distribute perpendicular to compression due to magnetoelasticity; the magnetization process is 90 degree domain wall movements in the domains. Based on this interpretation, the hysteresis loss under compression is well understood. Electrical steel sheets have crystal grains; so, the domain wall is trapped at the grain boundary in the movement process; then, hysteresis loss generates. On the other hand, nanocrytalline alloys have no crystal grains; therefore, the domain wall movement is smoothly and there is no hysteresis loss. [doi:10.2320/jinstmet.J2017024]