A team of researchers from Tohoku University and Johns Hopkins University has uncovered several key aspects of glass transition.
DSC traces of the La(Ce)NiAl system, the arrows indicate the calorimetric glass-transition temperature (Tg) (left). The temperature dependence of the loss modulus of the La(Ce)NiAl system normalized by the maximum peak value. The arrows indicate the α-relaxation temperature (Tα) (right). Image Credit: Tohoku University.
When a liquid undergoes rapid cooling, it acquires viscosity and eventually transforms into a rigid solid glass. The point at which it transforms so is called the glass transition. However, the precise physics responsible for the glass transition and the nature of glass are still a matter of investigation.
Metallic Glasses (MGs) are highly preferred as they possess plastic’s flexibility and steel’s strength. They are amorphous materials whose atomic structures are disordered. They show exclusive, divergent dynamic and thermodynamic properties, specifically when nearing the glass-transition temperature.
The glass transition in MGs is generally governed by calorimetric and dynamical measurements. The calorimetric glass transition can help detect the temperature at which the specific heat undergoes a sudden spike, while dynamical transition tracks the diverse relaxation responses that arise with rising temperature forms.
The calorimetric glass-transition temperature normally exhibits a trend the same as that of dynamic α-relaxation temperature.
The collaborative group observed that the high configuration entropy remarkably impacts the glass transition of MGs and causes decoupling between the calorimeter and dynamic glass transitions of high-entropy metallic glasses.
The findings of the study were published in the Nature Communications journal on June 22nd, 2021. The study proposes a new glass-forming system that makes use of high configurational entropy, which is known as high entropy metallic glasses (HEMGs).
The research group included Specially Appointed Professor Jing Jiang and Professor Hidemi Kato from the Institute for Materials Research at Tohoku University and Professor Mingwei Chen from Johns Hopkins University.
The researchers commented, “We are excited about this discovery and believe this work furthers our understanding of the fundamental mechanism behind the glass transition.”
Journal Reference:
Jiang, J., et al. (2021) Decoupling between calorimetric and dynamical glass transitions in high-entropy metallic glasses. Nature Communications. doi.org/10.1038/s41467-021-24093-w.
Source: https://www.tohoku.ac.jp/en/index.html