Abstract
Arguments are given for a model Hamiltonian of a disordered binary alloy, which includes the dependence of the vibrational frequencies on the atomic configuration. A new feature is that the short-range-order parameter α approaches a nonzero value in the high-temperature limit. Predictions for the T dependence of α(T) and the concentration dependence of α(∞) are in good agreement with experiment for nickel-copper alloys. The agreement for the magnitude of α(∞) is fair.