Simulation of mass transport processes in a high temperature Ni crystal under low energy ion bombardment

We have performed Molecular Dynamics (MD) calculations of low energy ion bo mbardment of a Ni crystal. The results from these calculations were used to solve the mixing equation as well as the equations for Radiation-Enhanced Diffusion (RED). In this way cascade assisted production of point defects a nd ion induced mass transport processes under 100 eV Ar ion bombardment of Ni(100) at 750 K were calculated. We investigated the influence of temperat ure on the production of vacancies, interstitials and ad-atoms. In general we find an increased relocation activity of cascade atoms with temperature. Finally the sputter depth profile of a near surface pseudo-marker of one a tomic layer thickness was evaluated. The distortion of this pseudo marker i n Ni under 100 eV Ar ion bombardment at 750 K is mainly due to RED processe s and not collisional mixing. Taking into account the influence of RED we o bserve an increase in the pseudo-marker broadening by about a factor of 20, as compared to ion induced collisional mixing alone. These results agree q ualitatively with experiments with Ni-63 isotope in a Ni matrix [M.P. Macht , R. Willecke, V. Naundorf, Nucl. Instr. and Meth. B 43 (1989) 507]. (C) 19 99 Elsevier Science B.V. All rights reserved.