# Self-diffusion and Interdiffusion in Al80Ni20 Melts: Simulation and Experiment

## TL;DR

This study combines experiments and molecular dynamics simulations to analyze self- and interdiffusion in Al80Ni20 melts, revealing temperature-dependent diffusion behaviors and validating the Darken equation's applicability.

## Contribution

It provides new simulation data on diffusion in undercooled Al80Ni20 melts and confirms the agreement with experimental measurements, extending understanding into the undercooled regime.

## Key findings

- Interdiffusion exceeds self-diffusion in the studied temperature range.
- The difference between diffusion coefficients increases in the undercooled regime.
- The Darken equation remains valid even under undercooling conditions.

## Abstract

A combination of experimental techniques and molecular dynamics (MD) computer simulation is used to investigate the diffusion dynamics in Al80Ni20 melts. Experimentally, the self-diffusion coefficient of Ni is measured by the long-capillary (LC) method and by quasielastic neutron scattering. The LC method yields also the interdiffusion coefficient. Whereas the experiments were done in the normal liquid state, the simulations provided the determination of both self-diffusion and interdiffusion constants in the undercooled regime as well. The simulation results show good agreement with the experimental data. In the temperature range 3000 K >= T >= 715 K, the interdiffusion coefficient is larger than the self-diffusion constants. Furthermore the simulation shows that this difference becomes larger in the undercooled regime. This result can be refered to a relatively strong temperature dependence of the thermodynamic factor \Phi, which describes the thermodynamic driving force for interdiffusion. The simulations also indicate that the Darken equation is a good approximation, even in the undercooled regime. This implies that dynamic cross correlations play a minor role for the temperature range under consideration.