The crystallization process in a new multicomponent Fe-based bulk amorphous alloy: A kinetic study approach

In the current work, a new alloy composition based on Fe-B-Si system with a high glass-forming ability was developed and its non-isothermal crystallization kinetics was investigated. The glass-forming ability of Fe74B20Nb2Si2Hf2 alloy was determined by thermodynamic calculations, including the significant negativity of the mixing enthalpy (−21.22 kJ/mol) and the high value of δ (12.69) and Δχ (0.12). Moreover, the critical cooling rate and critical thickness parameters for this bulk metallic glass were obtained as 80 K/s and 3.119 mm, respectively. Also, microstructural evolutions following the annealing process were evaluated by scanning and transmission electron microscopes. The study revealed the appearance of Fe23B6, α-Fe, and Fe2B crystalline phases, which were formed during partial annealing treatment. The local activation energy values in a wide range of α (0.1 < α < 0.9) were calculated in the range of 167–352 kJ/mol using the Starink and Friedman isoconversional methods. In addition, the invariant kinetic parameters, including lnAinv and Einv as well as the kinetic model were obtained by IKP and fitting model. The research findings demonstrated that the first, second, and third stages of crystallization were controlled by A2, A3, and A4 mechanisms, respectively.