Magnetic Properties and Crystallization Kinetics of a Mn-Doped FINEMET Precursor Amorphous Alloy
نویسندگان
چکیده
The kinetics of nanocrystallization of a Mn-doped FINEMET alloy from its amorphous precursor is reported. The alloy studied was of a composition (Fe1 Mn )73 5Nb3CuSi13 5B9 where = 0 05. X-ray diffraction (XRD) confirmed that -FeSi is the product of primary nanocrystallization. Crystallization kinetics were studied using time-dependent magnetization, ( ), as a measure of the volume fraction crystallized. This data was taken using vibrating sample magnetometry (VSM) and thermal analysis employing differential scanning calorimetry (DSC). Primary crystallization for the Mn-doped FINEMET alloy was found to occur at 505 C, for DSC data taken at a heating rate of 10 C/min. Fits to the Kissinger equation for constant heating transformations yield an activation energy for crystallization of 3.4 eV. VSM measurements of isothermal ( ) show that the maximum volume fraction transformed was reached at 20 min. Measurements of magnetic anisotropy as a function of time probe the structural evolution of the material upon nanocrystallization. Measurements show stress relaxation occurring at 20 minutes at 490 C, coinciding with the maximum volume fraction crystallized.
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