Atomic structure and diffusivity in liquid Al80Ni20 by ab initio molecular dynamics simulations

The atomic structure and diffusivity in liquid Al80Ni20 are studied by ab initio molecular dynamics simulations. The local structures are analyzed by the pair correlation function, structure factor, coordinate number, Honneycutt–Anderson bond pair, and Voronoi tessellation methods. It is observed that the amount of icosahedral clusters increases, and the liquid becomes more ordered as the temperature decreases. The predicted self-diffusion coefficients of Al and Ni via the mean square displacements are very close to each other and agree well with the quasi-elastic neutron scattering measurements in the literature. The observation of equal self-diffusivity of Al and Ni is attributed to the formation of local solute-centered polyhedra, coupling the migration of Al and Ni. The Manning dynamic correlation factor is evaluated and found to be close to unity. The predicted interdiffusion coefficients using the Darken equation agree well with experimental data in the literature.