In Search of Rare Earth-Free Magnets: Boron's Impact on the Magnetic Hysteresis of Mn-Al-Ga Alloys

The transition from a fossil fuel economy to one based on renewable energy has caused a surge in demand for magnets in clean-energy applications, such as wind turbines and electric vehicles. The most powerful magnets currently available rely on rare-earth elements; however, very little mining or processing of these materials occurs in the United States, creating a vulnerability to supply chain disruptions. Ferromagnetic alloys of manganese, aluminum, and gallium have emerged as potential alternatives to rare-earth-containing magnets, but they have yet to become commercially viable. Interstitial atoms alloyed in small quantities may hold the key to improving these materials’ magnetic properties, and boron, which shares the valence-shell electronic structure of aluminum and gallium, could show promise in this regard. This project examines the effects of adding small amounts of boron (1–3 atomic percent) to alloys of manganese, aluminum, and gallium. Key magnetic properties of boron-containing samples, such as coercivity and remanence, are measured and compared to those of a boron-free sample. In addition, boron-infused alloys are subjected to various heat treatments, and the resulting microstructures are examined to determine the presence of magnetic phases.