Wu You, Shi Lingxiang, Wang Ranbin, Jia Jili, Guo Wenhui, Su Yunshuai, Bu Hengtong, Xiang Siqi, Yang Weihong, Fu Mingli, Shao Yang, Yao Kefu
School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China.
Materials (Basel). 2025 Jun 17;18(12):2867. doi: 10.3390/ma18122867.
High-Cu-content (Cu-content > 1.3 at.%) nanocrystalline alloys exhibit wide heat-treatment windows and favorable soft magnetic properties due to the presence of pre-existing α-Fe nanocrystals. By fabricating ribbons with varying thicknesses to tailor cooling rates, distinct structural characteristics were achieved in FeBCu alloy ribbons. Notably, the face-centered cubic (fcc) γ-Fe phase was identified in Fe-based nanocrystalline alloys. The precipitation of the fcc γ-Fe phase originates from a phase-selection mechanism under specific cooling conditions, while its retention in the as-quenched ribbon with a thickness of 27 μm is attributed to kinetic suppression during rapid cooling and the nanoscale stabilization effect. The formation of the fcc γ-Fe phase significantly reduced the saturation flux density () and increased coercivity (), concurrently destabilizing the residual amorphous matrix. By suppressing the precipitation of the γ-Fe and FeB phases through precise control of ribbon thickness and annealing parameters, the alloy ribbon with a thickness of 16 μm achieved an optimal combination of (1.82 T) and (8.3 A/m). These findings on anomalous fcc γ-Fe phase precipitation provide novel insights into metastable phase engineering and offer structural design guidelines for alloys containing pre-existing α-Fe nanocrystals.
高铜含量（铜含量>1.3原子百分比）的纳米晶合金由于预先存在的α-Fe纳米晶体而表现出宽的热处理窗口和良好的软磁性能。通过制造具有不同厚度的薄带来调整冷却速率，在FeBCu合金薄带中实现了独特的结构特征。值得注意的是，在铁基纳米晶合金中鉴定出了面心立方（fcc）γ-Fe相。fccγ-Fe相的析出源于特定冷却条件下的相选择机制，而其在厚度为27μm的淬火薄带中的保留归因于快速冷却过程中的动力学抑制和纳米级稳定效应。fccγ-Fe相的形成显著降低了饱和磁通密度（）并增加了矫顽力（），同时使残余非晶基体不稳定。通过精确控制薄带厚度和退火参数来抑制γ-Fe和FeB相的析出，厚度为16μm的合金薄带实现了（1.82T）和（8.3A/m）的最佳组合。这些关于反常fccγ-Fe相析出的发现为亚稳相工程提供了新的见解，并为含有预先存在的α-Fe纳米晶体的合金提供了结构设计指导。
