Title :
Magnetic properties and crystallization kinetics of a Mn-doped FINEMET precursor amorphous alloy
Author :
Hsiao, A.C. ; McHenry, M.E. ; Laughlin, D.E. ; Tamoria, M.R. ; Harris, V.G.
Author_Institution :
Dept. of Mater. Sci. & Eng., Carnegie Mellon Univ., Pittsburgh, PA, USA
fDate :
7/1/2001 12:00:00 AM
Abstract :
The kinetics of nanocrystallization of Mn-doped FINEMET alloy from its amorphous precursor is reported. The alloy studied was of composition (Fe1-xMnx)73.5Nb3CuSi 13.5B9 where x=0.05. X-ray diffraction (XRD) confirmed that α-FeSi is the product of primary nanocrystallization. Crystallization kinetics were studied using time-dependent magnetization, M(t), 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 M(t) 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
Keywords :
X-ray diffraction; amorphous magnetic materials; boron alloys; copper alloys; crystallisation; differential scanning calorimetry; ferromagnetic materials; iron alloys; magnetic anisotropy; magnetisation; manganese alloys; nanostructured materials; niobium alloys; silicon alloys; soft magnetic materials; stress relaxation; (Fe1-xMnx)73.5Nb3CuSi 13.5B9; (FeMn)73.5Nb3CuSi13.5B9 ; Kissinger equation; Mn-doped FINEMET precursor amorphous alloy; X-ray diffraction; activation energy; crystallization kinetics; differential scanning calorimetry; magnetic anisotropy; magnetic properties; nanocrystalline material; soft ferromagnet; stress relaxation; thermal analysis; time-dependent magnetization; vibrating sample magnetometry; volume fraction; Amorphous materials; Crystallization; Heating; Kinetic theory; Magnetic anisotropy; Magnetic materials; Magnetic properties; Manganese alloys; Niobium alloys; Volume measurement;
Journal_Title :
Magnetics, IEEE Transactions on
