It is shown experimentally that a change in the mass of bombarding ions from [sup 40]Ar[sup +] to [sup 4]He[sup +] has a strong effect on the spatial distributions of the components sputtered from the alloy NiMoRe. A mechanism of sputtering by backscattered ions is proposed to describe the observed preferential ejection of the light component in the direction normal to the surface of the sample under bombardment by [sup 4]He[sup +] ions.