Evolution of hyperfine structure and magnetic characteristic in Fe-Si-Cr alloy with increasing heat treatment temperature.

Fe-Si based alloys have been widely studied because of the excellent high frequency, soft magnetic properties, which are determined by the hyperfine structure of alloys. The evolution of the hyperfine structure and magnetic characteristics in an Fe-Si-Cr alloy with increasing heat treatment temperature have been studied. Fe-21.5 at.% Si-2 at.% Cr alloy powder was prepared and observed. The Fe-Si based alloys have three-step phase transitions under heat treatment. Hyperfine magnetic fields are increased after A2 ordered as the localized degree of 3d electrons decreased. Quadrupole splitting in alloys mostly originate from the paramagnetic phase, and the asymmetry of charge could increase the polarization response under high frequency microwaves. This could increase the microwave permittivity and paramagnetic phase ratio, which can contribute to better soft magnetic properties. The Mössbauer effective thickness of a Fe-Si-Cr alloy particles sample is calculated as 7.3345. Theoretical magnetic moments from first principle calculations and the Mössbauer result can be obtained and are consistent with experiment results. The formation of the DO3 phase could deteriorate soft magnetic properties of samples. High permeability of Fe-Si-Cr alloys can be obtained under heat treatment of the critical temperature when the DO3 phase starts to form. [ABSTRACT FROM AUTHOR]