# An Additively Manufactured Fe-3 Si Stator for a High-Performance Electrical Motor
## 1 Introduction
It is desirable for electrical motor or generator applications, where the magnetic field is constantly changing directions, to eliminate magnetic anisotropy through the addition of silicon. The addition of silicon substitutes Fe atoms with Si atoms and reduces the number of atoms with a magnetic moment that requires magnetic field strength to align them in the direction of the magnetic field, increases the ease of magnetization, and reduces the magnetic anisotropy. However, very high Si content leads to drawbacks in material properties as well. Both saturation magnetization and maximum permeability decrease at very high Si levels. The addition of Si to iron reduces the magnetic polarization of iron. Magnetic polarization expresses the density of magnetic dipole moments within a material. The reduction in magnetic polarization leads to a reduction in the saturation magnetization. This also reduces magnetic permeability at high induction as the maximum flux density in a given volume of the material is reduced. When silicon content is higher than 3 weight percent, the brittleness of the steel is increased, and the cold deformability of the material is impaired. This increases the difficulty and costs of processing such materials [20; 21; 22; 23]. Fe-3 Si is the most widely used soft magnet. The lamination steel in most electric motor and generator cores is made of Fe-3 Si. The conventional method to manufacture this alloy is well developed and very cost-effective. However, there is a possibility for 3D printing to make it even more cost-effective. AM has the capability to print multimaterial composites, and this could potentially eliminate the necessity of the entire lamination process. Fe-3 Si printing has been explored to investigate the resulting microstructure and other characteristics. For example, conductive material powder and insulating material powder could be premixed into one feedstock for printing, or, by utilizing a two-feed printer, conductive layers, and insulating layers can be printed alternately. The process described herein is merely the first step towards achieving these ultimate goals in the additive manufacturing of electrical machine cores. In this paper, the possibility of AM for Fe-3 Si to produce an assembly of electrical stator core laminates from a monolithic print by SLM followed by electrical discharge machining is investigated. This research is focused on demonstrating the viability of printing the surface finish and stacking laminates of the Fe-3 Si alloy with comparable electrical and mechanical properties for a conventional, brushless, permanent-magnet motor by Arnold Magnetic Technologies. Selective laser melting was utilized in this study to additively manufacture the Fe-3 Si stator (to cut laminates out of them), cylinders (for machining rings of different thicknesses and characterizing magnetic and electrical properties), and cubes (for measuring mechanical properties). Each cut laminate was heat-treated under pure H\({}_{2}\) at 750 \({}^{\circ}\)C and 800 \({}^{\circ}\)C for 2 h, insulated separately by epoxy coating, and assembled in the fixture to form the stator core. Epoxy has high dielectric strength, low electrical conductivity, thermal stability, and good mechanical bonding, making it an ideal choice as an insulative material. The rotor of the motor was fabricated via AM with dipolar cylindrical encapsulated permanent magnets that were 3D printed using fused deposition modeling (FDM) out of a Nd\({}_{2}\)Fe\({}_{14}\)B-polyphenylene sulfide (NdFeB-PPS) composite and post-magnetized at room temperature at a 5 T magnetization field [24]. The DC and AC magnetic properties of the SLM-printed and heat-treated samples demonstrated a high relative permeability (7490) and low eddy current loss. The motor was wound manually by three-phase windings to provide a path for current flow and create a magnetic field to spin the Fe-3 Si stator.