Atomic radius dependence of impurity diffusion coefficients in liquid Pb.

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Materials Science

Background:

• Impurity diffusion coefficients are crucial for understanding liquid metal behavior.
• Existing prediction formulas often lack accuracy due to simplified atomic radius considerations.

Purpose of the Study:

• To verify a prediction formula for impurity diffusion coefficients.
• To investigate the use of effective atomic radii derived from molecular dynamics simulations for improved predictions.

Main Methods:

• Shear cell experiments were conducted for Pb-Cu and Pb-Sn systems at 773 K.
• Molecular dynamics simulations using neural network potentials were performed for various Pb-solute systems.
• Effective atomic radii were calculated from partial pair distribution functions.

Main Results:

• Effective atomic radii derived from simulations differed from Goldschmidt radii, reflecting liquid-state thermodynamic interactions.
• Radii decreased for high-affinity solutes (Cu, Ag, Sn) and increased for repulsive solutes (Ga) in Pb.
• The prediction formula incorporating these effective radii achieved high accuracy, with a maximum relative error of 2.4%.

Conclusions:

• The effective atomic radius calculated from partial pair distribution functions via molecular dynamics simulations is a reliable parameter for impurity diffusion predictions.
• The validated formula offers a more accurate method for predicting impurity diffusion coefficients in liquid metals.