On the glass formation of Pd-Ni-S metallic glass system: A fast differential scanning calorimetry study

This study investigates the glass formation and crystallization of the Pd₃₈Ni₃₈S₂₄ metallic glass-forming alloy using fast differential scanning calorimetry (FDSC) and conventional DSC. The high upper limit of the measuring temperature and ultrahigh scanning rates of the chip-based DSC enable in-situ melting and vitrification of the sample, providing a valuable opportunity to investigate the crystallization kinetics, even at the tip of the crystallization nose. By varying cooling rate, the critical cooling rate required to avoid crystallization is determined to be approximately 2,300 K/s. Calorimetric analyses reveal that the Pd-Ni-S alloy exhibits fragile liquid dynamics (D∗ = 8.5, m = 85.8) and a large driving force for crystallization, which are detrimental for glass formation. However, Johnson-Mehl-Avrami-Kolmogorov kinetics analyses of the constructed time-temperature-transformation diagram, based on classical nucleation theory, reveal a high interfacial energy of 0.096 J/m² between the liquid and crystal phases. This high interfacial energy likely compensates for the detrimental effect of large driving force and fragile liquid behavior, thereby leading to bulk glass formation in the Pd-Ni-S system. Overall, this work highlights the essential role of interfacial energy in glass formation and demonstrates the utility of FDSC in studying crystallization kinetics.