Calculation of short range order in Ni–Rh, Ni–Pd and Cu–Rh alloys

Transition metal model pseudopotential (TMMP) technique has been applied to study the short range order (SRO) in nickel alloys Ni100–x–Rhx and Ni100–x–Pdx and a copper alloy Cu100–x–Rhx (x = 2, 5, 8, 11 at. %). All these transition metal alloys form fcc solid solutions for the chosen compositions. The static electrical permittivity ε(q) was taken from the Hubbard–Sham model and/or Geldart–Vosko model to account for the exchange energies and correlation correction factors. Ordering energies and the Warren–Cowley SRO parameters have been calculated for all these alloys. Both models gave almost the same values for both the ordering energies and the Warren–Cowley SRO parameters. The TMMP model is found to predict the correct sign of SRO parameters for all these alloys.