Study on the Magnetic Viscosity of Multi-Step Magnetized Heterogeneous Alloys

Abstract

The multi-step magnetization behavior caused by a variety of microstructures is common in magnetic materials. The study of the effect of heterogeneous structure magnetization behavior on magnetic viscosity provides extensive guidance for the long-term stability of magnetic materials. The microstructure of Fe-Co-Ni-Al-Ti-Cu alloy was regulated by heat treatment process, and homogeneous structure (S810) and heterogeneous structure (S830) samples were prepared. In the S830 sample, there are three steps of magnetization reversal due to the presence of α1' phases (split α1 phases). Part of the α1' phases are reversed under a lower magnetic field, and the other part has strong interaction with the α1 phases forming a closed stable magnetic domain structure, which enhances the switch field of α1 phases. Both first-order reversal curve (FORC) analysis and electron holography have confirmed this phenomenon. The magnetic viscosity coefficient of S830 is higher, but its magnetic field dependence is better. The quantitative calculation of energy barriers shows that the energy barriers of α1' phases are lower, which leads to the instability of S830 sample under low magnetic fields. The superposition of three magnetization reversal steps makes the variation of magnetic viscosity coefficient gentler.

Keywords: Multi-step magnetization, Heterogeneous structure, Electron holography, First-order reversal curves, Magnetic viscosity