Near net shape fabrication of anisotropic Fe-6.5%Si soft magnetic materials

Efficient and cost-effective soft magnetic materials (SMMs) are essential for accelerating the adoption of electric vehicles and the sustainable growth of renewable electricity. While amorphous and nanocrystalline SMMs offer remarkably low magnetic losses, their poor mechanical properties, limited availability in size and shape (particularly ribbon widths), and high cost prevent them from widespread industrial application. Here, we show that ductile Fe-6.5%Si 2-D flakes could be used as building blocks for making high performance bulk SMMs. This approach bypasses the brittleness problem and creates a new morphology and a new fabrication method for the SMMs with improved energy efficiency and lower processing cost. Ductile Fe-6.5%Si flakes are mass-produced by melt spinning and are then consolidated to bulk SMMs with a brick-wall type of structure. The novel process introduces anisotropic electrical and magnetic properties and enables near net shape processing. Resulting Fe-6.5%Si thin sheets display low iron loss (W10/400 = 6.1 W/kg) and high permeability (µr = 28,000), which are comparable to the current state of the art high silicon steel. CaF2 coating reduces the iron losses for thick Fe-6.5%Si parts. Polymer coated Fe-6.5%Si flake cores show potential for high power inductors with greater permeability and lower losses than traditional powder cores.