The composition dependences of thermodynamic, dynamic and structural properties of Al–Ni melts

Abstract

We performed ab initio molecular dynamic simulations to investigate the thermodynamic, dynamic, and structural properties of Al–Ni melts at 2033 K. The calculated enthalpies of mixing exhibit a strong compositional dependence, and the relationship between chemical short-range order and thermodynamic mixing quantities is effectively described by the modified regular solution model. Furthermore, the self-diffusion coefficients with a strong non-linear compositional dependence in Al-rich melts are closely related to the structural evolution of Al–Ni melts. Examination of local ordering evolutions reveals that the strong chemical affinity between dissimilar species in Al–Ni melts gives rise to the formation of a heterogeneous structure characterized by string-like or solute-solvent network medium-range order. Finally, the coupling of chemical short-range order and string-like medium-range order demonstrates a clear correlation between structural features and dynamic properties. These aspects provide deeper insight into the structure-dynamics relationship.