Microstructure, Non-isothermal Crystallization Kinetics and Magnetic Behaviour Study of [FeCoNi100-x(SiMn)x] High Entropy Amorphous Alloys Synthesized by Mechanical Alloying

다국어 초록 (Multilingual Abstract)

In this study, FeCoNi100-x(SiMn)x high entropy amorphous alloys (HEAAs) were successfully synthesized by mechanicalalloying. The structural, non-isothermal crystallization kinetics and magnetic characteristics were investigated by utilizingX-ray diffraction, scanning electron microscopy coupled with energy dispersive spectroscopy, differential scanning calorimetry,and vibrating sample magnetometer. The structural analysis revealed that a simple solid solution of β-BCC + ε-FCCphases was formed for x = 0.0, 0.1 whereas the evolution of the amorphous phase takes place along with the ε-FCC in the caseof x = 0.25, 0.5, 0.75, 1.0 HEAAs. The non-isothermal crystallization kinetics showed two distinct exothermic peaks: onset(Ex1, Ex2)and the apparent (Ep1, Ep2)activation energies calculated using Kissinger, Ozawa, and Augis-Bennett equations.
This finding suggested that Ex1 > Ep1, Ex2 > Ep2 for the proposed HEAAs which confirmed that the nucleation process wasmore difficult than overcoming the energy barrier for the rearrangement of atoms and the grain growth process of crystallization.
Furthermore, Friedman and Ozawa−Flynn−Wall models were used to calculate the local activation energies (Ea1,Ea2),which give consistent results with the apparent activation energies (Ep1, Ep2).
In addition, Avrami exponents (n1, n2) and(Ψ1, Ψ2) were calculated by Johnson–Mehl–Avrami–Kolmogorov (JMAK) and Avrami-Ozawa combined approaches. Thisapproach revealed that the crystallization process becomes more accessible due to decreased local activation energies, leadingto high-dimensional growth with an increasing nucleation rate. Furthermore, the temperature-dependent magnetizationmeasurements showed a curie temperature below room temperature and fitted with Bloch and Curie–Weiss's law-modifiedmodel. The fitted results exhibited mixed phases, i.e., ferromagnetic and antiferromagnetic phases.