Magnetic Properties of Fe-based Amorphous Alloys Produced by Melt-spinning and Selective Laser Melting

Amorphous soft-magnetic materials play an important role as core constituents in improving the energy transformation efficiency of electrical machines and passive electrical components [1]. Although the melt-spinning process remains the main technique for obtaining amorphous soft-magnetic ribbons with remarkable soft magnetic properties, new and efficient production methods based on additive manufacturing have been developed in recent years, enabling the direct synthesis of larger elements. Metal manufacturing techniques allow shaping the material into the desired geometry while simultaneously engineering its microstructure and properties.<br/>Ribbons were obtained by a conventional melt-spinning process, where the pre-alloy was first inductively melted in a quartz tube equipped with a nozzle under vacuum and then injected onto a rotating copper wheel by insufflating high-purity Ar. The 3D-printed samples were produced by additive manufacturing via Selective Laser Melting (SLM), using powder of the same alloy as a precursor. In this study, we investigate the hysteresis properties of amorphous Fe-Si-B-based alloys in ribbon shape and 3D-printed bulk samples produced by different casting techniques. A digital wattmeter was used to measure the hysteresis loss behavior of ribbons and massive elements as a function of frequency (range 1 Hz to 1 kHz) at a fixed peak induction (J = 0.5 T). Room temperature quasi-static hysteresis loops of all printed samples and as-cast ribbons were measured using VSM magnetometry [2,3].<br/>The SLM processing conditions have been observed to play a crucial role in the microstructure of the printed parts and, therefore, in their magnetic properties, due to their dependence on morphology (i.e., surface roughness, porosity, density). The effect of different printing parameters on magnetic properties, such as laser power (20-60 W) and scan speed (350-900 mm/s), has been studied. The tuning of these parameters to maximize the amorphous fraction, control the formation of crystalline phases, and consequently optimize soft magnetic properties is discussed in detail. This study highlights the critical link between microstructure engineering through manufacturing techniques and the resulting magnetic performance, offering insights into optimizing both for enhanced energy efficiency in electrical applications.<br/><br/>[1] J. M Silveyra, E. Ferrara, D. L. Huber, T. C. Monson, <i>Science</i>, <b>362</b> (2018), 6413.<br/>[2] L. Thorsson et al. <i>Materials and Design, </i><b>215</b> (2022)<i>, </i>110483<br/>[3] M. Rodríguez-Sánchez et al., <i>Materialia, </i><b>35</b> (2024)<i>, </i>102111.