چكيده به لاتين
In the present research, rapidly solidified Fe89.3-xB7+xP3Cu0.7(x=0, 2, 4) ribbons were prepared by melt spinning process. The microstructural variation as well as magnetic properties of the as-spun and annealed ribbons were characterized by X-ray diffraction (XRD), transmission Mossbauer spectroscopy, Vibrating Sample Magnetometer (VSM) and alternating gradient field magnetometer (AGFM). The primary crystallization kinetics of the amorphous Fe85.3B11P3Cu0.7 alloy was analyzed using non-isothermal DSC measurements, as well. The amorphous ribbons were heat treated at 350, 370, 390, 420, 440, 530 and 650˚С for different times under Vacuum and Argon atmospheres and the structure and magnetic properties of the annealed ribbons were studied using XRD, Mossbauer Spectroscopy, VSM and AGFM.
The DSC results show two separated distinct exothermic peaks during heating resulting from the phase transition from amorphous to α-Fe and then to Fe3B, respectively. The average and local activation energies, Ea, were determined by different isokinetic and isoconversional methods. The results obtained for activation energy in this research, show that due to the complexity of the primary crystallization process in this alloy, isoconversional methods are more suitable than the isokinetic ones. The study of magnetic properties in the amorphous and nanocrystalline states revealed that annealing the amorphous ribbons at 440˚C for 10 minutes gives rise to a significant increase in saturation magnetization, Ms, i.e. from 187 in as-spun to 220 emu/g in annealed states. This amount of Ms makes this material a good candidate for different applications, especially in transformer cores.
