Optimum Soft Magnetic Properties of the FeSiBNbCu Alloy Achieved by Heat Treatment and Tailoring B/Si Ratio

Abstract

To increase the saturation magnetization (Ms) of commercially available soft magnetic Finemet alloys to the level comparable to that of Si-steel and Fe-based nanocrystalline alloys such as Nanoperm, Nanomet, the B or Si content in combination with annealing heat treatment was tailored. The ribbons of Fe95−xSi1BxNb3Cu1 (x = 11, 12, 13) and Fe87−xSixB9Nb3Cu1 (x = 6, 8, 10) were prepared by melt-spinning and annealed at different temperatures to develop nanocrystalline microstructure optimizing the soft magnetic properties. The magnetic properties of the as-spun and annealed ribbons were measured using a vibrating sample magnetometer and AC B-H loop tracer to acquire Ms of above 1.4 T in all as-spun ribbons. Among the alloys, Fe84Si1B11Nb3Cu1 annealed at 545 °C showed the highest Ms of 2 T, which exceeds that of the conventional Finemet and other Fe-based nanocrystalline alloys.