LOCAL SURFACE SEGREGATIONS OF IMPLANTED ALUMINUM IN AN IRON CRYSTAL WITH A LOW-DENSITY OF DEFECTS

The surface distribution of elements is studied by scanning a 3-MeV pr oton beam along the surface of a bcc-Fe sample implanted with aluminum ions in the dose interval (1-50). 10(16) cm(-2). Ring-shaped regions, up to 30 mu m in diameter, with a high density of aluminum, which app ear at implantation doses (5-20). 10(16) cm(-2), are observed. These r egions appear as a result of radiation-stimulated segregation processe s. A mechanism based on the existence of a low density of dislocations in the initial crystal is proposed to explain the implanted impurity segregation processes. (C) 1997 American Institute of Physics.