In-Situ alloying of high-silicon soft magnetic alloy in laser powder bed fusion

Additive manufacturing via laser powder bed fusion (LPBF) enables fabrication of complex high-silicon soft magnetic steels that are otherwise difficult to process. This study investigates the use of in-situ alloying of FeSi6.5 as a cost-effective alternative to pre-alloyed powder. As-built samples produced with commercial powder and as-blended samples using in-situ alloying were characterized for relative density, microstructure, and magnetic properties. The study showed that the commercial powder samples achieved higher densities (94.2–97.7%) than the as-blended samples (84.7–95.1%), while the as-blended specimens exhibited keyhole-type melt pools and finer, strongly < 001>-textured grains. Saturation magnetizations of blended and commercial samples were comparable (up to ~ 1.88 T), while as-blended specimens consistently showed lower coercivity (1159–2 245 A/m) versus commercial counterparts (1468–2 414 A/m). Heat treatment at 1100 °C for 1 h reduced coercivity below 1000 A/m in all cases. Optimal magnetic-microstructural performance in as-blended samples was achieved at 90 μm pulse point distance and 150 µs exposure time, and at 90 μm pulse point distance and 100 µs exposure time for commercial powder. The results demonstrate that in-situ alloying produces FeSi6.5 components with competitive density, uniform Si distribution, favourable texture, and low coercivity after heat treatment, highlighting its potential for flexible, cost-effective LPBF of soft magnetic steels.