Low-coercivity and high-resistivity medium-entropy alloy via binder jetting-enabled in-situ carbon doping

The advancement of power electronics demands soft magnetic materials combining magnetic properties with complex-shape manufacturability. Additive manufacturing (AM) offers a route for complex components but is limited by microstructural heterogeneity and residual stress, which degrade magnetic performance. Here, we report a binder jetting-enabled in-situ carbon doping strategy to fabricate a complex-shaped Fe43.2Co28.8Ni24Cr4 medium-entropy alloy. The non-melting binder jetting followed by high-temperature sintering promotes coarse, equiaxed FCC grains with negligible residual stress, enabling a low coercivity of 30 A/m, lower than that of previously reported additively manufactured soft magnetic alloys. Concurrently, carbon derived from binder decomposition is incorporated into the FCC lattice, elevating the electrical resistivity to 146 μΩ cm. The combination of low coercivity and high resistivity reduces core loss over 50–600 Hz. Direct domain observations reveal wide magnetic domains and highly mobile domain walls, supporting facile magnetization dynamics. This work establishes a manufacturing strategy coupling AM with in-situ compositional tuning for high-performance soft magnetic materials with complex geometries. This study reports a binder jetting-enabled in-situ carbon doping strategy to fabricate a complex shaped Fe43.2Co28.8Ni24Cr4 medium-entropy alloy with a low coercivity of 30 A/m and an electrical resistivity to 146 μΩ cm.