Advancements in Developing Fe-Based Metallic Glasses for Additive Manufacturing of Soft Magnetic Components

This research aims to create suitable Fe-based soft magnetic amorphous alloys for the 3D printing of motor components, concerning the iron-silicon-boron (Fe-Si-B) ternary system [1]. Since a fully amorphous structure of the 3D-printed parts is expected to improve motor efficiency, i.e. increased magnetic softness and decreased energy losses, the glass forming ability (GFA) is enhanced through the judicious change of the alloy chemical composition yet maintaining competitive soft magnetic properties. A higher GFA of the alloys enhances the possibility of achieving a fully amorphous structure of the printed parts.<br/>The GFA of the compositions was studied by evaluating the critical casting thickness (<i>d_c</i>) of the samples, which were produced in the form of ribbons and plates in the thickness range of 35 to 800 micrometers by melt spinning and suction casting. Subsequently, conventional X-ray diffraction (XRD) and high-intensity X-ray diffraction (wide-angle X-ray scattering by synchrotron), differential scanning calorimetry (DSC), and differential thermal analysis (DTA) were used to characterize the structure and thermal behavior of the samples of new alloys. The magnetic properties including saturation polarization (<i>J</i>_s) coercivity (<i>H</i>_c), and magnetic susceptibility (<i>χ</i>) were determined under quasi-static conditions by a vibrating sample magnetometer (VSM). Furthermore, hysteresis loops were measured in a low and medium frequency range up to 1 kHz using a digital wattmeter.<br/>Evaluation of quaternary and quinary component alloys involved studying the effects of promising elements such as niobium and nickel on GFA and magnetic properties. Finally, optimal compositions were identified with a critical casting (<i>d_c</i>) of 1.5 mm for the rods, supercooled liquid region (ΔX) of 45 to 50 degrees, saturation polarization <i>J_s</i> ranging from 1.1 to 1.3 T, and coercivity <i>H_c</i> between 3 and 5 A/m (ribbons, <i>J</i> = 0.5 T).