Enhanced Magnetization in Metastable Disordered Fe₄Ga

Recent research has focused on developing soft magnetic materials with superior magnetic properties for next-generation inductor cores in electrified vehicles. We explored an alternative alloy to the traditional Fe-Nb-Cu-Si-B alloy using Ga substitution for Si. The novel Fe-Nb-Cu-Ga-B alloys were found to have a ~35% larger magnetization from VSM measurements. Structural characterization performed with XRD and SAED determined the crystal structure and microstructure. The diffraction patterns show a competition between the stable ordered Fe₃Ga (sp. gr. 225) phase and metastable disordered Fe₄Ga (sp. gr. 229) phase. From the complex microstructure, we were able to determine that the Fe₄Ga phase formed as an intermediate step as the Fe₃Ga phase was crystallizing due to the rapid cooling rate ~10⁶°C/s. First principles calculations found that the Fe magnetic moment increased by 35% in the Fe₄Ga phase compared to the Fe₃Ga phase, correlating with the experimentally measured increase in magnetization. Our findings show a significant increase in magnetization due to the presence of metastable disordered nanocrystalline phases, which may be the future of soft magnetic materials.