Embedded-atom-method study of structural, thermodynamic, and atomic-transport properties of liquid Ni-Al alloys

Structural, thermodynamic, and atomic-transport properties of liquid Ni-Al alloys have been studied by Monte Carlo and molecular-dynamics simulations based upon three different embedded-atom method (EAM) interatomic potential s, namely those due to Foiles and Daw (FD) [J. Mater. Res. 2, 5 (1987)], Vo ter and Chen (VC) [in Characterization of Defects in Materials, edited by R . W. Siegel et al. MRS Symposia Proceedings. No. 82 (Materials Research Soc iety, Pittsburgh, 1987), p.175] and Ludwig and Gumbsch (LG) [Model. Simul. Mater. Sci. Eng. 3, 533 (1995)]. We present detailed comparisons between ca lculated results and experimental data for structure factors, atomic volume s, enthalpies of mixing, activities, and viscosities. Calculated partial st ructure factors are found to be in semiquantitative agreement with publishe d neutron scattering measurements for Ni20Al80 alloys, indicating that shor t-range order in the liquid phase is qualitatively well described. Calculat ed thermodynamic properties of mixing are found to agree very well with exp erimental data for Ni compositions greater than 75 atomic %, while for allo ys richer in Al the magnitudes of the enthalpies and entropies of mixing ar e significantly underestimated. The VC and LG potentials give atomic densit ies and viscosities in good agreement with experiment for Ni-rich compositi ons, while FD potentials consistently underestimate both properties at all concentrations. The results of this study demonstrate that VC and LG potent ials provide a realistic description of the thermodynamic and atomic transp ort properties for NixAl1-x liquid alloys with x greater than or equal to 0 .75, and point to the limitations of EAM potentials for alloys richer in Al .