传统软磁合金的力学性能难以满足复杂加工成型或高强度机械负荷的要求，而新型中/高熵软磁合金往往以部分牺牲比饱和磁化强度(M_s)为代价来实现优良力学性能。本工作通过调控冷轧态等原子比FeCoNi中熵合金的退火工艺，获得再结晶体积分数约为49%的异构组织。基于微观组织表征、直流软磁测试、磁光Kerr显微成像分析、拉伸力学测试等手段，研究了异构对FeCoNi中熵合金软磁和力学性能的影响机理。结果表明，该种异构合金的M_s约为152.5 A·m²/kg，与均匀再结晶合金在同等条件下测得的数值相近；其矫顽力约为205.3 A/m，低于均匀未再结晶合金(242.2 A/m)，但高于均匀再结晶合金(79.8 A/m)。异构FeCoNi中熵合金中，再结晶区磁畴壁的移动较平滑，仅在晶界和孪晶界处受到明显的钉扎作用；未再结晶区域缺陷密度较高，对磁畴壁的钉扎作用更强，磁畴壁在外加磁场作用下的移动较缓慢，使矫顽力升高。应力加载时，异构组织中的长程背应力效应可提升合金屈服强度，各区域的协调变形可优化加工硬化能力，使合金屈服强度(σ_y)达到467 MPa，抗拉强度(σ_u)达到610 MPa，且延伸率(δ)保持在30%，与均匀未再结晶合金(σ_y = 772 MPa、δ = 15%)和均匀再结晶合金(σ_y = 232 MPa、δ = 43%)相比拥有更好的强塑性搭配。

The equiatomic FeCoNi medium-entropy alloy (MEA) demonstrates promising attributes as a soft-magnetic material, including high saturation magnetization, high Curie temperature, and excellent ductility. However, its practical applications are constrained by relatively low yield and ultimate strengths. Recent studies explored strengthening FeCoNi alloy through the addition of other alloying elements or nanosized oxide particles (e.g., Al, Ti, Ta, and Y₂O₃). Although these additions often result in decreased saturation magnetization, they adversely affect the soft-magnetic properties. In this study, a heterostructured FeCoNi MEA, with approximately 49% (volume fraction) recrystallization, is achieved through annealing treatment. The influence of this heterostructure on mechanical and soft-magnetic behaviors of the MEA is systematically investigated. The results indicate that the heterostructured alloy maintains a specific saturation magnetization comparable to the fully-recrystallized version, approximately 152.5 A·m²/kg. Its coercivity, at 205.3 A/m, is lower than the non-recrystallized alloy (242.2 A/m) but higher than the fully recrystallized version (79.8 A/m). Magneto-optical Kerr analysis reveals that recrystallized zones in the heterostructure rapidly respond to external magnetic field changes, whereas non-recrystallized zones strongly interact with Bloch walls, pinning domain movement and thereby increasing coercivity. Furthermore, the heterostructured alloy exhibits enhanced mechanical properties: yield strength (σ_y) at 467 MPa, ultimate tensile strength (σ_u) at 610 MPa, and total elongation (δ) at 30%. This performance surpasses that of fully non-recrystallized (σ_y = 772 MPa, δ = 15%) and fully recrystallized (σ_y = 232 MPa, δ = 43%) alloys. These improved mechanical properties are partly attributable to long-range back stress, arising from the combination of soft recrystallized and strong non-recrystallized zones. This stress, produced by the strain gradient in the heterostructure, impedes geometrically necessary dislocations from slipping and enhances deformation compatibility, thereby preventing premature fracture. According to Ashby-type maps, the proposed heterostructured FeCoNi MEA bridges the gap between traditional soft-magnetic alloys and novel FeCoNi-based alloys in terms of soft-magnetic and mechanical properties.