A computational study of diffusion in a glass-forming metallic liquid

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Materials Science

Background:

• Liquid phase diffusion is key to phase transformations in marginal glass-forming systems like Al-Sm.
• Accurate diffusivity data, including composition and temperature dependencies, is needed to control these transformations.

Purpose of the Study:

• To computationally examine atomic diffusion in Al-Sm liquids.
• To determine Al and Sm diffusivities across various compositions.
• To develop a predictive model for Al-Sm liquid diffusion.

Main Methods:

• Utilized ab initio molecular dynamics (AIMD) simulations.
• Analyzed diffusion behavior in undercooled liquids.
• Constructed a diffusion mobility database incorporating composition and temperature dependence.

Main Results:

• Observed non-Arrhenius diffusion behavior linked to enhanced local structural ordering.
• Developed a general formulation for Al-Sm liquid diffusion, including a Volmer-Fulcher-Tammann (VFT) equation.
• Found strong composition dependence of diffusivity, even in Al-rich regions, contradicting previous findings.

Conclusions:

• The developed model, combined with thermodynamic data, accurately predicts Al-Sm alloy diffusivities.
• This work provides a comprehensive understanding of diffusion in Al-Sm systems, vital for materials design.