Structural Formation and Improved Performances of Chemically Synthesized Composition-Controlled Micron-Sized Fe_100−xCo _x Particles

Micron-sized composition-controlled Fe_100−x Co_x (20 < x < 75) alloy particles with high purity have been prepared by an optimized reduction reaction. The influence of Co content on the alloying process, structures, and magnetic properties of the products has been studied. The as-synthesized Fe_{100 −x}Co_x with x < 65 exhibit a single bcc crystal structure. A bcc-FeCo/fcc-Co composite structure can be formed in the Fe_100−xCo_x products with x > 65. Very slight surface oxidation is observed in all the products. The high purity and single bcc-FeCo phase for the well-alloyed Fe_{100 −x}Co_x particles with x < 65 lead to their high saturation magnetization of 182–220 A m² kg⁻¹. All the well-alloyed Fe_{100 −x}Co_x show nearly spherical morphologies with an average particle size of 2–8 μm, which results in their good compactibility with a high compacted density of about 7.4–7.6 g cm⁻³. The simple preparation and improved performances for these chemically synthesized composition-controlled FeCo particles show their great potential for applications in near-net-shaped and complex-shaped FeCo-based soft magnetic composite devices.