Atomic scale simulations of solute-atom segregation at grain boundaries in binary FCC alloys

Monte Carlo simulations are performed of solute-atom segregation to low-angle (002) twist boundaries employing embedded atom method (EAM) potentials for single-phase binary alloys in the Au-Pt and Ni-Pt systems. The following is obtained: (1) the Gibbsian interfacial excess of solute atoms (Γ_solute); (2) the angular dependence (θ) of Γ_solute; (3) the temperature dependence of Γ_solute for a Pt(Au) alloy; (4) solute-atom segregation profiles normal to the interface plane; and (5) the spatial distribution of solute atoms in (002) planes parallel to the interface. For Au(Pt) the atomic sites depleted in solute (Pt) are located in bipyramidal regions based on the square grid of primary grain boundary dislocations (PGBDs); whereas for the Pt(Au) system the same atomic sites are enhanced in solute (Au). For Pt(Ni) the atomic sites enhanced in solute (Ni) are arranged in hourglass-like structures centered on the PGBDs. In the Ni(Pt) system the atomic sites enhanced in solute (Pt) are located in bipyramidal regions based on the PGBDs.