Investigation on the thermal stability, crystallization kinetics and magnetic properties of Fe-Si-B-P-C-Nb amorphous alloys

This study examines the thermal stability, isothermal and non-isothermal crystallization kinetics, and soft magnetic properties of Fe-Si-B-P-C-Nb amorphous alloys. Phase transformations were analyzed using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Under non-isothermal conditions, activation energies, local activation energies and local Avrami exponents were calculated to investigate nucleation and growth mechanisms during crystallization. The results indicate that characteristic temperatures vary with the heating rate, while activation energy values confirm the superior thermal stability of the Fe_82.8Si_0.2B₁₂P_2.25C_2.25Nb_0.5 ​alloy. During crystallization, local activation energy initially increases before reaching a peak and subsequently decreasing. The local Avrami exponent further suggests that crystallization in both amorphous ribbons is predominantly governed by three-dimensional growth with fluctuating nucleation rates. Additionally, the isothermal crystallization kinetics of the Fe_82.8Si_0.2B₁₂P_2.25C_2.25Nb_0.5 amorphous ribbon were analyzed to deepen our understanding of the crystallization mechanisms and provide theoretical insights for optimizing material properties. By fine-tuning annealing parameters, the crystallization behavior can be controlled to achieve different crystallized volume fractions, thereby developing nanocrystalline materials with enhanced soft magnetic properties. Specifically, the saturation magnetization flux density (B_s) reached 1.79 ​T, while the coercivity (H_c) was as low as 5.2 A/m.