Composition and microstructure engineering of Fe–Si–Co soft magnetic alloys with enhanced performance

• Published in: Journal of materials science & technology 2024-10
• Main Authors: Chen, Qiming, Wang, Kebing, Wang, Lingfeng, Jin, Jiaying, Yan, Mi, Wu, Chen
• Format: Article
• Language: English
• Subjects: Compositional design; Fe–Si–Co alloy; Magnetic domain; Magnetic property; Microstructural evolution
• ISSN: 1005-0302
• DOI: 10.1016/j.jmst.2024.08.069

•Fe-Si-Co ternary alloys designed to break the trade-off between magnetization and coercivity.•Impacts of composition tuning on magnetic moment, anisotropy and magnetostriction unveiled.•Detailed microstructural and phase evolution revealed for the Fe-Si-Co during annealing.•Effects and underlying mechanisms of the DO3 growth on magnetic performance clarified. The growing demand for high-efficiency and low-loss energy conversion and transportation techniques urges the development of advanced Fe–Si based soft magnet alloys. Simultaneous achievement of low coercivity (Hc) and large saturation magnetization (Ms) however, remains challenging. In this study, soft magnetic alloys with the composition Fe82–xSi18Cox (x = 0 at.%, 4 at.%, 8 at.%, 12 at.%, 16 at.%, and 20 at.%) have been designed followed by microstructural tuning. The Co incorporation results in initially decreased Hc followed by increment due to reduced magnetocrystalline anisotropy and increased saturation magnetostriction from negative to positive values of the alloys. Meanwhile, the Ms raises with subsequent reduction, which origins from competitive mechanisms of increased average moment of Fe atoms and decreased average moment of Co atoms according to first principles calculations. Microstructural evolution during annealing of the Fe70Si18Co12 with synergistically optimized Hc and Ms has been revealed that after elevated-temperature annealing, the DO3 phase is predominately transformed from the B2 phase accompanied by an increase in the degree of ordering. The growth of the DO3 phase deteriorates the Hc due to the aggravating pinning effect on the domain wall movement, which arises from the inhomogeneous magnetization distribution caused by increasing antiphase boundaries. [Display omitted]