Evolution of structure and local magnetic fields during crystallization of HITPERM glassy alloys studied by in situ diffraction and nuclear forward scattering of synchrotron radiation

Evolution of structure and local magnetic fields in Fe1 xCox 76Mo8Cu1B15 HITPERM metallic glass ribbons with various amounts of Co x 0, 0.25, 0.5 were studied in situ using diffraction and nuclear forward scattering of synchrotron radiation. It was found that crystallization for all three glasses proceeds in two stages. In the first stage, bcc Fe,Co nanocrystals are formed, while in the second stage additional crystalline phases evolve. For all three glasses, the crystallization temperatures at the wheel side were found to be lower than at the air side of the ribbon. The crystallization temperatures were found to decrease with increasing Co content. The lattice parameters of the bcc nanocrystals decrease up to about 550 C and then increase pointing to squeezing Mo atoms out of the nanograins or to interface effects between the nanocrystals and the glassy matrix. Nuclear forward scattering enabled separate evaluation of the contributions that stem from structurally different regions within the investigated samples including the newly formed nanocrystals and the residual amorphous matrix. Even minor Co content x 0.25 has a substantial effect not only upon the magnetic behaviour of the alloy but also upon its structure. Making use of hyperfine magnetic fields, it was possible to unveil structurally diverse positions of Fe atoms that reside in a nanocrystalline lattice with different number of Co nearest neighbour

Mössbauer Spectrometry in FeMoCuB-Type Nanocrystalline Alloys

The applicability of the Mössbauer spectrometry to the study of $Fe_{91-x}Mo_8Cu_1B_x$ (x = 12, 15, 17) nanocrystalline alloys prepared by controlled annealing of ribbon-shaped amorphous precursors is demonstrated. Differences between both surfaces of the ribbons are pointed out to be due to preparation conditions. Conclusions from the Mössbauer spectrometry are supported by diffraction of synchrotron radiation, X-ray diffraction, and atomic field microscopy investigations

Thermomagnetic Properties and First-Order Reversal Curve Analysis of Annealed Fe-Co-Si-B-Mo-P Alloy

The paper presents thermomagnetic features and characterization of magnetic interactions in the Fe₅₁Co₁₂Si₁₆B₈Mo₅P₈ metallic glass after annealing at 798 K for 1 h. The first-order reversal curve analysis was used to investigate hysteresis curves which provide a more precise estimation of the strength of interactions. The presence of magnetically distinct regions was revealed

Impact of Ion-Irradiation upon Microstructure and Magnetic Properties of NANOPERM-Type Fe₈₁Mo₈Cu₁B₁₀ Metallic Glass

Microstructure and soft magnetic properties of the Fe₈₁Mo₈Cu₁B₁₀ amorphous alloy in the as-quenched state and after irradiation with N⁺ ions are investigated. CEMS spectra show that the irradiated surface at the air side of the ribbons was significantly affected. On the other hand, no noticeable changes were observed at the opposite wheel side. More deep subsurface regions are also not altered as evidenced by CXMS spectra. Thermomagnetic measurements have shown presence of two magnetically different phases with well distinguished Curie points. They can be ascribed to the amorphous matrix and crystalline phases. The latter were quenched-in during the production process and/or induced by ion bombardment. Curie temperatures of the amorphous matrixes were calculated using the Heisenberg model. For the as-quenched and irradiated ribbons they are of 223 K and 228 K, respectively. The behaviour of coercivity versus temperature was also analysed

Magnetic Properties of Ion Irradiated Fe₇₅Mo₈Cu₁B₁₆ Metallic Glass

Microstructure and thermomagnetic properties of ion-bombarded amorphous Fe₇₅Mo₈Cu₁B₁₆ alloy are investigated. The Mössbauer spectroscopy shows that surface regions at the air side of the ribbons irradiated with 2×10¹⁶ ions/cm² were significantly affected by 130 keV N⁺ ions. On the other hand, the opposite (wheel) side that was not exposed to ion irradiation is practically intact. The analysis of temperature dependences of magnetization shows the Curie points of 313 K and 316 K for as-quenched and irradiated samples, respectively. The maximum of magnetic entropy change calculated for the irradiated alloy in a magnetic field of 1.0 T occurs at 312.5 K and equals to 0.77 J kg¯¹ K¯¹ while that of the as-quenched sample is 0.74 J kg¯¹ K¯¹