The amorphous ribbon Fe_73.5Si_13.5B₉Nb₃ Au₁ has been prepared by rapid cooling on a copper wheel. The ribbon is 16.8 μm thick and 7 mm wide. The DSC curves show the first peak at 547-579 °C (corresponds to the crystallization of α-Fe(Si) phase) depending on heating rate from 10 to 50 °C/min which is a little higher than that of pure Finemet (542-570 °C, respectively). From the Kissinger plot, the crystallization activation energy is determined and shown to be 2.8 eV for α-Fe(Si) phase, less than that of Finemet ( E = 3.25 eV). By annealing at 530 °C for 30, 60 and 90 min, the crystallization volume fraction of α-Fe(Si) phase increased from 73% to 78% and 84%, respectively. After appropriate annealing, the ultrasoft magnetic properties are achieved. The maximum magnetic entropy change, {divides}ΔS_m{divides}_max, showed a giant value of 7.8 J/kg K which occurred at around Curie temperature of amorphous phase of the ribbon. © 2006.

Chau N., Hoa N.Q., The N.D., Niem P.Q.

643.pdf    Gửi cho bạn bè

Từ khóa : Activation energy; Annealing; Copper; Crystallization; Differential scanning calorimetry; Gold; Iron alloys; Magnetic field effects; Soft magnetic materials; Amorphous phase; Magnetocaloric effect; Nanoparticle; Soft magnetic amorphous system; Nanostructured materials