Thermotransport in binary system: case study on Ni₅₀Al₅₀ melt

Abstract

The formalism of thermotransport in a binary system is analysed. Focus is put on a detailed consideration of the heat of transport parameter characterizing diffusion driven by a temperature gradient. We introduce the reduced heat of transport parameter , which characterizes part of the interdiffusion flux that is proportional to the temperature gradient. In an isothermal system represents the reduced heat flow (pure heat conduction) consequent upon unit interdiffusion flux. It is demonstrated that is independent of reference frame and is useful in a practical way for direct comparison of simulation and experimental data from different sources obtained in different reference frames. In the case study of the liquid Ni₅₀Al₅₀ alloy, we use equilibrium molecular dynamics simulations in conjunction with the Green–Kubo formalism to evaluate the heat transport properties of the model within the temperature range of 1500–4000 K. Our results predict that in the presence of a temperature gradient Ni tends to diffuse from the cold end to the hot end whilst Al tends to diffuse from the hot end to the cold end.

Keywords:

• thermotransport
• heat of transport
• molecular dynamics
• Green–Kubo method
• liquid alloy
• Ni–Al system

Acknowledgements

We would like to thank Emeritus Professor Alan Allnatt (University of Western Ontario) for his very valuable comments on this research and his encouragement. This research was supported by the Australian Research Council through its Discovery Project Grants Scheme.