Sputtering of ordered nickel-aluminium alloys: I. Introduction and preferential sputtering of Ni3Al

A combination of several surface-sensitive microanalytical techniques have been applied to the study of selective or preferential sputtering by inert gas ion bombardment of aluminium from binary ordered nickel-aluminium alloys. Two discrete intermetallic compounds, Ni₃Al (this paper) and NiAl (the companion paper) have been examined in order to provide information regarding the contribution of surface binding states to sputter mechanisms. The use of atom-probe field-ion microscopy for analysis of ion-sputtered surfaces has permitted the depth of bombardment-induced composition profiles to be estimated and comparisons to be drawn between these depth profiles and those obtained by conventional surface analysis techniques. Studies of preferential sputtering in ordered structures have provided information through atom-probe analysis of fundamental and superlattice oriented specimens about composition profiles and bombardment-induced disordering processes. Consideration of these data have led to conclusions that two distinct “equilibria” may be involved in the formation of super-induced altered layers.