The ultrastable kinetic behavior of an Au-based nanoglass

Ultrastable glasses and nanoglasses are two emerging materials with novel properties that have been investigated separately. In order to explore the combined effect of ultrastable character and a nanoglass with a nanoglobular microstructure on the kinetic behavior, the glass transition and crystallization behaviors of an ultrastable nanoglass and a melt-spun ribbon of Au-based metallic glass were examined by differential scanning calorimetry at heating rates (φ) of up to 40,000 K s^-1. The nanoglass shows ultrastable kinetic characters at low φ (e.g. 300 K s^-1) and similar kinetic behaviors at high φ (e.g. 30,000 K s^-1) compared to the melt-spun ribbon. The nanoglobular interfaces remain amorphous and appear to act as a kinetic constraint to induce a higher crystallization temperature compared to the melt-spun ribbon. The interface constraint effect disappears at 30,000 K s^-1. These results indicate that the nanoglobular microstructure can act to increase metallic glass stability and provide another mechanism for the synthesis of ultrastable glass.