KINETICS OF -Fe NANOCRYSTALLIZATION IN Fe۵۵Cr۱۸Mo۷B۱۶C۴ BULK AMORPHOUS ALLOY

Abstract: In this research work, crystallization kinetics of Fe۵۵Cr۱۸Mo۷B۱۶C۴ alloy was evaluated by X-ray diffraction, TEM observations and differential scanning calorimetric tests. In practice, crystallization and growth mechanisms were investigated using DSC tests in four different heating rates. Results showed that a two -step crystallization process occurred in the alloy in which - Fe phase was crystallized in the first step after annealing treatments. Activation energy for the first step of crystallization i.e. - Fe was measured to be ۲۷۶ (kj/mol) according to Kissinger model. Further, avrami exponent calculated from DSC curves was ۲ and a three -dimensional diffusion controlled mechanism with decreasing nucleation rate was observed in the alloy. It is also known from the TEM observations that crystalline á – Fe phase nucleated in the structure of the alloy in an average size of ۱۰ nm and completely mottled morphology.

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Keywords: Bulk Metallic Glasses (BMGs) ، Structural amorphous steels (SASs) ، Avrami exponent ، Kinetic models