Role of alloying composition on crystallization kinetics of Fe(CoNi)PB bulk metallic glasses

In this study, the effects of Ni microalloying on the crystallization kinetics of Fe(CoNi)PB bulk metallic glass (BMG) under isothermal condition were studied. For this purpose, differential scanning calorimetry (DSC) was applied at six different temperatures, i.e. from 1.02 to 1.12 onset of crystallization temperature, to isothermally evaluate the crystallization kinetics in the Fe-based BMGs. Using exothermic peaks of thermal plots, the volume fraction of crystallization was measured, while the Johnson-Mehl-Avrami (JMA) approach was employed to characterize the crystallization kinetics. The results showed that with the increase in isothermal annealing temperature, the exothermic peak was sharply intensified and the incubation period for the crystallization decreased in both of Ni-free and Ni-added BMG samples. Moreover, it was found that the higher temperature of annealing process led to the sharper crystallization evolution. However, it was clearly seen that the Ni-added sample experienced more sluggish crystallization, which was due to its higher thermal stability and better glass forming ability (GFA). The JMA model also showed that the Avrami exponent factor had a close correlation with the activation energy of crystallization in both BMG compositions. Nevertheless, the Ni microalloying affected the crystallization evolution, which is discussed in details.

Automated summary

The study investigated the effects of Ni microalloying on the crystallization kinetics of Fe(CoNi)PB BMG, showing that Ni addition increased thermal stability and glass forming ability. Higher annealing temperatures intensified exothermic peaks and reduced incubation period for crystallization. Ni addition resulted in slower crystallization compared to Ni-free samples.