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Title: Effect of structural parameters on variation of microstructural and magnetic properties of nanocrystalline alloy of Fe73.5Cu1Nb3Si17.5B5
Authors: Uddin, M M
Hoque, S Manjura
Mahmud, M Sultan
Hakim, M A
Chowdhury, F U Z
Keywords: Amorphous alloy;Magnetic properties;Finemet;Nanocrystalline alloy;Superferromagnetism
Issue Date: Apr-2009
Publisher: CSIR
Abstract:  Amorphous ribbons of Fe73.5Cu1Nb3Si17.5B5 alloy have been annealed in the temperature range 475-700°C for X-ray diffraction (XRD) patterns. Crystallization induced by heat treatment resulted in the formation of a Fe-Si phase. The phase formed by primary crystallization has been found to be Fe-Si solid solution with a composition corresponding to disordered Fe-Si. Secondary crystallization of the Fe3B and Fe2B phases arises with the individual branches at the interfaces of the closely spaced crystals at the temperature 680°C, the spacing of such crystals was of the order of nanometer. Samples have been annealed in a controlled way in the temperature range 510-700°C with an interval of 10°C to 30°C for 1 h in order to study the effect of structural parameters of the nanocrystalline Fe(Si) grains on the variation of microstructural and soft magnetic properties. Temperature and frequency dependence of initial permeability of amorphous and devitrified toroid shaped samples have been measured. The permeability values showed little change as annealing time. Enrichment of Curie temperature has been observed for amorphous alloy due to the irreversible structural relaxation. The microstructures of the annealed samples are characterized as solid solutions of bcc Fe(Si) crystallites with grain sizes 5-19 nm and an abrupt increase 53 nm at 700°C. Silicon contents in the nanocrystalline phases determined from the lattice parameters are 12.67 to 15.48 At.%. The best magnetic properties have been observed when the annealing temperature is close to 575°C. Temperature dependence of real part of initial permeability of the annealed samples between the annealing temperature of 550°C and 575°C exhibits superparamagnetic/superferromagnetic behaviour at T >Tcam
Page(s): 289-299
ISSN: 0019-5596
Appears in Collections:IJPAP Vol.47(04) [April 2009]

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