Crystallization and magnetic hardening behaviour of Fe-rich FeSiBNb(Cu) melt-spun alloys

Murugaiyan, Premkumar and Bedanta, Subhankar and Jena, S K and Panda, A K and Mitra, A and Bysakh, S and Roy, Rajat K (2020) Crystallization and magnetic hardening behaviour of Fe-rich FeSiBNb(Cu) melt-spun alloys. Journal of Magnetism and Magnetic Materials, 502 (2.683).

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Abstract

The sequential, multi-stage crystallization and magnetic hardening behaviour of Fe82B14Si2Nb2, Fe83B13Si2Nb2, Fe83B12Si2Nb2Cu1 and Fe85B13Nb2 melt-spun alloys have been investigated. The microstructure-crystallizationmagnetic property relationship was established using X-ray diffractometry (XRD), differential scanning calorimetry (DSC), magnetometry, transmission electron microscopy (TEM) and magneto-optical Kerr effect microscopy (MOKE) techniques. The increase of Fe content (> 82 at%) of as-quenched ribbons imparts microstructural heterogeneity across the ribbon cross–section; i.e., textured α-Fe crystals at the free surface to heteroamorphous microstructure in the bulk matrix. The isochronal annealing of hetero-amorphous alloys depicts simultaneous surface and bulk crystallization process occurring before and after the crystallization onset temperature (Tx1) temperature. The annealing temperature range (Ta < Tx1) coinciding with the paramagnetic region of the thermo-magnetic plot, induces irreversible magnetic hardening due to simultaneous coarsening of pre-existing crystal nuclei and exchange de-coupling between nanocrystal and intergranular matrix. The onset of primary crystallization in the pre-crystallized ribbons results in bimodal nanocrystallite distribution having an average crystallite size exceeding the ferromagnetic exchange length of Fe-based alloys. The minor Cu addition alters the growth morphology of pre-existing nuclei from dendrite-like to equiaxed, assisting heterogeneous nucleation and improving intergranular amorphous stability by delaying boride precipitation. The soft-magnetic property deterioration of partially crystallized ribbons is discussed within the framework of Extended-Random Anisotropy models.

Item Type:Article
Official URL/DOI:https://doi.org/10.1016/j.jmmm.2020.166528
Uncontrolled Keywords:Hetero-amorphous alloy Nanocrystalline Soft-magnets Melt-spinning Magnetic domains
Divisions:Material Science and Technology
ID Code:8109
Deposited By:Mr. Premkumar M
Deposited On:19 Feb 2020 08:52
Last Modified:19 Feb 2020 08:52

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