Powder-to-near net shape manufacturing: in-situ friction stir forging of soft magnetic composites

Abstract

Abstract Soft magnetic materials are critical to the performance, energy efficiency, and miniaturization of electric motors. While laminated soft magnetic materials have dominated the industry, the demand for soft magnetic composites (SMCs) is rapidly growing in applications requiring three-dimensional magnetic flux paths, reduced eddy current losses, and high-frequency operation. This study reports for the first time, in-situ friction stir forging (I-FSF), an innovative and single-step consolidation process for Fe-3.5Si soft magnetic powders. By leveraging pre-oxidized powders, the process generates oxide layers that enhance electrical resistivity. Unlike conventional sintering methods that require prolonged diffusion times, I-FSF promotes rapid densification and enables near-net-shape fabrication of dense SMC components with exceptional structural integrity in a single-step. The resulting components exhibit outstanding performance metrics, including tensile strength exceeding 650 MPa, saturation magnetization of 187 emu/g, and coercivity below 10 Oe, achieving the ideal balance between mechanical durability and magnetic efficiency. The proposed I-FSF process offers a simplified manufacturing route for producing advanced SMCs tailored for next generation electric motor applications, providing an alternative approach to magnetic material fabrication.