Abstract: The traditional high-temperature annealing process is difficult to control the morphology and size of the crystallization phases in amorphous alloy systems with high ferromagnetic element content, leading to mechanical brittleness and soft magnetic properties deterioration. Here, we developed a flexible-annealing technique and successfully achieved a fine nanocrystalline structure in a high-ferromagnetic-content system of (Fe_0.8Co_0.2)₈₅Si₂B₁₂Cu_0.8Mo_0.2. It is exciting that the (Fe_0.8Co_0.2)₈₅Si₂B₁₂Cu_0.8Mo_0.2 nanocrystalline alloy exhibits high B_s up to 1.88 T, low coercivity of 6.3 A m^-1, as well as good plasticity. The excellent comprehensive properties are attributed to the controllable construction of diluted amorphous-nanocrystalline structure, the rapid release of internal stress, and the suppression of relaxation-induced uniformity achieved by the flexible annealing process. The results provide a fast and new paradigm for the development of next-generation high-B_s soft magnetic materials.

Key words: Nanocrystalline alloy, Flexible annealing, High saturation magnetic flux density, Low, coercivity, Plastic