Dynamic arrest in multicomponent glass-forming alloys.

Area of Science:

• Materials Science
• Physical Chemistry
• Condensed Matter Physics

Background:

• Understanding atomic diffusion in metallic alloys is crucial for materials design.
• Metallic glasses exhibit unique properties due to their disordered atomic structure.
• Dynamic asymmetry in diffusion is a key factor in glass formation.

Purpose of the Study:

• To present a complete dataset of radiotracer diffusivities for all components in a Pd43Cu27Ni10P20 melt.
• To investigate the relationship between component diffusivities and temperature, particularly around the glass transition.
• To explore the validity of the Stokes-Einstein relation and its implications for glass formation mechanisms.

Main Methods:

• Radiotracer diffusion experiments were conducted on a Pd43Cu27Ni10P20 melt.
• Measurements covered the entire relevant temperature range, including near the glass transition temperature (Tg).
• Diffusivities of all constituent elements (Pd, Cu, Ni, P) were determined.

Main Results:

• A significant decoupling of diffusivities was observed, with Pd diffusing orders of magnitude slower than smaller components.
• At the glass transition temperature (Tg), the diffusivities of all components converged.
• The Stokes-Einstein relation was found to hold for Pd over 14 orders of magnitude in diffusivity.

Conclusions:

• The findings suggest that a slow-diffusing component (Pd) and the formation of a slow subsystem are critical for glass formation in systems with dynamic asymmetry.
• The convergence of diffusivities at Tg supports the role of dynamic heterogeneity in the glass transition.
• The study provides comprehensive data for modeling diffusion and understanding glass formation in this alloy system.