Ni-Cr alloys having the compositions (in at. %) Ni-22 Cr, Ni-42 Cr, and Ni-80 Cr were sputtered in argon in a low-pressure supported discharge. Ion energy was varied from 200 to 1000 eV, ion current density from 0.1 to 0.8 mA∕cm2 and pressure from 2 to 6 μ. The ion-pumped sputtering tube was processed as a uhv system. Thin films were deposited on polished silicon, aluminum or sapphire. Results showed that the target composition was preserved in the sputtered films to within ± 1% in each component. Near the surface of the sputtered Ni-22 Cr target, a relative Cr enrichment was found. The alloy sputtering process has been codified in a phenomenological continuity equation, using sputtering yields as parameters. The equation gives quantitatively a transient-state and a steady-state solution. The steady-state solution shows that the sputtered film should have the same composition as the target bulk and that the surface of the target should, in general, change composition.