Transport properties and entropy-scaling laws for diffusion coefficients in liquid Fe0.9Ni0.1 up to 350 GPa

Abstract

Transport properties and entropy-scaling laws for diffusion coefficients in liquid Fe_0.9Ni_0.1 alloy under high pressure conditions have been studied by molecular dynamics simulations based upon the Quantum Sutton and Chen potential. We find that the entropy-scaling laws proposed independently by Rosenfeld and Dzugutov for diffusion coefficients under ambient pressure, approximating the excess entropy by the pair correlation entropy, can be fruitfully extended to liquid Fe–Ni alloy under high pressure conditions to understand and predict the transport properties of the Earth's core. In addition, our results suggest that the temperature dependence of the self-diffusion coefficient and viscosity follow the Arrhenius-type relation, and the activity energies for diffusion and viscosity increase with increasing pressure. The viscosity of liquid Fe_0.9Ni_0.1 alloy is slightly greater than that of pure liquid Fe, and lower than that of pure liquid Ni, at a given temperature and pressure. This result indicates that Ni has a slightly positive influence on the viscosity of liquid Fe–Ni alloy.