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

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.