The effect of Pd on the isothermal relaxation of short-range order in Au(Ag)-based ternary alloys

The effect of Pd on the isothermal relaxation of short-range order (SRO) was studied in AuxAgxPd100−2x (x=25, 40 at%) alloys, using the residual resistometry at 77 K. The short-range ordering resulted in an increase of electrical resistivity. The equilibrium values of this property characterizing the SRO-equilibrium states exhibit a linear dependence on the reciprocal of temperature. The analysis of the resistivity data using the fundamental laws of SRO-kinetics shows that the resistivity behavior can be satisfactorily explained by the two-exponentials law and leads to the determination of characteristic time constants and the activation enthalpies for the two processes. Further, it is found that both the equilibrium and kinetic behavior of these alloys are highly dependent on the concentration of Pd. The presence of Pd reduces the atomic mobility which results from a decrease in the vacancy mobility linked to the positive size effect of Pd in these alloys.