Interdiffusion and thermotransport in Ni–Al liquid alloys

ABSTRACT

In this paper, we present extensive self-consistent results of molecular dynamics (MD) simulations of diffusion and thermotransport properties of Ni–Al liquid alloys. We develop a new formalism that allows easy connection between results of the MD simulations and the real experiments. In addition, this formalism can be extended to the case of ternary and higher component liquid alloys. We focus on the temperature and composition dependence of the self-diffusion coefficients, interdiffusion coefficients, thermodynamic factor, Manning factor and the reduced heat of transport. The two latter quantities both represent measures of the off-diagonal Onsager phenomenological coefficients. The Manning factor and the reduced heat of transport can be related to experimentally obtainable quantities provided the thermodynamic factor is available. The simulation results for the reduced heat of transport show that for all compositions, in the presence of a temperature gradient, Ni tends to migrate to the cold end. This is in agreement with an available experimental study for a Ni_21.5Al_78.5 melt (only qualitative result is available so far).

KEYWORDS:

• Diffusion coefficients
• thermotransport
• partial enthalpies
• molecular dynamics
• Green–Kubo
• Ni–Al liquid

Acknowledgements

The authors would like to acknowledge useful discussions with Dr A.V. Evteev.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

William Yi Wang http://orcid.org/0000-0002-8814-525X

Additional information

Funding

This research was supported by the Australian Research Council through its Discovery Project Grants Scheme (DP160101634). WYW would like to thank the support by the National Natural Science Foundation of China (Grant Nos. 51690163). The contribution of one of the co-authors (RK) was partially funded from the European Community's Seventh Framework Programme (FP7-PEOPLE-2013-IRSES) under EC-GA no. 612552.