Effect of Alloying on Ion-bombardment-induced Surface Topography on Face-centred Cubic Mjztals

previous studies of sputter-induced topographical development have shown that it is possible to form pyramids on single-crystal fee metals oriented in the (1131) crystallographic direction. These pyramids form when the surface is bombarded with relatively large ( > 1 X 10” cmm2) doses of Ar+, Kr+ or Xe+ ions in the energy range 20-41 keV. Until recently most of the work was confined to pure fee metals (Cu, Pd, Ir, Ag, Au), ah of which exhibit similar pyramid formation on bombardment. Later studies involving (1131) Cu, however, showed that, although pyramids form with inert-gas ion (e.g. Ar+ on Cu) or self-ion (Cu+ on Cu) bombardment, they are not produced when either Br+, Fe+ or Ni+ ions are used. This observation led to further investigations of alloying effects on topographic evolvement during sputtering. We report here a study of the influence of alloying on pyramid formation on (1131) sit&e crystals, through comparison of that of Ni and Cu with that of Ni-8% Cu. We find that bombardment with Arf ions can produce pyramids on Ni-8%Cu but that the conditions necessary are different from those for pure metah. We have looked for sputter-educe segregation effects in the aIIoy but none have been observed.