Influence of Boron Content on Glass Forming Ability and Soft Magnetic Properties in Fe-Si-B-Nb-Cu Nanocrystalline Alloys for Gas Atomization

In this study, we investigated the effects of boron addition on glass forming ability (GFA) and soft magnetic properties of Fe_73.5Si_13.5-xB_9+xNb₃Cu₁ nanocrystalline alloys. By increasing the boron content in the alloys, GFA is expected to be increased via calculation on thermodynamic factors including mixing enthalpy, mixing entropy, and atomic radius differences. This enhancement in GFA is highly beneficial for powder production via gas atomization. Since gas atomization typically exhibits a lower cooling rate compared to the melt spinning process, achieving an amorphous structure is more challenging. However, by improving the GFA through alloy design, amorphous phase formation was successfully demonstrated even under these conditions. As a result, it was confirmed that the fully amorphous powders exhibited significantly improved coercivity compared to powders with initial crystallites. This alloy-design-based approach not only contributes to cost reduction in processing by enabling amorphous formation under less stringent cooling conditions, but also leads to enhanced magnetic properties.