Breaking conventional limits of silicon content in Fe-xSi magnetic alloys through additive manufacturing

Abstract

Silicon steels, e.g., Fe-3.2% Si alloys, are widely used in energy conversion and transmission. Increasing the Si content can enhance electrical resistivity and reduce magnetic hysteresis loss, improving the energy efficiency. However, high silicon content decreases ductility and workability, limiting the Si content of the alloys that can be produced by conventional manufacturing. Instead, we used additive manufacturing by the direct energy deposition technique to produce high Si content Fe-Si alloys. Dense samples with up to 20% Si were successfully fabricated for the first time. A substantial change in saturation magnetization (from 90 to 209 emu/g) and a three-fold increase in hardness was observed with higher Si content. The electrical resistivity values tripled, enhancing the attractiveness of these higher Si content alloys. The yield strength, ultimate tensile strength also increased, from 71 to 545 MPa, and 91 to 567 MPa, respectively. The coercivity remained relatively unchanged in the range of 9.1 to 10.8 Oe. Our results demonstrate the potential of fabrication of bulk high Si content Fe-Si alloys via additive manufacturing.