Improving the soft magnetic properties of binder jet printed iron-silicon alloy through boron addition

Abstract

Fe–Si alloys are an essential class of soft magnetic materials due to their high magnetic permeability and low hysteresis loss. Increasing the Si content above 3 wt% promotes coarser grain sizes and greater electrical resistivity, thereby enhancing the magnetic properties, such as magnetic permeability and specific loss density. However, the increased silicon content makes the machining challenging. Additive manufacturing technologies enable production of near net shape Fe–Si alloys with high silicon content, practically eliminating the machining challenges. This work investigated the effects of Si content, which ranged from 3 to 5 wt%, and B content, which ranged from 0 to 0.25 wt%, on the microstructure and magnetic properties. The Fe–Si–B alloys were binder jet printed, where the sintering temperature was varied between 1200 and 1250 °C, and microstructure-magnetic property relationships were investigated by characterizing the magnetic permeability, intrinsic coercivity, grain size, and density. The Fe-5wt.%Si alloy with 0.25% B sintered at 1200 °C exhibited the highest magnetic relative permeability (4447) and the lowest intrinsic coercivity (47.8 A/m).