On ordering in solid solutions of Cu-25 at % Au and Cu-75 at % Au

Abstract

Based on the X-ray diffuse scattering (XRDS) method, a methodology for experimental determination of the parameters of short-range order in disordered polycrystalline solid solutions is developed. The method is based on accounting for static displacements in the corresponding coordination spheres. Static displacements are described by introducing parameter $\beta = \frac{1} {\nu }\frac{{d\nu }} {{dc}}$, where v is the unit-cell volume, and c is the solid-solution concentration. The short-range order parameters of polycrystalline Cu-25 at % Au and Cu-75 at % Au solid solutions are calculated for a large number of coordination spheres using experimental values of the XRDS intensity and a refined methodology. It is established that the values of the short-range order parameters of a polycrystalline solid solution are close to analogous values for the Cu₃Au superstructure, despite the different character of the XRDS intensity. This points to the presence of long-range interatomic interactions in these solid solutions.