Effective Pairwise Potentials in Copper-Gold Alloys

抄録

The improved statistical mechanical approximation developed by one of us is applied to the analysis of published experimental data on the short range order parameters in, and the diffuse X-ray scattering intensities from, the three stoichiometric copper gold binary alloys Cu₃Au, CuAu and CuAu₃. From this analysis, the corresponding effective pair-wise interparticle potentials extending upto the third nearest neighbor separation are determined. Using a plausible interpolation procedure, from these results for the three stoichiometric compositions, effective pair-wise interparticle potentials are estimated for all compositions in the range Cu₃Au to CuAu₃. Finally, using these estimates, the variation of the magnitude of the order-disorder transition temperature, T_c, as a function of the system concentration is predicted. These predictions are then compared with the experimental data of Rhines, Bond and Rummel. The agreement of the theoretical predictions with the experimental data T_c is found to be excellent in the range Cu₃Au to CuAu and, in particular, the observed minimum in T_c for the composition Cu_0.64Au_0.36 is faithfully reproduced.