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 (H_c) and large saturation magnetization (M_s) however, remains challenging. In this study, soft magnetic alloys with the composition Fe_82–xSi₁₈Co_x (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 H_c followed by increment due to reduced magnetocrystalline anisotropy and increased saturation magnetostriction from negative to positive values of the alloys. Meanwhile, the M_s 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 H_c and M_s 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 H_c due to the aggravating pinning effect on the domain wall movement, which arises from the inhomogeneous magnetization distribution caused by increasing antiphase boundaries.

中文翻译：

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性能增强的 Fe–Si–Co 软磁合金的成分和微观结构工程


对高效和低损耗能量转换和传输技术的需求不断增长，推动了先进的 Fe-Si 基软磁合金的发展。然而，同时实现低矫顽力 （H_c） 和大饱和磁化强度 （M_s） 仍然具有挑战性。在这项研究中，设计了成分为 Fe_82–xSi₁₈Co_x（x = 0 at.%、4 at.%、8 at.%、12 at.%、16 at.% 和 20 at.%）的软磁合金，然后进行了微观组织调整。Co 掺入导致 H_c 最初降低，然后由于磁晶各向异性降低和合金的饱和磁致伸缩从负值到正值增加而增加。同时，M_s 升高，随后减少，这源于 根据第一性原理计算，Fe 原子平均矩增加和 Co 原子平均矩减少的竞争机制。Fe₇₀Si₁₈Co₁₂ 与协同优化的 H_c 和 M_s 退火过程中的微观结构演变表明，在高温退火后，DO₃ 相主要从 B2 相转变，伴随着有序程度的增加。DO₃ 相的增长使 H_c 恶化，这是由于反相边界增加引起的不均匀磁化分布引起的畴壁运动的固定效应。