Composition measurements of Cu–Ni and Au–Pd alloy surfaces annealed at 600 °C and under steady-state bombardment conditions are reported. A unique procedure for studying the effects of enhanced diffusion is employed. The ion-bombardment-induced alteration of the composition of the near surface region of a Cu–Ni, Ag–Au, and Au–Pd alloy has been studied between 200 ° and 550 °C. The results have been extrapolated to lower temperatures and used to explain conflicting reports of differential sputtering in these alloys.