Iron and Chromium Influence on Crystallization Kinetics of Cobalt-Based Amorphous Alloys

In this comprehensive study, the intricate crystallization process of cobalt-based amorphous alloys is investigated, focusing on three specific compositions: Co72Fe5Si11B12, Co68Cr9Si11B12, and Co72Fe2.5Cr2.5Si11B12. The examination is conducted over a temperature range spanning from 660 to 870 K. Differential scanning calorimetry is employed to analyze the crystallization behavior at three heating rates: 5, 10, and 20 K/min. Remarkably, the nanocrystallization processes, corresponding to the initial peaks observed in the differential scanning calorimetry curves, reveal the activation energies reaching up to 857 kJ/mol. The addition of iron and chromium into the alloy compositions introduces notable alterations in the nanocrystallization mechanism. The Avrami index, derived from the Matusita model, exhibits distinct values, indicating a variation in the nucleation and growth processes. Particularly, chromium-doped alloys showcase surface nucleation mechanisms, elucidating the profound impact of chromium on influencing and modulating the overall crystallization process. Meanwhile, a one-dimensional mechanism is proposed for alloys that undergo iron doping. The study delves into how cobalt-based alloys crystallize, revealing the complex relationship between alloy composition, heating rates, and nanocrystallization.