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    Crystallisation Kinetics of Co75-xMxSi15B10 (M = Fe, Mn, Cr and x=0, 5) Amorphous Alloys
    (Polish Acad Sciences Inst Physics, 2016) Bayri, N.; Kolat, V. S.; Izgi, T.; Atalay, S.; Gencer, H.; Sovak, P.
    In this study, the effect of Fe, Mn and Cr substitution for Co on the crystallization kinetics of amorphous Co75-xMxSi15B10 (M = Fe, Mn and Cr; x = 0 and 5) alloys were investigated. The broad diffraction peaks in the X-ray diffraction patterns for as-quenched ribbons indicated that all of the samples exhibit an amorphous structure. The activation energies of the alloys were calculated from differential thermal analysis data using the Kissinger, Ozawa and Augis-Bennett models. The increased activation energy for Fe, Mn and Cr doped samples indicated that the thermal stability and the crystallization kinetics were improved in the doped samples. The value of the Avrami exponent indicated that the crystallization is typical diffusion controlled three-dimensional growth for all of the samples.
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    Crystallization kinetics of Fe73.5-xMnxCu1Nb3Si13.5B9 (x=0, 1, 3, 5, 7) amorphous alloys
    (Elsevier Science Bv, 2009) Bayri, N.; Izgi, T.; Gencer, H.; Sovak, P.; Gunes, M.; Atalay, S.
    In this study, we have investigated the effect of substituting Mn for Fe on the crystallization kinetics of amorphous Fe73.5-xMnxCu1Nb3Si13.5B9 (x = 1, 3, 5, 7) alloys. The samples were annealed at 550 degrees C and 600 degrees C for 1 h under an argon atmosphere. The X-ray diffraction analyses showed only a crystalline peak belonging to the alpha-Fe(Si) phase, with the grain size ranging from 12.2 nm for x = 0 to 16.7 nm for x = 7. The activation energies of the alloys were calculated using Kissinger, Ozawa and Augis-Bennett models based on differential thermal analysis data. The Avrami exponent n was calculated from the Johnson-Mehl-Avrami equation. The activation energy increased up to x = 3. then decreased with increasing Mn content. The values of the Avrami exponent showed that the crystallization is typical diffusion-controlled three-dimensional growth at a constant nucleation rate. (C) 2008 Elsevier B.V. All rights reserved.
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    Magnetic and magnetoimpedance properties of Mn-doped FINEMET
    (Elsevier Science Bv, 2009) Kolat, V. S.; Bayri, N.; Michalik, S.; Izgi, T.; Sovak, P.; Atalay, F. E.; Gencer, H.
    In this study, the effect of substituting Mn for Fe on the magnetic and magnetoimpedance (MI) properties of amorphous and nanocrystalline Fe73.5-xMnxCu1Nb3Si13.5B9 (x = 1, 3, 5, 7) alloys has been investigated. A higher Mn content causes a decrease in the saturation magnetization and Curie temperature. For as-received Fe73.5-xMnxCu1Nb3Si13.5B9 (x = 0, 1, 3, 5, 7) ribbons, the measured values of the MI are 11%, 12%, 16%, 12% and 15% for x = 0, 1, 3, 5, 7, respectively. The magnitude of the MI ratio increases in annealed samples, indicating that they are magnetically softened by nanocrystallisation. The change in MI is found to be similar to 70% for the x = 3 sample annealed at 550 degrees C. It is also found that replacing a small amount of Fe by Mn improves the magnetic softness of Fe73.5-xMnxCu1Nb3Si13.5B9 alloys. (C) 2009 Elsevier B.V. All rights reserved.
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    Study of nanocrystallization process in FeCrCuNbSiB amorphous alloys by Young's modulus measurements
    (Natl Inst Optoelectronics, 2015) Bayri, N.; Atalay, S.; Kolat, V. S.; Izgi, T.; Sovak, P.
    This paper presents the influence of nanocrystallization process on magnetic field dependence of Young's Modulus of Fe74-xCrxCu1Nb3Si13B9 (x=0, 2, 4, 8, 11) alloys. The samples were annealed between 450 degrees C and 600 degrees C for 1 hour under argon atmosphere to induce various nanocrystalline fractions. The variation in the microstructure upon annealing was examined by the X-ray spectrum data. Samples annealed at 500 degrees C or at higher temperature showed nanocrystalline alpha-Fe (Si) phase embedded in amorphous matrix. It was observed that the magnitude of field dependence of Young's modulus varies from 40% to a nearly zero as the saturation magnetostriction is reduced by nano size alpha-Fe(Si) grains. The results are interpreted partly in terms of internal stress relief and reduced magnetostriction in nanocrystalline samples.