Quantifying the origin of metallic glass formation

Area of Science:

• Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Crystallization kinetics in undercooled liquids are crucial for material properties.
• The minimum crystallization time (τX*) occurs at a specific 'nose temperature' (T*).
• The role of glass transition temperature (Tg), melting temperature (TL), and fragility (m) in determining τX* is widely studied.

Purpose of the Study:

• To develop an empirical expression for predicting the minimum crystallization time (τX*) in metallic glasses.
• To assess the influence of dimensionless parameters like Tg/TL and fragility (m) on τX*.
• To determine if liquid/crystal interfacial free energy is a necessary factor in predicting τX*.

Main Methods:

• Survey and analysis of reported experimental data for TL, Tg, trg (Tg/TL), m, and τX* across various metallic glasses.
• Derivation of a simple empirical expression for τX* based on trg and m.
• Statistical analysis to validate the predictive power of the derived expression.

Main Results:

• A simple empirical expression for τX* was derived, showing exponential dependence on trg and m.
• The derived expression includes two fitting parameters.
• Statistical analysis confirmed that trg and m alone are sufficient to predict τX* within experimental error.
• Liquid/crystal interfacial free energy was found to be unexpectedly absent from the predictive expression for τX*.

Conclusions:

• The minimum crystallization time (τX*) in metallic glasses can be accurately predicted using only the Tg/TL ratio and the fragility parameter (m).
• This finding simplifies the understanding of crystallization kinetics in metallic glasses.
• The study highlights the dominant roles of Tg/TL and m, while suggesting interfacial energy is less critical for predicting τX*.